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Radiology Anatomy > Narrow thorax > Flashcards

Narrow thorax Flashcards

1
Q

5th Lumbar Vertebrae - feature

A

• L5 is the largest, most inferior lumbar discovertebral unit in the vertebral column
• Participates in forming the lumbar lordosis (from L1 to L5, ranging from 20 to 40°)
• Components
o large vertebral body with transverse width > AP diameter (kidney shaped if looking axial sections)
o pedicles which project directly posteriorly
o short, massive, pyramidal transverse processes
o broad, thick lamina
o single, short, thick spinous process which is roughly horizontal
o superior and inferior articular processes with pars interarticularis between
o facet joints obliquely oriented

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2
Q

5th Lumbar Vertebrae - articulation

A
  • Superior articular facet with inferior articular facet of L4
  • Inferior articular facet with superior articular facet of sacrum
  • Intervertebral discs - superior and inferior
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3
Q

5th Lumbar Vertebrae - muscular attachments

A
  • Psoas major (origin from transverse processes of T12-L5 and lateral aspects of IV discs)
  • Erector spinae muscle
  • Quadratus lumborum muscle (inserts into transverse processes and last rib)
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4
Q

5th Lumbar Vertebrae - ligamentous attachments

A
  • Anterior longitudinal ligament
  • Posterior longitudinal ligament
  • Ligamentum flavum
  • Interspinous ligament
  • Supraspinous ligament
  • Iliolumbar ligament
  • Lumbosacral ligament
  • Intertransverse ligaments
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5
Q

5th Lumbar Vertebrae - relations

A
  • External vertebral venous plexus (lying within muscle)
  • Lumbar fascia
  • Thecal sac and cauda equina
  • Basivertebral veins and internal vertebral venous plexus
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6
Q

5th Lumbar Vertebrae - variants

A
  • Sacralisation: assimilation of L5 to the sacrum

* Limbus vertebra

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7
Q

C7 - description

A
  • Seventh cervical vertebra and looks like vertebrae C3-C6, but has some distinct features making it an atypical vertebrae
  • C7 also called vertebra prominens (long spinous process) which is easily palpable
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8
Q

C7 - features

A

o spinous process ends in a rounded tubercle and is not bifid
o C7 transverse foramen are small, and do not transit the vertebral artery
o C7 transverse process anterior tubercle is small, and is the site of attachment for scalenus pleuralis and suprapleural membrane
o C8 nerve, which does not have an associated cervical vertebrae, exits in the C7-T1

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9
Q

Typical cervical vertebra features

A

o small, oval-sized vertebral bodies
o relatively wide vertebral arch with large vertebral foramen
o relatively long, bifid (except for C7) inferiorly pointing spinous processes
o transverse foramina protecting the vertebral arteries and veins
o anterior components: body
o posterior components: lamina, pedicle, spinous process, superior and inferior articular process, transverse process

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10
Q

C7 - articulations

A

• Intervertebral discs (superior and inferior): interposed between hyaline cartilage on the centrum of the vertebral bodies
• C6 and T1 uncovertebral joint (Luschka’s joints): in the cervical spine, the superior surface of the vertebra below curves upward to form a hyaline covered lip that articulates with the bevelled inferior surface of the vertebra above
• C6 and T1 facet (zygapophyseal) joint: articular processes lie at the junction of pedicle and lamina
o upper facets face obliquely up and back
o lower facets face down and forward

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11
Q

C7 - muscle attachments

A
  • Trapezius
  • Longus colli
  • Middle scalene
  • Posterior scalene
  • Rhomboid minor
  • Semispinalis cervicis
  • Spinalis cervicis
  • Longissimus cervicis
  • Semispinalis capitis
  • Splenius capitis
  • Longissimus capitis
  • Semispinalis dorsi
  • Rotares
  • Intertransversarius
  • Mutlifidus
  • Interspinales
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12
Q

C7 - ligament attachments

A
  • Anterior longitudinal ligament
  • Posterior longitudinal ligament
  • Ligamentum flavum
  • Interspinous ligament
  • Supraspinous ligament
  • Nuchal ligament
  • Intertransverse ligaments
  • Sibsons’s fascia
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13
Q

C7 - relations

A
  • Inferior: C8 spinal nerve
  • Superior: vertebral artery, C7 spinal nerve
  • Intervertebral foramen: spinal cord, anterior and posterior spinal arteries, thecal sac, CSF
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14
Q

C7 - variant anatomy

A

• C7 may possess a cervical rib
o anterior root of the transverse process attains a large size and exists as a separate bone
• C7 foramen may transmit:
o posterior vertebral vein
o vertebral artery
o grey ramus from the inferior cervical ganglion to the anterior ramus of C7
• Hemivertebrae
• Butterfly vertebrae
• Block vertebrae
• Bifid spinoud process
• Limbus vertebrae: well-corticated osseous fragment due to herniation of the nucleus pulposus through the the vertebral body endplate

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15
Q

Spinal cord arterial supply - description

A

• Spinal cord blood supply is formed by many different vessels with an extensive collateral supply and drainage
• The spinal cord is supplied by three longitudinal arteries:
o single anterior spinal artery: supplies the anterior two-thirds of the spinal cord
o paired posterior spinal arteries: supply the posterior one-third of the spinal cord
o anastomoses between the anterior and posterior spinal arteries (arterial vasocorona) supply the peripheral lateral aspect of the spinal cord (lateral columns)
• Reinforcement by segmental spinal arteries -> radicular + medullary
o which are branches of:
 ascending cervical artery (branch of the inferior thyroid)
 deep cervical artery (branch of costocervical trunk)
 intercostal arteries
 lumbar arteries
 lateral sacral arteries
o segmental arteries pass through the intervertebral foramen and divide into anterior and posterior radicular arteries
 they have variable anastomoses with the spinal arteries
o the dominant segmental artery is called the artery of Adamkiewicz
 can have a variable origin and side
 damage to this vessel can cause paralysis from spinal cord infarction
 critical to the supply of the lumbar enlargement
• If arterial supply being interrupted from the aorta (eg. surgery, trauma) collateral arterial flow can come from the internal thoracic and lateral thoracic arteries which anastomose with the posterior intercostal arteries

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16
Q

Spinal cord arterial supply - variants

A

• Anterior spinal artery:
o origin from right vertebral only (9%)
o origin from left vertebral only (3%)
o origin from angle between two vertebrals (3%)
o anterior spinal arteries do not fuse and travel as two separate arteries
• Posterior spinal artery normally arises from the vertebral arteries adjacent to the medulla, but may arise from PICA
o and origin may be intra- or extra-dural
• The artery of Adamkiewicz has a variable origin (most commonly arises on the left (~80%) and at the level of T9-T10)
o lumbar arteries at the level of L1 or L2 (10%)
o intercostal arteries at the level of T5 to T8 (15%)
o arises on the right (20%)
• Variation in number of radicular branches

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17
Q

Atlantoaxial articulation - description

A
  • Synovial joint in the upper part of the neck between the first and second cervical vertebrae; the atlas and axis
  • Primary articulation which allows rotation of the head
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18
Q

Atlantoaxial articulation - Aricular surfaces

A

• There are two atlantoaxial joints: median and lateral
o The median atlantoaxial joint
 one between the posterior surface of the anterior arch of atlas and the front of the odontoid process
 one between the anterior surface of the ligament and the back of the odontoid process
o The lateral atlantoaxial joint involves the lateral mass of atlas and axis
 arthrodial or gliding joint

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19
Q

Atlantoaxial articulation - ligaments

A

ligament of the atlas: unites the medial aspects of the lateral masses
• Longitudinal bands (superior and inferior): attaches to the foramen magnum and the body of the axis
o together with the transverse ligament = the cruciate ligaments of the atlas
o this ligament holds the anterior part of the dens against the posterior side of the anterior arch of the atlas
• ALL: thick fibrous band attaches from inferior border of anterior arch of C1 to the anterior axial body
• Median apical ligament and two lateral alar ligaments: connect the dens to the occipital bone
• Tectorial membrane: the upward continuation of the PLL, anchored to the basilar part of the occipital bone
• Posterior atlantoaxial membrane: continuation of ligamenta flava, attaches the lower border of atlantal arch to the lamina of C2
• Anterior atlantoaxial membrane
• Accessory atlanto-axial ligament: connects posterior body of C2 to lateral mass of C1

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20
Q

Atlantoaxial articulation - movement

A
  • 10-15 degrees of flexion/extension

* 30 degrees of axial rotation

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21
Q

Atlantoaxial articulation - variants

A 
•	Atlas
o	aplasia
o	hypoplasia
o	clefts of the atlas arches 
o	split atlas
o	arcuate foramen
•	Axis
o	persistent ossiculum terminale
o	odontoid aplasia
o	os odontoideum
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22
Q

