Author: Jana Vasković•Reviewer: Francesca Salvador MScLast reviewed: September 16, 2021Reading time: 7 minutes

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Proximal radioulnar share (Articulatio radioulnaris proximalis)

The proximal radioulnar joint is a synovial joint the connects the proximal ends of the radius and also ulna.

You are watching: The proximal radioulnar joint is a __________ joint.

In this joint, the circumferent head the radius is placed within the ring created by the radial notch the ulna and also the annular ligament. This configuration makes this joint a pivot joint.

The proximal radioulnar joint is a uniaxial joint, allowing movements in one level of freedom; pronation-supination. In humans, this movement is distinct for the upper limb.

This write-up will comment on the anatomy and duty of the proximal radioulnar joint.

Key facts around the proximal radioulnar joint
TypeSynovial pivot joint; uniaxial
Articular surfacesHead the radius, radial fossa that ulna
LigamentsAnnular ligament, quadrate ligament
InnervationMedian, musculocutaneous, radial and also ulnar nerves
Blood supplyDeep brachial, radial and common interosseous arteries
MovementsPronation - supination

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The articular surface of the proximal radioulnar joint space the head of radius and the radial fossa of ulna.

Both surfaces room lined through hyaline cartilage. The radial head is circular and convex, when the radial fossa is reciprocally concave.

However, the radial fossa is in touch with just one-fifth of the radial head. Because that the sake of completeness the this pivot joint, the annular ligament surrounding the radial head and also holds the tight versus the radial fossa that ulna.

Ligaments and also joint capsule

The fibrous capsule that the radioulnar share attaches come the annular ligament distally, if proximally it is consistent with the capsule that the elbow joint. The synovial membrane attaches come the spare of the articular surfaces and also to the annular ligament. The lines the internal surface of the capsule,where it is constant with the synovial membrane the the elbow joint. Thus, the elbow and proximal radioulnar joints re-superstructure one constant synovial cavity.

The proximal radioulnar joint is reinforced through the annular and also quadrate ligaments.

Annular ligament


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The annular ligament extends native the anterior margin of radial fossa that ulna, encircles the radial head and attaches come the posterior margin the the radial fossa. Thus, the annular ligament help to develop a steady ring within which the radial head can rotate.

The proximal margin that the ligament is fused with the share capsule, when the distal margin attaches come the neck the radius. The interior surface that the annular ligament is covered by a thin layer the cartilage i beg your pardon is in direct call with the surface ar of the radius. The superficial surface is fused with the radial collateral ligament and also is among the attachments sites of the supinator muscle.

The quadrate ligament is a short fibrous band that spans from the superior component of the supinator fossa the ulna come the neck of radius, just proximal come the radial tuberosity.

Innervation

The proximal radioulnar share is supplied by the branches the median, musculocutaneous, radial and also ulnar nerves.

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Blood supply

The blood supply to the proximal radioulnar joint comes from a periarticular network created by the radial collateral branch that deep brachial artery, radial and also recurrent branches the the radial and common interosseous arteries.


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Movements


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The proximal radioulnar joint works in a unit with the distal radioulnar share to enable rotatory motions of the forearm; pronation and also supination. As soon as the arm is in the relaxing position next to the body, the selection of movement for pronation is 61–66°, while because that supination it is 70–77°

In the proximal radioulnar joint, the head the radius rotates in ~ the ring developed by the radial fossa and also annular ligament. The axis that rotation is dynamic and also depends on the position of the forearm. As soon as the forearm is in supination, the axis passes through the facility of the head of radius proximally, and also through the ulnar attachments of the articular disc in the distal radioulnar joint. As soon as the forearm is pronated, the distal allude of the axis move medially, passing through the head the ulna.


Besides rotation the the radial head, the supination and also pronation are adhered to by a sequence of added movements in the proximal radioulnar joint;

The exceptional surface the the radial head rotates against the capitulum that humerusThe head the radius tilts laterally and also inferiorly in the transverse planeSince the head that radius is ellipsoid top top cross-section, its broader axis comes right into a transverse, for this reason displacing the radial head laterally

The proximal radioulnar joint takes a closed packed position in ~ the 5° that supination. The open pack (resting) position occurs once the forearm is flexed in ~ 70° and also supinated in ~ 35°. The capsular pattern that the share is characterized and minimal by pronation and also supination. The proximal radioulnar share permits the accessory movements the anteroposterior gliding that the radial head against the ulna and the capitulum the humerus.

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Sources

References:

Cael, C. (2010). Functional anatomy: Musculoskeletal anatomy, kinesiology, and also palpation for manual therapists. Philadelphia, PA: Wolters Kluwer Health/Lippincott, Williams & Wilkins.Hall, S. J. (2015). An easy biomechanics (7th ed.). New York, NY: McGraw-Hill EducationMagee, D. J. (2014). Orthopedic physics assessment (6th ed.). St. Louis: Elsevier Saunders.Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.Netter, F. (2019). Atlas of human Anatomy (7th ed.). Philadelphia, PA: Saunders.Palastanga, N., & Soames, R. (2012). Anatomy and human movement: structure and function (6th ed.). Edinburgh: Churchill Livingstone.Richards, J. (2018). The comprehensive textbook of clinical biomechanics (2nd ed.). Amsterdam, The Netherlands: Elsevier.Standring, S. (2016). Gray\"s Anatomy (41tst ed.). Edinburgh: Elsevier Churchill Livingstone.

Illustrations:

Proximal radioulnar share (Articulatio radioulnaris proximalis) - Irina Münstermann