Elbow Joint

Angular Movements at Elbow

Flexion / Extension

145 o


75 o


80 o

Above: Elbow Joint Movements

The elbow joint is a synovial joint that can be described using a labelled diagram of the bones at the elbow. Three bones (humerus, radius and ulna) meet at the elbow joint where each of these bones articulates with each of the other two, so the elbow joint includes:

  • the humeroulnar joint
  • the humeroradial joint, and
  • the proximal radioulnar joint
    (the distal radioulnar joint being at the wrist)

The following labelled diagrams of the elbow joint includes the humerus (upper-arm) bone and the radius and ulna, both of which are lower-arm bones. These are also shown on the page about arm bone names. The 3 joints listed above are indicated in red, the 3 bones in green and some of the features on the bones at the elbow joint are shown in pink:

Radiographs of the Elbow Joint

Medial epicondyle Humerus Bone Humerus Bone Humerus Bone Radius Bone Ulna bone Humerus Bone Lateral epicondyle Lateral epicondyle Humerus Bone Medial epicondyle Humerus Bone Humerus Bone Medial epicondyle Medial epicondyle Radius Bone Radius Bone Ulna bone Ulna bone Ulna bone Ulna bone

Parts / Portions of the Elbow Joint

There are three parts (or portions) of the elbow joint, each of which is named according to the bones articulating at that part.

Name of Joint
Articulating Bones
Range (from - to)
Joint Type

Humeroulnar joint

  • Humerus
  • Ulna

From: trochlear notch of ulna
To: trochlea of humerus

  • Flexion
  • Extension

Humeroradial joint

  • Humerus
  • Radius

From: head of the radius
To: capitulum of humerus

  • Flexion
  • Extension

Proximal radioulnar joint
(the distal radioulnar joint being at the wrist)

  • Radius
  • Ulna

From: head of radius
To: radial notch of ulna

  • Rotation, including:
    • Pronation
    • Supination

The bones and the features on the bones at and around the elbow joint are shown in the radiographs above.
The three parts of the elbow joint are listed in the table above. Although these three parts involve specific articulatory surfaces on just the pairs of bones involved in each case, all of these articular surfaces are enveloped by a common synovial membrane, hence they are generally considered as one joint (with three parts) rather than as separate individual joints.

Articular Capsule of the Elbow Joint

The elbow joint capsule enclosing the articulating surfaces is made up of tough fibrous bands. It is lax both in front and behind in order to enable full flexion and extension of the elbow joint. The medial and lateral epicondyles on either side of the humerus bone are outside of the area enclosed by the articular capsule.

Ligaments of the Elbow Joint

The articular capsule of the elbow joint is thickened and supported medially and laterally, and, to a lesser extent, in front and behind by ligaments.

Muscles that control movement of the elbow joint






  • biceps brachii (most powerful supinator)
  • supinator (weaker supinator than biceps)
  • extensor pollicis longus (weaker supinator than biceps)
  • extensor pollicis brevis (weaker supinator than biceps)

End of these notes about the elbow joint.

See also types of joints, features on bones, elbow pain, types of fractures and the structure and functions of bones.

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