Unit 2 - Upper Limb: Metacarpal Muscles (Ex. II)

Question 1

2nd lumbrical

Answer 1

O: radial sides of tendons of flexor digitorum profundus
I: dorsal digital expansion of digit 3
Inn: median N (C8, T1)
A: flexion @ MCP joint of digits 2-5; extension @ PIP and DIP joints of digits 2-5

Question 2

3rd lumbrical

Answer 2

O: tendons of flexor digitorum profundus (bipennate from M and L sides)
I: dorsal digital expansion of digit 4
Inn: ulnar N (C8, T1)
A: flexion @ MCP joint of digits 2-5; extension @ PIP and DIP joints of digits 2-5

Question 3

4th lumbrical

Answer 3

O: tendons of flexor digitorum profundus (bipennate from M and L sides)
I: dorsal digital expansion of digit 5
Inn: ulnar N (C8, T1)
A: flexion @ MCP joint digits 2-5; extension @ PIP and DIP joints of digits 2-5

Question 4

1st dorsal interossei

Answer 4

O: adjacent sides of 1st and 2nd metacarpals (2 heads)
I: dorsal digital expansion of digit 2; radial side of 2nd proximal phalanx
Inn: ulnar N (C8, T1)
A: flexion @ MCP joint of digits 2-4; extension and abduction from 3rd digit @ PIP and DIP joints of digits 2-4

Question 5

2nd dorsal interossei

Answer 5

O: adjacent sides of 2nd and 3rd metacarpals (2 heads)
I: dorsal digital expansion of digit 3; radial side of 3rd proximal phalanx
Inn: ulnar N (C8, T1)
A: flexion @ MCP joint of digits 2-4; extension and abduction from digit 3 @ PIP and DIP joints of digits 2-4

Question 6

3rd dorsal interossei

Answer 6

O: adjacent sides of 3rd and 4th metacarpals (2 heads)
I: dorsal digital expansion of digit 3; ulnar side of 3rd proximal phalanx
Inn: ulnar N (C8, T1)
A: flexion @ MCP joint of digits 2-4; extension and abduction from digit 3 @ PIP and DIP joints of digits 2-4

Question 7

4th dorsal interossei

Answer 7

O: adjacent sides of 4th and 5th metacarpals (2 heads)
I: dorsal digital expansion of digit 4; ulnar side of 4th proximal phalanx
Inn: ulnar N (C8, T1)
A: flexion @ MCP joint of digits 2-4; extension and abduction from digit 3 @ PIP and DIP joints of digits 2-4

Question 8

1st palmar interossei

Answer 8

O: ulnar side of 2nd metacarpal
I: dorsal digital expansion of digit 2; base of 2nd proximal phalanx
Inn: ulnar N (C8, T1)
A: flexion @ MCP joint of digits 2, 4, and 5; extension and addduction toward digit 3 @ PIP and DIP joints of digits 2, 4, and 5

Question 9

2nd palmar interossei

Answer 9

O: radial side of 4th metacarpal
I: dorsal digital expansion of digit 4; base of 4th proximal phalanx
Inn: ulnar N (C8, T1)
A: flexion @ MCP joint of digits 2, 4, and 5; extension and adduction toward digit 3 @ PIP and DIP joints of digits 2, 4, and 5

Question 10

3rd palmar interossei

Answer 10

O: radial side of 5th metacarpal
I: dorsal digital expansion of digit 5; base of 5th proximal phalanx
Inn: ulnar N (C8, T1)
A: flexion @ MCP joint of digits 2, 4, and 5; extension and adduction toward digit 3 @ PIP and DIP joints of digits 2, 4, and 5

Question 11

1st lumbrical

Answer 11

O: radial sides of tendons of flexor digitorum profundus
I: dorsal digital expansion of digit 2
Inn: median N (C8, T1)
A: flexion @ MCP joint of digits 2-5; extension @ PIP and DIP joints of digits 2-5