Joints and ligaments · Upper limb
Quadrate ligament !
The quadrate ligament is a thin sheet just below the annular ligament at the elbow; it limits how far the radius spins at the end of rotation.
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What it is
A thin band under the annular ligament, from the radial neck to the ulna.
What it does
Limits spinning of the radius at the end of rotation.
Key facts
- Attaches
- Radial notch of the ulna to the neck of the radius
- Function
- Limits spin of the radial head
- Tight in
- End of supination (and pronation)
Relations
- Above
- Lower border of the annular ligament
- Medial
- Lower edge of the radial notch of the ulna
- Lateral
- Medial side of the radial neck
- Deep
- Synovial membrane of the proximal radioulnar joint (sacciform recess)
How to find it
Not palpable: it lies deep to the supinator, just below the annular ligament. In a lateral approach to the radial head and neck it is met as a thin layer of capsule after the annular ligament is exposed.
On imaging
Too thin to see on radiographs. High-resolution MRI of the elbow may show it as a thin low-signal band below the annular ligament; it is rarely reported on its own.
Clinical notes
- Rarely injured alone; it tears with the annular ligament in radial head dislocations and Monteggia injuries
- Dissection on the radial neck below the annular ligament, where this ligament lies, puts the posterior interosseous nerve at risk; pronating the forearm moves the nerve away
- Rheumatoid synovitis can distend the capsule around the radial neck and is one recognised cause of posterior interosseous nerve compression
Test yourself
Think of the answer, then tap the question to see it.
Where does the quadrate ligament lie?
Just below the annular ligament, from the lower edge of the radial notch of the ulna to the neck of the radius.
What movement does the quadrate ligament limit?
Spin of the radial head, becoming taut at the end of supination and pronation.
In which injuries is the quadrate ligament torn?
Rarely alone; it tears with the annular ligament in radial head dislocations and Monteggia injuries.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- ligamentum quadratum TA2 1779
- Official Spanish (DeCS)
- Ligamento cuadrado
- English (TA2)
- Quadrate ligament
Related
Sources: Terminologia Anatomica (TA2); Anatomy, Shoulder and Upper Limb, Elbow Annular Ligament; Anatomy, Shoulder and Upper Limb, Proximal Radio-Ulnar Joint; Anatomy of the Human Body (20th ed.): Radioulnar Articulation (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain.
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Representative model, for educational purposes only.
