Quiz 18

Question 1

Palmar interossei (4)

Answer 1

Origin:
- 1st: ulnar side of palmar surface of base of 1st metacarpal
- 2nd: ulnar side of 2nd metacarpal bone
- 3rd: radial side of 4th metacarpal
- 4th: radial side of 5th metacarpal
Insertion:
- 1st: sesamoid bone on ulnar side of the base of proximal phalanx of thumb
- 2nd: ulnar side of proximal phalanx of 2nd finger
- 3rd: radial side of proximal phalanx of 4th finger
- 4th: radial side of proximal phalanx of 5th finger
Action:
- Adducts the fingers
- Flexes fingers (at the McP while IP joints are extended)
Nerve:
- Ulnar
- C8, T1

Question 2

Dorsal interossei (4)

Answer 2

Origin:
- By two heads from adjacent sides of metacarpal bones
Insertion:
- 1st: radial side of proximal phalanx of 2nd finger
- 2nd: radial side of proximal phalanx of 3rd finger
- 3rd: ulnar side of proximal phalanx of 3rd finger
- 4th: ulnar side of proximal phalanx of 4th finger
Action:
- Abducts the fingers
- Flexes fingers (at the McP while IP joints are extended)
Nerve:
- Ulnar
- C8, T1

Question 3

Lumbricals (4)

Answer 3

Origin:
- Tendons of flexor digitorum profundus (2nd -5th)
Insertion:
- Tendons of extensor digitorum communis (extensor expansion)
Action:
- Flexes the knuckles (MCP joints)
- Extends IP’s
Nerve:
- 1&2: median
- 3&4: ulnar

Question 4

Abductor pollicis brevis

Answer 4

Origin:
- Trapezium, scaphoid tubersoity and transverse carpal ligament
Insertion:
- Radial side of proximal phalanx of thumb
Action:
- Abducts thumb
- Helps flex the thumb
- If attached to extensor pollicis longus, it may assist to extend the thumb
Nerve:
- Median
- C8, T1