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Infraglenoid tubercle

The infraglenoid tubercle is a prominent bony projection located on the scapula just inferior to the glenoid cavity. It serves as an important attachment point for muscles contributing to shoulder and arm function and is a key landmark in shoulder anatomy, trauma evaluation, and musculoskeletal imaging.

It plays a significant role in force transmission from the upper limb to the scapula and is routinely assessed in shoulder injuries and imaging studies.

Synonyms

  • Tuberculum infraglenoidale

  • Inferior glenoid tubercle

Location

  • Situated on the scapula immediately inferior to the glenoid cavity

  • At the lateral angle of the scapula

  • Inferior to the articular surface of the glenoid

  • Posterior to the coracoid process

  • Superior to the lateral border of the scapular body

Anatomical components

  • Bony prominence of the scapula

  • Cortical shell with underlying cancellous bone

  • Muscle attachment site:

    • Long head of the triceps brachii

  • Adjacent structures:

    • Glenoid cavity superiorly

    • Scapular neck medially

Relations

Superiorly:

  • Glenoid cavity

Inferiorly:

  • Lateral border of the scapular body

Anteriorly:

  • Shoulder joint capsule

Posteriorly:

  • Posterior scapular surface and triceps muscle belly

Medially:

  • Neck of the scapula

Laterally:

  • Proximal humeral head (indirectly via the joint space)

X-ray appearance

Plain radiographs (AP shoulder and scapular Y views):

  • Infraglenoid tubercle: Appears as a small bony projection inferior to the glenoid

  • Cortical outline: Well-defined

  • Visibility: Best appreciated on scapular Y and axillary views

CT appearance

Non-contrast CT:

  • Tubercle: Well-defined osseous projection beneath the glenoid cavity

  • Cortical margins: Smooth and sharply outlined

  • Trabecular pattern: Normal cancellous bone

  • Spatial definition: Excellent for assessing morphology and subtle cortical irregularities

  • Relationship to glenoid: Clearly visualized

MRI appearance

T1-weighted images:

  • Cortical bone: Low signal intensity

  • Marrow of tubercle: High signal intensity

  • Contour: Clearly delineated against adjacent soft tissues

T2-weighted images:

  • Cortex: Low signal

  • Adjacent joint fluid: High signal outlining the tubercle

  • Triceps origin: Seen as low-to-intermediate signal structure attached to the tubercle

STIR:

  • Fat suppression: Uniform suppression of marrow fat

  • Tubercle margins: Well visualized

  • Muscle and tendon interfaces: High contrast

Proton density fat-saturated (PD FS):

  • Bone marrow: Suppressed fat signal

  • Joint fluid: High signal

  • Long head of triceps tendon: Well visualized as a low-signal band inserting at the tubercle

CT VRT 3D image

Infraglenoid tubercle

CT image

Infraglenoid tubercle ct