C1 - description

A
  • 1st cervical vertebrae
  • Does not have a body nor spinous process
  • Consists of two lateral masses connected by a short anterior and a longer posterior arch
  • Each lateral mass has an upper and lower facet
  • Vertebral foramen exists in the lateral masses, through which the vertebral artery ascends
  • The transverse processes are long
  • Anterior arch presents an anterior tubercle in front (for the anterior longitudinal ligament) and a facet posteriorly (for the dens of the axis)
  • Posterior arch is grooved above by the vertebral artery and the small C1 nerve on each side, and has a posterior tubercle behind
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23
Q

C1 - articulation

A
  • Superior articular facet with occipital condyle
  • Posterior aspect of the anterior arch of C1 articulates with the dens
  • Inferior articular facet with superior articular facet of C2
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24
Q

C1 - muscle attachments

A
  • Rectus capitis anterior
  • Rectus capitis lateralis
  • Rectus capitis posterior minor
  • Obliquus capitis superior
  • Obliquus capitis inferior
  • Splenius cervicis
  • Levator scapulae
  • Intertransversarius posterior cervicis
  • Intertransversarius anterior cervicis
  • Interspinalis cervicis
  • Longus colli
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25
Q

C1 - ligament attachments

A
  • Anterior longitudinal ligament
  • Posterior longitudinal ligament / tectorial membrane
  • Transverse ligament - provides the most stability retaining the dens in contact with the atlas (C1)
  • Anterior atlanto-axial ligament
  • Posterior atlanto-axial ligament
  • Nuchal ligament
  • Ligamentum flavum / posterior atlanto-occipital membrane
  • Intertransverse ligament
  • Anterior atlanto-occipital membrane
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26
Q

C1 - variants

A

• Accessory ossicle of the anterior arch of the atlas
o observed as a corticated osseous density that articulates with the inferior aspect of the anterior arch of the atlas
• Arcuate foramen of the atlas
o vertebral arteries pass through this foramina.
o seen over the posterosuperior aspect of the atlas on lateral projections
• Incomplete fusion of posterior arch
• Occipital vertebrae

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27
Q

C1 - relations

A
  • Superior: brain stem
  • Inferior: C2
  • Lateral: vertebral arteries and veins,
  • Intervertebral foramen: spinal cord, anterior and posterior spinal arteries, basivertebral veins
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28
Q

C2 - description

A

• Axis is the second cervical vertebra and is an atypical cervical vertebra
• Prominent feature is the odontoid process (which is embryologically the body of the atlas)
• Important role in rotation of the head - majority of movement occurring around the dens and at the atlanto-axial joint
• Five primary and two secondary ossification centres
• Body with the attached dens, two lateral masses, a posterior neural arch (formed by the pedicle and a thick lamina), and a large spinous process, which is commonly bifid
• Components: body, lateral mass, superior and inferior articular processes, pars interarticularis, transverse process, transverse foramen, lamina, pedicle, spinous process
• Typical cervical features:
o relatively wide vertebral arch with large vertebral foramen
o transverse foramina protecting the vertebral arteries and veins
• ADI < 3 mm in adults and < 5 mm in childrens
• BDI < 12 mm in adults

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29
Q

C2 - Articulations

A
  • Superior articular facet with inferior articular face of C1
  • Dens articulates with the posterior aspect of the anterior arch of C1
  • Inferior articular facet with superior articular facet of C3
  • Uncovertebral articulation (Luschka’s joints) with C3
  • Intervertebral discs (inferior): interposed between hyaline cartilage on the centrum of the vertebral bodies
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30
Q

C2 - muscle attachments

A
  • Semispinalis cervicis
  • Obliquus capitis inferior
  • Rectus capitis posterior major
  • Longus colli
  • Levator scapulae
  • Rotatores
  • Intertransversarius
  • Interspinales
  • Middle scalene
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31
Q

C2 - ligament attachments

A
  • Anterior longitudinal ligament
  • Cruciate ligaments - superior and inferior longitudinal bands
  • Transverse ligament - provides the most stability retaining the dens in contact with the atlas (C1)
  • Apical ligament - embryological remnant of the notochord, anchors dens to occipital bone
  • Alar ligament - anchors dens to occipital bone
  • Accessory ligament
  • Posterior atlanto-axial ligament (ligamentum flavum)
  • Tectorial membrane (posterior longitudinal ligament)
  • Interspinous ligament
  • Nuchal ligamentum
  • Intertransverse ligaments
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32
Q

C2 - relations

A
  • Superior: brain stem
  • Inferior: C3
  • Lateral: vertebral arteries and veins,
  • Intervertebral foramen: spinal cord, anterior and posterior spinal arteries, basivertebral veins
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33
Q

C2 - variant anatomy

A

• Hypoplasia
• Aplasia (rare)
• Single spinous process
• Os odontoideum
o separation of the odontoid process from the body of the axis
o two main types
 orthotopic: normal position with a wide gap between C2 and os odontoideum
 dystopic: displaced
• Persistent ossiculum terminale
o ossiculum terminale appears as a secondary ossification centre between 3-6 years and normally fuses by 12 years
o failure of fusion results in a persistent ossiculum terminale
o small, well-corticated ossicle at the tip of the dens

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34
Q

Spinal Cord - Description

A

• Spinal cord is the part of the CNS that is found within the central canal of the vertebral column
• Divided into cervical, thoracic and lumbar parts and ends at the conus medullaris (approximately L1 level)
• 31 segmental nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
o C1-C7 arise above pedicle of the corresponding vertebra, rest arise below pedicle of corresponding vertebra
• Spinal nerve is formed by the dorsal and ventral roots
o dorsal root is afferent sensory (cell body in the DRG), ventral root is efferent motor (cell body close to target tissue)
• Expansions of the cord occur at C5 - T1 due to the brachial plexus, and L2 - S3 due to the lumbosacral plexus
• Nerve roots that exit below the conus at L1/L2 are called the cauda equina
• 3 layers of meninges surround the cord: the pia, arachnoid and dura mater
• 21 pairs of denticulate ligaments attach the pia mater of the cord to the arachnoid and dura mater of the sac
• Anterior median fissure dips into it anteriorly, posterior median sulcus exists posteriorly
• Central canal is filled with CSF
• Grey matter is central (dorsal, lateral and ventral horns)
• White matter is peripheral and has spinal cord tracts (dorsal, lateral and ventral columns)

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35
Q

Spinal Cord - neurovasculature

A

Arterial supply:
• Posterior spinal arteries
• Anterior spinal artery
• Segmental supply from ascending cervical, intercostal and lumbar arteries
• Artery of Adamkiewicz: critical to the supply of the lumbar enlargement (usually from left side, T8-L1)
Venous drainage:
• Anterior and posterior spinal veins –> internal vertebral venoux plexus –> external vertebral venous plexus –> regional veins
o Neck: vertebral veins
o Thorax: azygos veins
o Lumbar: lumbar veins

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36
Q

Spinal Cord - variants

A

• Spinal dysraphism
o includes neural tube defects:
 incomplete closure of the neural tube in very early pregnancy
 spina bifida
 anencephaly
o categorised into two groups
 open spinal dysraphism: meningocele, myelomeningocoele
 closed spinal dysraphism
• Tethered cord
• Spinal cord may end at a variable level

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37
Q

Epidural space - Decription

A
  • The spinal epidural space is located between the spinal dura mater and the vertebral column
  • It extends from the foramen magnum to the sacral canal at the level of S2-S3
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38
Q

Epidural space - boundaries

A
  • Inner: spinal dura mater

* Outer: PLL, neural arches/intervertebral foramen, ligamentum flavum

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39
Q

Epidural space - contents

A
  • Loose areolar connective tissue
  • Fat
  • Vertebral venous plexus
  • Lymphatics
  • Radicular arteries
  • Spinal nerve roots
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40
Q

Facet joints - description

A

• Synovial joints that have a fibrous capsule and connect the articular facets of the vertebrae
• Facet joints are situated between the pedicle and lamina of the same vertebra and form the articular pillars that act to provide structural stability
• Articular surfaces have different orientations in the various vertebral regions
o Cervical Region = 45 degrees; frontal plane; all movements are possible such as flexion, extension, lateral flexion, and rotation
o Thoracic Region = 60 degrees; frontal plane; lateral flexion and rotation; no flexion/extension
o Lumbar Region = 90 degrees; sagittal plane; only flexion and extension

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41
Q

Facet joints - articular surface

A
  • Hyaline covered

* Superior facet of the lower vertebra articulates with the interior facet of the vertebra above

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42
Q

Facet joints - Ligaments

A

• Posterior ligamentous complex acts to hold the facet joints of the neighbouring vertebrae in fixed relation with each other
o ligamentum flavum
o interspinous ligament
o supraspinous ligament
o fibrous joint capsule is including in posterior ligamentous complex

