Musculoskeletal, Skin, and Connective Tissue - Anatomy and Physiology Flashcards Preview

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Flashcards in Musculoskeletal, Skin, and Connective Tissue - Anatomy and Physiology Deck (34)
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1
Q

Epidermis layers from surface to base

A
  • Californians Like Girls in String Bikinis​
  • Stratum Corneum (keratin)
  • Stratum Lucidum
  • Stratum Granulosum
  • Stratum Spinosum (spines = desmosomes)
  • Stratum Basale (stem cell site)
2
Q

Epithelial cell junctions (410)

  • Tight junction
  • Adherens junction
  • Desmosome
  • Gap junction
  • Integrins
  • Hemidesmosome
A
  • Tight junction (zonula occludens)
    • Prevents paracellular movement of solutes
    • Composed of claudins and occludins.
  • Adherens junction (zonula adherens)
    • Below tight junction, forms “belt” connecting actin cytoskeletons of adjacent cells with CADherins (Ca2+-dependent adhesion proteins).
    • Loss of E-cadherin promotes metastasis.
  • Desmosome (macula adherens)
    • Structural support via keratin interactions.
    • Autoantibodies –> pemphigus vulgaris.
  • Gap junction
    • Channel proteins called connexons permit electrical and chemical communication between cells.
  • Integrins
    • Membrane proteins that maintain integrity of basolateral membrane by binding to collagen and laminin in basement membrane.
  • Hemidesmosome
    • Connects keratin in basal cells to underlying basement membrane.
    • Autoantibodies –> bullous pemphigoid.
      • Hemidesmosomes are down “bullow”
3
Q

Knee injury

  • Presents with…
    • “Anterior” and “posterior” in ACL and PCL refer to…
    • Abnormal passive abduction –>
    • Abnormal passive adduction –>
  • McMurray test
  • Unhappy triad
A
  • Presents with acute knee pain and signs of joint injury/instability:
    • “Anterior” and “posterior” in ACL and PCL refer to sites of tibial attachment.
      • Anterior drawer sign –>Ž ACL injury
      • Posterior drawer sign –>Ž PCL injury
    • Abnormal passive abduction (valgus stress) –>Ž MCL injury
    • Abnormal passive adduction (varus stress) –>Ž LCL injury
  • ƒƒMcMurray test
    • Pain on external rotation –>Ž medial meniscus
    • Pain on internal rotation –>Ž lateral meniscus.
  • Unhappy triad
    • Common injury in contact sports due to lateral force applied to a planted leg.
    • Classically, consists of damage to the ACL, MCL, and medial meniscus (attached to MCL)
    • However, lateral meniscus injury ismore common.
4
Q

Clinically important landmarks

  • Pudendal nerve block
  • Appendix
  • Lumbar puncture
A
  • Pudendal nerve block (to relieve pain of delivery)
    • Ischial spine.
  • Appendix
    • 2/3 of the distance between the umbilicus and the anterior superior iliac spine (ASIS), just proximal to the ASIS (McBurney point).
  • Lumbar puncture
    • Iliac crest.
5
Q

Rotator cuff muscles

  • Shoulder muscles that form the rotator cuff:
  • Innervation
A
  • Shoulder muscles that form the rotator cuff:
    • Supraspinatus (suprascapular nerve)
      • Abducts arm initially (before the action of the deltoid)
      • Most common rotator cuff injury.
    • Infraspinatus (suprascapular nerve)
      • Laterally rotates arm
      • Pitching injury.
    • Teres minor (axillary nerve)
      • Adducts and laterally rotates arm.
    • Subscapularis (subscapular nerve)
      • Medially rotates and adducts arm.
    • SItS (small t is for teres minor).
  • Innervated primarily by C5-C6.
6
Q

