Part 9: Wrist and Hand Flashcards
Describe the cutaneous innervation of the dorsum of the hand
Radial nerve: radial 3.5/2.5 digits
Ulnar nerve: ulnar 1.5/2.5 digits
Median nerve: Distal radial phalanges
Distal ulnar phalanges supplied by superficial ulnar
Describe the venous drainage network of hand
Large veins drain from palm form dorsal venous network (superficial to extensor tendons) and forms cephalic (radial) and basilic vein (ulnar side)
Why is the venous network largely dorsal?
Pressure of palmar gripping does not impede flow
What is the posterior carpal arch?
Arterial anastomosis of radial, ulnar and anterior IO art. Sends branches distal to spaces deep to tendons
List the bones of the wrist joint
Distal radius, scaphoid, lunate and triquetral bones.
RU articular disc is also involved
The wrist capsule is thicker at which aspect
Palmar
Palmaris brevis is attached to what?
Attached to dermis across base of hypothenar eminence. Part of panniculus carnosus
Describe the cutaneous innervation of palm
Superficial and palmar branches of ulnar supply ulnar side and digits
Median nerve and palmar branch supply majority of palmar surface
Radial nerve supplies base of thenar eminence
Describe palmar aponeurosis and function
Degenerating tendon of palmaris longus as it fans out towards fingers in 4 slips. Superficial fibres are inserted into skin, deep insertion to transverse ligament of palm. Provides grip by securing skin and protects underlying tendons
Flexor retinaculum attachments
Radial side:
Scaphoid tubercle and trapezium ridge
Ulnar side:
Pisiform and hook of hamate
What muscles arise from flexor retinaculum
thenar and hypothenar eminence muscles
Which tendon fuses with flexor retinaculum
PL
Describe the ulnar nerve path in relation to flexor retinaculum
Nerve lies ulnar side of PL tendon on pisiform. Divides into superficial and deep branches at distal border
Contents of Carpal Tunnel
FDS and FDP (in one synovial sheath), median nerve, FPL, FCR
Muscles of thenar eminence with origins and attachments
Abductor pollicis brevis (FR/scaphoid tubercle to radial side base proximal phalanx and tendon EPL) Flexor pollicis brevis (FR and trapezium to radial sesamoid of thumb thus radial border prox phalanx) Opponens pollicis (FR + trapezium to radial border MC of thumb)
Innervation of muscles of thenar eminence
Muscular (recurrant) branch of median nerve. Rarely EPB has double supply with ulnar, more frequently opponens had double supply
(C8-T1)
Muscles of hypothenar eminence and origins and attachments
Opponens digiti minimi (FR + hook of hamate inserts to ulnar border 5th MC)
Flexor digiti minimi brevis (FR inserted to base prox phalanx)
Abductor digiti minimi (FR and pisiform bone inserts to ulnar base prox phalanx extensor expansion)
Innervation of hypthenar eminence
Ulnar nerve (deep branch C8-T1)
Describe the superficial palmar arch
Arterial arcade continuation of ulnar art. (often not arch unless anastomses with radial art.)
Gives off palmar digital artery and 3 common palmar digital arteries to web spaces
Describe digital nerves
Common palmar nerves lie deep to superficial arch arising form medial and lateral branches of median nerve and superficial branch of ulnar nerve. Divide into proper palmar digital nerves and run superficially on both ulnar and radial aspect of digits to supply palmar surface of digits.
Lumbrical Muscles origin and attachment
O: Radial side FDP I: Extensor expansions A: Likely proprioception between flexor and extensor compartments for fine movements ? if actually works in movement significantly at all N: 2 ulnar = ulnar 2 radial = median
Adductor Pollicis origin, insertion, action and innervation
O: transverse head - length 3rd MC
Oblique head - base 2nd + 3rd MC and carpal bones
I: Ulnar sesamoid (thus ulnar side prox phalanx)
A: Adduction
N: Deep branch ulnar nerve (C8,T1)
Radial artery path in hand
Slopes across snuffbox over trapezium between 1st dorsal IO and adductor pollicis. Gives off arteria radialis indicis and princeps pollicis then terminates into deep palmar arch which combines with deep branch of ulnar
Ulnar nerve in hand path
Enters beneath FCU and over FR where it divides into superficial and deep branches.
Superficial supplies palmaris brevis and ulnar digital nerves
Deep branch supplies hypothenar muscles, 2 lumbricals, all interossei and 2 heads of adductor pollicis
Describe interossei muscles
Palmar: smaller and arise from their own MC bone. Adduct finger towards middle finger. Middle finger has no palmar interossei.
Dorsal: large, arise from adjacent MC. Abduct.
Supplied by deep branch of ulnar nerve.
Describe fibrous flexor sheaths
Strong unyielding sheaths of connective tissue from MC heads over all 5 digits and are occupied by flexor tendons
Describe the synovial flexor sheaths
Flexor tendons are invested in synovial sheath from lower forearm to terminal phalanx to allow frictionless movement of tendons (apart from a short distance on index, middle and ring fingers in mid palm)
Describe digital attachments of flexor tendons
FDS: enters fibrous sheath on palmar surface of FDP. FDS divides into 2 and attaches to base middle phalanx
FDP passes distal and base terminal phalanx and is attached to sides of middle phalanx
Describe extensor tendons and expansions
Extensor tendons cross MCPJ partly form capsule. Splits into 3 slips:
Central inserts into middle phalanx
Lateral - augmented by IO and lumbricles inserted into terminal phalanx
Describe the tendons of MCs
Superficial transverse MC - Beneath palmar skin at free margins of webs
Deep transverse MC lig - Joins palmar ligs of MCPJ and lies deep and proximal to superficial transverse MC lig
