The palmar interossei are three intrinsic muscles of the hand, located between the metacarpals. Some texts include a fourth muscle at the base of the proximal phalanx of the thumb. These muscles assist in the adduction of the digits, allowing for greater flexion at the metacarpophalangeal joints and extension at the interphalangeal joints.
Each of the interossei muscles originate from a medial or lateral surface of a metacarpal bone, and attach into the extensor hood and proximal phalanx of the same finger.
The palmar interossei are responsible for adduction of the digits, or movement towards the midline of the body. This assists in flexion of the metacarpophalangeal joints, as well as extension of the interphalangeal joints.
The palmar interossei are innervated by the ulnar nerve, a branch of the medial cord of the brachial plexus. This nerve supplies motoric signals to the palmar interossei, allowing them to initiate contraction and adduction.
The palmar interossei are supplied by the palmar metacarpal arteries, a structure related to the common palmar digital arteries. Blood vessels of this nature are used to provide oxygenated blood to the muscles and surrounding structures in the hand.
Due to the adduction provided by palmar interossei muscles, the hand can produce complex movements capable of fine motor tasks. Additionally, this adduction reduces strain on the metacarpophalangeal joints and allows for greater dexterity and precision in hand movements.
The palmar interossei are involved in a wide variety of tasks that humans accomplish with their hands. They are needed to pinch and grasp objects between the thumb and forefinger, and provide the stability needed during activities such as writing and typing. In terms of sports, they play a major role in activities such as golf, baseball, and tennis, providing the precision needed for the controlling movements required in these sports.
In conclusion, the palmar interossei are integral muscles that allow humans to use their hands with great dexterity. The adduction provided by these muscles allows for the hand to make precise and complex movements, which ultimately lead to the many activities that humans are able to do with their hands.