Wrist bones

  • Wrist bones
  • Most commonly fractured carpal bone
  • Carpal tunnel syndrome
  • Guyon canal syndrome
A
  • Wrist bones
    • Scaphoid, Lunate, Triquetrum, Pisiform, Hamate, Capitate, Trapezoid, Trapezium [A].
    • So Long To Pinky, Here Comes The Thumb
  • Scaphoid (palpated in anatomical snuff box) is the most commonly fractured carpal bone and is prone to avascular necrosis owing to retrograde blood supply.
  • Carpal tunnel syndrome
    • Entrapment of median nerve in carpal tunnel
    • Nerve compression –>Ž paresthesia, pain, and numbness in distribution of median nerve.
    • Dislocation of lunate may cause acute carpal tunnel syndrome.
  • Guyon canal syndrome
    • Compression of the ulnar nerve at the wrist or hand, classically seen in cyclists due to pressure from handlebars.
    • A fall on an outstretched hand that damages the hook of the hamate can cause ulnar nerve injury.
7
Q

Brachial plexus (proximal –> distal) (413)

A
  • Randy Travis Drinks Cold Beer
  • Roots
  • Trunks
  • Divisions
  • Cords
  • Branches
8
Q

Brachial plexus lesions (413)

  • Upper trunk
  • Lower trunk
  • Posterior cord
  • Long thoracic root
  • Axillary nerve
  • Radial nerve
  • Musculocutaneous branch
  • Median branch
  • Ulnar branch
A
  • Upper trunk
    • Erb palsy (“waiter’s tip”)
  • Lower trunk
    • Claw hand (Klumpke palsy)
  • Posterior cord
    • Wrist drop
  • Long thoracic root
    • Winged scapula
  • Axillary nerve
    • Deltoid paralysis
  • Radial nerve
    • “Saturday night palsy” (wrist drop)
  • Musculocutaneous branch
    • Difficulty flexing elbow, variable sensory loss
  • Median branch
    • Decreased thumb function, “Pope’s blessing”
  • Ulnar branch
    • Intrinsic muscles of hand, claw hand
9
Q

Erb palsy

  • Injury
  • Causes
  • Muscle deficit
  • Functional deficit
A
  • Injury
    • Traction or tear of upper (Erb-er”) trunk: C5-C6 roots
    • “Waiter’s tip”
  • Causes
    • Infants—lateral traction on neck during delivery
    • Adults—trauma
  • Muscle deficit
    • (1) Deltoid, supraspinatus
    • (2) Infraspinatus
    • (3) Biceps brachii
  • Functional deficit
    • (1) Abduction (arm hangs by side)
    • (2) Lateral rotation (arm medially rotated)
    • (3) Flexion, supination (arm extended and pronated)
10
Q

Klumpke palsy

  • Injury
  • Causes
  • Muscle deficit
  • Functional deficit
A
  • Injury
    • Traction or tear of lower trunk: C8-T1 root
  • Causes
    • Infants—upward force on arm during delivery
    • Adults—trauma (e.g., grabbing a tree branch to break a fall)
  • Muscle deficit
    • Intrinsic hand muscles: lumbricals, interossei, thenar, hypothenar
  • Functional deficit
    • Total claw hand: lumbricals normally flex MCP joints and extend DIP and PIP joints
11
Q

Thoracic outlet syndrome

  • Injury
  • Causes
  • Muscle deficit
  • Functional deficit
A
  • Injury
    • Compression of lower trunk and subclavian vessels
  • Causes
    • Cervical rib injury
    • Pancoast tumor
  • Muscle deficit
    • Intrinsic hand muscles: lumbricals, interossei, thenar, hypothenar
  • Functional deficit
    • Atrophy of intrinsic hand muscles
    • Ischemia, pain, and edema due to vascular compression
12
Q

Winged scapula

  • Injury
  • Causes
  • Muscle deficit
  • Functional deficit
A
  • Injury
    • Lesion of long thoracic nerve
  • Causes
    • Axillary node dissection after mastectomy, stab wounds
  • Muscle deficit
    • Serratus anterior
  • Functional deficit
    • Inability to anchor scapula to thoracic cage –>Ž cannot abduct arm above horizontal position
13
Q

