MSK - OMG - SCURRED - DIES. Flashcards
what are tight junctions composed of?
- occludins / claudins
- prevent paracellular solute movement
what are cadherins?
Ca2+ dependent adhesion proteins –> found in adherins junction & connects actin cytoskeletons of adjacent cells
what is the significance of cadherins?
loss of E-cadherin –> metastasis
what is the disease associated w/ autoantibodies against desmosomes?
pemphigus vulgaris
what are desmosomes?
structural support via keratin interactions
what are integrins?
membrane proteins binding to collagen / laminin in BM –> maintain “BM integrity)
what is the significance of an abnormal passive abduction test (Valgus)
MCL injury
significance of an abnormal passive adduction? (varus)
LCL injury
mcmurray test
pain on external rotation –> medial meniscus
pain on internal rotation –> lateral meniscus
unhappy triad
-ACl
MCL
medial meniscus injury
where do you inject to relieve delivery pain?
pudendal nerve –> ischial spine
rotator cuff muscles (4)
1) supraspinatus
2) infraspintaus
3) teres minor (axillary nerve)
4) subscapularis
supraspinatus function
abducts arm
infraspintaus function
laterally rotates arm
teres minor function
adducts / laterally rotates arm
subscapularis function
medially rotates / adducts arm
where is scaphoid found and why is ti prone to avascular necrosis?
- anatomical snuff box
- most commoonly fractured carpal bone
- avascular necrosis b/c: retrograde blood supply
what are the wrist bones / describe what is seen on xray?
So Long To Pinky, Here Comes The Thumb Scaphoid Lunate Triquetrum Pisiform Hamate Capitate Trapezoid Trapezium
Trapezium / trapezoid overlap on the base of the thumb. Capitate is the largest, well differentiated bone on the 1st row.
Scaphoid is the biggest bone on the bottom row (right next to distal radius)
Triquetrum/pisiform overlap
what nerve runs adjacent to the hook of the hamate?
ulnar nerve
guyon canal syndrome?
compression of the ulnar nerve
erbs palsy injury
tear of upper trunks C5-C6 roots
examples of erb palsy injuries:
infants: lateral traction on neck during delivery
adults: trauma
functional deficits from erb’s palsy
1) deltoid/supraspinatus = no abduction (arm hangs loose)
2) infraspinatus = no lateral rotation (arm rotated medially)
3) biceps = no flexion / supination (arm pronated + extended
klumpke palsy injury + causes
tear of lower trunk: C8-T1
1) infants: upward force during delivery
2) adults: trauma: grabbing tree to break a fall
klumpke deficits
intrinsic hand muscles: lumbricals, interossei, thenar, hypothenar –>
1) total CLAW hand: unable to flex MCP, unable to extend DIP / PIP
thoracic outlet syndrome
compression of lower trunk / subclavian vessels
typical injury causing thoracic outlet syndrome
cervical rib injury / pancoast tumor
deficits in thoracic outlet syndrome
intrinsic hand muscles:
1) lumbricals
2) interossei
3) thenar
4) hypothenar
thoracic outlet syndrome presentation
atrophy of intrinsic hand muscles: ischemia, pain, edema due to vascular compression
winged scapula injury / causes
axillary node dissection / stab wounds –> long thoracic nerve
deficit on winged scapula
serratus anterior: inability to anchor scapula –> cannot abduct arm above horizontal
axillary (C5-C6) cause of injury
cause: fractured surgical neck of humerus (or anterior humerus dislocation)
axillary presentation
1) flattened deltoid
2) loss of arm abduction at shoulder (>15 degrees)
3) loss of sensation over deltoid muscle / lateral arm
musculocutaneous (C5-C7) causes of injury
upper trunk compression
musculocutaneous presentation
1) loss of forearm flexion / supination
2) loss of snsation over the lateral forearm
radial nerve (C5-T1) causes of injury (2)
1) midshaft fracture of humerus
2) compression of axilla
radial nerve presentation
1) wrist drop (loss of extension along elbow, wrist, fingers)
2) dec. grip strength (limited action of flexors)
3) loss of sensation over posterior arm / forearm + dorsal hand
median (C5-T1) causes of injury (2)
1) supracondylar fracture of humerus (Proximal)
2) carpal tunnel syndrome via wrist laceration (distal)
median nerve presentation
“ape hand” / “pope’s blessing
1) loss of wrist / lateral finger flexion, thumb opposition, 2/3 lumbricals
2) loss of sensation over thenar eminence
ulnar nerve (C8-T1) causes of injury (2)
1) fracture of medial epicondyle of humerus –> HAHA FUNNY BONE (proximal)
2) hook of hamage (distal)
ulnar deficit presentation
Ulnar claw on digit extension
1) if proximal: radial deviation
2) loss of wrist / medial finger flexion, abduction/adduction
3) loss of sensation over medial 1.5 fingers, including hypothenar eminence
what nerve deficit best defines clawing?
distal median / ulnar nerves
when do proximal ulnar / median lesions present?
voluntary flexion of the digits
thenar muscles are controlled by?
median OAF:
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis