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Flashcards in Anatomy Deck (180):

what are the two main types of neurones?




what is the difference between multipolar neurones and unipolar neurones?

multipolar = most common, 2 or more dendrites, all motor neurones and their cell body is in CNS

unipolar = double process, sensory, their cell body is in PNS 


what is the difference between motor and sensory neurones?

motor (efferent) = impulse moves towards body wall, body cavity or organ 

sensory (afferent) = impulse moves towards brain


what is a group of nerve cell bodies in the CNS called and how is this named differently in the PNS?

CNS - nucleus 

PNS - ganglion 


a nerve is a bundle of what?


this is called a tract in the CNS


tracts tend to be of a "single modality" - what does this mean?

all axons contained within it have the same job 

ie somatic motor/sensory, special sensory etc 


what is meant by "mixed modality" nerves?

axons for somatic motor and sensory and sympathetic all together in one nerve 


what cranial nerves connect to CNS in forebrain?



what cranial nerves connect to CNS via the midbrain?



where does CNV connect to the CNS?



what cranial nerves connect to the CNS at the pons-medullary junction?



which of CNIX, X, XI and XII does not connect to CNS at medulla?

CNXI - connects at spinal cord

(cause spinal accessory nerve lol) 


spinal nerves are actualy very small - true or false?


they are only found in the intervertebral foraminae as on one side they are rootlets/roots or rami on the opposite side 


what do the anterior and posterior rami supply?

anterior - anterolateral body wall

poserior - posterior body wall 


are roots and rootlets single or mixed modality?


posterior root/rootlets = somatosensory 

  • all sensory axons pass from the spinal nerve into posterior root then posterior rootlets then into posterior horn of spinal cord 

anterior root/rootlets = somatomotor 

  • all motor axons pass from anterior horn of spinal cord into anterior rootlets then into the anterior root then into the spinal nerve 


are spinal nerves and rami single or mixed modality?

mixed - anterior and posterior roots come together and mix forming spinal nerve 


what is the name given to the swelling on the posterior (or dorsal) root and what does it contain?

dorsal root ganglion - contains collection of cell bodies


rami supply what in their segment of the body?

sensory supply to area 

somatic motor supply to skeletal muscles 

sympathetic supply to the skin and to the smooth muscle of arterioles 


what is a dermatome?

area of skin supplied with sensory innervation from a single spinal nerve (eg T4 = nipple level)


what is a myotome?

skeletal muscles supplied with motor innervation from a single spinal nerve 


myotomes lie under the corresponding spinal nerve dermatome - true or false?

false - not always the case

eg C3,4,5 dermatome = shoulder and upper arm 

but myotome = diaphragm 


dermatomes for spinal nerves can overlap - true or false?



why is dermatome overlap a clinical issue?

if a patient experiences a symptom (eg numbness / tingling) in a specific dermatome then we must contemplate that nerves in the adjacent dermatome may also be damaged 


what dermatome levels mark the nipple and umbilicus?

T4 = nipple 

T10 = umbilicus 


roughly describe what each segment of spinal nerves innervates (ie cervical, thoracic etc)?

cervical = upper limbs, posterior head and neck

thoracic = thorax

lumbar = anterior of lower limbs 

sacral = posterior of lower limbs 


what makes up a nerve plexus?

anterior rami 


what anterior rami make up each plexus?

cervical = C1-C4

brachial = C5-T1

lumbar = L1-L4

sacral = L5-S4


it is possible for more than one named cutaneous nerve to pass through one dermatome - true or false?

true eg lateral cutaneous nerve of thigh, femoral nerve and obturator nerve all pass through L2 dermatome



between what spinal level does sympathetic outflow leave the spinal cord?



what extra horns are found in the spinal cord where sympathetics or sacral parasympathetics leave?

lateral horns (on edge of grey matter in spianl cord) 


what 4 ways are used by sympathetics to leave spinal cord?

