Lumbricals and Interossei

Question 1

1st and 2nd Lumbrical

Answer 1

O: Lateral two tendons of flexor digitorum profundus (as unipennate muscles)
I: Lateral Side of extensor expansions of 2nd-5th digits
N: Median Nerve (C8, T1)
A: Flex MCP Joints; extend IP joints of 2nd-5th digits

Question 2

3rd and 4th Lumbricals

Answer 2

O: Medial three tendons of flexor digitorum profundus (as bipinnate muscles)
I: Lateral Side of extensor expansions of 2nd-5th digits
N: Deep Branch of Ulnar Nerve (C8, T1)
A: Flex MCP Joints; extend IP joints of 2nd-5th digits

Question 3

Dorsal Interossei (1st-4th)

Answer 3

O: Adjacent sides of two metacarpals (as bipennate muscles)
I: Bases of proximal phalanges; extensor expansions of 2nd-4th digits
N: Deep Branch of Ulnar Nerve (C8, T1)
A: Abduct 2nd-4th digits from axial line; act with lumbricals in flexing MCP joints and extending IP Joints

Question 4

Palmar Interossei (1st-3rd)

Answer 4

O: Palmar surfaces of 2nd, 4th, and 5th Metacarpals (as unipennate muscles)
I: Bases of proximal phalanges; extensor expansions of 2nd, 4th, and 5th digits
N: Deep Branch of Ulnar Nerve (C8, T1)
A: Adduct 2nd, 4th, and 5th digits toward axial line; assist lumbricals in flexing MCP joints and extending IP joints