Dorsal interossei of the hand
Encyclopedia
The dorsal interossei of the hand are muscles that occupy the space between the metacarpals.
The dorsal interosseous muscles are bipennate, with each muscle arising by two heads from the adjacent sides of the metacarpal bones, but more extensively from the metacarpal bone of the finger into which the muscle is inserted.
They are inserted into the bases of the proximal phalanges and into the extensor expansion
of the corresponding extensor digitorum tendon. The middle digit has two dorsal interossei insert onto it while the first digit (thumb) and the fifth digit (little finger) have none.
The first dorsal interosseous muscle is larger than the others. Between its two heads, the radial artery
passes from the back of the hand into the palm.
Between the heads of dorsal interossei two, three, and four, a perforating branch from the deep palmar arch
is transmitted.
.
.
In addition, a secondary function is to abduct
the fingers away from the middle finger. This is in contrast to the palmar interossei, which adduct the fingers. This is often remembered by the mnemonic DAB PAD, short for "Dorsal ABducts, Palmar ADducts".
Structure
There are four dorsal interossei in each hand. They are specified as 'dorsal' to contrast them with the palmar interossei, which are located on the anterior side of the metacarpals.The dorsal interosseous muscles are bipennate, with each muscle arising by two heads from the adjacent sides of the metacarpal bones, but more extensively from the metacarpal bone of the finger into which the muscle is inserted.
They are inserted into the bases of the proximal phalanges and into the extensor expansion
Extensor expansion
A extensor expansion is an anatomical term that refers to the special connective attachments by which the extensor tendons insert into the phalanges....
of the corresponding extensor digitorum tendon. The middle digit has two dorsal interossei insert onto it while the first digit (thumb) and the fifth digit (little finger) have none.
| # | Origin | Insertion >- | first |
on the radial side of the second metacarpal and the proximal half of the ulnar side of the first metacarpal | extensor expansion Extensor expansion A extensor expansion is an anatomical term that refers to the special connective attachments by which the extensor tendons insert into the phalanges.... >- | second |
on the radial side of the third metacarpal and the ulnar side of the second metacarpal | extensor expansion Extensor expansion A extensor expansion is an anatomical term that refers to the special connective attachments by which the extensor tendons insert into the phalanges.... >- | third |
on the radial side of the fourth metacarpal and the ulnar side of the third metacarpal | extensor expansion Extensor expansion A extensor expansion is an anatomical term that refers to the special connective attachments by which the extensor tendons insert into the phalanges.... >- | fourth |
on the radial side of the fifth metacarpal and the ulnar side of the fourth metacarpal | on the ulnar side of the fourth proximal phalanx (the ring finger) and the extensor expansion Extensor expansion A extensor expansion is an anatomical term that refers to the special connective attachments by which the extensor tendons insert into the phalanges.... |
The first dorsal interosseous muscle is larger than the others. Between its two heads, the radial artery
Radial artery
In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm.-Course:The radial artery arises from the bifurcation of the brachial artery in the cubital fossa. It runs distally on the anterior part of the forearm...
passes from the back of the hand into the palm.
Between the heads of dorsal interossei two, three, and four, a perforating branch from the deep palmar arch
Deep palmar arch
The deep palmar arch is an arterial network found in the palm. It is usually formed mainly from the terminal part of the radial artery, with the ulnar artery contributing via its deep palmar branch...
is transmitted.
Innervation
All interosseous muscles of the hand are innervated by the deep branch of the ulnar nerveUlnar nerve
In human anatomy, the ulnar nerve is a nerve which runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest unprotected nerve in the human body , so injury is common...
.
Actions
The primary action of the dorsal interossei is to: flex the metacarpophalangeal joint (MCP) and to extend the interphalangeal joints and thus assist the lumbricalsLumbricals of the hand
The lumbricals are intrinsic muscles of the hand that flex the metacarpophalangeal joints and extend the interphalangeal joints.-Structure:There are four of these small, worm-like muscles on each hand. These muscles are unusual in that they do not attach to bone...
.
In addition, a secondary function is to abduct
Abduction (kinesiology)
Abduction, in functional anatomy, is a movement which draws a limb away from the median plane of the body. It is thus opposed to adduction.-Upper limb:* of arm at shoulder ** Supraspinatus** Deltoid* of hand at wrist...
the fingers away from the middle finger. This is in contrast to the palmar interossei, which adduct the fingers. This is often remembered by the mnemonic DAB PAD, short for "Dorsal ABducts, Palmar ADducts".