Wrist & Hand Flashcards
(44 cards)
What is the look component of the wrist exam?
Skin discoloration:
- erythema (cellulitis)
- white (arterial insufficiency)
- blue/purple (venous congestion)
- black spots (melanoma)
Trophic changes e.g. increased hair growth, altered sweat production,
Swelling
Muscle atrophy:
- thenar (median nerve)
- interossei (ulnar nerve)
Deformity:
- asymmetry
- angulation
- rotation
- amputation
- absent cascade sign
How can the carpal bones be identified?
Put finger on Lister’s tubercle of radius and slide distal to find scaphoidand lunate after “cliff”
Middle finger —> wrist to find capitate (largest carpal bone)
Trapezium and trapezoid under thumb
What is the function and innervation of palmaris brevis?
Improves grip
Superficial branch of ulnar nerve (C8, T1)
What is the function and innervation of the dorsal interossei?
Abduction of index, middle, and ring fingers at MCP
Deep branch of ulnar nerve (C8, T1)
What is the function and innervation of the palmar interossei?
Adduction of tumb, index, ring, and little fingers at MCP
Deep branch of ulnar nerve (C8, T1)
What is the function and innervation of adductor pollicis?
Adducts thumb
Deep branch of ulnar nerve (C8, T1)
What is the function and innervation of the lumbricals?
Flex MCP whilst extending IP
Medial 2 = deep branch of ulnar nerve
Lateral 2 = digital branches of median nerve
What is the function and innervation of opponens pollicis?
Medial rotation of the thumb
Recurrent branch of median nerve (C8, T1)
What is the function and innervation of abductor pollicis brevis?
Abducts thumb at MCP (point thumb towards ceiling)
Recurrent branch of median nerve (C8, T1)
What is the function and innervation of flexor pollicis brevis?
Flexes thumb at MCP
Recurrent branch of median nerve (C8, T1)
What is the function and innervation of opponens digiti minimi?
Lateral rotation of fifth metacarpal
Deep branch of ulnar nerve (C8, T1)
What is the function and innervation of abductor digiti minimi?
Abducts little finger at MCP
Deep branch of ulnar nerve (C8, T1)
What is the function and innervation of flexor digiti minimi brevis?
Flexes little finger at MCP
Deep branch of ulnar nerve (C8, T1)
What are the testing areas of the dermatomes in the hand?
Median = radial side of index finger/fingertip of index finger
Ulnar = ulnar side of little finger/fingertip of little finger
Radial = radial side of dorsum/anatomical snuffbox/2st dorsal webspace
Describe the functions of the median nerve.
Sensation: volar thumb and radial 2 and a half digits and palm
Muscles:
- superficial forearm: pronator teres, flexor carpi radialis, palmaris longus
- intermediate forearm: flexor digitorum superficialis
- deep forearm (via ant. interosseous nerve): flexor pollicis longus, pronator quadratus, radial half of flexor digitorum profundus
- intrinsic hand: thenar muscles via recurrent branch, and radial two lumbricals (LOAF)
Branches: ant. interosseous nerve and palmar cutaneous nerves
What are the causes of carpal tunnel syndrome?
TRAMP
Trauma RA Acromegaly Myxodema (hypothyroidisim) Pregnancy
What is the result of a lesion at the wrist causing damage to the median nerve e.g. lacerations proximal to flexor retinaculum?
Paralysis of thenar muscles —> cannot oppose thumb
Paralysis of radial two lumbricals —> cannot flex at MCP or extend at IP of index and middle fingers
= hand of Benediction (when trying to make a fist, can only flex little and ring fingers)
Describe the functions of the ulnar nerve.
Sensation: volar and dorsal ulnar one and a half digits and palm/dorsum
Muscles:
- ant. forearm: flexor carpi ulnaris, flexor digitorum profundus
- hypothenar muscles: abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi, palmaris brevis
- intrinsic hand: ulnar two lumbricals, adductor pollicis, interossei (all except LOAF)
Branches: palmar cutaneous branch, dorsal cutaneous branch, superficial branch
What is the result of a lesion at the wrist damaging the ulnar nerve?
Loss of palmar branch and superficial branch —> sensory loss over palmar ulnar one and a half fingers
Paralysis of interossei —> fingers cannot aduct or adduct
Paralysis of ulnar two lumbricals —> cannot flex at MCP joints or extend at IP joints of ring or little fingers
Unopposed action of extensor muscles —> hyper-extension of MCP joints and hyper-flexion of IP joints
= ulnar claw (presentation at rest)
Describe the functions of the radial nerve.
Sensation: radial half of dorsum
Muscles:
- superficial foream: brachioradialis, extensor carpi radialis longus and brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, anconeus
- deep forearm: supinator, abductor pollicis longus, extensor pollicis longus and brevis, extensor indicis
Branches: lower lateral cutaneous nerve of arm, posterior cutaneous nerve of arm and forearm, superficial branch of radial nerve
What is Phalen’s test?
Hold wrist in forced flexion by pressing against each other for 30s-60s
In carpal tunnel causes paraesthesia in distribution of digital branch of median nerve
What is Tinel’s test?
Tapping the flexor retinaculum elicits paraesthesia in the distribution of the digital branch of the median nerve in carpal tunnel.
How do you test for the function of flexor digitorum superficialis?
PIP flexion
Isolate by extending other three digits to fix other FDPs (one common muscle belly)
How do you test for the function of flexor digitorum profundus?
DIP flexion
Isolate by fixing FDS at same finger (four separate muscle bellies)
