CT Shoulder Anatomy – Labeled Axial, Coronal & Sagittal Views

Topic

Acromial end of clavicle

The acromial end of the clavicle is the flattened lateral extremity of the clavicle that articulates with the acromion of the scapula to form the acromioclavicular (AC) joint. Unlike the sternal end, the acromial end is broad and compressed. Its articular surface is oval, directed downward and medially, and covered with fibrocartilage.

The AC joint is stabilized by the acromioclavicular ligaments (superior and inferior) and reinforced by the coracoclavicular ligaments (conoid and trapezoid), which prevent vertical displacement. Small intra-articular fibrocartilaginous discs may be present.

This region is highly mobile, allowing scapular rotation, gliding, and elevation, which are essential for full shoulder motion. It is clinically significant as a frequent site of degeneration, separation injuries, fractures, and osteoarthritis.

Synonyms

Lateral end of clavicle
Acromioclavicular end
Acromial extremity of clavicle

Function

Forms the AC joint, connecting the clavicle and scapula
Transmits forces from the upper limb to the axial skeleton
Provides attachment for the acromioclavicular and coracoclavicular ligaments
Enables scapular rotation and stability of the shoulder girdle

MRI Appearance

T1-weighted images:

Bone marrow: intermediate signal
Cortical bone: hypointense rim
AC joint space: visible as a thin hypointense line

T2-weighted images:

Cartilage: hyperintense
Joint fluid or effusion: bright signal
Detects degenerative changes and joint inflammation

PD-FS (Proton Density Fat-Suppressed):

Enhances visualization of capsule, ligaments, and marrow edema
AC joint pathology (arthritis, capsular injury, synovitis) appears hyperintense
Excellent for trauma and subtle instability assessment

STIR:

Suppresses fat, highlighting marrow edema and soft tissue inflammation
Useful in acute fractures and ligamentous injuries

T1 Post-Gadolinium (MR Arthrography or contrast-enhanced MRI):

Highlights capsule, synovium, and ligamentous insertions
Detects synovitis, capsular tears, and enhancing arthropathy

MRI Non-Contrast 3D Imaging:

Provides 3D reconstructions of joint morphology, acromial end alignment, and cartilage surface
Useful in pre-surgical planning for distal clavicle excision or AC reconstruction

CT Appearance

Non-contrast CT:

Best for cortical detail: fractures, erosions, bone spurs, and joint alignment
Defines the relationship of the acromial end with the acromion

CT Post-Contrast (CT Arthrography):

Contrast highlights the AC joint capsule and articular cartilage
Detects capsular tears, cartilage loss, osteoarthritis, and subtle osseous injury
3D reconstructions help in planning reconstructive surgery or distal clavicle excision

MRI images