Interossei Hand Muscles

Bones

Radius
Ulna
Hand

Overview:

• The dorsal and palmar interossei lie between the metacarpals of the hand.

A helpful mnemonic:

• DAB: Dorsal interossei Abduct digits 2-4.
• PAD: Palmar interossei Adduct digits 1,2, 4, and 5.
• Abduction/Adduction are in reference to the midline of the hand; digit 3.

Dorsal interossei:

• Bipennate
• Originate on the adjacent sides of the metacarpals
• Insert onto the lateral sides of the proximal phalanges of digits 2 and 3, and onto the medial sides of the proximal phalanges of digits 3 and 4.
• Abduct digits 2-4; they do NOT act upon digits 1 and 5.

Palmar interossei:

• Unipennate

First palmar interossei (often poorly developed or absent)

• Originates on the medial side of the first metacarpal
• Inserts into the base of the proximal phalanx of digit 1.

Second palmar interossei

• Originates on the medial side of the second metacarpal
• Inserts into the proximal phalange of digit 2.

Third palmar interossei

• Originates on the lateral side of metacarpal 4
• Inserts into the lateral side of the proximal phalange of digit 4.

Fourth palmar interossie

• Originates on the lateral side of the 5th metacarpal
• Inserts into the proximal phalange of digit 5.

Both dorsal interossei and palmar interossei also insert into the extensor hoods.