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The muscles of the thumb are nine skeletal muscles located in the hand and forearm. The muscles allow for flexion , extension , adduction , abduction and opposition of the thumb . The muscles acting on the thumb can be divided into two groups: The extrinsic hand muscles, with their muscle bellies located in the forearm, and the intrinsic hand ...
The carpometacarpal (CMC) joints are five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones.. The CMC joint of the thumb or the first CMC joint, also known as the trapeziometacarpal (TMC) joint, differs significantly from the other four CMC joints and is therefore described separately.
These joints are of the condyloid kind, formed by the reception of the rounded heads of the metacarpal bones into shallow cavities on the proximal ends of the proximal phalanges. [1] Being condyloid, they allow the movements of flexion, extension, abduction, adduction and circumduction (see anatomical terms of motion) at the joint. [1]
It joins with the scapula above at the shoulder joint (or glenohumeral joint) and with the ulna and radius below at the elbow joint. Notice: When the arm is spun so that the thumb point to the outside of the body, meaning the palm of the hand looks forward then it is said the hand is supinated. But when the thumb remains in the inside and the ...
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 ...
Saddle joints are said to be biaxial, [5] allowing movement in the sagittal and frontal planes. [2] Examples of saddle joints in the human body include the carpometacarpal joint of the thumb, [6] [7] the sternoclavicular joint of the thorax, [8] the incudomalleolar joint of the middle ear, [9] and the calcaneocuboid joint of the heel. [2]
In human anatomy, the radial (RCL) and ulnar (UCL) collateral ligaments of the metacarpophalangeal joints (MCP) of the hand are the primary stabilisers of the MCP joints. [1] A collateral ligament flanks each MCP joint - one on either side. Each attaches proximally at the head of the metacarpal bone, and distally at the base of the phalynx.
The carpometacarpal joint connects the carpal bones to the metacarpus or metacarpal bones which are joined at the intermetacarpal articulations. In the fingers, finally, are the metacarpophalangeal joints (including the knuckles) between the metacarpal bones and the phalanges or finger bones which are interconnected by the interphalangeal joints