Hand And Wrist

Question 0

Carpal bones

Answer 0

• Eight carpal bones -> arranged in proximal and distal rows of four.  
• Lateral -> medial in proximal row: 
• Scaphoid (“boat”) – most commonly fractured 
• Lunate (“moon”) 
• Triquetrum (“3 cornered”) 
• Pisiform (“pea”) 
Lateral -> medial in distal row: 
• Trapezium (“Table”) 
• Trapezoid (resembles trapezium) 
• Capitate (“Head”) 
• Hamate (“Little hook”)

Question 1

Bones of the hand & wrist

Answer 1

3 groups of bones: 
• Carpals, n=8 
• Metacarpals, n=5 
• Phalanges, n=14 
• Cartilaginous at birth. 
• Ossified by 12-years-of-age.

Question 2

Condyloid joint

Answer 2

Oval articular surface of one bone fits into complementary concavity in another.

Question 3

Wrist (Radiocarpal) joint

Answer 3

• Synovial (condyloid) joint between the distal end of the radius and the articular disc overlying the distal end of the ulna, and the scaphoid, lunate and triquetrum.
• Anterior & posterior ligaments strengthen the joint capsule.
• Movements: flexion, extension, abduction, adduction and circumduction.

Question 4

Wrist ligaments

Answer 4

Palmar radiocarpal and palmar ulnocarpal ligaments reinforce the wrist joint capsule.
Dorsal roadiocarpal and radial and ulnar collateral ligaments reinforce the wrist joint.

Question 5

Phalanx ligaments

Answer 5

Deep transverse metacarpal ligament holds metacarpals together to prevent abduction.

Question 6

Carpometacarpal (CMC) joint

Answer 6

Synovial Plane joint

Question 7

Phalangeal (finger) joints

Answer 7

Metacarpophalangeal (MCP) joint synovial condyloid
Proximalinterphalangeal (PIP) joint hinge joint
Distalinterphalangeal (DIP) joint hinge joint

Question 8

What is the function of the phalangeal ligaments

Answer 8

To secure tendons of flexor digitorum superficialis and profundus to phalanges

Question 9

What is the function of the extensor retinaculum?

Answer 9

To secure extensor muscles/ tendons to wrist.

Question 10

What is the function of the synovial sheaths?

Answer 10

To protect, cushion and nourish surrounding tendons/ muscles/ bones.

Question 11

Flexor Retinaculum

Answer 11

Thickening of deep fascia that holds long flexor tendons in position at the wrist.
Proximal border = distal transverse skin crease on anterior wrist.
Distal border = attached to palmar aponeurosis.
Medial attachment = pisiform bone and hook of hamate.
Lateral attachment = tubercle of scaphoid and trapezium bones.

Question 12

Carpal Tunnel

Answer 12

Created by position of carpal bones and flexor retinaculum.
• 4 tendons of flexor digitorum profundus
• 4 tendons of flexor digitorum superficialis
• Tendon of flexor pollicis longus
• Median nerve

Question 13

Carpal Tunnel Syndrome

Answer 13

• Entrapment syndrome.
• Pressure on median nerve.
• Aetiology: overuse, swelling of tendons and tendon sheaths (e.g.
rheumatoid arthritis) and cysts arising from carpal joints.
• Symptoms: pain and pins and needles in distribution of median nerve.
• Treatment: surgery, corticosteroid injections.

Question 14

Palmar aponeurosis

Answer 14

Gives firm attachment to overlying skin to improve grip and protect underlying tendons.

Question 15

Intrinsic hand muscles

Answer 15

• Entirely within hand (on palmar side)
• Execute precision movements.
• Palmaris brevis
• Interossei (dorsal or palmar) (n=7 or 8)
• Lumbrical muscles (n=4)
• Adductor pollicis
• Thenar
• Hypothenar

Question 16

Arteries of the palm

Answer 16

Ulnar artery => superficial palmar arch
Radial artery => deep palmar arch
Anastomoses between the two

Question 17

Thumb movements

Answer 17

• Abductor pollicis brevis (abducts thumb, moves anterior in AP
plane)
• Adductor pollicis (adducts thumb)
• Extensor pollicis longus
• Flexor pollicis brevis (flexes thumb at CM and MCP joints)
• Flexor pollicis longus
• Opponens pollicis (moves thumb to touch tip of little finger)

Question 18

Superficial palmar arch

Answer 18

Ulnar artery anterior to flexor retinaculum
Superficial palmar arch (deep to palmar aponeurosis)
Anastomoses with radial artery
4 digital arteries

Question 19

Deep palmar arch

Answer 19

Direct continuation of the radial artery.
Joins with deep branch of ulnar artery.
Sends branches superiorly to anastomose around wrist joint and inferiorly to join digital branches of superficial palmar arch.

Question 20

Arteries of the palm

Answer 20

Thumb and lateral side of index finger mainly supplied by radial artery
Medial side of index finger, middle, ring and little finger mainly
supplied by ulnar artery

Question 21

Venous network

Answer 21

Dorsal venous network drain back into basilic and cephalic veins

Question 22

Dermatomes

Answer 22

C6 =  Thumb 
C7 =  index & middle finger 
C8 =  ring & little finger

Question 23

Median nerve palsy

Answer 23

Median nerve lesion result in inability to flex thumb, index and
middle finger at MCP joint.
Ring and little fingers still flexed because the ulnar nerve is intact.

Question 24

Ulnar nerve palsy “Claw hand”

Answer 24

Ulnar nerve lesion results in inability to flex the DIP joint of ring and little finger.
Patients can’t make a complete fist.
Also can’t extend interphalangeal joints to straighten fingers.

Question 25

Radial nerve palsy “Wrist drop”

Answer 25

Radial nerve lesion results in denervation of extensor muscles in forearm.
Because forearm flexor muscles no longer opposed, wrist drops.