Hand

Question 1

Intrinsic Hand Muscles + Innervation

Answer 1

• Thenar - abductor pollicus brevis, opponens pollicus, flexus pollicus brevis (all oppose) - median
  
  • Except deep head of FBP is 50% ulnar
• Adductor pollicus - ulnar
• Hypothenar - abductor digiti min, opponens digiti min, flexor digitorum min - ulnar
• Interosseous and lumbricals (abduct and adduct fingers and flex phalanges) - ulnar

Question 2

Extrinsic Hand Muscles + Innervation in General

Answer 2

Flexors (median nerve)

Extensors (radial nerve)

Question 3

Median Nerve

Ulnar Nerve

Radial Nerve

Answer 3

• Median - Passes thru wrist just deep to palmaris longus and w/in flexor retinaculum –> motor branch to thumb and sensory to “volar hand”, thumb, index, middle and 1/2 ring finger
• Ulnar - Passes thru wrist Guyon’s canal and provides sensory to ulnar half of hand and motor to hypothenar, interosseous and adductor pollicus muscles
• Radial- No motor to intrinsic hand muscles but motor to extensors and sensation to DORSAL thumb, index, middle fingers

Question 4

Blood Supply

Answer 4

• Radial and ulnar arteries –> superficial and deep branches (communication b/n radial and ulnar in each arch)
• Superficial arch (mainly ulnar) - supplies digital arteries
• Deep Palmar arch (mainly radial)

Question 5

7 Causes of Carpal Tunnel

Answer 5

• Occupational prolonged wrist flexion or extension - typing, biking
• Bone overgrowth after fracture (bony impinges on nerve)
• Rheumatoid arthritis –> flexor tendon sheath thickening (tenosynovitis)
• Hypothyroidism –> mucin deposition
• Amyloidosis - amyloid deposition
• Pregnancy - inc connective tissue deposition
• Lipomas or ganglion cysts can reduce space in Carpal Tunnel

Question 6

Pathophysiology of Carpal Tunnel

Answer 6

• axon ischemia b/c perineural vascular plexus is compressed –> dec venous return, intramural edema, axonal membrane instability, dec signal transduction and if chronic … fibrosis

Question 7

3 Physical Exam Tests

Answer 7

• Dec 2-pt discrimination
• Tinel Test - percuss over median nerve (try to reproduce symptoms - POS)
• Phelan Test - forced wrist flexion for 1 min (try to reproduce symptoms - POS)

Question 8

Carpal Tunnel Tx

Answer 8

• Non-surgical - (early) night splints, steroid injection into Carpal tunnel if inflammatory cause
• Surgical - (successful if in first 2 yrs) transect transverse carpal ligament to open tunnel roof

Question 9

8 Carpal Bones

Answer 9

• Prox - scaphoid, Junate, triquetrum, pisiform
• Distal - trapezium, trapezoid, capitate, hamate
• “Some Lovers Try Positions That They Can’t Handle”

Question 10

What runs in Guyon’s canal?

Answer 10

Ulnar artery and ulnar nerve

Question 11

Classification (3) and Tx of Wrist Sprains

Answer 11

• I - stretch or micro-tear
• II-partial tear w/ mild joint instability
• III- severe or complete tear w/ sig instability

Tx - RICE, braces, NSAIDs

Question 12

Scaphoid Fracture

Answer 12

Scaphoid - in anatomic snuff box (point tenderness in box)

• high risk of avascular necrosis (retrograde and limited blood supply)
• present w/ difficulty grabbing objects
• often take awhile to declare themselves; may not come up on Xray for 2 wks (CT or MRI)

Tx- place in long or short arm cast; arrange 2 wk follow-up; may need closed reduction (screws) or open reduction

Question 13

Hamate Fracture

Answer 13

• present w/ injury from hammer, racket, golf club use
• point tenderness in hypothenar region
• may be seen on carpal view but may also take time to declare themselves
• Tx – ulnar gutter splint or cast; arrange 2 wk follow-up films; may resect hamate bone, decompress ulnar artery or ulnar artery bypass to reperfuse ulnar aspect of hand