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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.
The extrinsic muscle groups are the long flexors and extensors. They are called extrinsic because the muscle belly is located on the forearm. The intrinsic group are the smaller muscles located within the hand itself. The muscles of the hand are innervated by the radial, median, and ulnar nerves from the brachial plexus. [1]
It contains tendons of the flexor digitorum superficialis and the flexor digitorum profundus, but not the flexor pollicis longus. [ 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 .
The extensor retinaculum (dorsal carpal ligament, or posterior annular ligament) is a thickened portion of the antebrachial fascia that holds the tendons of the extensor muscles in place. [1] It is located on the back of the forearm , just proximal to the hand . [ 2 ]
On the radial side of the retinaculum is the tendon of the flexor carpi radialis, which lies in the groove on the greater multangular between the attachments of the ligament to the bone. The tendons of the palmaris longus and flexor carpi ulnaris are partly attached to the surface of the retinaculum; below, the short muscles of the thumb and ...
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 .
Flexor digitorum profundus lies deep to the superficialis, but it attaches more distally. Therefore, profundus's tendons go through the tendons of superficialis, and end up attaching to the distal phalanx. For this reason profundus is also called the perforating muscle. [2] The lumbricals of the hand arise from the radial side of its tendons. [2]
In contrast to the volar plates of the MCP joints of the fingers, the volar plate of the thumb MCP joint is a thick structure firmly attached to the base of the proximal phalanx. It forms the bottom of a two-sided box, the sides of which are made up of the collateral ligaments .