Axillary nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Upper extremity nerve (C5-C6)
  • Causes of injury
    • Fractured surgical neck of humerus
    • Anterior dislocation of humerus
  • Presentation
    • Flattened deltoid
    • Loss of arm abduction at shoulder (> 15 degrees)
    • Loss of sensation over deltoid muscle and lateral arm
14
Q

Musculocutaneous nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Upper extremity nerve (C5-C7)
  • Causes of injury
    • Upper trunk compression
  • Presentation
    • Loss of forearm flexion and supination
    • Loss of sensation over lateral forearm
15
Q

Radial nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Upper extremity nerve (C5-T1)
  • Causes of injury
    • Midshaft fracture of humerus
    • Compression of axilla (e.g., due to crutches or sleeping with arm over chair (“Saturday night palsy”)
  • Presentation
    • Wrist drop: loss of elbow, wrist, and finger extension
    • Decreased grip strength (wrist extension necessary for maximal action of flexors)
    • Loss of sensation over posterior arm/forearm and dorsal hand
16
Q

Median nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Upper extremity nerve (C5-T1)
  • Causes of injury
    • Supracondylar fracture of humerus (proximal lesion)
    • Carpal tunnel syndrome and wrist laceration (distal lesion)
  • Presentation
    • “Ape hand” and “Pope’s blessing”
    • Loss of wrist and lateral finger flexion, thumb opposition, lumbricals of 2nd and 3rd digits
    • Loss of sensation over thenar eminence and dorsal and palmar aspects of lateral 31⁄2 fingers with proximal lesion
    • Tinel sign (tingling on percussion) in carpal tunnel syndrome
17
Q

Ulnar nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Upper extremity nerve (C8-T1)
  • Causes of injury
    • Fracture of medial epicondyle of humerus “funny bone” (proximal lesion)
    • Fractured hook of hamate (distal lesion)
  • Presentation
    • “Ulnar claw” on digit extension
    • Radial deviation of wrist upon flexion (proximal lesion)
    • Loss of flexion of wrist and medial fingers, abduction and adduction of fingers (interossei), actions of medial 2 lumbrical muscles
    • Loss of sensation over medial 11/2 fingers including hypothenar eminence
18
Q

Recurrent branch of median nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Upper extremity nerve (C5-T1)
  • Causes of injury
    • Superficial laceration of palm
  • Presentation
    • “Ape hand”
    • Loss of thenar muscle group: opposition, abduction, and flexion of thumb
    • No loss of sensation
19
Q

Distortions of the hand

  • At rest
  • Distal vs. proximal lesions
  • Thenar vs. hypothenar atrophy
A
  • At rest, a balance exists between the extrinsic flexors and extensors of the hand, as well as the intrinsic muscles of the hand—particularly the lumbrical muscles (flexion of MCP, extension of DIP and PIP joints).
  • Distal vs. proximal lesions
    • “Clawing” is seen best with distal lesions of median or ulnar nerves.
      • Remaining extrinsic flexors of the digits exaggerate the loss of the lumbricals –>Ž fingers extend at MCP, flex at DIP and PIP joints.
    • Deficits are less pronounced in proximal lesions
      • Deficits present during voluntary flexion of the digits.
  • Thenar vs. hypothenar atrophy
    • Atrophy of the thenar eminence (unopposable thumb Ž–> “ape hand”) can be seen in median nerve lesions
    • Atrophy of the hypothenar eminence can be seen in ulnar nerve lesions.
20
Q

Distortions of the hand

  • For each
    • Location of lesion
    • Context
    • Presentation (image)
  • “Ulnar claw”
  • “Pope’s blessing”
  • “Median claw”
  • “OK gesture” (with digits 1-3 flexed)
A
  • “Ulnar claw”
    • Location of lesion: Distal ulnar nerve
    • Context: Extending fingers/at rest
    • Presentation: Image 1
  • “Pope’s blessing”
    • Location of lesion: Proximal median nerve
    • Context: Making a fist
    • Presentation: Image 1
  • “Median claw”
    • Location of lesion: Distal median nerve
    • Context: Extending fingers / at rest
    • Presentation: Image 2
  • “OK gesture” (with digits 1-3 flexed)
    • Location of lesion: Proximal ulnar nerve
    • Context: Making a fist
    • Presentation: Image 2
21
Q

