[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/) › Elbow capsule [Joints and ligaments](https://durgical.com/en/anatomy/system/joints-and-ligaments/) · [Upper limb](https://durgical.com/en/anatomy/region/upper-limb/) # Elbow capsule The elbow capsule is the sleeve that seals the elbow joint; after an injury it can stiffen and stop the elbow straightening fully. Official name: Elbow joint capsule [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=upper_limb&select=elbow_capsule&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The thin bag of tissue around the elbow joint. ## What it does Seals the joint; a stiff capsule after injury limits straightening. ## Key points - Fat pads lie inside the capsule but outside the synovium, in the coronoid and olecranon fossae; an effusion lifts them, so a visible posterior fat pad on a lateral X-ray means fluid in the joint - The elbow stiffens easily after trauma: the anterior capsule contracts and the last degrees of extension are lost first - Aspiration goes through the lateral soft spot, the centre of the triangle formed by the lateral epicondyle, radial head and olecranon tip - Carrying angle: with the elbow straight and palm forward the forearm angles outward (about 10–15°, more in women) and lines up in pronation and full flexion; reversal is cubitus varus ## Key facts **Attaches** [Humerus](https://durgical.com/en/anatomy/humerus/) above the coronoid, radial and olecranon fossae to the coronoid margin and annular ligament **Function** Encloses the humeroulnar, humeroradial and proximal radioulnar joints; thickened by the collateral ligaments; flexion–extension arc about 140–145° ## Relations **In front** [Brachialis](https://durgical.com/en/anatomy/brachialis/), partly attached to it; in the [cubital fossa](https://durgical.com/en/anatomy/cubital-fossa/) in front, the [brachial artery](https://durgical.com/en/anatomy/brachial-artery/) and [median nerve](https://durgical.com/en/anatomy/median-nerve/) **Behind** [Triceps tendon](https://durgical.com/en/anatomy/triceps-tendon/) and [anconeus](https://durgical.com/en/anatomy/anconeus/), with the posterior fat pad between capsule and bone in the olecranon fossa **Medial** Thickened by the ulnar collateral ligament (UCL); the [ulnar nerve](https://durgical.com/en/anatomy/ulnar-nerve/) lies against the posteromedial capsule behind the medial epicondyle **Lateral** Thickened by the radial collateral ligament and blended with the [annular ligament](https://durgical.com/en/anatomy/annular-ligament-of-the-radius/); the [radial nerve](https://durgical.com/en/anatomy/radial-nerve/) divides in front of it, and its posterior interosseous branch enters the [supinator](https://durgical.com/en/anatomy/supinator/) ## How to find it With the elbow bent at 90°, the soft spot is felt in the triangle between the lateral epicondyle, the radial head (which turns under the thumb as the forearm rotates) and the olecranon tip; a bulge here means an effusion. ## Examination - Elbow extension test: after a fall, full active extension makes a fracture needing treatment unlikely; inability to straighten the elbow fully suggests an effusion or fracture and calls for X-rays ## On imaging Lateral X-ray at 90° flexion: a raised anterior fat pad forms a sail sign, and any visible posterior fat pad is abnormal. In children this suggests a supracondylar fracture, in adults a radial head fracture, even with no fracture line. Ultrasound shows fluid distending the posterior recess. ## Clinical notes - Septic arthritis of the elbow: painful, swollen joint held flexed; fluid is aspirated through the soft spot for cell count, Gram stain, culture and crystals - Post-traumatic stiffness that does not respond to therapy is treated by open or arthroscopic capsular release; a functional arc of about 30–130° of flexion is the commonly quoted goal - Arthroscopy portals sit close to nerves (the radial nerve in front laterally, the ulnar nerve medially); the joint is distended with fluid first to push them away ## Development The joint cavity appears in the embryo when the central interzone tissue between the cartilage models dies back, the outer mesenchyme forming the capsule; in children, the ossification centres that appear inside it in a fixed order (CRITOE) must be known to read elbow films. ## Related conditions - [Elbow dislocation](https://durgical.com/en/conditions/elbow-dislocation/) ## Test yourself Think of the answer, then tap the question to see it. ## What does a visible posterior fat pad on a lateral elbow X-ray mean? Fluid in the joint: the fat pads lie inside the elbow capsule but outside the synovium, and an effusion lifts them. ## Where is the elbow joint aspirated? Through the lateral soft spot, the centre of the triangle formed by the lateral epicondyle, radial head and olecranon tip. ## Which movement is lost first when the elbow capsule stiffens after trauma? The last degrees of extension, as the anterior capsule contracts. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/elbow-joint-capsule/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** capsula articularis articulationis cubiti TA2 1536 **Official Spanish (DeCS)** Cápsula articular de la articulación del codo **English (TA2)** Elbow joint capsule ## Related - [Humerus](https://durgical.com/en/anatomy/humerus/) - [Radius](https://durgical.com/en/anatomy/radius/) - [Ulna](https://durgical.com/en/anatomy/ulna/) Sources: Terminologia Anatomica (TA2); [Anatomy, Shoulder and Upper Limb, Elbow Joint](https://www.ncbi.nlm.nih.gov/books/NBK532948/); [9.7 Development of Joints](https://openstax.org/books/anatomy-and-physiology-2e/pages/9-7-development-of-joints) (OpenStax (Rice University), 2022) · adapted, [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/); Anatomía humana (4.ª ed.), tomo 1, cap. 56: Articulación del codo. Músculos del brazo. ## **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/elbow-joint-capsule/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/elbow-joint-capsule/