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In early human fetal development, webbing (syndactyly) of the toes and fingers is normal. At about 6 weeks of gestation, apoptosis takes place due to a protein named sonic hedgehog, also known as SHH, which dissolves the tissue between the fingers and toes, and the webbing disappears. In some fetuses, this process does not occur completely ...
Flexion and extension are movements that affect the angle between two parts of the body. These terms come from the Latin words with the same meaning. [a] Flexion is a bending movement that decreases the angle between a segment and its proximal segment. [9] For example, bending the elbow, or clenching a hand into a fist, are examples of flexion ...
The radial nerve innervates the finger extensors and the thumb abductor; that is, the muscles that extend at the wrist and metacarpophalangeal joints (knuckles) and abduct and extend the thumb. The median nerve innervates the flexors of the wrist and digits, the abductors and opponens of the thumb, the first and second lumbricals. The ulnar ...
the antecubital region encompassing the front of the elbow, the antebrachial region encompassing the forearm, the carpal region encompassing the wrist, the palmar region encompassing the palm, the digital/phalangeal region encompassing the fingers. The thumb is referred to as the pollex. The posterior view contains, from superior to inferior,
The extensor digitorum muscle extends the phalanges, [2] then the wrist, and finally the elbow. It tends to separate the fingers as it extends them. In the fingers, the extensor digitorum acts principally on the proximal phalanges, acting to extend the metacarpophalangeal joint. Extension of the proximal and distal interphalangeal joints ...
An example of interdigital webbing on an Abah River flying frog.. In oryzomyines, a mainly South American rodent group, the marsh rice rat, Pseudoryzomys simplex, and Sigmodontomys alfari all have small webs, which do not extend to the end of the proximal phalanges, whereas Amphinectomys savamis, Lundomys molitor and the members of the genera Holochilus and Nectomys have more expansive webbing ...
The entire arm is referred to as the brachium and brachial, the front of the elbow as the antecubitis and antecubital, the back of the elbow as the olecranon or olecranal, the forearm as the antebrachium and antebrachial, the wrist as the carpus and carpal area, the hand as the manus and manual, the palm as the palma and palmar, the thumb as ...
A joint, or articulation is the region where adjacent bones contact each other, for example the elbow, shoulder, or costovertebral joint. Terms that refer to joints include: articular process, referring to a projection that contacts an adjacent bone. suture, referring to an articulation between cranial bones.