Hand (4A)

Question 1

Attachments of abductor pollicis brevis (ABP)

Answer 1

• most radial (lateral) of the three thenar muscles
• proximal = flexor retinaculum, trapezium, and scaphoid
• distal = base of 1st proximal phalanx

Question 2

Innervation of abductor pollicis brevis (ABP)

Answer 2

Median nerve

Question 3

Actions of abductor pollicis brevis (ABP)

Answer 3

• abduct the thumb (CMC and MCP)
• opposition of the thumb (assist)

Question 4

Attachments of flexor pollicis brevis (FPB)

Answer 4

• medial to abductor pollicis brevis (ABP)
• proximal = flexor retinaculum, trapezium, trapezoid, and capitate
• distal = base of 1st proximal phalanx - more of a medial line pull that makes it flex instead of abduct

Question 5

Innervation of flexor pollicis brevis (FPB)

Answer 5

• median nerve
• ulnar nerve
  no need to separate

Question 6

Actions of flexor pollicis brevis (FPB)

Answer 6

• flex the thumb (CMC and MCP)
• opposition of the thumb (assist)

Question 7

Attachments of opponens pollicis

Answer 7

• deep to abductor pollicis brevis (APB) and flexor pollicis brevis (FPB)
• proximal = flexor retinaculum and trapezium
• distal = entire length of 1st metacarpal - allows for the opposition motion

Question 8

Innervation of opponens pollicis

Answer 8

Median nerve

Question 9

Actions of opponens pollicis

Answer 9

• opposition of the thumb (CMC)

Question 10

Attachments of palmar interossei

Answer 10

• proximal = 2nd, 4th, 5th metacarpals facing the middle finger
• distal = base of 2nd, 4th, 5th proximal phalanx as part of extensor mechanism

Question 11

Innervation of palmar interossei

Answer 11

Ulnar nerve

Question 12

Actions of palmar interossei

Answer 12

• adduction 2nd, 4th, 5th fingers toward the 3rd finger
• flex 2nd, 4th, 5th fingers (MCP) (assist)
• extend 2nd, 4th, 5th fingers (IP) (assist)

Question 13

Attachments of dorsal interossei

Answer 13

• middle finger has 2, one on each side (2nd and 3rd interosseus muscles)
• proximal = 1-5 metacarpals facing the middle finger
• distal = proximal phalanx facing the middle finger as part of extensor mechanism

Question 14

Innervation of dorsal interossei

Answer 14

Ulnar nerve (if you lose the ulnar nerve, you can’t do the key pinch)
- first dorsal interosseus = large (palpate)
- along with adductor pollicis, important with key (lateral) pinch

Question 15

Actions of dorsal interossei

Answer 15

• abduct 2nd, 3rd, 4th fingers (MCP)
• flex 2nd, 3rd, 4th fingers (MCP) (assist)
• extend 2nd, 3rd, 4th fingers (IP) (assist)

Question 16

Attachments of lumbricals

Answer 16

• proximal = flexor digitorum profundus (FDP) tendon - FDP also has 2 innervation
• distal = extensor hood (extensor mechanism)

Question 17

Innervation of lumbricals

Answer 17

• median nerve = index and middle fingers
• ulnar nerve = ring and small fingers

Question 18

Actions of lumbricals

Answer 18

• extend 2nd-5th fingers (IP)
• flex 2nd-5th fingers (MCP)

Question 19

Attachments of opponens digiti minimi

Answer 19

• deep to abductor and flexor (like thenar)
• proximal = hook of hamate and flexor retinaculum
• distal = shaft of 5th metacarpal

Question 20

Innervation of opponens digiti minimi

Answer 20

Ulnar nerve

Question 21

Actions of opponens digiti minimi

Answer 21

• opposition of 5th finger at CMC joint

Question 22

Thenars

Answer 22

• abductor pollicis brevis (APB)
• flexor pollicis brevis (FPB)
• opponens pollicis (OP)
• identified as the fat pad of the thumb

Question 23

Hypothenars

Answer 23

• abductor digiti minimi
• flexor digiti minimi
• opponens digiti minimi
• identidad as the fat pad of the small finger