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43
Q

Facet joints - relations

A

• Structures that pass through the intervertebral foramen
o spinal nerve
o dorsal root ganglion
o spinal artery of the segmental artery
o communicating veins between the internal and external plexuses
o meningeal (sinu-vertebral) nerves
o transforaminal ligaments

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44
Q

Facet joints - neurovasculature

A

Nerve Supply:
• Meningeal branch of the spinal nerve
Blood Supply:
• Cervical Area - Ascending Cervical Artery and Spinal branch from Verterbral Arteries
• Thoracic - Posterior Intercostal Arteries
• Lumbar - Lumbar Arterie

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45
Q

Intervertebral disc - Description

A

• Intervertebral discs are located between the vertebral bodies
• Account for approximately 25% of the total height of the vertebral column
• Decreases with age as disc height is lost
• Greater thickness anteriorly contributes to the normal cervical and lumbar lordosis
• Each intervertebral disc is comprised of:
o peripheral annulus fibrosus
o central nucleus pulposus
• L4/5 and L5/S1 most prone to herniation
• Embryology: notochord becomes the nucleus pulposus

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46
Q

Intervertebral disc - relations

A
  • Above and below the intervertebral disc are the vertebral body endplates
  • Posterior spinal nerve
  • Anterior spinal artery
  • ALL, PLL
  • Anterior: muscles/organs at that particular level
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47
Q

Intervertebral disc - supply

A

• Inner layers of the annulus fibrosus and nucleus pulposus have neither innervation nor blood supply
o receives nutrition via diffusion across the vertebral body endplates
o outer fibres of the annulus fibrosus are innervated by sinuvertebral nerves arising from the dorsal root ganglia

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48
Q

Ligaments of the lumbar spine - description

A

• Spinal ligaments essential in keeping joints between vertebrae congruent / strong

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49
Q

Ligaments of the lumbar spine - ligaments

A
  • Anterior longitudinal ligament (ALL): arises from anterior tubercle of the atlas, travels downwards, anterior to the vertebral body (firmly united to the periosteum) and discs (attaching to the anterior annulus), attaches to the front of the upper part of the sacrum; it broadens as it travels downward
  • Posterior longitudinal ligament (PLL): arises from the back of the axis (C2) body, travels downward posterior to the vertebral body (attached loosely) and discs (firmly attaching to the posterior annulus), attaching to the back of the sacrum; narrows as it travels downward
  • Ligamentum flavum: yellowish, elastic ligament, runs between adjacent laminae (front of the upper lamina to the back of the lower lamina); in the lumbar region, it runs laterally, covering the anterior aspect of the facet joints
  • Interspinous ligaments: join spinous processes along adjacent borders, relatively weak fibrous tissue that fuses with supraspinous ligaments
  • Supraspinous ligaments: join tips of adjacent spinous processes, strong bands of fibrous tissue
  • Intertransverse ligaments: join transverse processes along adjacent borders, relatively weak fibrous tissue
  • Iliolumbar ligaments: strong band of connective tissue which courses from the transverse process of L5 to the posterior iliac wing and iliac crest; it functions to maintain the alignment of L5 on the sacrum during various movements
  • Lumbosacral ligament
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50
Q

Spinal meninges - Description

A

• Three layers of meninges cover the spinal cord - dura, arachnoid and pia mater
• Dura mater
o extends from the foramen magnum to the sacrum and coccyx
o attached to the foramen magnum and the periostium covering the uppermost cervical vertebrae
o remainder of the vertebral canal, the dura is not attached to the vertebrae, being separated by the epidural space
• Arachnoid mater
o invests the spinal cord loosely
o continuous with the cerebral arachnoid above
o traverses the foramen magnum and descends to around the S2 vertebral level (spinal cord ends at ~L2)
• Pia mater
o much thicker than cerebral pia mater (two layers in the spine)
o invests the spinal cord closely
o ensheathes the anterior and posterior spinal arteries
o enters the anterior median fissure
o laterally, the pia forms 21 pairs of denticulate ligaments which attaches to the arachnoid and dura on each side
o inferiorly the pia is thickened as the filum terminale, which continues into the sacrum and fuses with the dura mater

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51
Q

Spinal meninges - spaces

A

• Epidural space
o contains fat and the internal vertebral venous plexus
• Subdural space
o potential space between dura and arachnoid, has no contents
• Subarachnoid space
o wide interval which contains CSF

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52
Q

Trapezius - origin

A
  • External occipital protuberance
  • Nuchal ligament
  • Medial superior nuchal line
  • Spinous processes of vertebrae C7-T12
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53
Q

Trapezius - insertion

A
  • Posterior border of the lateral third of the clavicle
  • Acromion process
  • Spine of scapula
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54
Q

Trapezius - neurovasculature

A 
Artery:
•	Transverse cervical artery
Innervation:
•	Accessory nerve (motor)
•	Cervical spinal nerves C3 and C4 (motor and sensation)
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55
Q

Trapezius - actions

A

• Rotation, retraction, elevation, and depression of scapula

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56
Q

Trapezius - relations

A
  • Anterior border forms the posterior margin of the posterior triangle
  • Shares insertion with the deltoid
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57
Q

Anterior Mediastinum - Borders

A
  • Anteriorly: sternum, transverse thoracic, 5th-7th costal cartilages
  • Inferiorly: diaphragm
  • Superiorly: thoracic plane
  • Posteriorly: pericardium
  • Laterally: mediastinal pleura
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58
Q

Anterior Mediastinum - Contents

A
  • Loose areolar tissue
  • Lymph nodes
  • Small mediastinal branches of the internal thoracic artery
  • Thymus (involuted in adults)
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59
Q

Aortic Arch Variants - Double aortic arch

A
  • formation of a vascular ring from the splitting of the ascending aorta into two limbs that pass to either side of the trachea and oesophagus (both of which gets encircled), which then joins as a single descending aorta
  • right dominant arch ~75%
  • co-dominant arch ~5%
  • left dominant arch ~25%
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60
Q

Aortic Arch Variants - Right sided aortic arch

A

• right sided arch can be divided into at least three types
o type I: right sided aortic arch with mirror image branching (associated with congenital heart disease)
o type II: right sided aortic arch with aberrant left subclavian artery (most common)
o type III: right sided aortic arch with isolation of the left subclavian artery (*isolated subclavian means artery no longer arises from aorta)

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61
Q

Aortic Arch Variants - Interrupted aortic arch

A

• uncommon congenital cardiovascular anomaly where there is a separation between the ascending and descending aorta
• can either be complete or connected by the a remnant fibrous band
• an accompanying large ventricular septal defect (VSD) and/or patent ductus arteriosus (PDA) is frequently present
• classified to three types according to location of occurrence:
o type a: second commonest, interruption occurs distal to the left subclavian arterial origin
o type b: commonest (>50%), interruption occurs between left common carotid arterial and left subclavian origins
o type c: rare, interruption occurs proximal to left common carotid arterial origin
• each type is divided into 3 subtypes:
o sub-type 1: normal subclavian artery
o sub-type 2: aberrant subclavian artery
o sub-type 3: isolated subclavian artery that arises from the ductus arteriosus

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62
Q

Aortic Arch Variants - Coarctation of the aorta

A

• refers to a narrowing of the aortic lumen
• primarily divided into two types:
• infantile (pre-ductal) form
o diffuse hypoplasia or narrowing of the aorta from just distal to brachiocephalic artery to the level of ductus arteriosus
o blood supply to the descending aorta is via the patent ductus arteriosus
• adult (post-ductal) form
o short segment abrupt stenosis of the post-ductal aorta
o due to thickening of the aortic media and typically occurs just distal to the ligamentum arteriosum (remnant of the ductus arteriosus)

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63
Q

Azygous vein System - Description

A
  • Azygos (venous) system is a collective term given to the H-shaped configuration of the azygos, hemiazygos, accessory hemiazygos veins and left superior intercostal vein
  • Responsible for draining the thoracic wall and upper lumbar region
  • Provides important collateral circulation between the SVC and IVC should they become obstructed
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64
Q

Azygous vein System - origin/course/relations

A

• Azygos
o formed by the union of the right ascending lumbar vein and the right subcostal veins at the level of T12
o enters the thorax through the aortic hiatus in the diaphragm, and passes along the right side of the vertebral column
o in the aortic hiatus, it lies with the thoracic duct on the right side of the aorta
o in the thorax it lies upon the intercostal arteries
o arching over the right main bronchus at T5-T6
o ends: by emptying into the SVC at T4
• Hemiazygos
o formed by the confluence of the left ascending lumbar vein and the left subcostal veins (sometimes communicates with the left renal vein)
o enters the thorax through the left crus of the diaphragm
o receives the lower left intercostal veins
o ascends on the left side of the vertebral column as high as T9 and then passes across the column, behind the aorta, esophagus, and thoracic duct, to end in the azygos vein
• Accessory hemiazygos
o formed by veins of 3 or 4 intercostal veins below the superior intercostal vein
o descends on the left side of the vertebral column
o either crosses the body of T8 to empty into the azygos or hemiazygos vein

