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Sesamoid Bones
In anatomy, a sesamoid bone () is a bone embedded within a tendon or a muscle. Its name is derived from the Greek word for 'sesame seed', indicating the small size of most sesamoids. Often, these bones form in response to strain, or can be present as a normal variant. The patella is the largest sesamoid bone in the body. Sesamoids act like pulleys, providing a smooth surface for tendons to slide over, increasing the tendon's ability to transmit muscular forces. Structure Sesamoid bones can be found on joints throughout the human body, including: * In the knee—the patella (within the quadriceps tendon). This is the largest sesamoid bone. * In the hand—two sesamoid bones are commonly found in the distal portions of the first metacarpal bone (within the tendons of adductor pollicis and flexor pollicis brevis). There is also commonly a sesamoid bone in distal portions of the second metacarpal bone and fifth metacarpal bone. * In the wrist—The pisiform of the wrist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
First Metatarsal Bone
The first metatarsal bone is the bone in the foot just behind the big toe. The first metatarsal bone is the shortest of the metatarsal bones and by far the thickest and strongest of them. Like the four other metatarsals, it can be divided into three parts: base, body and head. The base is the part closest to the ankle and the head is closest to the big toe. The narrowed part in the middle is referred to as the body of the bone. The bone is somewhat flattened, giving it two sides: the plantar (towards the sole of the foot) and the dorsal side (the area facing upwards while standing). The base presents, as a rule, no articular facets (joint surfaces) on its sides, but occasionally on the lateral side there is an oval facet, by which it articulates with the second metatarsal. On the lateral part of the plantar surface there is a rough oval prominence, or tuberosity, for the insertion of the tendon of the fibularis longus. The first metatarsal articulates (forms joints) with th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flexor Pollicis Brevis
The flexor pollicis brevis is a muscle in the hand that flexes the thumb. It is one of three thenar muscles. It has both a superficial part and a deep part. Origin and insertion The muscle's superficial head arises from the distal edge of the flexor retinaculum and the tubercle of the trapezium, the most lateral bone in the distal row of carpal bones. It passes along the radial side of the tendon of the flexor pollicis longus. The deeper (and medial) head "varies in size and may be absent."Gray's 37th British Edition, p. 630" It arises from the trapezoid and capitate bones on the floor of the carpal tunnel, as well as the ligaments of the distal carpal row. Both heads become tendinous and insert together into the radial side of the base of the proximal phalanx of the thumb; at the junction between the tendinous heads there is a sesamoid bone.'' Gray's Anatomy'' 1918, see infobox Innervation The superficial head is usually innervated by the lateral terminal branch of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metatarsophalangeal Joint
The metatarsophalangeal joints (MTP joints) are the joints between the metatarsal bones of the foot and the proximal bones (proximal phalanges) of the toes. They are analogous to the knuckles of the hand, and are consequently known as toe knuckles in common speech. They are condyloid joints, meaning that an elliptical or rounded surface (of the metatarsal bones) comes close to a shallow cavity (of the proximal phalanges). The region of skin directly below the joints forms the Ball (foot), ball of the foot. The ligaments are the plantar and two collateral. Movements The movements permitted in the metatarsophalangeal joints are flexion, Extension (kinesiology), extension, List of abductors of the human body, abduction, List of adductors of the human body, adduction and Circumduction (anatomy), circumduction. File:The feet of C. H. Unthan, the armless fiddler Wellcome L0034227.jpg, Left: toes adducted (pulled towards the center) and spread (abducted); right, both feet clenched (p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
