[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) › Annular ligament [Joints and ligaments](https://durgical.com/en/anatomy/system/joints-and-ligaments/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) # Annular ligament The annular ligament is a ring around the top of the [radius](https://durgical.com/en/anatomy/radius/) at the elbow; it holds the radial head against the ulna while it spins. Official name: Annular ligament of the radius [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=upper_limb&select=annular_lig&side=r) Opens in the Durgical app, no sign-up needed. ## What it is A ring of ligament around the head of the radius, fixed to the ulna at both ends. ## What it does Holds the radial head against the ulna while it spins. ## Key points - Forms about four-fifths of a ring that the radial notch of the ulna completes; it is narrower below than above (funnel-shaped), which keeps the radial head from pulling out in adults - Pulled elbow (nursemaid's elbow, radial head subluxation): in children of about 1 to 4 years, a pull on the hand with the forearm pronated slips the ligament up over the head into the joint - Torn or displaced in a Monteggia fracture-dislocation (ulna fracture with radial head dislocation); a radial head out of line with the capitulum calls for a look at the whole forearm ## Key facts **Attaches** Anterior and posterior margins of the radial notch of the ulna, encircling the radial head **Function** Holds the radial head against the ulna while it spins **Tight in** Constant during rotation ## Relations **Contents** Radial head rim, which turns within it; its smooth inner surface continues the radial notch **Medial** Radial notch of the [ulna](https://durgical.com/en/anatomy/ulna/), to whose front and back edges it attaches **Above** [RCL (elbow)](https://durgical.com/en/anatomy/radial-collateral-ligament-of-the-elbow/) blending into it from the lateral epicondyle; the capitulum above the radial head **Below** Radial neck, the [quadrate ligament](https://durgical.com/en/anatomy/quadrate-ligament/) and the synovial pouch that bulges below it (sacciform recess) **Lateral** [Supinator](https://durgical.com/en/anatomy/supinator/), which partly arises from it, and the common extensor origin **In front** [Distal biceps tendon](https://durgical.com/en/anatomy/distal-biceps-tendon/) heading for the radial tuberosity; the [posterior interosseous nerve](https://durgical.com/en/anatomy/posterior-interosseous-nerve/) passes round the radial neck to enter the supinator under the arcade of Frohse **Behind** [Anconeus](https://durgical.com/en/anatomy/anconeus/) and the LUCL ## How to find it Place a finger in the small hollow just below the lateral epicondyle at the back of the extended elbow and turn the forearm: the radial head rolls under the finger inside this ligament. At surgery it lies deep to the supinator and the common extensor origin. ## Examination - Reduction of a pulled elbow confirms the diagnosis: supination with flexion, or hyperpronation, of the forearm; a click over the radial head and the child using the arm again within minutes are typical (studies suggest hyperpronation succeeds slightly more often) ## On imaging On every elbow X-ray the radiocapitellar line, drawn along the radial neck, must pass through the capitulum in all views; if not, the radial head is dislocated and a Monteggia ulna fracture is sought. In a typical pulled elbow X-rays are normal; ultrasound can show the ligament caught in the joint. ## Common problems - Nursemaid's elbow: in young children a sudden pull on the hand slips the radial head partly out of the ring. - Torn with radial head dislocations and some forearm fractures. ## How it is diagnosed A child who will not use the arm after a pull, with normal-looking X-rays. MRI for adult injuries. ## Treatment - A gentle reduction move by a clinician usually fixes nursemaid's elbow at once. - Repair or reconstruction in complex adult injuries. ## Clinical notes - Bado classification of Monteggia injuries: I anterior radial head dislocation (most common in children), II posterior, III lateral, IV with fractures of both bones - A missed, chronic Monteggia lesion may need annular ligament reconstruction (for example with a strip of triceps fascia) together with correction of the ulna - Congenital radial head dislocation (usually posterior, often both sides, with a dome-shaped head) differs from a traumatic one ## Anatomical variants - Its shape varies: dissection and MRI studies describe single, two-lobed and other forms ## Memory aid MUGR: Monteggia = Ulna fracture (with radial head dislocation), Galeazzi = Radius fracture (with distal radioulnar joint injury). ## Related conditions - [Radial head subluxation (pulled elbow)](https://durgical.com/en/conditions/radial-head-subluxation/) ## Test yourself Think of the answer, then tap the question to see it. ## What does the annular ligament attach to, and what does it do? The front and back margins of the radial notch of the ulna, encircling the radial head; it holds the radial head against the ulna while it spins. ## What happens to the annular ligament in a pulled elbow (radial head subluxation)? In children of about 1 to 4 years, a pull on the pronated hand slips the annular ligament up over the radial head into the joint. ## How is a pulled elbow reduced, confirming the diagnosis? By supination with flexion, or hyperpronation, of the forearm; a click over the radial head and the child using the arm again confirm it. ## Which fracture-dislocation tears or displaces the annular ligament? The Monteggia injury: an ulna fracture with radial head dislocation; type I (anterior) is the most common in children. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/annular-ligament-of-the-radius/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** ligamentum anulare radii TA2 1778 **Official Spanish (DeCS)** Ligamento anular del radio **English (TA2)** Annular ligament of the radius ## Related - [RCL (elbow)](https://durgical.com/en/anatomy/radial-collateral-ligament-of-the-elbow/) - [Quadrate ligament](https://durgical.com/en/anatomy/quadrate-ligament/) - [Radius](https://durgical.com/en/anatomy/radius/) - [Ulna](https://durgical.com/en/anatomy/ulna/) Sources: Terminologia Anatomica (TA2); [Anatomy, Shoulder and Upper Limb, Elbow Annular Ligament](https://www.ncbi.nlm.nih.gov/books/NBK538494/); [Anatomy, Shoulder and Upper Limb, Proximal Radio-Ulnar Joint](https://www.ncbi.nlm.nih.gov/books/NBK551614/); Anatomy of the Human Body (20th ed.): Surface Anatomy of the Upper Extremity (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain; [9.6 Anatomy of Selected Synovial Joints](https://openstax.org/books/anatomy-and-physiology-2e/pages/9-6-anatomy-of-selected-synovial-joints) (OpenStax (Rice University), 2022) · adapted, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/annular-ligament-of-the-radius/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/annular-ligament-of-the-radius/