1) signal ascends sympathetic chain before synapsing 

2) signal synapses on same spinal level it leaves 

3) signal descends sympathetic chain before synapsing 

4) passes through sympathetic chain without synapsing, passes onto splanchnic nerves and then synapses onto viscera 


what term is used to describe parasympathetic outflow and why is this?

craniosacral outflow 

cranial nerves III, VII, IX and X

sacral spinal nerves 



what is the role of the extrinsic back muscles?

attach to back of pectoral girdle (outwith back) and move the upper limb 


what is the role of the intrinsic muscles within the back and what is the two groups?

muscles which attach within the spine which maintain back posture and move spine 

2 groups = erector spinae (superficial - located lateral to spine) and transversospinalis (deep - located within grooves between transverse and spinous processes)


lower back pain may be due to the strain of which muscle?

erector spinae 


what nerves supply the extrinsic vs the intrinsic muscles?

extrinsic = anterior rami 

intrinsic = posterior rami 


identify an axial image of erector spinae in context of transversospinalis?


if the erector spinae contracts bilaterally then the spine extends but what occurs if it contracts unilaterally?

lateral flexion 


why do vertebrae get larger towards the lumbar region and then progressively smaller again?

larger to bear more weight until the weight is transferred to hip bones


what curves of the spine are secondary (ie not present from birth, they have adapted to new functions of spine)?

cervical and lumbar lordosis 


describe the structure of a typical vertebra?


where are spinal nerves found and where is the spinal cord found in relation to the vertebrae?

spinal nerves = intervertebral foramen 

spinal cord = vertebral foramen 


what is the role of intervertebral discs and describe the difference between the outer ring and inner pulp?

weight bearing, strength and small amounts of movement at each disc 

outer fibrous ring (annulus fibrosus) = provides strong bond 

inner soft pulp (nucleus pulposus) = up to 90% water in newborns, flexibility and protection 


what ligaments are found on the outside of vertebral body and what is their role?

posterior longitudinal ligament (narrow and weak, prevents over-flexion of spine)

anterior longitudinal ligament (broad and strong, prevents over-extension of spine) 


what ligament connects the adjacent laminae posterior to the spinal cord?

ligamentum flavum


where are the supraspinous ligament and interspinous ligament found?

supraspinous = connects tips of spinous processes (strong)

interspinou ligament = connects adjacent spinous processes (weak)



thwt are the common typical features of a cervical vertebrae?

transverse foramen 

bifid spinous process

triangular shapes vertebral foramen 


C1 (atlas) does not have a body or spinous process - true or false?

true - body is donated to a C2 as odontoid process 

has a posterior arch and anterior arch instead



why is C7 important?

first palpable spinous process in 70% of people 


how does C1 atlas connect to the base of the skull?

atlanto-occipital joints = between the occipital condyles and the superior articular facets of the atlas 

these are synovial joints with loose capsule for maximum movement


what movements does the atlanto-occipital joint allow?

flexion and extension of neck

a little lateral flexion and rotation 


identify the components of a lateral C-spine radiograph?


what are the four stages of cervical vertebrae dislocation?

stage I - flexion sprain 

stage II - anterior subluxation, 25% translation 

stage III - 50% translation 

stage IV - complete dislocation 


how many articulations are part of the atlanto-axial joint?

3 - all synovial 

2 are between the inferior articular facets of the atlas and the superior articular facets of the axis 

1 between the anterior arch of the atlas and odontoid process of the axis 


what is the main function of the atlanto-axial joint?



C1 disappears on a radiograph as it has no spinous process - true or false?

false - the posterior arch appears like a spinous process would 


it is easier to fracture cervical vertebrae than dislocate them - true or false?

false - much easier to dislocate them 

sometimes they will reduce by themselves 


what nerves pass through the anterior and posterior sacral foraminae?

rami of spinal nerves 


what is the cauda equina made up of?

nerve roots from L2 -> CO1 descending to their intervertebral foramen at their level 


why is it safer to perform an epidural or LP at the level of the cauda equina (below L2)?

no damage to spinal cord 

nerve roots more likely to move out of way of needle 


where does the spinal cord begin and end?

begins at foramen magnum (C1 - continuous with medulla oblongata)

ends around vertebral level L1/2 (Co segment of spinal cord)


what can result from an epidural or lumbar puncture which damages the venous plexus in the epidural fat?

epidural haematoma which can compress the spinal cord



what layer of meninges needs to be reached during a lumbar puncture?

subarachnoid space containing CSF for extraction 


what is a laminectomy?

removal of one or more spinous processes and the adjacent lamina 

used to access spinal canal / relieve pressure on spinal cord or nerve roots caused by tumour, herniated disc or bone hypertrophy 


the posterior rami supply a strip of skin where?

centrally down the back and posterior neck (C2-C8)


what plexuses are formed by the anterior rami?

cervical plexus 

brachial plexus 

lumbar plexus 

sacral plexus 


give examples of named nerves from the anterior rami which supply the trunk wall?


