Hand and Wrist Flashcards
What forms the flexor retinaculum?
Thickening of the antebrachial (deep) fascia of the anterior forearm = firstly at aspect of wrist joint then deeper and distally as transverse carpal ligament
Where does the flexor retinaculum attach laterally and medially?
Laterally = scaphoid/trapezoid Medially = pisiform and hamate
What does the flexor retinaculum prevent?
Bowstringing of the tendons during flexion, which would reduce muscle efficiency
What strengthens the flexor retinaculum?
Distal tendon of palmaris longus (fuses with flexor retinaculum)
What forms the carpal tunnel?
Carpal bones posteriorly and the flexor retinaculum anteriorly
What are the contents of the carpal tunnel?
Long tendons of forearm flexor muscles (FDS, FDP, FPL) and the median nerve (enters palm via tunnel)
What causes carpal tunnel syndrome?
Compression of the median nerve due to swelling in the tunnel
Why is the palmar cutaneous branch of the median nerve spared from carpal tunnel syndrome?
Given off proximal to tunnel and travels superficially to reach the skin of the palm (sensation to central palm unaffected)
What forms the superficial palmar arch?
Superficial palmar branch of the ulnar artery anastomoses with the superficial branch of the radial artery
Where is the superficial palmar arch formed?
Immediately deep to the palmar aponeurosis
What forms the deep palmar arch?
Deep branch of the radial artery anastomosing with the deep branch of the ulnar artery
Where does the deep palmar arch lie?
Runs across anterior aspects of the bases of the metacarpals
What is Dupuytren’s contracture?
Pathology affecting palmar fascia = causes thickening and shortening leading to fixed flexions of the ring and little fingers
What are the four neurovascular bundles that supply each finger?
Medial palmar, lateral palmar, medial dorsal, lateral dorsal
How does the ring block anaesthetic technique work?
Local anaesthetic deposited in ring around base of finger to block all four proper digital nerves = surgery/suturing can be performed distal to block
What nerves innervate the dorsal hand?
Ulnar, median and radial nerves
Where does the ulnar nerve supply on the dorsal hand?
Medial part of dorsum of hand, little finger, medial half of ring finger
Where does the median nerve supply on the dorsal hand?
Skin over distal phalanges/nail beds of thumb, index finger, middle and ring fingers
Where does the radial nerve supply on the dorsal hand?
Skin over anatomical snuff box, lateral part of dorsum of hand, proximal thumb, middle and ring fingers
How many lumbricals are there?
Four = one for each finger
Where do the lumbricals attach?
Between the FDP tendon and extensor expansion of same digit
Where do the lumbricals span?
Anterior aspect of second to fifth MCP joints and then the posterior aspect of the second to fifth PIP joints
What action do the lumbricals perform?
Flexion of the MCPs and extension of the PIPs
What nerves supply the lumbricals?
Median two lumbricals = ulnar nerve
Lateral two lumbricals = median nerve