65
Q

Azygous vein System - Tributaties

A 
•	Azygos
o	right ascending lumbar vein
o	subcostal vein
o	5th to 11th right intercostal veins
o	right superior intercostal vein (which drains 2nd to 4th intercostal veins)
o	hemiazygos vein (and sometimes accessory hemiazygos vein)
o	some oesophageal veins
o	right bronchial vein
•	Hemiazygos
o	left ascending lumbar vein
o	left subcostal vein
o	9th to 11th left posterior intercostal veins
o	some oesophageal veins
•	Accessory hemiazygos
o	5th to 8th left posterior intercostal veins
o	left bronchial vein
o	some oesophageal veins
66
Q

Azygous vein System - variants

A

• Azygos
o absence of the azygos vein (rare)
o azygos continuation of the IVC
o azygos occasionally opens into the right brachiocephalic or the right subclavian veins
o can groove the right lung before entering the SVC: azygos lobe/fissure
• Hemiazygos
o hemiazygos continuation of the IVC (often occurs with duplicated IVC)
• Accessory hemiazygos
o drains via a common trunk with the hemiazygos vein into the azygos vein
o forms a common trunk with the hemiazygos vein that passes anterior to the aorta called the interazygos vein
o drains directly into the left brachocephalic vein (rare)
o may communicate with left superior intercostal vein

67
Q

Breast - Description

A

• The breast is an apocrine gland in both males and females
• In females it is responsible for the production of milk
• Composed of adipose and glandular tissue
• Suspensory Cooper’s ligaments and connective tissue
o Retromammary space directly posteriorly
o Cooper’s ligament attach the breast to skin anteriorly and pectoralis fascia/serratus posterior fascia posteriorly
• Adult breast has nearly multiple lactiferous lobules -> lactiferous ducts -> lactiferous sinus -> nipple-areola complex
• Areola contain sebatious glands
• Borders
o superior: clavicle
o inferior: middle of sternum
o lateral: midaxillary line
o medial: sternum
o axillary tail: extension of breast tissue into the axilla
Relations:
• Overlies pectoralis major, serratus anterior

68
Q

Breast - Neurovasculature

A

Arterial supply:
• Internal thoracic perforators (through 2nd and 3rd intercostal spaces)
• Lateral thoracic artery (branch of axillary artery)
• Pectoral branch of the thoracoacromial artery (branch of axillary artery)
• Intercostal perforators
Venous drainage:
• Internal thoracic vein
• Axillary vein
• Posterior intercostal veins
Lymphatic drainage:
• Three pathways: axillary, internal mammary, retromammary
• 75% of lymph drainage passes to the axillary nodes (mainly anterior and posterior nodes)
• Remaining drainage is mainly to the parasternal nodes along the internal thoracic artery (medial side) and to the posterior intercostal nodes
Innervation:
• Thoracic intercostal nerve T3-T5
• Supraclavicular nerve from the cervical plexus

69
Q

Breast - Variants

A
  • Breast hypoplasia: underdevelopment of the breast
  • Amastia: absence of breast tissue, nipple or areola
  • Amazia: absence of glandular parenchyma
  • Polythelia: supranumerary nipple
  • Polymastia: accessory breast tissue
  • Variations with hormonal level (puberty, pregnancy, post-menopause)
70
Q

Coronary Arteries - description

A

• The coronary arteries supply the myocardium with oxygenated blood

71
Q

Coronary Arteries - origin/course

A

Origin:
• Arise just distal to the aortic valve from the coronary sinuses
Course:
• Left coronary artery
o arises from left coronary sinus
o short common stem (left main) before dividing into the LCx and LAD (occassionally trifurcates with third branch being ramus intermedius)
o LCx runs in the left atrioventricular groove (with the great cardiac vein)
o LAD passes towards the apex in the anterior interventricular groove (also alongside great cardiac vein)
o in left dominant hearts, the LCx supplies the posterior descending artery (8%)
• Right coronary artery
o arises from the right coronary sinus
o runs in the right atrioventricular groove to the inferior surface of the heart
o turns anteriorly to run in the posterior interventricular groove as the posterior descending artery (92%)

72
Q

Coronary Arteries - branches

A 
•	LAD
o	diagonal branches
o	septal perforators
•	LCx
o	obtuse marginal branches
o	left posterolateral branch
•	RCA
o	conus artery
o	sinoatrial artery
o	atrioventricular artery
o	marginal arteries
o	posterior descending artery
o	posterior left ventricular branch
73
Q

Coronary Arteries - supply

A
  • LAD: anterolateral myocardium and apex, anterior two-thirds of the interventricular septum
  • LCx: lateral and posterolateral walls of the left ventricle
  • RCA: pulmonary outflow tract (conus artery), SA node, AV node, anterior wall of the right ventricle, inferior wall of both ventricles and the inferior 1/3 of the interventricular septum
74
Q

Coronary Arteries - Variants

A

• Left circumflex arising from the RCA
• Left circumflex and LAD having separate origins
• One coronary artery arising from the aorta
o RCA branches off the LCA
o LCA branches off the RCA
• RCA, LCA or both coronary arteries branching off the pulmonary trunk
• Left dominant circulation
• Conus artery arising separately

75
Q

Coronary veins - Features

A

• The coronary veins return blood from the myocardium back to the right atrium
• Coronary venous anatomy is highly variable, but is generally comprised of:
o coronary sinus:
 wide venous channel situated in the posterior part of the coronary sulcus
 Drains into right atrium between SVC opening and tricus valve
o cardiac veins (drain into the coronary sinus)
 great cardiac vein: ascends to drain along the anterior longitudinal sulcus (adjacent to LAD)
 middle cardiac vein: ascends in the posterior longitudinal sulcus (with posterior interventricular artery)
 small cardiac vein: runs in the coronary sulcus between the right atrium and ventricle (with RCA)
 posterior left ventricular vein: runs on the diaphragmatic surface of the left ventricle
 Marginal vein of the left ventricle
 oblique vein of the left atrium: descends on the back of the left atrium
o thebesian veins (drain directly into the right atrium)
 anterior cardiac veins
 venae chordis minimae arise in the muscular wall of the heart

76
Q

Coronary veins - variants

A
  • Coronary sinus may act as a conduit between a persistent left SVC and the right atrium
  • Coronary sinus may drain into the left atrium (causing right to left shunt)
  • Great cardiac vein may drain into the SVC or left brachiocephalic via the oblique vein of Marshall
  • Great cardiac vein may drain into the azygous vein
  • Cardiac veins may converge to empty into a common opening or directly into the right atrium
77
Q

Diaphragm - description

A
  • Diaphragm is a dome-shaped fibromuscular septum which separates the thoracic from the abdominal cavity
  • Important for breathing
78
Q

Diaphragm - Origin/insertion

A

Origin:
• Muscle slips can be grouped according to their origins:
o sternal: arises from two strips under the xiphoid process
o costal: arise from the inner surfaces of the costal cartilages of ribs 6-12 on either side (interdigitates with transversus abdominis)
o lumbar: arise from the lubocostal arches and from the crura
• Two paired tendinous lumbocostal arches:
o medial lumbocostal arch (medial arcuate ligament): covers psoas major, attaches to the L2 vertebral body
o lateral lumbocostal arch (lateral arcuate ligament): covers quadratus lumborum, attached to the L1 transverse process tip of the 12th rib
• Crura are tendinous structures the blend with the anterior longitudinal ligament of the vertebral column:
o right crus arises from the vertebral bodies of L1-3
o left crus arises from the vertebral bodies of L1-2
o the crura meet in the midline to form an arch called the median arcuate ligament
Insertion:
• Central tendon: thin, strong aponeurosis situated immediately below and is fused to the fibrous pericardium

79
Q

Diaphragm - openings

A
  • Aortic Hiatus (T12): aorta, azygos vein, thoracic duct
  • Oesophageal Hiatus (T10): esophagus, vagus nerves, esophageal arteries/veins from left gastric
  • Vena Caval Foramen (T8): IVC, right phrenic nerve
  • Medial arcuate ligament: the sympathetic trunk
  • Lateral arcuate ligament: the subcostal vessels and nerve
  • Left phrenic pierces the left muscle dome
  • Greater, lesser and least splanchnic nerves pierce each crus
  • Hemiazygos vein passes through the left crus
80
Q

Diaphragm - action

A

• Contraction lowers diaphragm and increases thoracic cavity size

81
Q

Diaphragm - neurovasculature

A

Nerve supply:
• Phrenic nerves (C3-5) supply the ipsilateral hemidiaphragm with motor fibres
• Lower intercostal nerves supply proprioceptive fibres to the margins
Blood supply:
• Inferior and superior phrenic arteries (branches of the aorta)
• Intercostal arteries
• Subcostal arteries
• Some supply from pericardiophrenic and musculophrenic arteries (branches of the internal thoracic artery)