state the difference between a spinal nerve and a named nerve?

spinal nerve = contains axons originating from one spinal cord level (eg C5 spinal nerve)

named nerve = contains axons originating from one or more spina cord levels supplying a particular area (eg musculocutaneous nerve - C5, 6, 7)


explain how the area of innervation of femoral nerve crosses 3 true dermatomes?

femoral nerve contains axons that connect via spinal nerve roots L2, 3 and 4 with spinal cord segments L2, 3 and 4

this means that the area of cutaneous innervation of the femoral nerve crosses 3 true dermatomes - those of L2, L3 and L4 spinal nerves 


what is the "nerve point" of neck?

where the sensory nerves of cervical plexus converge and pass from superficial to deep fascia 

this occurs at midpoint of posterior border of SCM 


what is the clinical significance of T1 and T2 anterior rami?

important for referred pain from the myocardium 


what supplies the anatomical snuff box?

cutaneous branches of the radial nerve 


identify the named nerve cutaneous innervation of the upper limb?


identify the names nerve cutanous innervation of the lower limb?


describe the route of sensory action potentials from the skin to the primary somatosensory cortex (postcentral gyrus)?

stimulation in the area innervated by femoral nerve shown 

AP generated by receptors in that area (L2 dermatome) 

AP continues along axons weaving through lumbar plexus 

AP continues to L2 anteior rami 

AP continues along axons to L2 spinal nerve then posterior root then posterior rootlets 

AP continues into posterior horn of spinal cord 

once in dorsal horn, going to cross and synapse in spinothalamic tract


in which three areas can pathology cause problems with the sensory pathway?

primary somatosensory cortex

internal capsule (common location of CVA)

CNS ascending tract (spinothalamic or dorsal column)


how can you tell the difference between a spinal nerve injury and nerve compression?

spinal nerve injury = dermatomal pattern 

nerve compression = overlaps


explain why the femoral nerve will still have power if L3 is disrupted?

it crosses 3 myotomes 

if L3 disrupted, L2 and L4 are still intact so will still have some power 


explain what the following myotomes supply:

a) cervical plexus (C1-C4 motor axons)

b) brachial plexus (C5-T1 motor axons)

c) T2-L3 motor axons 

d) lumbosacral plexus (L1-S4 motor axons)

a) neck postural, strap muscles and diaphragm 

b) muscles of upper limb and extrinsic back muscles that move the upper limb or scapula 

c) postural back muscles (via posterior rami), intercostal muscles (via anterior rami) and anterolateral abdominal wall muscles

d) muscles of lower limb and perineal skeletal muscles 


describe the action and muscle being tested for the following dermatomes:

C5, C6, C7, C8, T1, L2, L3, L4, L5, S1, S2


where is the cell body of the upper neurone cell body located?

within primary somatomotor cortex of precentral gryrus 

this fires into brain 

85% crosses over and axons now within spinal cord descending tract 


describe the route of AP from the primary somatomotor cortex then a NMJ?

APs are generated by voluntary intention in the primary somatomotor cortex

AP conducted via UMN axons of the corticospinal tract 

AP continues along axons to anterior horn of L3 spinal cord

UMN synapse with L3 LMN stimulating AP

AP continued along axons to L3 spinal nerve then continues to either anterior or posterior rami 

APs via L3 anterior rami often weave through a lumbar plexus via named nerve and then reach NMJ of supplied muscle 


what is a reflex?

involuntary response to stimulus


give an example of a reflex and the steps involved?

patellar reflex 

1. patellar tendon tapped

2. stretched quadriceps fibres

3. muscle spindles initiate APs in anterior rami axons within femoral nerve 

4. sensory APs conduct to dorsal horn of L3

5. axons pass onto anterior horn to synapse on LMNs that supply quadriceps 

6. APs conducted via LMN axons in femoral nerve to reach quadriceps NMJ

7. muscle contracts to extend knee joint 


what type of pathways control reflex muscle contractions?

descending pathway 

*upper motor neurone lesion = spasticity 

*lower motor neurone lesion = flaccidity 


identify the location of the testable stretch reflexes in the limbs and their associated spinal cord levels?


what functions are described as "special sensory"?

sight, smell, taste, hearing and balance 


CNI only has a special sensory function - true or false?


