Distal Humerus Osteology Study Notes

Distal Humerus Osteology

Overview of the Lecture

  • Focus on elbow, forearm, wrist, and hand osteology.

  • Objectives include:

    • Identifying bony prominences of:

    • Distal humerus

    • Radius

    • Ulna

    • Carpals

    • Metacarpals

    • Phalanges

    • Understanding attachment sites for muscles and ligaments.

    • Discussing relationships between bony structures and their classifications, types, functions, and contributions to upper extremity stability.

Distal Humerus

  • Transitioning from the proximal humerus explored in the previous module to the distal humerus.

  • Components of the distal humerus:

    • Articular Structures: Form surfaces for elbow articulation.

    • Non-Articular Structures: Act as attachment sites and pathways for ligaments, muscles, and nerves.

Articular Structures

  • Trochlea:

    • Description: A pulley-shaped surface.

    • Location: Covers anterior, posterior, and inferior surfaces of the medial condyle of the humerus.

    • Function: Forms the proximal half of the humeral ulnar articulation.

  • Capitulum:

    • Description: A convex and rounded projection.

    • Location: Covers anterior and inferior surfaces of the lateral condyle of the humerus but does not cover the posterior surface.

    • Function: Forms the proximal half of the articulation of the humeral radial joint.

Non-Articular Structures

  • Focus on various fossae:

    • Fossa: A shallow depression or hollow area in bone serving as a socket for another bone.

Specific Fossae and Their Functions

  • Olecranon Fossa:

    • Description: Deep hollowed area on the posterior surface, superior to the trochlea.

    • Importance: Key in the humeral ulnar articulation and movement.

  • Coronoid Fossa:

    • Description: Smaller depression on the anterior surface, superior to the trochlea.

    • Importance: Significant for the humeral ulnar articulation.

  • Radial Fossa:

    • Description: Depression located on the lateral side, superior to the capitulum.

    • Importance: Important for the humeral radial articulation.

Additional Anatomical Features

  • Medial Supracondylar Ridge:

    • Location: Distal thickening of the medial border of the humeral shaft.

    • Importance: Increases surface area for the attachment of ligaments and muscles.

  • Lateral Supracondylar Ridge:

    • Location: Distal thickening on the lateral border of the humeral shaft.

    • Importance: Functions as an attachment site for forearm muscles.

  • Medial Epicondyle:

    • Description: Bony projection at the distal end of the medial condyle.

    • Importance: Acts as an attachment site for muscles and ligaments. Also, significant as the final ossification center of the elbow, which does not complete until 14 to 15 years of age, making it a common injury site in adolescents.

  • Groove for Ulnar Nerve:

    • Location: Shallow depression on the posterior surface of the medial epicondyle.

    • Importance: It provides a protected passageway for the ulnar nerve.

  • Lateral Epicondyle:

    • Description: Bony eminence located at the distal end of the humerus, the lateral component of the non-articular part.

    • Importance: Palpable landmark; however, it is less prominent compared to the medial epicondyle, serving as an important site for ligamentous and muscular attachments.