| Oblique cord |
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 Left elbow-joint, showing anterior and ulnar collateral ligaments. (Oblique cord visible as diagonal white line near center bottom.) |
 The supinator. (Oblique cord visible at center.) |
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| Latin | chorda obliqua membranae interosseae antebrachii |
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| TA98 | A03.5.06.003 |
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| TA2 | 1762 |
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| FMA | 39484 |
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| Anatomical terminology |
The oblique cord is a ligament between the ulnar and radius bones in the forearm near the elbow. It takes the form of a small, flattened band, extending distally and laterally, from the lateral side of the ulnar tuberosity at the base of the coronoid process to the radius a little below the radial tuberosity. [1] Its fibers run in the opposite direction to those of the Interosseous membrane of the forearm. [1]
It is called by other names including oblique ligament, chorda obliqua, radio-ulnar ligament, chorda oblique antebrachii anterior, proximal interosseous band, dorsal oblique accessory cord, proximal band of the interosseous membrane, superior oblique ligament, oblique ligament proper, round ligament, and ligament of Weitbrecht . [2]
It has no known function and can be cut without apparent consequence. [2]
Function
It has been suggested to strengthen the interosseus membrane proximally, [1] provide restraint for the rotatory movements of the forearm, [3] or that the ligament may stop bone bending and preventing buckling failure. [3] However, due to the orientation of its fibers, the oblique cord is unlikely to transfer force due to limb loading from the radius to the ulna. [5]
One recent comparative study upon primates concluded:
The oblique cord does not limit supination, nor does it seem to have a role in preventing radial buckling failure or reducing bending strain. What, then, is the oblique cord for? The oblique cord may simply be an additional tie between the radius and ulna aiding other soft tissue structures such as the annular ligament and interosseous membrane. Additionally, the oblique cord may prevent anterior shearing of the proximal radius under extreme compressive loads. [5]
A study on humans concluded that it "appears insignificant in stability of the proximal forearm." [2] It has been suggested that its presence in modern humans may be a vestigial body part for a biped that was important due to the load-bearing function of the upper limb in evolutionarily earlier quadruped human ancestors. [5]
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.
The ulna or ulnal bone is a long bone found in the forearm that stretches from the elbow to the wrist, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of the forearm as the little finger. It runs parallel to the radius, the other long bone in the forearm. The ulna is longer and the radius is shorter, but the radius is thicker and the ulna is thinner. Therefore, the ulna is considered to be the smaller bone of the two bones in 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 extensor pollicis longus muscle (EPL) is a skeletal muscle located dorsally on the forearm. It is much larger than the extensor pollicis brevis, the origin of which it partly covers and acts to stretch the thumb together with this muscle.
The flexor pollicis longus is a muscle in the forearm and hand that flexes the thumb. It lies in the same plane as the flexor digitorum profundus. This muscle is unique to humans, being either rudimentary or absent in other primates. A meta-analysis indicated accessory flexor pollicis longus is present in around 48% of the population.
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.
In human anatomy, the abductor pollicis longus (APL) is one of the extrinsic muscles of the hand. Its major function is to abduct the thumb at the wrist. Its tendon forms the anterior border of the anatomical snuffbox.
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 proximal radioulnar articulation, also known as the proximal radioulnar joint (PRUJ), is a synovial pivot joint between the circumference of the head of the radius and the ring formed by the radial notch of the ulna and the annular ligament.
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 coronoid process of the ulna is a triangular process projecting forward from the anterior proximal portion of the ulna.
The midcarpal joint is formed by the scaphoid, lunate, and triquetral bones in the proximal row, and the trapezium, trapezoid, capitate, and hamate bones in the distal row. The distal pole of the scaphoid articulates with two trapezial bones as a gliding type of joint. The proximal end of the scaphoid combines with the lunate and triquetrum to form a deep concavity that articulates with the convexity of the combined capitate and hamate in a form of diarthrodial, almost condyloid joint.
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 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.
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 muscles, with their muscles bellies located in the hand proper.