Functions of hand muscles

  • Thenar vs. hypothenar
    • Thenar
    • Hypothenar
  • Dorsal vs. palmar
    • Dorsal interosseous muscles
    • Palmar interosseous muscles
  • Lumbrical muscles
A
  • Thenar vs. hypothenar
    • Thenar
      • Median
      • Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis.
    • Hypothenar
      • Ulnar
      • Opponens digiti minimi, Abductor digiti minimi, Flexor digiti minimi brevis.
    • Both groups perform the same functions: Oppose, Abduct, and Flex (OAF).
  • Dorsal vs. palmar
    • Dorsal interosseous muscles
      • Abduct the fingers.
      • DAB = Dorsals ABduct.
    • Palmar interosseous muscles
      • Adduct the fingers.
      • PAD = Palmars ADduct.
  • Lumbrical muscles
    • Flex at the MCP joint
    • Extend PIP and DIP joints.
22
Q

Obturator nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Lower extremity nerve (L2–L4)
  • Causes of injury
    • Pelvic surgery
  • Presentation
    • Decreased thigh sensation (medial)
    • Decreased adduction.
23
Q

Femoral nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Lower extremity nerve (L2–L4)
  • Causes of injury
    • Pelvic fracture
  • Presentation
    • Decreased thigh flexion and leg extension.
24
Q

Common peroneal nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Lower extremity nerve (L4–S2)
  • Causes of injury
    • Trauma or compression of lateral aspect of leg
    • Fibular neck fracture
  • Presentation: Foot drop
    • Loss of eversion and dorsiflexion.
    • Inverted and plantarflexed at rest
    • “Steppage gait.”
    • Loss of sensation on dorsum of foot.
  • PED
    • Peroneal Everts and Dorsiflexes
    • If injured, foot dropPED.
25
Q

Tibial nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Lower extremity nerve (L4–S3)
  • Causes of injury
    • Knee trauma, Baker cyst (proximal lesion)
    • Tarsal tunnel syndrome (distal lesion)
  • Presentation
    • Inability to curl toes and loss of sensation on sole of foot.
    • In proximal lesions, foot everted at rest with loss of inversion and plantarflexion.
  • TIP
    • Tibial Inverts and Plantarflexes
    • If injured, can’t stand on TIPtoes.
26
Q

Superior gluteal nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Lower extremity nerve (L4–S1)
  • Causes of injury
    • Posterior hip dislocation, polio
  • Presentation: Trendelenburg sign/gait
    • Pelvis tilts because weight-bearing leg cannot maintain alignment of pelvis through hip abduction (superior nerve Ž–> medius and minimus).
    • Lesion is contralateral to the side of the hip that drops, ipsilateral to extremity on which the patient stands.
27
Q

Inferior gluteal nerve

  • Nerve type and level
  • Causes of injury
  • Presentation
A
  • Nerve type and level
    • Lower extremity nerve (L5–S2)
  • Causes of injury
    • Posterior hip dislocation
  • Presentation
    • Difficulty climbing stairs, rising from seated position.
    • Loss of hip extension (inferior nerve –>Ž maximus).
28
Q

Sciatic nerve

  • Nerve type and level
  • Presentation
A
  • Nerve type and level
    • Lower extremity nerve (L4–S3)
  • Presentation
    • Posterior thigh
    • Splits into common peroneal and tibial nerves.
29
Q

