Intrinsic Muscles of the Hand

Question 1

Thenar eminence - Opponens pollicis

Answer 1

Attachments: 
Origin = trapezium + flexor retinaculum
Insertion = along MC 1
Actions:
- allow us to oppose our fingers = sit deep to the other two

Question 2

Thenar eminence - abductor pollicis brevis

Answer 2

Attachments:
Origin = scaphoid, trapezium + flexor retinaculum 
Insertion = 1st digit (proximal phalanx)
Actions: 
- allows us to abduct, sit most radially

Question 3

Thenar eminence - flexor pollicis brevis

Answer 3

Attachments:
Origin = trapezium + flexor retinaculum
Insertion = 1st digit (proximal phalanx)
Actions:
- assist in flexing, more towards the midline 
- flexes MCP + CMC of phalanx 1

Question 4

Hypothenar eminence - opponens digiti minimi

Answer 4

Attachments: 
Origin = hamate + flexor retinaculum
Insertion = along MC 5
Actions:
- allow us to oppose our fingers = sit deep to the other two

Question 5

Hypothenar eminence - abductor digiti minimi

Answer 5

Attachments: 
Origin = pisiform + flexor retinaculum
Insertion = 5th digit (proximal phalanx)
Actions:
- allows us to abduct, sit most ulnarly

Question 6

Hypothenar eminence - flexor digiti minimi

Answer 6

Attachments:
Origin = hamate 
Insertion = 5th digit (proximal phalanx)
Actions:
- assist in flexing, more towards the midline 
- flexes MCP + CMC of 5

Question 7

Adductor pollicis

Answer 7

Attachments:
Origin = from capitate to 3rd MC
Insertion = proximal phalanx of digit 1: via one of the sesamoid bones
Actions:
- adducts the thumb = gives power to grip
- active in later stage of opposition

Question 8

Lumbricals (ARE LATERAL)

Answer 8

Attachments:
Origin = come off the (anterior) tendons of FDP
Insertion = DDE of fingers 2-5 (lateral side)
Actions:
- flex the MCP joints + extend both IP joints = at same time
INFO:
- Radial side: first two lumbricals = unipennate
- Last two = bipennate

Question 9

Palmar Interossei

Answer 9

Attachments:
Origin = MC of 2,4,5 (ulnar side of digit 2, radial side of digits 4,5)
Insertion = to proximal phalanx of same digit on the DDE
- unipennate
Actions:
- adduction of digits 2,4,5
- Also Flex MCP + extend DIP + PIP (Digits 2,4,5) (same as lumbricals)

Question 10

Dorsal interossei

Answer 10

Attachments:
Origin = from MC bones on either side (1st DI = sits at back of thumb + index finger web space)
Insertion = DDE of digits 2,3,4,5 on proximal phalanx
- bipennate
Actions:
- abduction of digits 2,3,4,5
- Also Flex MCP + extend DIP + PIP (Digits 2,3,4) (same as lumbricals)