82
Q

Diaphragm - variants

A
  • Scalloped or serrated appearance: due to abnormal insertion of individual muscle slips
  • Dromedary diaphragm (hump)
  • Accessory diaphragm
  • Congenital diaphragm defects: Bochdalek, Morgagni, eventration, agenesis, central tendon defect
83
Q

1st Rib - Description

A

• Most superior of the twelve ribs
• Important anatomical landmark and is one of the borders of the superior thoracic aperture
• First rib is short and thick and it has single articular facet for the costovertebral joint
• First rib has a head, neck and shaft but lacks a discrete angle
• No costal groove on its inferior surface
• It has two tubercles
o transverse tubercle: posterior and lateral to the neck, bears an articular facet for the transverse process of T1
o scalene tubercle: anteriorly between the grooves for the subclavian artery and vein, anterior scalene muscle inserts here
• There is a groove on lateral aspect which contains the lowest brachial plexus trunk and the subclavian artery
• Anterior to the scalene tubercle is another groove for the subclavian vein

84
Q

1st Rib - articulations

A
  • Costovertebral joint: articular facet on head of the rib with single articular facet on body of T1 vertebra
  • Costotransverse joint: articular facet on transverse tubercle with transverse process of T1
  • Costochondral joint: distal shaft with first costal cartilage
85
Q

1st Rib - muscle attachments

A
  • Anterior scalene muscle: scalene tubercle
  • Middle scalene muscle
  • Intercostal muscles: from the outer border
  • Subclavius muscle: arises from distal shaft and first costal cartilage
  • First digitation of the serratus anterior muscle
86
Q

1st Rib - ligamentous attachments

A
  • Parietal pleura: from the inner border (Sibson’s fascia)

* Costoclavicular ligament: anterior to the groove for the subclavian vein

87
Q

1st Rib - relations

A
  • Superior: lower trunk of the brachial plexus, subclavian vessels, clavicle
  • Inferior: intercostal vessels and nerves, parietal pleura
  • Anterior: sympathetic trunk (over neck), superior intercostal artery, ventral T1 nerve root
  • Posterior: parietal pleura, lung apex
88
Q

1st Rib - variants

A
  • Ossesous or fibrous articulation or fusion with a cervical rib
  • Bifid (forked) rib
  • Rudimentary (hypoplastic) rib: most commonly the first rib (0.2%)
  • Pseudoarthrosis of the first rib (0.1%)
89
Q

Internal Thoracic Artery - origin/termination

A
  • Arises from the first portion of the subclavian (prior to anterior scalene)
  • Terminates by dividing into the musculophrenic and superior epigastric arteries (~6th intercostal space)
90
Q

Internal Thoracic Artery - course/relations

A
  • It descends behind the cartilages of the upper six ribs lateral to the margin of the sternum
  • As it branches from the subclavian, it is directed downward and forward
  • It passes posterior to the subclavian veins
  • It then passes posterior to the first costal cartilage, lateral to the brachiocephalic vein
  • In the thorax, the phrenic nerve passes posterior to the artery moving from lateral to medial
91
Q

Internal Thoracic Artery - branches

A

• Intercostal Branches
o supply the upper six intercostal spaces, two in number in each space
• Pericardiophrenic artery
o long slender branch, which accompanies the phrenic nerve to supply the the diaphragm
• Pericardial Branches
o supply the upper part of the anterior surface of the pericardium
• Perforating branches
o supplies the Pectoralis major and the skin
o second, third, and fourth spaces give branches to the breast
• Musculophrenic artery (terminal branch)
o intercostal branches to the seventh, eighth, and ninth intercostal spaces
o also supplies the lower part of the pericardium
• Superior epigastric artery (terminal branch)
o descends through the interval between the costal and sternal attachments of the diaphragm
o enters the rectus sheath and anastomoses with the inferior epigastric artery to supply anterior part of abdominal wall

92
Q

Internal Thoracic Artery - supply

A

• Supplies the anterior body wall from clavicle to umbilicus including the sternum and the breasts
o via the Pericardiophrenic Artery it supplies the mediastinum, thymus, phrenic nerves and pericardium

93
Q

Internal Thoracic Artery - variants

A

• Anomalous origin in 20%
o Second part of subclavian artery (uncommon ~7%)
o Third part of subclavian artery (rare ~1%)
o Common origin with thyrocervical trunk
o Right internal thoracic artery may arise from the ascending aorta
• Terminal trifucation (~12.5%) with an additional xiphoid branch

94
Q

Left ventricle - Description

A

• One of the four heart chambers
• Receives oxygenated blood from the left atrium and pumps it into the systemic circulation via the aorta
• Conical shape
• Apex projects anteroinferiorly
• Thicker walled than right ventricle
• Separated from right ventricle by interventricular septum which is concave in shape (bulges into right ventricle)
• Smooth inflow and outflow tracts, but rest of ventricle lined by trabeculae carnae
• Blood flows in via the atrioventricular orifice lined by the mitral valve and flows out passing through the aortic valve into the aorta
o There are two papillary muscles that attach to the mitral valve:
 anterolateral group which attaches to the anterolateral leaflet
 posteromedial group which attaches to the posteromedial leaflet

95
Q

Left ventricle - Relations

A
  • Superior: carina, trachea
  • Posterior: oesophagus, left atrium
  • Lateral: left pleural cavity, left lungs
  • Inferior: diaphragm
96
Q

Left ventricle - Neurovasculature

A

Arterial supply:
• Left Anterior Descending artery - supplies free wall and most of the papillary muscles
• Left Circumflex artery - supplies free wall
• Marginal and Diagonal branches
Venous drainage:
• Great cardiac vein, Middle cardiac vein, Posterior vein of left ventricle, Left marginal vein
o Drains into Coronary sinus
Nerve supply:
• Sympathetic and Parasympathetic (vagal) stimuli flow through the paired cardiac plexus near the base of the heart

97
Q

Left ventricle - variants

A
  • Double-inlet ventricle - in-flow from both the right and left atria
  • Parachute valve - mitral valve chordae tendinae inserting into a single papillary muscle
  • VSD
  • Transposition of great vessels
98
Q

Lungs - description

A

• Lungs are the functional units of respiration
• Apex extends above the sternal end of the first rib, base rests on the diaphragm
• Fissures
o oblique fissure divides the left lung into LUL and LLL
o oblique fissure and horizontal fissure divides right lung into RUL, RML, RLL
• Segments
o right lung is composed of three lobes subdivided into 10 segments (APA LM PALMS)
o left is composed of two lobes and 8 segments (ASIA ALPS)
• Surrounded by the pleura which separated them from the chest wall
• Tracheobronchial tree is a branching structure of ever-decreasing diameter air tubes
o can broadly be divided into conduction (air heating) and respiratory zones (gas exchange)

99
Q

Lungs - segments

A
  • LUL (ASIA): apicoposterior, anterior, superior lingular, inferior lingular
  • LLL (ALPS): superior, anteromedial, lateral, posterior
  • RUL (APA): apical, posterior, anterior
  • RML: lateral, medial
  • RLL (PALMS): superior, anterior, medial, lateral, posterior
100
Q

Lungs - relations

A
  • Medial: pericardium, SVC, right brachiocephalic vein, brachiocephalic artery, aortic arch, left subclavian artery, descending aorta, oesophagus, trachea, vagus nerves, phrenic nerves, heart
  • Anterior: ribs, intercostal vessels and nerves
  • Posterior: ribs, intercostal vessels and nerves, vertebral bodies, sympathetic trunk
  • Azygos vein arches over the right lung hila
101
Q

Lungs - arterial supply

A

• Pulmonary arteries: supplies de-oxygenated blood from the right ventricle
o right pulmonary artery runs posterior to ascending aorta and anterior to right main bronchus
o left pulmonary artery runs anterior to left main bronchus and enters root of left lung without dividing
 it is attached to the aortic arch by the ligamentum arteriosum (remnant of the ductus arteriosum)
o within the lung, the pulmonary arteries divide with each bronchus division
• Bronchial arteries: branches of the thoracic aorta that supply oxygenated blood
o two arteries arise from the left side of the thoracic aorta: superior left bronchial artery, inferior left bronchial artery
o one arises from the right: right bronchial artery
 common origin with an intercostal artery and this is called the intercostobronchial trunk

