Day 1.3 MSK Flashcards
How is the upper trunk lesioned? What happens when it is?
Lesioned by trauma- most often in birth, but also from hyperextension of neck- so MVA.
Causes Erb-Duchenne Palsy (waiter’s tip)
What are the characteristics of Erb-Duchenne Palsy?
Traction/tear of upper trunk (C5, C6 roots). “Waiter’s tip”:
paralysis of abductors (limb hangs by side)
medially rotated (paralysis of lateral rotators)
forearm is pronated (loss of biceps to supinate)
How is the C7 root injured?
Compressed by cervical disk lesion/herniation
How is the axillary nerve lesioned?
Fracture of surgical neck of humerus
Dislocation of humerus
Intramuscular injection
What are the characteristics of an axillary nerve lesion?
Axillary goes to deltoid m, which is the primary abductor of the arm. So loss of abduction, also decreased sensation over deltoid- check this before and after fixing a dislocation.
How is the radial nerve in the spiral groove lesioned?
Midshaft fracture to the humerus
How is the deep branch of the radial nerve injured?
Stretched by sublexation of the radius
How is the recurrent branch of the median nerve injured?
Lesioned by superficial laceration
How is the lower trunk of the brachial plexus injured?
Compressed by a cervical rib or by Pancoast’s tumor. Leads to Klumpke’s palsy
What is klumpke’s palsy?
Childbirth defect affecting the inferior trunk of the brachial plexus (C8, T1)
What is thoracic outlet syndrome?
Cervical rib can compress the subclavian artery and inf trunk of brachial plexus, resulting in thoracic outlet syndrome
- atrophy of thenar and hypothenar eminance
- atrophy of interosseous muscles
- sensory deficits on medial side of forearm and hand
- disappearance of radial pulse when head is moved toward opposite side
Other than a cervical rib/Klumpke’s palsy, what can cause thoracic outlet syndrome?
Hypertrophy of the anterior scalene muscle
What is Klumpke’s total claw?
Lesion of lower trunk (C8, T1), leading to loss of fn of all lumbricals.
forearm finger flexors (part of median nerve w C5-C7) and finger extensors radial nerve) are unopposed, so there is clawing of all digits
How is the radial nerve injured in the axilla?
Compressed:
Incorrect use of crutch
Drunk on bench- Saturday night palsy
How is the median nerve injured near the elbow?
Compressed by supracondylar fracture of the humerus
Pronator teres syndrome
How is the ulnar nerve lesioned near the elbow?
Lesioned by repeated minor trauma
Fracture of the medial epicondyle of the humerus
How is the anterior interosseous nerve lesioned?
Compressed in deep forearm
How is the median nerve injured near the wrist?
Compressed by carpal tunnel syndrome (9 tendons run through carpal tunnel) or by dislocated lunate