Sechenov School
Home › Human Anatomy › Elbow Joint

Elbow Joint

Articulatio cubiti

For medical students2 min readUpdated 2026-10-10

Elbow joint (articulatio cubiti) is a classic example of a compound joint in human anatomy. Its uniqueness lies in the fact that it combines three distinct articulations that function together and are enclosed within a single joint capsule.

ClassificationCompound joint (consists of three articulations)
CapsuleCommon, lax anteriorly and posteriorly
LigamentsCollateral (ulnar, radial) and annular ligaments
BiomechanicsMovements around frontal and vertical axes

Morphological Characteristics: Why is it a Compound Joint?

According to anatomical classification, the elbow joint is categorized as a compound joint. This means that more than two articular surfaces participate in its formation, and structurally it includes exactly three separate articulations. These three elements are not isolated from one another; rather, they share a single joint cavity enclosed by a common capsule.

The articulatio cubiti comprises the following articulations:

  1. Humeroulnar joint (articulatio humeroulnaris). Based on the shape of its articular surfaces, it is a classic hinge (ginglymus) joint.
  2. Humeroradial joint (articulatio humeroradialis). Its geometric shape is a ball-and-socket (spheroid) articulation. However, despite its spherical shape, its functional range and directions of movement are significantly restricted by neighboring anatomical structures.
  3. Proximal radioulnar joint (articulatio radioulnaris proximalis). This articulation is classified by shape as a pivot (trochoid) joint.

Features of the Joint Capsule

All three aforementioned articulations (humeroulnar, humeroradial, and proximal radioulnar) are enclosed by a single common joint capsule. The line of attachment of this capsule runs strictly along the margins of the articular surfaces of the bones forming the joint.

A critical topographical and functional feature of the elbow joint capsule is the unevenness of its tension. Anteriorly and posteriorly, the joint capsule is lax. This anatomical property is directly related to ensuring freedom of movement during flexion and extension, as the lax areas of the capsule do not restrict the excursion of the bones.

Ligamentous Apparatus of the Elbow Joint

The stability of the complex elbow joint and the maintenance of the bones in the correct anatomical position are ensured by a robust complex of ligaments. This complex includes structures that restrict lateral displacement and stabilize the radius.

Key ligaments of the elbow joint:

Biomechanics: Axes and Types of Movement

Despite possessing a ball-and-socket element (the humeroradial articulation), the elbow joint as a whole functions with certain restrictions, and movements occur around two main axes.

Available movements in the articulatio cubiti:

  1. Around the frontal axis, flexion and extension of the forearm take place. These functions are primarily provided by the humeroulnar and humeroradial components.
  2. Around the vertical axis, pronation and supination (rotation of the forearm) occur. The cylindrical proximal radioulnar joint, in combination with the humeroradial joint, is responsible for these rotational movements.

Mnemonic

Remember the three joints within the elbow easily with the rule "Two H, One P": Humeroulnar, Humeroradial, Proximal radioulnar.

Frequently asked questions

Where does the capsule of the elbow joint attach on the humerus?

The joint capsule is common to all three of its articulations (humeroulnar, humeroradial, and proximal radioulnar) and attaches along the margins of the articular surfaces.

Anteriorly and posteriorly, the joint capsule is lax. Longitudinal bundles of the articularis cubiti muscle (m. articularis cubiti) blend into the anterior wall of the capsule; these arise from the anterior surface of the distal epiphysis of the humerus and tauten the capsule during movement, preventing its impingement.

Which ligaments reinforce the elbow joint?

The elbow joint is reinforced by three primary ligaments that provide lateral stabilization and fixation of the radius.

  • Ulnar collateral ligament (lig. collaterale ulnare) — provides medial stabilization of the joint.
  • Radial collateral ligament (lig. collaterale radiale) — provides lateral stabilization of the joint.
  • Annular ligament of the radius (lig. anulare radii) — secures the head of the radius.
Which muscles perform flexion of the forearm at the elbow joint?

Flexion of the forearm at the elbow joint is performed by three main muscles of the anterior and lateral groups.

  • Biceps brachii (m. biceps brachii) — a powerful flexor of the forearm.
  • Brachialis (m. brachialis) — acts as the primary flexor of the forearm.
  • Brachioradialis (m. brachioradialis) — also participates in flexing the forearm at the elbow joint.
Which arteries form the articular network of the elbow (rete articulare cubiti)?

The elbow articular network (rete articulare cubiti) is formed by anastomoses between recurrent and collateral arteries in the anterior and posterior elbow regions.

  • Superior and inferior ulnar collateral arteries (a. collateralis ulnaris superior et inferior) — branches of the brachial artery.
  • Radial and middle collateral arteries (a. collateralis radialis et a. collateralis media) — branches of the profunda brachii artery.
  • Radial recurrent artery (a. recurrens radialis) — branch of the radial artery.
  • Anterior and posterior ulnar recurrent arteries (a. recurrens ulnaris anterior et posterior) — branches of the ulnar artery.
  • Interosseous recurrent artery (a. interossea recurrens) — branch of the posterior interosseous artery.
Which muscles perform supination of the forearm at the elbow joint?

Supination of the forearm at the elbow joint is performed by two main muscles that ensure the rotation of the radius around the ulna.

These include:

  • Biceps brachii (m. biceps brachii) — a powerful supinator and flexor of the forearm.
  • Supinator (m. supinator) — a specialized muscle of the posterior compartment of the forearm responsible for supination.
Why is the elbow joint called a compound joint?

Because it includes three separate articulations (humeroulnar, humeroradial, and proximal radioulnar) enclosed within a single joint capsule.

Which parts of the elbow joint capsule are most vulnerable?

The joint capsule is most lax anteriorly and posteriorly, whereas it firmly attaches along the margins of the articular surfaces laterally and medially.

Around which axes do movements occur in the elbow joint?

Movements occur around the frontal axis (flexion and extension) and around the vertical axis (pronation and supination).

Go deeper

More topics in Human Anatomy

Esophagus: Anatomy, Histology and RelationsLungsAdrenal GlandsBasal Nuclei (Basal Ganglia): Anatomy and StructureMiddle EarTemporal BoneMuscles of the Lateral Abdominal WallParasympathetic Ganglia of the HeadMaxillary NerveVas Deferens and Seminal VesiclesOsseous Labyrinth of the Internal EarSubclavian ArteryHuman Anatomy →