BMS271 - Hand

Question 1

Carpometacarpal and Intermetacarpal Joints

Answer 1

Plane synovial joints except:
Carpometacarpal joint of thumb = saddle joint
Not much movement at these joints, except thumb; flexion-extension, abduction-adduction
The 1st carpometacarpal joint is primarily responsible for the movement of opposition
2/3 movement here, 1/3 at 4th and 5th carpometacarpal joints (and intercarpal joints)
2nd + 3rd MCP joints = very stable

Question 2

Metacarpophalangeal Joints

Answer 2

Condyloid synovial joints
Flexion-extension, abduction-adduction and circumduction of digits 2-5
Palmar and collateral ligaments support joints
Deep transverse metacarpal ligament joins mets 2-5
Digit 1 MCP joint
little abduction-adduction or extension from neutral
supported anteriorly by sesamoids
1st MCP joint increases flexion of thumb in opposition
Palmar ligaments are fibrocartilaginous and prevent pinching of flexor tendons in flexion. They are firmly attached to phalanx and loosely attached to metacarpal.

Question 3

Interphalangeal Joints

Answer 3

1st digit has only one IP joint, digits 2-5 have a proximal IP joint and a distal IP joint (PIP, DIP)
Each IP joint is a synovial hinge joint, has a palmar ligament and two collateral ligaments
Palmar plates increase joint congruence, and resist hyperextension and compressive forces
Proximal articular surface is larger than distal
Flexion of these joints increases medially
ie the 5th is more able to flex than the 2nd

Question 4

Palmaris Brevis

Answer 4

Attachments:
- flexor retinaculum and medial border of palmar aponeurosis
- dermis of medial border of hand
Actions:
- deepens groove along medial aspect of hypothenar eminence, wrinkles skin, slightly accentuates eminence
may contribute to grip
Innervation:
- superficial branch of the ulnar nerve (C8, T1)

Question 5

Flexor Pollicis Brevis

Answer 5

Attachments:
- Flexor retinaculum, tubercles of trapezium and trapezoid
- Lateral aspect of base of 1st proximal phalanx
Actions:
- Flexion of thumb
Innervation:
- Median nerve (C8, T1) (deep head often ulnar nerve)

Question 6

Abductor Pollicis Brevis

Answer 6

Attachments:
- Flexor retinaculum, tubercles of trapezium and scaphoid
- Lateral aspect of base of 1st proximal phalanx
Actions:
- Abducts 1st digit
- Assists in opposition by rotating 1st digit medially
Innervation:
- Median nerve (C8, T1)

Question 7

Opponens Pollicis

Answer 7

Attachments:
- Flexor retinaculum, tubercles of trapezium and scaphoid
- Lateral surface of 1st metacarpal
Actions:
- Opposes (draws medially and medially rotates) 1st metacarpal
Innervation:
- Median nerve (C8, T1)

Question 8

Adductor Pollicis

Answer 8

Attachments:
- Oblique head: capitate, bases of metacarpals 2 and 3
- Transverse head: anterior shaft 3rd metacarpal
- Medial aspect of base of 1st proximal phalanx
Actions:
- Adducts 1st digit
Innervation:
- Deep branch of ulnar nerve (C8, T1)

Question 9

Flexor Digiti Minimi Brevis

Answer 9

Attachments:
- Hook of hamate and flexor retinaculum
- Medial aspect of base of 5th proximal phalanx
Actions:
- Flexion of 5th proximal phalanx
Innervation:
- Deep branch of ulnar nerve (C8, T1)

Question 10

Abductor Digiti Minimi

Answer 10

Attachments:
- Pisiform
- Medial aspect of base of 5th proximal phalanx
Actions:
- Abducts 5th digit
Innervation:
- Deep branch of ulnar nerve (C8, T1)

Question 11

Opponens Digiti Minimi

Answer 11

Attachments:
- Hook of hamate and flexor retinaculum
- Medial border of 5th metacarpal
Actions:
- Opposes (flexes and laterally rotates) 5th metacarpal
Innervation:
- Deep branch of ulnar nerve (C8, T1)

Question 12

Lumbricals

Answer 12

Attachments:
Tendons of flexor digitorum profundus
Lateral aspect of extensor expansion of digits 2-5
Actions:
Flexion of metacarpophalangeal joints of digits 2-5
Extension of interphalangeal joints of digits 2-5
Innervation:
1 and 2 = median nerve (C8, T1)
3 and 4 = deep branch of ulnar nerve (C8, T1)

Question 13

Palmar Interosseus Muscles

Answer 13

Attachments:
- 1 = medial aspect 2nd metacarpal, 2 = lateral aspect 4th metacarpal, 3 = lateral aspect 5th metacarpal
- Base of proximal phalanx and extensor expansion of digit 2, 4 or 5 (same aspect as proximal attachment)
Actions:
- Adduct digits 2, 4 and 5 respectively
- Assist in flexion of metacarpophalangeal joints and extension of interphalangeal joints
Innervation:
- Deep branch of ulnar nerve (C8, T1)

Question 14

Dorsal Interosseus Muscles

Answer 14

Attachments:
- Adjacent sides of 2 metacarpals (bipennate) 1:1+2, 2:2+3, 3:3+4, 4:4+5
- Base of proximal phalanges 2-4, extensor expansion of digits 2-4
Actions:
- Abduct digits 2, 3and 4
- Assist in flexion at metacarpophalangeal joints and extension at interphalangeal joints
Innervation:
- Deep branch of ulnar nerve (C8, T1)