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Spine of scapula

The spine of the scapula is a prominent triangular bony ridge on the posterior surface of the scapula. It begins at the medial border of the scapula and projects laterally and superiorly, widening to form the acromion process. The spine divides the posterior surface of the scapula into two unequal fossae: the supraspinous fossa above and the infraspinous fossa below.

The superior border of the spine gives attachment to the trapezius muscle, while its inferior border serves as attachment for the deltoid muscle. The spine provides important leverage for these muscles, contributing to scapular stability and shoulder motion. The lateral extension into the acromion forms the highest point of the shoulder and articulates with the clavicle at the acromioclavicular joint.

Clinically, the spine of the scapula is a crucial landmark in fractures, shoulder dislocations, rotator cuff tears, and surgical approaches to the scapula and shoulder joint.

Synonyms

  • Scapular spine

  • Spina scapulae

Function

  • Divides the posterior scapula into supraspinous and infraspinous fossae

  • Provides attachment for trapezius and deltoid muscles

  • Acts as a leverage and stabilization point for shoulder motion

  • Extends laterally to form the acromion and acromioclavicular joint

MRI Appearance

T1-weighted images:

  • Cortical bone: very low signal intensity

  • Bone marrow within spine: intermediate signal intensity

  • Good for assessing fracture lines and marrow replacement

T2-weighted images:

  • Cortex remains dark hypointense

  • Marrow signal varies with pathology (edema, tumor, or fracture show hyperintensity)

PD-FS (Proton Density Fat-Suppressed):

  • Excellent for detecting bone marrow edema, subtle fractures, and soft tissue attachments

  • Highlights deltoid and trapezius tendon insertion injuries

  • Sensitive for rotator cuff interval involvement and scapular stress injuries

STIR:

  • Strong fat suppression accentuates bone marrow edema and inflammatory changes

  • Very sensitive for occult fractures or osteomyelitis of the scapular spine

T1 Post-Gadolinium (contrast-enhanced MRI):

  • Enhances in cases of infection, neoplasm, or postoperative changes

  • Differentiates soft tissue masses from cortical bone involvement

  • Useful for evaluating tumor infiltration or inflammatory processes

MRI Non-Contrast 3D Imaging:

  • Provides 3D visualization of scapular orientation and acromion extension

  • Useful for surgical planning in fractures, bone grafting, or deformity correction

CT Appearance

Non-contrast CT:

  • Excellent for evaluating cortical bone detail, fractures, and bony morphology

  • Identifies sclerosis, lytic lesions, or osseous malformations

CT Post-Contrast:

  • Enhances soft tissue planes adjacent to the scapular spine

  • Helps in evaluating tumor extension, infection, and vascular involvement

  • 3D reconstructions clearly show the relationship of the spine to acromion and glenoid

MRI image

Spine of scapula MRI axial image -img-00000-00000

CT images

Spine of scapula CT axial image -img-00000-00000

CT images

Spine of scapula CT coronal image -img-00000-00000

CT images

Spine of scapula CT sag image -img-00000-00000

CT 3D VRT image

Spine of scapula ct 3d image