102
Q

Lungs - venous + lymphatic drainage

A

Venous drainage:
• Pulmonary veins: drains to the left atrium
• Bronchial veins: drains to the pulmonary veins, SVC and the azygos venous system
Lymphatic drainage:
• Bronchopulmonary nodes at the hilum
• Bronchopulmonary foregut malformations
o pulmonary sequestration: aberrant formation of segmental lung tissue that has no connection with the bronchial tree or pulmonary arteries
o foregut duplication cysts: bronchogenic cyst are abnormal development of bronchial-tree during embryogenesis resulting in a cyst that does not communicate with the bronchial tree
o congenital pulmonary airway malformation: multicystic mass of segmental lung tissue with abnormal bronchial proliferation
o oesophageal lung: main bronchus arises from the oesophagus
• Pulmonary aplasia: unilateral or bilateral absence of lung tissue
• Accessory fissures:
o azygos fissure: laterally displaced azygos vein makes a deep pleural fissure into the apical segment of the right upper lobe during embryological development
o inferior accessory fissure: divides the right medial basal bronchopulmonary segment from the rest of the lower lobe
o superior accessory fissure: separates the right lower lobe into superior and basal segments
o left minor fissure: separates the lingula from the rest of the left upper lobe

103
Q

Lungs - innervation

A

• Pulmonary plexus, which is composed of fibres from the vagus nerve (parasympathetic and visceral afferent) and sympathetic ganglia

104
Q

Lymphatic drainage from the breast

A

• Lymphatic drainange of breast originate from breast lobules and flow into a sub-areolar plexus, called Sappey’s plexus
• From Sappey’s plexus, lymphatic drainage takes place through three main routes:
o Axillary pathway
 fed by Sappey’s Plexus, as well as by ducts satellite lymphatics and by most of parenchymal lymphatics
 this pathway runs around the inferior edge of the pectoralis major and reach the anterior group of axillary nodes
 level 1 spread is below pectoralis minor, level 2 is behind pectoralis minor, level 3 is above pectoralis minor
o Internal mammary pathway
 parasternal nodes
 originates from both the lateral and medial halves of the breast and passes through the pectoralis major
 connections may lead across the median plane and hence to the contralateral breast
o Retromammary pathway
 comes from the posterior portion of the breast
 retromammary space nodes
• Lymphatics may reach the sheath of the rectus abdominis and the subperitoneal and subhepatic plexuses
• Usually axillary lymph nodes receive more than 75% of the lymph drained from the breast (mainly anterior nodes and posterior group)

105
Q

Middle mediastinum

A 
Borders:
•	Bounded by the pericardial sac
Contents
•	Heart
•	Ascending aorta
•	SVC
•	Azygos vein opening into SVC
•	Tracheal bifurcation
•	Pulmonary artery dividing into left and right
•	Right and left pulmonary veins
•	Phrenic nerves
•	Lymph nodes
•	Pericardiocophrenic arteries and veins
106
Q

Oesophagus - description

A

• The oesophagus is a muscular tube that conveys food and fluids from the oropharynx to the stomach
• Divided into three parts:
o cervical: continuous with the oropharynx, commences at the lower border of cricoid cartilage (at level of C5/6) or cricopharyngeus muscle
o thoracic: from thoracic aperture (T1) to the oesophageal hiatus (T10)
o abdominal: from oesophageal hiatus to the cardia of the stomach at the gastro-oesophageal junction
• Three normal oesophageal constrictions
o cervical constriction: due to cricoid cartilage at the level of C5/6
o thoracic constriction: due to aortic arch at the level of T4/5
o abdominal constriction: at oesophageal hiatus at T10/11
• Muscular wall: skeletal muscle in the upper part and smooth muscle in the lower part
• Non-keratinised stratified squamous epithelium which is replaced by columnar epithelium at the gastro-oesophageal junction
• Layers: mucosa, submucosa, muscularis (inner circular, outer longitudinal layers), serosa

107
Q

Oesophagus - relations

A
  • Posteriorly: vertebral column, descending aorta, thoracic duct, accessory hemiazygos and hemiazygos veins (at T8/9), longus colli
  • Anteriorly: trachea (T4/5), recurrent laryngeal nerves (in tracheo-oesophageal groove), left main bronchus, left atrium, pulmonary trunk and veins
  • Left lateral: lung, pleura, aorta, left subclavian artery, thoracic duct
  • Right lateral: lung, pleura, azygos vein
  • Descends with the left and right vagus nerve through the oesophageal hiatus
108
Q

Oesophagus - arterial supply

A
  • Upper third: inferior thyroid artery
  • Middle third: oesophageal branches of the thoracic aorta
  • Lower third: oesophageal branches of the left gastric artery (site of portal-systemic collateral pathway)
109
Q

Oesophagus - venous drainage

A
  • Upper third: inferior thyroid veins to brachiocephalic veins
  • Middle third: azygos vein to SVC
  • Lower third: left gastric vein to portal vein
110
Q

Oesophagus - lymphatic drainage

A
  • Follows arterial supply
  • Upper third: deep cervical lymph nodes
  • Middle third: posterior mediastinal lymph nodes
  • Lower third: left gastric and coeliac group lymph nodes
111
Q

Oesophagus - innervation

A
  • Sympathetic trunk (sympathetic)
  • Vagal plexus (parasympathetic)
  • Enteric nervous system
112
Q

Oesophagus - variation

A
  • Oesophageal bronchus: bronchus arises directly from oesophagus
  • Oesophageal atresia: oesophagus not continuous due to an inappropriate division of the primitive foregut into the trachea and oesophagus
  • Tracheo-oesophageal fistula: abnormal communication between trachea and oesophagus (congenital or acquired)
  • Oesophageal duplication cysts
  • Aberrant right subclavian artery passing anterior or posterior to the oesophagus
113
Q

Pericardium - Description

A

• Pericardium is a conical, flask-like, fibroserous sac, in which contains the heart and the roots of the great vessels
• Defines the middle mediastinum
• Two parts: fibrous and serous
o Fibrous
 fused with the external coats of the great vessels and is attached to the central tendon of the diaphragm
 attached to the posterior surface of the sternum by the superior and inferior sternopericardiac ligaments
o Serous
 serous pericardium is a closed sac which lines the fibrous pericardium and is invaginated by the heart
 has a visceral and a parietal portion
 visceral layer covers the heart and great vessels
 parietal layer lines the pericardium and is inseparable
 between layers of serous pericardium is the pericardial space which contains 15-50 mL of serous fluid
 space formed between the aorta and pulmonary artery is the transverse sinus (sits posterior to left atrium)
 space formed between the pulmonary veins and IVC is the oblique sinus (blind ending)
• Recesses (SIPPP):
 superior aortic recess: lies along the ascending aorta
 inferior aortic recess: lies between the right lateral aspect of the ascending aorta and the right atrium
o pulmonic recess: forms the lateral extent of the transverse sinus
o pulmonary venous recess: lies between the superior and inferior pulmonary veins
o postcaval recess: extends along the lateral aspect of the superior vena cava

114
Q

Pericardium - Relation

A
  • Anteriorly: body of the sternum, cartilages of left third-to-seventh ribs, pleura and lungs, thymus
  • Posteriorly: oesophagus, descending thoracic aorta, pleura and lungs
  • Laterally: pleura and lungs, phrenic nerves
115
Q

Pericardium - neurovasculature

A

Blood supply:
• Pericardiophrenic artery (branch of internal thoracic artery)
• Pericardial branches from the thoracic aorta
Venous drainage:
• Pericardiophrenic vein to the internal thoracic vein
• Tributaries to the azygos system
Nerve supply:
• Vagus nerve
• Phrenic nerves
• Sympathetic trunks
Lymph drainage:
• Anterior and posterior mediastinal nodes

116
Q

Phrenic Nerve - Description

A

• Phrenic nerve is important for breathing → passes motor information to the diaphragm and receives sensory information from it

117
Q

Phrenic Nerve - origin

A

• Arises C3-5 (ventral rami)

118
Q

Phrenic Nerve - course/relation

A

• In the neck
o phrenic nerve lies on the anterior scalene muscle
o passes over the dome of the pleura and enters the thorax posterior to the subclavian vein
 note: right and left phrenic nerves have a different course in the thorax but as a general rule they descend as lateral as possible whilst keeping in contact with the mediastinal pleura
• Left phrenic nerve
o enters the thorax posterior to the subclavian vein
o descends antero lateral to the left arch of the aorta, left auricle and left ventricle (in contact with pericardium)
o courses anterior to root of the lung/hilum, then with pericardiophrenic artery from pericardium to diaphragm
o crossed by the thoracic duct at the root of the lung
o pierces the dome of the left hemidiaphragm to enter the abdominal cavity
• Right phrenic nerve
o enters the thorax posterior to the subclavian vein
o right descends laterally to the superior vena cava, right atrium and ventricle, and inferior vena cava
o courses anterior to root of the lung/hilum, then with pericardiophrenic artery from pericardium to diaphragm
o passes through the vena caval foramen to enter the abdominal cavity
• Within the abdominal cavity
o both the left and right phrenic nerves divide into three main branches - anterior, lateral and posterior
 these course peripherally in a radial pattern to supply diaphragm

