The carpal bones are the eight small bones that make up the wrist (carpus) that connects the hand to the forearm. The term "carpus" and "carpal" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, the main role of the carpal bones is to articulate with the radial and ulnar heads to form a highly mobile condyloid joint, to provide attachments for thenar and hypothenar muscles, and to form part of the rigid carpal tunnel which allows the median nerve and tendons of the anterior forearm muscles to be transmitted to the hand and fingers.
A joint or articulation is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole. They are constructed to allow for different degrees and types of movement. Some joints, such as the knee, elbow, and shoulder, are self-lubricating, almost frictionless, and are able to withstand compression and maintain heavy loads while still executing smooth and precise movements. Other joints such as sutures between the bones of the skull permit very little movement in order to protect the brain and the sense organs. The connection between a tooth and the jawbone is also called a joint, and is described as a fibrous joint known as a gomphosis. Joints are classified both structurally and functionally.
The ulna or ulnar bone is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the radius, the forearm's other long bone. Longer and thinner than the radius, the ulna is considered to be the smaller long bone of the lower arm. The corresponding bone in the lower leg is the fibula.
The humerus is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a rounded head, a narrow neck, and two short processes. The body is cylindrical in its upper portion, and more prismatic below. The lower extremity consists of 2 epicondyles, 2 processes, and 3 fossae. As well as its true anatomical neck, the constriction below the greater and lesser tubercles of the humerus is referred to as its surgical neck due to its tendency to fracture, thus often becoming the focus of surgeons.
In human anatomy, the wrist is variously defined as (1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; (2) the wrist joint or radiocarpal joint, the joint between the radius and the carpus and; (3) the anatomical region surrounding the carpus including the distal parts of the bones of the forearm and the proximal parts of the metacarpus or five metacarpal bones and the series of joints between these bones, thus referred to as wrist joints. This region also includes the carpal tunnel, the anatomical snuff box, bracelet lines, the flexor retinaculum, and the extensor retinaculum.
The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is used to describe the entire appendage of the upper limb, but which in anatomy, technically, means only the region of the upper arm, whereas the lower "arm" is called the forearm. It is homologous to the region of the leg that lies between the knee and the ankle joints, the crus.
The radius or radial bone is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna. The ulna is longer than the radius, but the radius is thicker. The radius is a long bone, prism-shaped and slightly curved longitudinally.
In human anatomy, the supinator is a broad muscle in the posterior compartment of the forearm, curved around the upper third of the radius. Its function is to supinate the forearm.
The posterior interosseous nerve is a nerve in the forearm. It is the continuation of the deep branch of the radial nerve, after this has crossed the supinator muscle. It is considerably diminished in size compared to the deep branch of the radial nerve. The nerve fibers originate from cervical segments C7 and C8 in the spinal column.
The annular ligament is a strong band of fibers that encircles the head of the radius, and retains it in contact with the radial notch of the ulna.
The radial notch of the ulna is a narrow, oblong, articular depression on the lateral side of the coronoid process; it receives the circumferential articular surface of the head of the radius.
The radial collateral ligament (RCL), lateral collateral ligament (LCL), or external lateral ligament is a ligament in the elbow on the side of the radius.
The distal radioulnar articulation is a synovial pivot joint between the two bones in the forearm; the radius and ulna. It is one of two joints between the radius and ulna, the other being the proximal radioulnar articulation. The joint features an articular disc, and is reinforced by the palmar and dorsal radioulnar ligaments.
The interosseous membrane of the forearm is a fibrous sheet that connects the interosseous margins of the radius and the ulna. It is the main part of the radio-ulnar syndesmosis, a fibrous joint between the two bones.
The triangular fibrocartilage complex (TFCC) is formed by the triangular fibrocartilage discus (TFC), the radioulnar ligaments (RULs) and the ulnocarpal ligaments (UCLs).
The coronoid process of the ulna is a triangular process projecting forward from the anterior proximal portion of the ulna.
The humeroradial joint is the joint between the head of the radius and the capitulum of the humerus, is a limited ball-and-socket joint, hinge type of synovial joint.
The head of the radius has a cylindrical form, and on its upper surface is a shallow cup or fovea for articulation with the capitulum of the humerus. The circumference of the head is smooth; it is broad medially where it articulates with the radial notch of the ulna, narrow in the rest of its extent, which is embraced by the annular ligament.
The elbow is the region between the upper arm and the forearm that surrounds the elbow joint. The elbow includes prominent landmarks such as the olecranon, the cubital fossa, and the lateral and the medial epicondyles of the humerus. The elbow joint is a hinge joint between the arm and the forearm; more specifically between the humerus in the upper arm and the radius and ulna in the forearm which allows the forearm and hand to be moved towards and away from the body. The term elbow is specifically used for humans and other primates, and in other vertebrates it is not used. In those cases, forelimb plus joint is used.
In human anatomy, the quadrate ligament or ligament of Denucé is one of the ligaments of the proximal radioulnar joint in the upper forearm.
