Pivot joint

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Pivot joint
Gelenke Zeichnung01.jpg
1: Ball and socket joint; 2: Condyloid joint (Ellipsoid); 3: Saddle joint; 4 Hinge joint; 5: Pivot joint;
Details
Identifiers
Latin articulatio trochoidea
TA98 A03.0.00.045
TA2 1557
FMA 75294
Anatomical terminology

In animal anatomy, a pivot joint (trochoid joint, rotary joint or lateral ginglymus) is a type of synovial joint whose movement axis is parallel to the long axis of the proximal bone, which typically has a convex articular surface.

Contents

According to one classification system, a pivot joint like the other synovial joint —the hinge joint has one degree of freedom. [1] Note that the degrees of freedom of a joint is not the same as a joint's range of motion.

Movements

Pivot joints allow for rotation, which can be external (for example when rotating an arm outward), or internal (as in rotating an arm inward). When rotating the forearm, these movements are typically called pronation and supination. In the standard anatomical position, the forearms are supinated, which means that the palms are facing forward, and the thumbs are pointing away from the body. In contrast, a forearm in pronation would have the palm facing backward and the thumb would be closer to the body, pointing medially.

Examples

Examples of a pivot joint include:

In contrast, spherical joints (or ball and socket joints) such as the hip joint permit rotation and all other directional movement, while pivot joints only permit rotation.

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Motion, the process of movement, is described using specific anatomical terms. Motion includes movement of organs, joints, limbs, and specific sections of the body. The terminology used describes this motion according to its direction relative to the anatomical position of the body parts involved. Anatomists and others use a unified set of terms to describe most of the movements, although other, more specialized terms are necessary for describing unique movements such as those of the hands, feet, and eyes.

<span class="mw-page-title-main">Annular ligament of radius</span>

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<span class="mw-page-title-main">Proximal radioulnar articulation</span>

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.

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A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking.

<span class="mw-page-title-main">Elbow</span> Joint between the upper and lower parts of the arm

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.

<span class="mw-page-title-main">Anatomical terminology</span> Scientific terminology used by anatomists, zoologists, and health professionals

Anatomical terminology is a form of scientific terminology used by anatomists, zoologists, and health professionals such as doctors, physicians, and pharmacists.

References

PD-icon.svgThis article incorporates text in the public domain from page 285 of the 20th edition of Gray's Anatomy (1918)

  1. Platzer, Werner (2008) Color Atlas of Human Anatomy, Volume 1, p.28