Midterm- Hand Muscles

Question 1

Opponens pollicis

Answer 1

Origin: Flexor retinaculum and tubercles of scaphoid and trapezium
Insertion: Lateral side of 1st metacarpal
Action: opposition of the thumb
Innervation: Median C8, T1

Question 2

Abductor pollicis brevis

Answer 2

Origin: Flexor retinaculum and tubercles of scaphoid and trapezium
Insertion: lateral side of base of proximal phalanx of thumb
Action: abduction of thumb
Innervation: Median C8, T1

Question 3

Flexor pollicis brevis

Answer 3

Origin: Flexor retinaculum and tubercles of scaphoid and trapezium
Insertion: lateral side of base of proximal phalanx of thumb
Action: flexion of thumb
Innervation: Median C8, T1

Question 4

Adductor pollicis

Answer 4

Origin: Transverse head: anterior surface of base of 2nd and 3rd metacarpals
Oblique head: bases of 2nd and 3rd metacarpals, capitate, and adjacent carpals
Insertion: Ulnar side of base of proximal phalanx of thumb
Action: adduction of thumb toward lateral border of palm (ulnar deviation)
Innervation: Ulnar C8, T1

Question 5

Abductor digiti minimi

Answer 5

Origin: Pisiform
Insertion: Ulnar side of base of proximal phalanx of 5th digit
Action: abduction of 5th digit, assist in flexion of 5th digit at MCP joint
Innervation: Ulnar C8, T1

Question 6

Flexor digiti minimi

Answer 6

Origin: Hook of hamate, flexor retinaculum
Insertion: Ulnar side of base if proximal phalanx of 5th digit
Action: Flexion of proximal phalanx of 5th digit
Innervation: Ulnar C8, T1

Question 7

Opponens digiti

Answer 7

Origin: Hook of hamate, flexor retinaculum
Insertion: Ulnar border of 5th metacarpal
Action: Draws 5th metacarpal anterior and rotates it, bring 5th digit into opposition with thumb
Innervation: Ulnar C8, T1

Question 8

Lumbricals

Answer 8

Origin:
1st and 2nd: radial sides of flexor digitorum profundus tendons at 2nd and 3rd tendons (unipennate)
3rd and 4th: Adjacent sides of flexor digitorum profundus tendons at 3rd, 4th, & 5th tendons (bipennate)
Insertion: radial sides of extensor expansions (dorsal hood) of digits 2-5
Action: Flexion of digits at MCP joints of 2nd-5th digits, extension of digits at IP joints of 2nd-5th digits
Innervation:
1st and 2nd: median C8, T1
3rd and 4th: Ulnar C8, T1

Question 9

Dorsal interossei (1st-4th)

Answer 9

Origin: Adjacent sides of two metacarpals (bipennate)
1st 1-2
2nd 2-3
3rd 3-4
4th 4-5
Insertion: Base of proximal phalanx of digits 1-5, extensor expansions of 2nd-4th digits
Action: abduction of 2nd-4th digits from axial line, assists flexion of digits at MPC joints, assists extension of digits at IP joints
Innervation: Ulnar C8, T1

Question 10

Palmar interossei (1st-3rd)

Answer 10

Origin: Palmar surfaces of 2nd, 4th, & 5th metacarpals (unipennate)
1st: ulnar side of 2nd metacarpal
2nd: radial side of 4th metacarpal
3rd: radial side of 5th metacarpal
Insertion: bases of proximal phalanx of digits 2, 4, &5
Action: Adduction of 2nd, 4th, & 5th digits towards axial line, assists flexion of digits 2, 4, &5 at MCP joints, Assists extension of digits at IP joints
Innervation: Ulnar C8, T1