only special sensory for smell


for CN I, name the:

a) extracranial part

b) cranial foramina 

c) intracranial part

a) bipolar neurones in the olfactory mucosa of nasal cavity 

b) cribiform plate of ethmoid 

c) synapse in olfactory bulb then pass along tract to cortical areas 


is CN II sensory or motor?

special sensory - sight 


for CN II, name the:

a) extracranial part

b) cranial foramina 

c) intracranial part 


a) neurones in retina travel posteriorly via optic nerve through the orbit

b) optic canal (in middle of cranial fossa)

c) optic chiasm to form optic tract 



does CN II connect to the CNS?

yes - at the diencephalon 


how is CN I clinically tested?

ask patient to smell a familar smell while covering the contralateral nostril eg orange peel, coffee or vinegar 

*not routinely tested


name the 5 ways that CN II is clinically tested?

acuity (snellen charts)

colour (ishihara plates_

fields (four quadrants)

reflexes (pupillary light reflexes)



is CNIII sensory of motor and what are its functions?

motor - eye movement 

parasympathetic - pupil constriction 


where does CNIII connect with the CNS?

midbrain (mesencephalon)


for CN III, name the:

a) intracranial part 

b) cranial foramina 

c) extracranial part

a) travels towards orbit in lateral wall of cavernous sinus 

b) superior orbital fissure

c) passes into orbit and supplies all extraocular muscles except two, the parasympathetics synapse in the ciliary ganglion 


where does the trochlear nerve communicate with CNS?

midbrain (mesencephalon)


is CN IV sensory or motor?

motor (moves superior oblique)


for CN IV, name the

a) intracranial part 

b) cranial foramina 

c) extracranial part

a) travels towards orbit in the lateral wall of cavernous sinus but does not pass through common tendinous ring 

b) superior orbital fissure

c) passes into orbit to supply superior oblique 


how are CNIII and IV different in the way they innervate the muscles of the eye?

CN III passes through common tendinous ring to innervate from deep to the muscles 

CNIV does not pass through ring and instead sits on top of superior oblique to innervate 


is CNVI sensory or motor, and what is its main function?

motor to lacteral rectus (abducts eye)


where does CNVI connect with the CNS?

pontomedullary junction 


for CNVI, name the:

a) intracranial part 

b) cranial foramina 

c) extracranial part

a) travels towards orbit within the cavernous sinus 

b) superior orbital fissure

c) orbit to supply lateral rectus 


how can each ocular muscle be isolated to test the cranial nerve?

the H test 


what is the function of CN VIII?

special sensory (hearing and balance)


for CN VIII, name the:

a) extracranial part

b) cranial foraminae 

c) intracranial part 

a) axons from cochlear and vestibular apparatus 

b) internal accoustic meatus in posterior cranial fossa 

c) travels posteromedially from IAM to pontomedullary junction 


how is CNVIII clinically tested?

rinne's = tuning fork on mastoid process for conductive hearing loss 

weber's = tuning fork on forehead for sensorineural hearing loss


CN XI has a motor supply to which two muscles?

sternocleidomastoid and trapezius 


for CNXI, name the:

a) intracranial part 

b) cranial foramina 

c) extracranial part

a) ascends through foramen magnum then travels towards jugular foramen in posterior cranial fossa 

b) jugular foramen in posterior cranial fossa 

c) axons supply SCM on deep surface then continue across the posterior triangle to supply trapezius and SCM


where does CNXI connect with the CNS?

cervical spinal cord (C1 - 4/5)


how can CN XI be clinically tested?

ask patient to shrug shoulders - trapezius 

ask them to flex neck and turn toward oppposite side - sternocleidomastoid 


if a patient has trapzeium weakness but the sternocleidomastoid is intact, where may the damage / lesion be located?

after CNXI passess through posterior triangle as it has already supplied SCM by this point 


is CNXII sensory or motor?

what does it supply?

motor to muscles of tongue 


where does CNXII connect to the CNS?

many rootlets lateral to the pyramids of medulla oblongata 


for CNXII, name the:

a) intracranial part

b) cranial foramina 

c) extracranial part

a) passes anteriorly to hypoglossal canal 

b) hypoglossal canal in posterior cranial fossa 

c) descends lateral to carotid sheath and at the level of the hyoid turns anteriorly towards lateral aspect of tongue 


which of the tongue muscles does CNXII not innervate?



how can CN XII be clinically tested?

ask patient to stuck tongue straight out 

if unilateral CNXII pathology then the tongue tip will point towards the side of injured nerve 


where does CNV connect to CNS?


