Shoulder Flashcards
Shoulder muscles that form the rotator cuff
Supraspinatus, Infraspinatus, Teres minor, Subscapularis (SItS)
Supraspinatus: innervation, action, and injury (+ test)
suprascapular nerve, abducts arm initially (before the action
of the deltoid); most common rotator
cuff injury (trauma or degeneration and impingement leads to tendinopathy/tears (empty/full can test)
Infraspinatus: innervation, action, and injury
suprascapular nerve, externally rotates arm; pitching injury
Teres minor: innervation, action
axillary nerve, adducts and externally rotates arm
Subscapularis: innervation, action
upper and lower subscapular nerves, internally rotates and adducts arm
Arm abduction 0 to > 90 degrees
Supraspinatus (0-15), deltoid (15-90), trapezius and serrates ant (>90)
Causes of injury to axillary nerve
Fractured surgical neck of humerus/Anterior dislocation of humerus
Presentation of axillary nerve lesion
Flattened deltoid
Loss of arm abduction at shoulder (> 15°)
Loss of sensation over deltoid and lateral arm
Causes of injury to musculocutaneous
Upper trunk compression
Presentation of musculocutaneous nerve lesion
decreased biceps (C5-6) reflex
Loss of forearm flexion and supination
Loss of sensation over radial and dorsal forearm
Causes of radial nerve lesion
Compression of axilla, eg, due to crutches or sleeping with arm over chair (“Saturday night palsy”)
Midshaft fracture of humerus
Repetitive pronation/supination of forearm, eg, due to screwdriver use (“finger drop”)
Presentation of radial nerve lesion
above elbow: loss of sensation over posterior arm/forearm and dorsal hand, wrist drop (loss of elbow, wrist, and finger extension) with decreased grip strength (wrist extension necessary for maximal action of flexors)
below elbow: cause distal paresthesias without wrist drop
Tricep function and posterior arm sensation spared in midshaft fracture
Causes of injury to median nerve (proximal & distal)
Supracondylar fracture of humerus (proximal lesion)
Carpal tunnel syndrome and wrist laceration (distal lesion)
Presentation of median nerve lesion
“Ape hand” and “Hand of benediction”
Loss of wrist flexion and function of the lateral two Lumbricals, Opponens pollicis, Abductor pollicis brevis, Flexor pollicis brevis (LOAF)
Loss of sensation over thenar eminence and dorsal and palmar aspects of lateral 3 1/2 fingers with proximal lesion
Causes of ulnar nerve lesion (proximal, distal, compression)
Fracture of medial epicondyle of humerus (prox lesion)
Fractured hook of hamate (distal lesion) from fall on outstretched hand
Compression of nerve against hamate as the wrist rests on handlebar during cycling
Presentation of ulnar nerve lesion
“Ulnar claw” on digit extension
Radial deviation of wrist upon flexion (proximal lesion)
Decreased flexion of ulnar fingers, abduction and adduction of fingers (interossei), thumb adduction, actions of ulnar 2 lumbrical muscles
Loss of sensation over ulnar 1 1/2 fingers including hypothenar eminence
Causes of recurrent branch of median nerve injury
superficial laceration of palm
Presentation of recurrent branch of median nerve lesion
“Ape hand”
Loss of thenar function (opposition, abduction, & flexion of thumb)
no loss of sensation
What is injured in Erb’s palsy
Upper trunk (C5-C6 roots)
How does upper trunk lesions (Erb’s) occur in infants & adults
Infants: lateral traction of neck on delivery
Adults: trauma = neck traction
Presentation of Erb’s palsy
Arm hangs by the side (no abduction)
Arm medially rotated (no lateral rotation)
Arm extended & pronated (no flexion, supination)
Injury in Klumpke’s palsy
Lower trunk (C8-T1)
Causes of Klumpke’s in infants & adults
Infants: upward force on arm in delivery
Adults: trauma (grabbing tree branch in fall)
Muscle deficit in Klumpke’s
intrinsic hand muscles (lumbricals, interossei, thenar, hypothenar)
