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The primary function of the extensors is to straighten out the digits. The thumb has two extensors in the forearm; the tendons of these form the anatomical snuff box. Also, the index finger and the little finger have an extra extensor, used, for instance, for pointing. The extensors are situated within 6 separate compartments.
The absence of the tendon of the extensor digitorum communis to the little finger is associated with the thicker type 3r juncturae tendinum in the fourth intermetacarpal space. [ 3 ] Hirai et al. reported type 1 junturae tendinum between the extensor digiti minimi and the extensor digitorum communis to the ring finger in 6% of the specimens.
In human anatomy, the annular ligaments of the fingers, often referred to as A pulleys, are the annular part of the fibrous sheathes of the fingers.Four or five such annular pulleys, together with three cruciate pulleys, form a fibro-osseous tunnel on the palmar aspect of the hand through which passes the deep and superficial flexor tendons.
Fingers do not contain muscles (other than arrector pili). The muscles that move the finger joints are in the palm and forearm. The long tendons that deliver motion from the forearm muscles may be observed to move under the skin at the wrist and on the back of the hand. Muscles of the fingers can be subdivided into extrinsic and intrinsic muscles.
Joints of the hand, X-ray Interphalangeal ligaments and phalanges. Right hand. Deep dissection. Posterior (dorsal) view. The PIP joint exhibits great lateral stability. Its transverse diameter is greater than its antero-posterior diameter and its thick collateral ligaments are tight in all positions during flexion, contrary to those in the metacarpophalangeal joint.
On the back of the hand, the ED tendons diverge to follow the fingers and the EI tendon joins the ulnar side of one of the ED tendons along the back of the index finger. The EDM takes a similar course as the EI except it follows the ED tendon along the little finger. The ECU crosses from the lateral to the medial side of the forearm.
[2] The sheath which surrounds the flexor digitorum extends downward about halfway along the metacarpal bones, where it ends in blind diverticula around the tendons to the index, middle, and ring fingers. It is prolonged on the tendons to the little finger and usually communicates with the synovial sheath of these tendons.
The other three palmar interossei originate on the side of the metacarpal facing the hand's midline (ray of long finger); [4] the second is attached to the medial side of the index finger; the third to the lateral side of the ring finger; and the fourth to the lateral side of the little finger. The tendons of these three muscles pass posterior ...