*only one that connects here 


what is the intracranial part of CN V?

inferior to the edge of the tentorium cerebelli between the posterior and middle cranial fossa 


what cranial foraminae are used by the divisions of CNV?

V1 = superior orbital fissure 

V2 = foramen rotundum 

V3 = foramen ovale 


what structures are found in the CN V1 dermatome?

upper eyelid

cornea (corneal reflex)


skin of root / bridge / tip of nose 


what is covered by the CN V2 dermatome?

the skin of lower eyelid

skin over maxilla 

skin of the ala of nose 

skin / mucoa of upper lib 


what structures are covered by CN V3 dermatome?

skin over mandible and TMJ 

*apart from angle of mandible (supplied by C2, 3 spinal nerves - great auricular nerve)


what larger muscles does CN V3 supply and what is their main function?

muscles of mastication 

close = masseter, temporalis, medial pterygoid 

open = lateral pterygoid 


what two small muscles are supplied by CNV3 and what are their functions?

tensor veli palatini - tenses palate

tensor tympani - muffles sound 


how is the sensation of of CN V1, V2 and 3 dermatomes tested?

brush the skin in each dermatome with a fine tip of cotton wool


how is the motor function of CNV3 tested?

palpate the contraction of masseter and temporalis by asking patient to clench teeth 

ask the patient to open their jaw against resistance 


what forms the first part of the afferent limb of the blink (corneal) reflex?

long ciliary nerves


is CN VII sensory or motor?

special sensory (taste) 

motor and parasympathetics 


where does CNVII connect to the CNS?

pontomedullary junction 


how does CNVII enter and exit the cranium?

enter = IAM

out = stylomastoid foramen 


describe the extracranial course of CNVII?

smator motor axons pass into the parotid gland

then forms 6 branches that supply the muscles of facial expression


what part of the CN VII course does the chorda tympani arise from?

found in temporal bone at the posterior surface of the middle ear 


what does the chorda tympani go on to supply?

taste - anterior 2/3rds of the tongue 

parasympathetic - salivary gland 


what is the smallest muscle in the body, which is supplied by CNVII, and what is the function of this muscle?


reduces stapeus movement to protect the internal ear from excessive noise 


what nerve does the chorda tympani piggy back on, in order to supply the salivary glands and the tongue?

lingual nerve (CNV3)

*CNVII also sends fibres that supply parasympathetics to the pterygopalatine ganglion linking to lacrimal gland and mucous glands of midface


what muscles of facial expression does the CNVII supply?

frontalis (forehead)

orbicularis oculi 

elevators of lips 

orbicularis oris 


how are the muscles of facial expression used to test CNVII?

raise eyebrows (frontalis)

close eyes tightly (orbicularis oculi)

smile (lip elevators)

puff out cheeks and hold air (orbicularis oris)


what are the main functions of CN IX?

special sensory (vallate papillae - taste)

sensory - posterior 1/3 of tongue, pharynx, palatine tonsil, eustachian tube and middle ear 

motor - stylopharyngeus muscle 

visceral afferent - carotid body and sinus 

parasympathetics (motor) - parotid gland 


where does CNIX connect with CNS and which cranial foramen does it pass through?

connection with CNS = lateral aspect of superior medulla oblongata 

then goes directly towards jugular foramen in posterior cranial fossa 

*then descends towards pharynx and mouth


where does CN X connect with the CNS?

lateral aspect of medulla oblongata, immediately inferior to CNIX 


for CN X, name the:

a) intracranial part 

b) cranial foramen 

c) extracranial part

a) directly towards jugular foramen in posterior cranial fossa 

b) jugular foramen 

c) axons supply lots of structures between the palate and the midgut


the vagus nerve runs just lateral to carotid sheath - true or false?


CNXII runs just lateral to sheath 

whereas CNX runs within the carotid sheath 


what does the vagus nerve curve under on each side?

