STRUCTURE AND POSITION :

•         Dorsal Interossei of the Hand are present inside the hand at its dorsal side. They are four in numbers and arranged between the Metacarpal Bones.
•         Dorsal Interossei of the Hand are Bipinnate leaf-like muscles and have two head of origin.

ATTACHMENTS :

Each Dorsal Interosseous Muscle has two origins and one insertion.

•         Origin : Dorsal Interosseous Muscles arise between the Metacarpal bones. Each Muscle arises by two heads each of which is attached to the adjacent Metacarpal.
•         They are bipennate hence each head joins and forms a leaf-like appearance and runs towards the phalanges.
•         Insertion : Each of the Dorsal Interosseous muscle is inserted into Extensor Expansion however they have separate insertions too.

1st Interosseous from medial side is inserted into the medial side of the 4th finger Proximal Phalanx. 2nd and 3rd Muscles are inserted onto the medial and lateral aspects respectively of the Proximal Phalanx of the Middle Finger. 4th Muscle is inserted into the lateral aspect of the Proximal Phalanx of the Index Finger.

BLOOD SUPPLY :

Dorsal Interossei of the Hand are supplied by the Dorsal Metacarpal, Palmar Metacarpal, Princeps Pollicis, Radialis Indicis, Deep Palmar Arch, Common and Proper Digital Arteries.

NERVE SUPPLY :

Dorsal Interossei of the Hand are innervated by the Ulnar Nerve.

ACTION :

Dorsal Interossei of the Hand abduct the 2nd, 3rd and 4th fingers away from the midline. They also assist flexion of the Metacarpophalangeal Joints and also extension of the Interphalangeal Joints.