The index finger expansions also receive the extensor indicis and the little finger expansions also receive the extensor digiti minimi. The interossei muscles dorsal and palmar also insert into the extensor expansions, with some fibers of both dorsal and palmar tendons also inserting into the base of the proximal phalanx. On the thumb, the extensor pollicis brevis tendon attaches to the dorsal aspect of the base of the proximal phalanx, and the extensor pollicis longus tendon attaches to the distal phalanx 1.
The palmar ligaments or volar plates are thick bands of dense fibrous tissue that attach the metacarpophalangeal and interphalangeal joints.
At the metacarpophalangeal joint, these are also united by the deep transverse ligament of the palm. Fibrous flexor sheaths bridge the palmar ligaments and attach along the proximal phalanges before surrounding the flexor digitorum profundus tendons on the distal phalanges.
They form a series of annular A1 to A5 from proximal to distal and cruciform C1 to C3 pulleys that surround the synovial sheath coverings of the flexor tendons. The A1, A3 and A5 pulleys arise from the volar plates; A2 and A4 arise from the periosteum on the proximal half of the proximal phalanx and the mid body of the middle phalanx respectively.
Collateral ligaments also attach on either side of the metacarpophalangeal and interphalangeal joints 1. From the superficial palmar arch , a palmar digital artery supplies the ulnar aspect of the little finger. Three common palmar digital arteries then run distallly along the webspaces between the fingers, and bifurcate into proper palmar digital arteries that supply adjacent fingers on either side. From the deep palmar arch , the thumb is supplied by the princeps pollicis artery and the radial side of the index finger is supplied by the radialis indicis artery.
The dorsal metacarpal arteries also provide anastomotic branches to the dorsal arch, superficial arch and common palmar digital arteries 1. Sesamoid bones can sometimes be found at the metacarpal heads, especially the second and fifth, within the palmar capsule of the metacarpophalangeal joints. They can also occasionally be found at the interphalangeal joints 1.
The phalanges are ossified from the body and proximal extremity. Ossification of the body commences during the eighth week of fetal development. Ossification of the proximal extremity commences in the bones of the first row between the third and fourth years, and a year later in those of the second and third rows. The two centers become united in each row between the eighteenth and twentieth years 2. Please Note: You can also scroll through stacks with your mouse wheel or the keyboard arrow keys.
Distal Interphalangeal Joint: Articulations between the distal end of the middle phalanges and the proximal end of the distal phalanges. This is the only interphalangeal joint within the thumb [11]. Interphalangeal joints form the knuckles of hand [12] and are a simple form of hinge joint in the human body [13].
Both the metacarpophalangeal joints and interphalangeal joints are attached by the thick fibrous bands of the volar plates also called the palmar ligaments. These are further united at the metacarpophalangeal joint by the deep transverse metacarpal ligament [1]. The superficial palmar arch gives rise to a palmar digital artery to supply the ulnar side of the little finger. There are three common palmar digital arteries that run along the web spaces distally, dividing into proper palmar digital arteries to supply the fingers that are adjacent on either side.
The deep palmar arch gives rise to the princeps pollicis artery to supply the thumb and the radialis indicis artery to supply the radial aspect of the index finger. The dorsal metacarpal arteries have vascular connections with the dorsal, and superficial arch, as well as the common palmar digital arteries [9]. Each phalanx has two centers of ossification, the first one for the body or shaft, and the second for the base or proximal extremity.
The shaft starts to ossify quite early, around the eighth week of fetal growth. Among the bases or proximal extremities, the base of the proximal row is the first to begin ossifying between 3 and 4 years of age, with those for the middle and distal rows following a year later.
The base and shaft unite with each other when one is eighteen to twenty years old [14]. The phalanges play a vital role in the movement and flexibility of digits, as well as the whole hand. These bones allow us to flex and fold the fingers and thumb to hold or pick something up, and carry on all daily activities like using a phone, typing, eating and so on.
The phalanges also create insertion points for various muscles that help with the flexion of the fingers and hand [15, 16]. Wrist retinacula…. The elbow is one of the largest joints in the body. In conjunction with the shoulder joint and wrist, the elbow gives the arm much of its versatility….
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