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Acromion process of scapula

The acromion process is a large, flattened bony projection extending laterally from the spine of the scapula, forming the highest point of the shoulder. It arches over the glenohumeral joint, providing attachment for muscles and ligaments while contributing to the acromioclavicular (AC) joint, where it articulates with the lateral end of the clavicle.

The acromion process serves as the origin of the deltoid muscle and attachment for the trapezius muscle, playing an essential role in shoulder elevation and stability. Its anterior border gives attachment to the coracoacromial ligament, forming the coracoacromial arch, which protects the humeral head and rotator cuff tendons.

Morphologically, the acromion varies (flat, curved, hooked) — these variations are important in the development of subacromial impingement syndrome and rotator cuff tears.

Synonyms

  • Acromial process

  • Acromion

  • Acromial extremity of scapula

Function

  • Forms the acromioclavicular (AC) joint with the clavicle

  • Provides attachment for deltoid and trapezius muscles

  • Gives attachment to the coracoacromial ligament, completing the coracoacromial arch

  • Protects the humeral head and rotator cuff tendons from superior trauma

  • Contributes to shoulder stability and overhead arm motion

MRI Appearance

T1-weighted images:

  • Cortical bone: low signal intensity

  • Subcortical marrow: intermediate signal depending on fat content

  • Adjacent deltoid and trapezius attachments visualized clearly

T2-weighted images:

  • Cortical bone remains dark

  • Highlights subacromial bursal fluid or inflammatory changes

  • Useful in assessing impingement and rotator cuff pathology

PD-FS (Proton Density Fat-Suppressed):

  • Provides excellent contrast of tendons, ligaments, and bursae

  • Detects rotator cuff tears, tendinosis, bursitis, and subtle marrow edema of acromion

  • Useful for impingement evaluation and subacromial–subdeltoid bursa pathology

STIR:

  • Fat suppression highlights bone marrow edema in stress reactions, fractures, or inflammatory processes

T1 Post-Gadolinium:

  • Not routinely used for bone assessment, but helpful in detecting enhancement with infection, tumor, or bursitis

  • Subacromial bursitis appears with contrast-enhancing synovial lining

MRI Non-Contrast 3D Imaging:

  • 3D reconstructions provide assessment of acromial shape (flat, curved, hooked)

  • Valuable in preoperative planning for impingement or AC joint surgery

CT Appearance

Non-contrast CT:

  • Best modality for bony detail: acromial shape, fractures, and osteophytes

  • Used for classification of acromial morphology and outlet narrowing

CT Post-Contrast (CT Arthrography):

  • Outlines adjacent rotator cuff tendons and subacromial space

  • Useful in detecting rotator cuff tears with associated impingement

  • 3D CT reconstructions allow detailed evaluation of acromial morphology and AC joint degeneration

MRI image

Acromion process mri sag image

MRI image

Acromion process of scapula MRI axial image -img-00000-00000

CT image

acromion process of scapula coronal ct image

CT VRT image

Acromion 3d ct image