The oblique cord is a ligament

Ligament

In anatomy, the term ligament is used to denote any of three types of structures. Most commonly, it refers to fibrous tissue that connects bones to other bones and is also known as articular ligament, articular larua, fibrous ligament, or true ligament.Ligament can also refer to:* Peritoneal...

 between the two ulnar and radius

Radius

In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...

 bones in the lower arm near its elbow

Elbow

The human elbow is the region surrounding the elbow-joint—the ginglymus or hinge joint in the middle of the arm. Three bones form the elbow joint: the humerus of the upper arm, and the paired radius and ulna of the forearm....

. It takes the form of a small, flattened band, extending downward and lateralward, from the lateral side of the ulnar tuberosity

Tuberosity of the ulna

At the junction of the antero-inferior surface of the coronoid process with the front of the body is a rough eminence, the tuberosity of the ulna , which gives insertion to a part of the Brachialis; to the lateral border of this tuberosity the oblique cord is attached....

 at the base of the coronoid process

Coronoid process

The Coronoid process can refer to:* The coronoid process of the mandible, part of the ramus mandibulae of the mandible...

 to the radius

Radius

In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...

 a little below the radial tuberosity

Radial tuberosity

Beneath the neck of the radius, on the medial side, is an eminence, the radial tuberosity; its surface is divided into:* a posterior, rough portion, for the insertion of the tendon of the biceps brachii....

. Its fibers run in the opposite direction to those of the Interosseous membrane of the forearm

Interosseous membrane of the forearm

The interosseous membrane of the forearm is a fibrous sheet that connects the radius and the ulna...

.

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

Josias Weitbrecht

Josias Weitbrecht was a known German Professor of Medicine and Anatomy in Russia.-Life and career:...

.

It has no known function and can be cut without apparent consequence.

Dimensions

A study upon the arms of 38 people found that its mean length is 3.4 cm (range 2.4 to 4.2 cm) and in most people it tapers from the ulna to the radius end, being at the ulna 9 mm, in its middle, 7mm and its radius end 4 mm.

Function

It has been suggested to strengthen the interosseus membrane proximally, provide restraint for the rotatory movements of the forearm, or that the ligament may stop bone bending and preventing buckling failure. However, due the orientation of its fibers, the oblique cord is unlikely to transfer force due to limb loading from the radius to the ulna.

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.

A study on humans concluded that it "appears insignificant in stability of the proximal forearm." It has been suggested that its presence in modern humans may be a vestigial body part for a biped

Biped

Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning "two feet"...

 that was important due to the load-bearing function of the upper limb in evolutionarily earlier quadruped

Quadruped

Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...

 human ancestors.

Variability

The shape and form of the ligament have been found in humans cadaver

Cadaver

A cadaver is a dead human body.Cadaver may also refer to:* Cadaver tomb, tomb featuring an effigy in the form of a decomposing body* Cadaver , a video game* cadaver A command-line WebDAV client for Unix....

s to vary from a rounded cord to a flat membrane. Further, it is not found in all humans being variably found to be absent in half of arms, and a third or 15% of people. It is found in most primates though not in the family of New World monkey

New World monkey

New World monkeys are the five families of primates that are found in Central and South America: Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae. The five families are ranked together as the Platyrrhini parvorder and the Ceboidea superfamily, which are essentially synonymous since...

s that includes spider

Spider monkey

Spider monkeys of the genus Ateles are New World monkeys in the subfamily Atelinae, family Atelidae. Like other atelines, they are found in tropical forests of Central and South America, from southern Mexico to Brazil...

 and woolly monkey

Woolly monkey

The woolly monkeys are the genus Lagothrix of New World monkeys, usually placed in the family Atelidae.There are four species of woolly monkey. All originate from the rainforests of South America...

s called atelines.