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Glenoid fossa

The glenoid fossa, also called the glenoid cavity, is the shallow articular depression on the lateral angle of the scapula, forming the socket of the glenohumeral (shoulder) joint. It is pear-shaped, wider inferiorly than superiorly, and articulates with the head of the humerus.

Its surface is covered by hyaline cartilage and surrounded by the fibrocartilaginous glenoid labrum, which deepens the cavity and provides stability. The superior aspect of the fossa gives attachment to the long head of the biceps tendon via the supraglenoid tubercle, while the inferior part relates to the long head of the triceps tendon at the infraglenoid tubercle.

The glenoid fossa is oriented slightly anteriorly and superiorly, permitting a wide range of motion but predisposing the joint to instability. Pathology includes labral tears (Bankart lesion, SLAP tear), osteoarthritis, fractures, and dislocations.

Synonyms

  • Glenoid cavity

  • Glenoidal fossa of scapula

  • Articular fossa of scapula

Function

  • Serves as the socket for the humeral head, forming the glenohumeral joint

  • Provides articulation and stability through the glenoid labrum

  • Acts as the anchor point for ligaments and tendons, including biceps long head and triceps long head

  • Allows wide mobility in multiple planes while balancing joint stability

Anatomical Relations

  • Superior: supraglenoid tubercle (origin of long head of biceps)

  • Inferior: infraglenoid tubercle (origin of long head of triceps)

  • Anterior: coracoid process and subscapularis tendon

  • Posterior: infraspinatus and teres minor tendons

MRI Appearance

T1-weighted images:

  • Glenoid fossa appears as low signal cortical bone with intermediate subchondral marrow

  • Articular cartilage is intermediate-to-low signal

  • Labrum is triangular, low signal intensity structure

T2-weighted images:

  • Cartilage appears hyperintense relative to bone

  • Labrum remains low signal, tears appear as high-signal fluid extending into labral substance

  • Subchondral bone marrow edema shows as bright hyperintensity

STIR:

  • Highlights marrow edema, labral injury, and joint effusion as hyperintense regions

  • Useful in detecting occult fractures of the glenoid rim

T1 Post-Gadolinium (MR Arthrography):

  • Intra-articular contrast fills the joint space and outlines labrum

  • Labral tears appear as contrast extension into or under the labrum

  • Detects cartilage defects, capsular injury, and subtle labral detachments

MRI Non-Contrast 3D Imaging (Shoulder protocol):

  • Provides detailed 3D visualization of the glenoid contour, cartilage, and labrum

  • Useful for surgical planning of instability and labral repair

CT Appearance

Non-contrast CT:

  • Shows cortical and trabecular architecture of glenoid

  • Identifies fractures, bone loss, and dysplasia

CT Post-Contrast (CT Arthrography):

  • Outlines the labrum, cartilage, and capsular recesses with contrast

  • Detects labral tears, cartilage defects, and subtle glenoid rim fractures

  • Multiplanar and 3D reconstructions essential for preoperative planning in instability and arthroplasty

CT image

Glenoid fossa CT axial image -img-00000-00000

MRI image

Glenoid fossa MRI axial image -img-00000-00000