Neurovascular pairing

  • Nerves and arteries are frequently named/
  • For each of these exceptions to this naming convention
    • Nerve
    • Artery
  • Axilla/lateral thorax
  • Surgical neck of humerus
  • Midshaft of humerus
  • Distal humerus / cubital fossa
  • Popliteal fossa
  • Posterior to medial malleolus
A
  • Nerves and arteries are frequently named together by the bones/regions with which they are associated.
  • Axilla/lateral thorax
    • Nerve: Long thoracic
    • Artery: Lateral thoracic
  • Surgical neck of humerus
    • Nerve: Axillary
    • Artery: Posterior circumflex
  • Midshaft of humerus
    • Nerve: Radial
    • Artery: Deep brachial
  • Distal humerus / cubital fossa
    • Nerve: Median
    • Artery: Brachial
  • Popliteal fossa
    • Nerve: Tibial
    • Artery: Popliteal
  • Posterior to medial malleolus
    • Nerve: Tibial
    • Artery: Posterior tibial
30
Q

Muscle conduction to contraction (417)

A
  1. Action potential depolarization opens presynaptic voltage-gated Ca2+ channels, inducing neurotransmitter release.
  2. Postsynaptic ligand binding leads to muscle cell depolarization in the motor end plate.
  3. Depolarization travels along muscle cell and down the T tubule.
  4. Depolarization of the voltage-sensitive dihydropyridine receptor, mechanically coupled to the ryanodine receptor on the sarcoplasmic reticulum, induces a conformational change, causing Ca2+ release from sarcoplasmic reticulum.
  5. Released Ca2+ binds to troponin C, causing a conformational change that moves tropomyosin out of the myosin-binding groove on actin filaments.
  6. Myosin releases bound ADP and subsequently, inorganic PO43– Ždisplacement of myosin on the actin filament (power stroke).
    • Contraction results in shortening of H** and **I** bands and between **Z lines
      • HIZ shrinkage
    • The A band remains the same length
      • A band is Always the same length
31
Q

Types of muscle fibers

  • Type 1 muscle
  • Type 2 muscle
A
  • Type 1 muscle
    • Slow twitch
    • Red fibers resulting from increased mitochondria and myoglobin concentration (increased oxidative phosphorylation) –>Ž sustained contraction.
    • 1 slow red ox
  • Type 2 muscle
    • Fast twitch
    • White fibers resulting from decreased mitochondria and myoglobin concentration (increased anaerobic glycolysis)
    • Weight training results in hypertrophy of fast-twitch muscle fibers.
32
Q

Smooth muscle contraction (418)

A
  • Increased _Ca_2+ –> _C_ontraction
  • Nitric oX**ide –> rela**Xaxation
33
Q

Bone formation

  • Endochondral ossification
  • Membranous ossification
A
  • Endochondral ossification
    • Bones of axial and appendicular skeleton, and base of the skull.
    • Cartilaginous model of bone is first made by chondrocytes.
    • Osteoclasts and osteoblasts later replace with woven bone and then remodel to lamellar bone.
    • In adults, woven bone occurs after fractures and in Paget disease.
  • Membranous ossification
    • Bones of calvarium and facial bones.
    • Woven bone formed directly without cartilage.
    • Later remodeled to lamellar bone.
34
Q

Cell biology of bone

  • Osteoblasts
  • Osteoclasts
  • Parathyroid hormone
  • Estrogen
A
  • Osteoblasts
    • Build bone by secreting collagen and catalyzing mineralization.
    • Differentiate from mesenchymal stem cells in periosteum.
  • Osteoclasts
    • Multinucleated cells that dissolve bone by secreting acid and collagenases.
    • Differentiate from monocytes/macrophages.
  • Parathyroid hormone
    • At low, intermittent levels, exerts anabolic effects (building bone) on osteoblasts and osteoclasts (indirect).
    • Chronic high PTH levels (1° hyperparathyroidism) cause catabolic effects (osteitis fibrosa cystica).
  • Estrogen
    • Estrogen inhibits apoptosis in bone-forming osteoblasts and induces apoptosis in bone-resorbing osteoclasts.
    • Under estrogen deficiency (surgical or postmenopausal), excess remodeling cycles and bone resorption lead to osteoporosis.

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