119
Q

Phrenic Nerve - branches

A
  • Left and right phrenic nerve branch into anterior, lateral and posterior and supply diaphragm
  • Filaments given off throughout course to supply sensory nerves to pleura, pericardium
120
Q

Phrenic Nerve - supply

A

• Motor: diaphragm
• Sensory: diaphragm, mediastinal pleura, fibrous pericardium, parietal layer of the serous pericardium
Blood supply:
• Pericardiophrenic artery (branch of the internal thoracic artery)

121
Q

Phrenic Nerve - variants

A

• Accessory phrenic nerve
o nerve that joins the phrenic nerve at the root of the neck or in the thorax
o forms a loop around the subclavian vein
o usually arises from nerve to subclavius, others include hypoglossal nerve, trigeminal nerve
• Forms an annulus around subclavian vein or passes anterior to it
• May supply a branch to scalenus anterior

122
Q

Pleura - description

A
  • Pleura are a serous membrane covering each lung
  • Divided into parietal and visceral layers
  • Visceral pleura covers the surface of the lung and dips into the fissures
  • Parietal pleura lines the inner surface of the chest wall, covers the diaphragm, and is reflected over the structures occupying the middle of the thorax
  • The pleural cavity is the potential space between the two cavities
  • Right and left pleural sacs are entirely separate from one another only touching each other for a short distance anteriorly opposite the second and third costal cartilages
  • At the lower border of the root of the lung, a triangular sheet is formed, the pulmonary ligament
  • The superior portion (cervical pleura) is strengthened by a dome-like thickening of connective tissue (Sibson’s fascia) which is attached to the inner border of the first rib onto the transverse process of C7
123
Q

Pleura - relations

A
  • Anterior: Ribs, Intercostal Vessels / Nerves, Internal thoracic artery
  • Posterior: Ribs, Intercostal Vessels / Nerves, Vertebral Body, Sympathetic Trunk
  • Medial: Heart / Great Vessels, Phrenic / Vagus Nerve
124
Q

Pleura - neurovasculature

A 
Arterial supply:
•	Internal Thoracic, Intercostal, Musculophrenic, Pericardial and Bronchial Vessels
Venous drainage:
•	Internal Thoracic Vein
•	Azygos System
Lymphatic drainage:
•	Intercostal Lymph Nodes
•	Tracheobronchial Lymph Nodes
Nerve supply:
•	Phrenic Nerve
125
Q

Pleura - boundaries

A
  • The pleura meet each other at the second costal cartilage and descend together till the fourth.
  • The right continues but the left diverges
  • At the 6th costal cartilage, each turns laterally passing the midclavicular line at the 8th costal cartilage
  • Midaxillary line at the 10th costal cartilage
  • The lower border crosses the erector spinae at the level of the 12th vertabra and continues horizontally
126
Q

Posterior mediastinum

A 
Borders:
•	Anteriorly: pericardium
•	Inferiorly: diaphragm
•	Superiorly: thoracic plane
•	Posteriorly: T5-T12 vertebral bodies
•	Laterally: mediastinal pleura
Contents
•	Artery
o	thoracic part of the descending aorta
•	Veins
o	azygos vein
o	the hemiazygos vein and the accessory hemiazygos vein
•	Nerves
o	vagus nerve
o	splanchnic nerves
o	sympathetic chain
•	Esophagus
•	Thoracic duct
•	Lymph nodes
127
Q

Pulmonary hilum

A 
Right side (superior to inferior):
•	Bronchus (eparterial)
•	Artery
•	Bronchus (hyparterial)
•	Veins
Left side (superior to inferior):
•	Artery
•	Bronchus
•	Veins
Pulmonary ligament
•	The parietal pleura surrounding the root of the lung extends downwards from the hilum in a fold called the pulmonary ligament
128
Q

Pulmonary veins - descriptions

A

• Pulmonary veins (along with the bronchial veins) are part of the venous drainage system of the lungs
• Pulmonary veins drain oxygenated blood to the left atrium
• There are typically four pulmonary veins:
o right superior - drains right upper and middle lobes
o right inferior - drains right lower lobe
o left superior - drains left upper lobe
o left inferior - drains left lower lobe
• Pulmonary veins course in the intersegmental septa and as such do not run with the bronchi

129
Q

Pulmonary veins - course

A

• Superior pulmonary veins takes an oblique inferomedial course
• Inferior pulmonary veins run horizontally peripherally before taking a more vertical course
• Pass through the lung hilum, antero-inferiorly to the pulmonary arteries
• Has a short intrapericardial segment, to drain into the left atrium
• Extensive communication with deep bronchial veins within the lung and with the superficial bronchial veins at the hilum
• Pulmonary veins are covered by a short (~9mm) myocardial layer
o often the focus of atrial fibrillation (left superior pulmonary vein being the foci for almost half of cases)

130
Q

Pulmonary veins - relations

A
  • Anterior: left atrium, left ventricle, arch of aorta, phrenic nerve
  • Posterior: vagus nerve, oesophagus
  • Lateral: SVC, lungs
  • Inferior: diaphragm
  • Superior: arch of aorta, left and right main bronchi
131
Q

Pulmonary veins - variants

A

• Common trunks
o common draining trunk of left superior and inferior pulmonary veins
• Accessory pulmonary veins
o single accessory right middle pulmonary vein (~10%)
o two accessory right middle pulmonary veins
o one accessory right middle pulmonary vein and one accessory right upper pulmonary vein
o superior segment right lower lobe vein
o basilar segment right lower lobe vein
o right top pulmonary vein (drains right superior basal segment)
• Partial anomalous pulmonary venous return (PAPVR)
o where the some (not all) pulmonary veins drain into a structure besides the left atrium
o SVC (most common), persistant left SVC, right atrium, brachiocephalic vein, portal vein, IVC
• Total anomalous pulmonary venous return (TAPVR)
o occurs where there is no drainage of pulmonary veins into the left atrium (cyanotic congentical heart anomaly)
o all systemic and pulmonary venous blood enters the right atrium
o right-to-left shunt is required for survival (usually patent PFO or ASD)

132
Q

Sternoclavicular joint - description

A

• SC joint is a synovial joint
• The articular surfaces are covered with fibrocartilage (rather than hyaline cartilage is in most other synovial joints)
• The joint space is divided into two separate recesses by an articular disc, also made of fibrocartilage
o attached to the joint capsule anteriorly and posteriorly, first costal cartilage inferiorly and the clavicle superiorly

133
Q

Sternoclavicular joint - articular surface

A

• Two non-congruent articular surfaces forming a saddle-type joint
o medial clavicle: larger of the two
o clavicular notch of the manubrium: smaller of the two

134
Q

Sternoclavicular joint - ligaments

A
  • Anterior and posterior sternoclavicular ligaments (thickenings of the joint capsule)
  • Interclavicular ligament (between superomedial ends of the clavicles)
  • Costoclavicular ligament
135
Q

Sternoclavicular joint - capsule

A
  • Capsule invests the articular surfaces

* Thickened in front and behind by the anterior and posterior sternoclavicular ligaments

136
Q

Sternoclavicular joint - relations

A

Relations:
• Anteriorly: sternocleidomastoid muscle
• Posteriorly: sternohyoid muscle, sternothyroid muscle, brachiocephalic veins form, origin of the great vessels, vagus nerves, right lymph duct, thoracic duct

137
Q

Sternoclavicular joint - neurovasculature

A 
Arterial supply:
•	Internal thoracic artery
•	Suprascapular artery 
Innervation:
•	Supraclavicular nerves
•	Nerve to the subclavius
138
Q

Sternoclavicular joint - variants

A
  • Inferior facet for articulation with the first rib

* Perforation of the articular disc (meaning the joint recesses are in communication)

139
Q

Superior mediastinum

A 
Borders:
•	Anteriorly: manubrium
•	Inferiorly: thoracic plane
•	Superiorly: superior thoracic aperture
•	Posteriorly: T1-T4 vertebral bodies
•	Laterally: mediastinal pleura
Contents
•	Muscles
o	origins of the sternohyoid and sternothyroid
o	lower ends of the longus colli
•	Arteries
o	aortic arch
o	brachiocephalic artery
o	left common carotid
o	left subclavian
•	Veins
o	brachiocephalic veins
o	SVC
o	left highest intercostal vein
•	Nerves
o	vagus nerve
o	superficial and deep cardiac plexuses
o	phrenic nerve
o	left recurrent laryngeal nerve
•	Trachea
•	Oesophagus
•	Thoracic duct
•	Thymus
•	Lymph nodes
140
Q

Thoracic inlet - description

A
  • Connects the root of the neck with the thorax
  • Superior thoracic aperture lies in an oblique plane, tilted anterosuperiorly
  • Also known as thoracic inlet
  • Thoracic outlet syndrome (TOS) refers to a group of clinical syndromes caused by compression of brachial plexus, subclavian artery or subclavian vein as they pass through the thoracic inlet
141
Q

