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]
Structure
A study upon the arms of 38 people found that its mean length is 3.4cm (range 2.4 to 4.2cm) and in most people it tapers from the ulna to the radius end, being at the ulna 9mm, in its middle, 7mm and its radius end 4mm.[2]
Variation
The shape and form of the ligament have been found in humans cadavers to vary from a rounded cord to a flat membrane.[3] Further, it is not found in all humans being variably found to be absent in half of arms,[2] and a third[3] or 15% of people.[4] It is found in most primates though not in the family of New World monkeys that includes spider and woolly monkeys called atelines.[5]
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]
Notes
1 2 3 Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol. 1: Locomotor System. p 122 (5thed.). Thieme. ISBN3-13-533305-1.
1 2 3 4 5 Tubbs RS, O'Neil JT Jr, Key CD, Zarzour JG, Fulghum SB, Kim EJ, Lyerly MJ, Shoja MM, George Salter E, Jerry Oakes W. (2007). The oblique cord of the forearm in man. Clin Anat. 20(4):411–5. PMID16683244
↑ Skahen JR 3rd, Palmer AK, Werner FW, Fortino MD. (1997). The interosseous membrane of the forearm: anatomy and function. J Hand Surg Am. 22(6):981–5. PMID9471064
1 2 3 4 Patel BA. (2005). Form and function of the oblique cord (chorda obliqua) in anthropoid primates.Primates. 46(1):47–57. PMID15241636
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 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.
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.
The upper limbs or upper extremities are the forelimbs of an upright-postured tetrapod vertebrate, extending from the scapulae and clavicles down to and including the digits, including all the musculatures and ligaments involved with the shoulder, elbow, wrist and knuckle joints. In humans, each upper limb is divided into the shoulder, arm, elbow, forearm, wrist and hand, and is primarily used for climbing, lifting and manipulating objects. In anatomy, just as arm refers to the upper arm, leg refers to the lower leg.
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.
In human anatomy, the adductor pollicis muscle is a muscle in the hand that functions to adduct the thumb. It has two heads: transverse and oblique.
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 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 posterior compartment of the forearm contains twelve muscles which primarily extend the wrist and digits. It is separated from the anterior compartment by the interosseous membrane between the radius and ulna.
The following outline is provided as an overview of and topical guide to human anatomy:
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.
The extrinsic extensor muscles of the hand are located in the back of the forearm and have long tendons connecting them to bones in the hand, where they exert their action. Extrinsic denotes their location outside the hand. Extensor denotes their action which is to extend, or open flat, joints in the hand. They include the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor digitorum (ED), extensor digiti minimi (EDM), extensor carpi ulnaris (ECU), abductor pollicis longus (APL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL), and extensor indicis (EI).
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.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