CNX becomes recurrent laryngeal nerve to supply larynx 

left curves under arch of aorta 

right curves under the subclavian artery 


how does CNX travel in relation to the thorax?

both pass posterior to lung root and onto oesophagus 

both pass through diaphragm with oesophagus 


what does the vagus nerves very last parasympathetic axons pass to?

splenic flexure of the colon 


how is the vagus nerve transported to the structures in the gut?

on arteries 


how can CNX be clinically tested?

ask patient to say ahhhhhh - muscles of palate (unilateral pathology will pull uvula away from non functioning side)

ask patient to swallow small amount of water - pharyngeal muscles (splutter suggests abnormal swallow)

listen to speech - laryngeal muscles (hoarseness = abnormal function)


why are SOLs such a problem in the skull?

can cause raised ICP and contents can be compressed or attempt to herniate 


what are the 5 layers of the scalp?

s = skin 

c = connective tissue 

a = aponeurosis 

l = loose connective tissue 

p = pericranium 


which layer of the scalp contains the anastomotic network of arteries?

layer 2 = connective tissue


why does the scalp tend to bleed a lot when injured?

connective tissue layer housing blood vessels is very strudy and holds vessels open when they are cut into 


identify the different bones within the skull?


what is thought to be the thinnest part of the skull and what artery is found deep to this?


middle meningeal artery 


identify the bones and key features of the base of the skull?


the dura mater has two layers - what are these called and what can arise between them?

periosteal layer (over bone) and meningeal layer (over arachnoid layer) 

dural venous sinuses form between them


a fracture of the skull is likely to penetrate through a stuture - true or false?

false - sutures stop the propagation of fractures in skull


the middle meningeal artery creates a groove in the base of skull which leads to which foramina?

foramen spinosum


where does the pain in meningitis arise from, and why?

stretching of dura mater 

*dura is the only meningeal layer with sensory innervation


what are the arachnoid granulations from the arachoid mater?

projections up into the dural venous sinuses which reabsorb CSF


what is the pia mater adherent to?

the brain and the blood vessels and nerves entering or leaving brain 


what lies between the arachnoid mater and the pia mater?

subarachoid space containing CSF


what layer of the dura mater does not extend down to the spinal cord?

periosteal - as no part is needed to cover bone


what tough sheet of dura matter forms a roof over the pituitary fossa?

diaphragm sellae 


what name is given to the sheet of dura mater which covers the cerebellum, attaches to the ridges of the petrous temporal bones and has central gap to permit brainstem to pass through?

tentorium cerebelli 


what is the falx cerebri?

midline structure made of dura matter which attaches to the deep aspect of skull 

- crista galli of ethmoid bone anteriorly 

- internal aspect of the sagittal suture 

- internal occipital protruberance posteriorly 

it separates the right and left hemispheres 



how does blood from the cerebral hemispheres of the brain drain to the dural venous sinuses?

cerebral veins 


what is a secondary function of the dural venous sinuses?

reabsorb CSF from arachnoid granulations 


why is an infection to the facial vein (superficial) dangerous?

can track back to cavernous sinus in brain and cause infection 


what artery does the vertebral artery branch from?

the right subclavian 


what are the main arteries in the circle of willis supplying the cerebrum?

anterior, middle and posterior cerebral arteries 


in which layer of the meninges is the circle of willis found?

subarachnoid space (it is bathed in CSF)


when would damage to the circle of willis or one of its branches be suspected?

if blood was found in CSF


describe the course of CSF from production to the subarachnoid space?

1. secreted by choroid plexus 

2. lateral ventricles via the foraminae of monro 

3. into the 3rd ventricle 

4. then via cerebral aqueduct into 4th ventricle 

5. then into subarachnoid space 

7. then reabsorbed from subarachnoid space via arachnoid granulations

8. into dural venous sinuses 


what 3 situations can cause hydrocephalus?


flow obstriction 

inadequate reabsorption 


what intervention can be done for hydrocephalus?

ventricular peritoneal shunt 

(moves CSF reabsorption point down to peritoneal cavity)


where is it possible to bleed in the cranial cavity and what can cause this?

extradural - between bone and dura, ruptured middle meningeal artery due to trauma to pteroin 

subdural - separates dura from arachnoid, torn cerebral veins due to falls in eldelry 

subarachnoid - into CSF of subarachnoid space, ruptured circle of willis by aneurysm 


how can parts of the brain herniate if there is raised ICP?

parts above tentorium cerebelli:

1. subfalcine (can move under falx cerebri)

2. central (move over the tentorium cerebelli)

3. transcalvarial (move out through fractured bone)

4. uncal (moves down towards tentorium cerebelli)


parts under tentorium cerebelli:

1. upward cerebellar (move towards tentorium cerebelli)

2. tonsillar (cerebellum moves downwards into foramen magnum)


what symptom can be caused by compression of the oculomotor nerve by an uncal herniation?

ipsilateral fixed dilated pupil (ie blown pupil)