Thoracic inlet - boundaries

A
  • Posteriorly: T1 vertebral body
  • Laterally: first rib and costal cartilage
  • Anteriorly: manubrium
142
Q

Thoracic inlet - Contents

A 
•	Viscera
o	thymus
o	trachea
o	oesophagus
o	lung apices
o	abnormally enlarged thyroid can extend through thoracic inlet
•	Vessels
o	left and right common carotid arteries
o	left and right subclavian arteries
o	left and right internal jugular and subclavian vein confluence
•	Nerves
o	phrenic nerves
o	vagus nerves
o	recurrent laryngeal nerves
o	T1 branch to brachial plexus
o	Sympathetic trunk
•	Lymphatics
o	thoracic duct
o	Jujular trunks from above
o	Bronchomediastinal from below
•	Fascia
o	Prevertebral fascia and anterior longitudinal ligament 
o	Retropharyngeal and danger space posteriorly
o	Visceral fascia
o	Carotid fascia
o	Superficial layer of the deep cervical fascia attaching at the outlet
•	Muscles
o	sternohyoid muscle
o	sternothyroid muscle
o	longus colli
143
Q

SVC - Description

A
  • Large valveless venous channel formed by the union of the brachiocephalic veins
  • Receives blood from the upper half of the body (except the heart) and returns it to the right atrium
144
Q

SVC - origin/course

A

Origin:
• Union of the brachiocephalic veins at the first right costal cartilage
Course:
• SVC begins behind the lower border of the first right costal cartilage
• Descends vertically behind the second and third intercostal spaces
• Drain into the right atrium at the level of the third costal cartilage

145
Q

SVC - relation

A
  • Left lateral: aortic arch, trachea
  • Right lateral: pleura, right upper lobe, phrenic nerve
  • Anteriorly: thymus, manubrium
  • Posterior: right vagus nerve, oesophagus
146
Q

SVC - tributaries

A
  • Azygos vein (at level T4)

* Small veins draining the pericardium and other mediastinal structures

147
Q

SVC - variants

A
  • Brachiocephalic veins: drain into the right atrium separately
  • SVC duplication: both right and left sided SVC
  • Left sided SVC: left anterior cardinal vein is not obliterated during normal foetal development, the persistent SVC usually drains into the coronary sinus
  • Unusual Tributaries: right internal thoracic, right supreme intercostal, thyroid ima vein
148
Q

Thoracic Duct - Description

A
  • Main lymphatic channel for the return of lymph to the venous system
  • Drains lymph from both lower limbs, abdomen (except the convex area of the liver), left hemithorax, left upper limb and left face and neck
  • Transports up to 4L of lymph per day
149
Q

Thoracic Duct - origin/course/relations

A

• Commences: from right side of L2 at the cisterna chyli
o cisterna chyli formed by left and right lumbar lymphatic trunks (drains abdominal wall, pelvic viscera, kidneys, adrenals, lower limbs) and the intestinal trunk
• Enters the thorax through the aortic hiatus of the diaphragm, and ascends to the right of the midline, between the aorta and azygos vein, posterior to the oesophagus
• Crosses to the left of midline at the thoracic plane (~T4)
• Continues superiorly through the superior thoracic aperture, between the left side of the esophagus and the left pleura
• Continues to the neck anterior to the subclavian artery, anterior scalene muscle and phrenic nerve
o posterior to the carotid sheath (IJV, CCA, vagus) and subclavian vein
• Thoracic duct then drains into the angle of the left subclavian and IJV

150
Q

Thoracic Duct - tributaries

A
  • Intercostal Lymph Glands: open into the commencement of the thoracic duct, draining the lower six or seven intercostal spaces. A trunk also joins it in the thorax draining the upper six left spaces
  • Left Jugular
  • Left Subclavian Trunks
  • Left Bronchomediastinal Trunks
151
Q

Thoracic Duct - variants

A
  • The thoracic duct has variant anatomy in ~40%
  • Double thoracic ducts (i.e. multiple ducts)
  • Aberrant termination: left internal jugular vein, left external jugular vein, azygos vein, brachiocephalic vein or left subclavian vein
  • Multiple terminal divisions
  • Continues on the right to terminate in the right internal jugular vein
152
Q

Thoracic plane - T4

A

Structures found at the level of the thoracic plane is: CLAPTRA
• C: carina/tracheal bifurcation
• L: ligamentum arteriosum
• A: aortic arch starts and ends
• P: pulmonary arterial trunk
• T: thoracic duct moves from right to left (posterior to the oesophagus)
• R: left recurrent laryngeal nerve loops under aortic arch
• A: azygos vein drains into SVC

153
Q

Trachea - Description

A
  • Connects the upper respiratory tract to the lungs via the bronchial tree, enabling gas exchange
  • Tube shaped structure consisting of 15-to-20 D-shaped cartilage rings anterolaterally bridged by annular ligaments
  • Trachealis muscle encircles the trachea completely but is most prominent posteriorly due the lack of cartilage
  • Trachea extends from the larynx at the level of the cricoid cartilage (C6) and branches into the right and left main bronchus at the carina (T4)
  • Usually situated in a midline position, and can be displaced slightly to the right at the arch of the aorta
  • Approximately 10-13cm with a width of 1.5-2 cm and is wider in men than in women
154
Q

Trachea - relations

A
  • Anterior: sternum, strap muscles, thyroid isthmus, ascending aorta, brachiocephalic artery, right common carotid artery, superior vena cava, left brachiocephalic vein
  • Posterior: oesophagus
  • Lateral: lateral walls of the thyroid gland, left common carotid artery, recurrent laryngeal nerves, right and left vagus nerves, pleura, lungs
155
Q

Trachea - neurovasculature

A 
Arterial supply:
•	Proximal half: tracheo-oesophageal branches of the inferior thyroid artery
•	Distal half and carina: superior and middle bronchial arteries (branches of the thoracic aorta)
Venous drainage:
•	Brachiocephalic vein
•	Bronchial veins drain into the azygos and accessory hemiazygos vein
Lymphatics:
•	Prelaryngeal lymph nodes
•	Pretracheal lymph nodes
•	Paratracheal lymph nodes
Nerves
•	Vagus + recurrent laryngeal
•	Sympathetics
156
Q

Trachea - variants

A
  • Tracheal diverticulum: projects posteriorly where the cartilage rings are deficient
  • Tracheal bronchus: accessory bronchus originates directly from the supracarinal trachea and supplies an upper lobe (usually right)
  • Oesophageal bronchus: bronchus arises directly from the oesophagus
  • Tracheo-oesophageal fistula: improper division of foregut by tracheo-oesophageal septum (associated with oesophageal and tracheal atresia)
  • Tracheal stenosis and atresia: associated with tracheo-oesophageal fistula
  • Bronchogenic cyst
  • Cardiac bronchus
  • Short trachea (< 15 rings)
157
Q

Vagus Nerve - Description

A
  • Vagus nerve is the 10th and longest cranial nerve
  • Provides the bulk of the parasympathetic input to the gastrointestinal system and to the heart
  • It is a mixed sensory/motor/parasympathetic nerve
158
Q

Vagus Nerve - Origin/course/relations

A

• The vagus nerve is attached by eight or ten filaments to the medulla oblongata in the groove between the olive and the inferior cerebellar peduncle
o below glossopharyngeal nerve
• Filaments of the nerve unite, and travels through the cisterna magna to exit the jugular foramen
• Passes vertically down the neck within the carotid sheath, lying between the IJV and ICA (and then CCA)
• Right vagus:
o passes between subclavian artery and right brachiocephalic vein
o nerve and descends by the side of the trachea to the back of the root of the lung
o then spreads out in the posterior pulmonary plexus, then part of oesophageal plexus (around the oesophageal hiatus)
o then travels medially to the oesophageal hiatus, which it passes through to enter the abdominal cavity
• Left vagus:
o passes between subclavian artery and left brachiocephalic vein
o course takes it lateral to the aorta arch as it descends posterior to the hilum of the left lung
 here it forms part of the pulmonary plexus, then forms part of oesophaegeal plexus more inferiorly (around the oesophageal hiatus)
o then travels towards the oesophageal hiatus, which it passes through to enter the abdominal cavity
• From the oesophageal plexus anterior and posterior vagal trunk emerge
o anterior trunk is composed of fibres mainly from the left vagus, posterior trunk is mainly composed of fibres from right vagus

159
Q

Vagus Nerve - Branches

A
  • Auricular nerve
  • Pharyngeal branch
  • Esophageal plexus
  • Superior laryngeal nerve: gives internal laryngeal (sensory) and external laryngeal (motor) nerves
  • Cardiac nerves: superior and inferior
  • Recurrent laryngeal nerves
  • Anterior vagal trunk
  • Posterior vagal trunk

Radiology Anatomy (14 decks)

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