Part 9: Wrist and Hand

Question 1

Describe the cutaneous innervation of the dorsum of the hand

Answer 1

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

Question 2

Describe the venous drainage network of hand

Answer 2

Large veins drain from palm form dorsal venous network (superficial to extensor tendons) and forms cephalic (radial) and basilic vein (ulnar side)

Question 3

Why is the venous network largely dorsal?

Answer 3

Pressure of palmar gripping does not impede flow

Question 4

What is the posterior carpal arch?

Answer 4

Arterial anastomosis of radial, ulnar and anterior IO art. Sends branches distal to spaces deep to tendons

Question 5

List the bones of the wrist joint

Answer 5

Distal radius, scaphoid, lunate and triquetral bones.

RU articular disc is also involved

Question 6

The wrist capsule is thicker at which aspect

Answer 6

Palmar

Question 7

Palmaris brevis is attached to what?

Answer 7

Attached to dermis across base of hypothenar eminence. Part of panniculus carnosus

Question 8

Describe the cutaneous innervation of palm

Answer 8

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

Question 9

Describe palmar aponeurosis and function

Answer 9

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

Question 10

Flexor retinaculum attachments

Answer 10

Radial side:
Scaphoid tubercle and trapezium ridge
Ulnar side:
Pisiform and hook of hamate

Question 11

What muscles arise from flexor retinaculum

Answer 11

thenar and hypothenar eminence muscles

Question 12

Which tendon fuses with flexor retinaculum

Answer 12

PL

Question 13

Describe the ulnar nerve path in relation to flexor retinaculum

Answer 13

Nerve lies ulnar side of PL tendon on pisiform. Divides into superficial and deep branches at distal border

Question 14

Contents of Carpal Tunnel

Answer 14

FDS and FDP (in one synovial sheath), median nerve, FPL, FCR

Question 15

Muscles of thenar eminence with origins and attachments

Answer 15

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)

Question 16

Innervation of muscles of thenar eminence

Answer 16

Muscular (recurrant) branch of median nerve. Rarely EPB has double supply with ulnar, more frequently opponens had double supply
(C8-T1)

Question 17

Muscles of hypothenar eminence and origins and attachments

Answer 17

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)

Question 18

Innervation of hypthenar eminence

Answer 18

Ulnar nerve (deep branch C8-T1)

Question 19

Describe the superficial palmar arch

Answer 19

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

Question 20

Describe digital nerves

Answer 20

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.

Question 21

Lumbrical Muscles origin and attachment

Answer 21

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

Question 22

Adductor Pollicis origin, insertion, action and innervation

Answer 22

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)

Question 23

Radial artery path in hand

Answer 23

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

Question 24

Ulnar nerve in hand path

Answer 24

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

Question 25

Describe interossei muscles

Answer 25

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.

Question 26

Describe fibrous flexor sheaths

Answer 26

Strong unyielding sheaths of connective tissue from MC heads over all 5 digits and are occupied by flexor tendons

Question 27

Describe the synovial flexor sheaths

Answer 27

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)

Question 28

Describe digital attachments of flexor tendons

Answer 28

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

Question 29

Describe extensor tendons and expansions

Answer 29

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

Question 30

Describe the tendons of MCs

Answer 30

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