MEDICAL UNIVERSITY OF SOUTH CAROLINA
COLLEGE OF HEALTH PROFESSIONS
REHABILITATION SCIENCES DEPARTMENT

Functional Anatomy of the Elbow

The elbow is sometimes termed a "power" joint, and is important in lifting. The elbow is operated largely by powerful muscles of the arm, and is created by the humeroulnar joint, where the articulation actually occurs. The humeroradial joint which is created by the surrounding articular capsule, is not an actual functional joint, but represents a bony relationship which is included in the elbow complex.

A. Classification of the joints of the elbow complex:

  1. Humeroulnar joint - the joint is a hinge joint, and extension, flexion are the only motions occurring here.
  2. The humeroradial joint is unclassified.

B. Direction of excursion of the humeroulnar joint and elbow ligaments and muscles:

  1. In the normal subject, full extension should be achieved to 180o; whereas 0° to 145° flexion is considered normal. The forearm, however, does not normally hang along the line of the humerus, but rather achieves a laterally produced angle of about 170o (males) to 165° (females). This is called the "carrying angle" and is produced by the lateral shaft of the trochlea of the humerus as it articulates with the trochanteric notch of the ulna.
  2. The normal subject should be able to achieve up to approximately 145o flexion of the forearm upon the humerus.
  3. Elbow ligaments:
    a. Articular capsule - This capsule is loose and surrounds the elbow complex. Thinner posteriorly, the capsule allows for movement of the elbow, while offering good protection for the integrity of the joint. Most dislocations of the elbow, however, occur posteriorly, due to the relatively thin aspect of the posterior capsule.
    b. Anconeus - The anconeus is a small muscle attaching to the articular capsule of the elbow and ulna. Its function is to pull the capsule out of the elbow joint upon active extension of the elbow. The anconeus also assists the triceps brachii in extending the elbow.
    c. Collateral ligaments: The collateral ligaments support the elbow complex, and may be observed running along either side. The collateral ligaments strengthen the articular capsule medially and laterally. They are termed the ulnar (medial) collateral ligament of the elbow and the radial (lateral) collateral ligament of the elbow.
  4. Muscles acting on the elbow include the large muscles of the arm, i.e. for flexion, the biceps brachii and brachialis, and for extension the triceps brachii. A muscle of the posterior compartment of the forearm, the brachioradialis also functions as an elbow flexor.

Innervation, Blood Supply and Tendons of the Wrist and Hand-Muscles of the Hand -Movements of the Hand - Surface Anatomy of the Hand -Skeleton of the Hand - Wrist and Hand Index

Last modified: 9:18 PM on 10/19/96

© 1996 Reigart, Murphy