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Lateral border of humerus

The lateral border of the humerus refers to the lateral margin of the humeral shaft, extending from the proximal humerus toward the distal region. It is an important anatomical surface that serves as a landmark for muscular attachments and for orientation in imaging, trauma assessment, and orthopedic procedures.

It contributes to the contour and biomechanical stability of the arm and is a key reference in evaluating humeral shaft integrity.

Synonyms

  • Lateral margin of the humerus

  • Lateral border of the humeral shaft

Location

  • Situated along the lateral aspect of the humeral shaft

  • Extends from the region of the greater tubercle proximally

  • Continues inferiorly toward the lateral supracondylar ridge

  • Forms the lateral outline of the arm

  • Subcutaneous in its distal portion

Anatomical components

  • Cortical margin of the humeral shaft

  • Underlying cancellous bone proximally and distally

  • Muscle attachment zones:

    • Deltoid (near lateral shaft via deltoid tuberosity)

    • Brachialis (anterolateral aspect)

    • Brachioradialis (near distal lateral supracondylar ridge)

  • Continuity with:

    • Greater tubercle proximally

    • Lateral supracondylar ridge distally

Relations

Anteriorly:

  • Brachialis muscle

  • Anterior compartment of the arm

Posteriorly:

  • Triceps brachii muscle

  • Posterior compartment of the arm

Medially:

  • Humeral shaft and medullary cavity

Laterally:

  • Skin and subcutaneous tissue (especially distally)

Superiorly:

  • Greater tubercle and surgical neck region

Inferiorly:

  • Lateral supracondylar ridge and lateral epicondyle region

X-ray appearance

Plain radiographs (AP and lateral humerus views):

  • Lateral border: Seen as a smooth, continuous cortical line along the outer margin of the humeral shaft

  • Cortical density: Uniform and well defined

  • Alignment: Symmetric with the medial border in normal humerus

  • Best visualized on: AP and lateral projections

CT appearance

Non-contrast CT:

  • Lateral border: Sharply defined cortical surface of the humeral shaft

  • Cortical thickness: Uniform along the shaft

  • Trabecular pattern: Normal cancellous bone within

  • Contour assessment: Precise evaluation of the humeral outline and geometry

MRI appearance

T1-weighted images:

  • Cortical bone: Low signal intensity

  • Marrow cavity: High signal intensity

  • Lateral border: Clearly demarcated interface between cortex and surrounding soft tissues

T2-weighted images:

  • Cortex: Low signal

  • Marrow: Intermediate signal

  • Surrounding muscles: Higher signal than cortex, defining the border

STIR:

  • Fat suppression: Uniform suppression of marrow fat

  • Cortical outline: Well visualized against suppressed marrow

  • Muscle planes: Bright signal from surrounding soft tissues

Proton density fat-saturated (PD FS):

  • Bone marrow: Suppressed fat signal

  • Cortex: Persistently low signal

CT VRT 3D image

Lateral border of humerus

CT image

Lateral border of humerus ct