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Inferior transverse scapular ligament

The inferior transverse scapular ligament (ITSL), also known as the spinoglenoid ligament, is a fibrous band of connective tissue that spans across the spinoglenoid notch of the scapula. It forms a fibro-osseous tunnel through which the suprascapular nerve and vessels pass before entering the infraspinous fossa.

The ligament plays a key role in stabilizing the suprascapular neurovascular bundle, preventing excessive traction or compression as the shoulder moves, particularly during abduction and external rotation. Pathological thickening or ossification of this ligament can lead to suprascapular nerve entrapment at the spinoglenoid notch.

Synonyms

  • Spinoglenoid ligament

  • Inferior transverse ligament of scapula

  • Transverse scapular ligament (inferior)

Location and Attachments

  • Location: Spans the spinoglenoid notch, a depression between the lateral edge of the scapular spine and the posterior aspect of the glenoid cavity.

  • Superior attachment: Lateral border of the scapular spine near its junction with the glenoid.

  • Inferior attachment: Adjacent posterior glenoid rim or spinoglenoid notch floor.

  • Orientation: Extends horizontally over the notch, converting it into an osseoligamentous tunnel.

Relations

  • Superiorly: Infraspinatus muscle and fascia

  • Inferiorly: Posterior scapular surface and infraspinous fossa

  • Anteriorly: Suprascapular nerve and vessels passing beneath the ligament

  • Posteriorly: Infraspinatus tendon and posterior shoulder joint capsule

Structure and Composition

  • Composed of dense fibrous connective tissue, occasionally containing elastic fibers

  • Variable thickness, sometimes replaced by fascia in thin individuals

  • May show partial ossification with aging or chronic traction stress

  • Converts the spinoglenoid notch into a tunnel-like structure

Function

  • Stabilization: Maintains the position of the suprascapular nerve and vessels within the spinoglenoid notch

  • Protection: Shields the neurovascular bundle from external compression during shoulder motion

  • Mechanical restraint: Prevents excessive stretching of the suprascapular nerve during abduction and external rotation

  • Clinical role: Involved in suprascapular neuropathy secondary to fibrous thickening or entrapment

Clinical Significance

  • Suprascapular nerve entrapment: The most significant pathology involving this ligament; may cause infraspinatus muscle atrophy and weakness in external rotation

  • Fibrous thickening or ossification: May compress the suprascapular nerve or vessels, producing chronic posterior shoulder pain

  • Overhead athletes: Repetitive overhead motion (e.g., volleyball, baseball) can cause microtrauma and ligament hypertrophy

  • Post-traumatic fibrosis: May develop after scapular or glenoid fractures

  • Surgical relevance: Recognized and often released during decompression procedures for suprascapular neuropathy

MRI Appearance

  • T1-weighted images:

    • Ligament appears as a thin, low-signal (dark) band bridging the spinoglenoid notch.

    • Surrounding fat in the infraspinatus fossa appears bright, improving visualization.

    • Chronic thickening appears as a slightly broadened low-signal structure.

  • T2-weighted images:

    • Normal ligament: low signal (dark) structure, clearly delineated against bright fat or fluid.

    • Pathology: Thickened or irregular ligament; intermediate-to-bright signal may indicate fibrosis, inflammation, or entrapment-related changes.

    • Associated infraspinatus muscle edema or atrophy may be present in chronic compression.

  • STIR:

    • Normal: dark to intermediate signal.

    • Pathologic: bright hyperintense periligamentous signal suggesting edema, neuritis, or perineural inflammation.

  • Proton Density Fat-Saturated (PD FS):

    • Normal: thin, dark linear band spanning the notch.

    • Thickened or fibrotic ligament: intermediate signal with adjacent high-signal edema.

    • Useful for detecting subtle ligament hypertrophy or perineural fluid.

  • T1 Fat-Sat Post-Contrast:

    • Normal ligament: minimal or no enhancement.

    • Pathologic ligament: mild peripheral or heterogeneous enhancement due to inflammation or vascular proliferation.

    • Enhancing perineural tissue indicates chronic nerve irritation or fibrosis.

CT Appearance

Non-Contrast CT:

  • Ligament itself is usually not visualized unless calcified or ossified.

  • Ossified ligament: Appears as a small linear or crescentic hyperdense band spanning the spinoglenoid notch.

  • Indirect findings: Bony remodeling or sclerosis around the notch due to chronic traction.

Post-Contrast CT (standard):

  • Ligament remains non-enhancing unless vascularized by surrounding granulation tissue.

  • Adjacent soft tissue enhancement may indicate inflammation or fibrosis secondary to entrapment or trauma.

  • Useful for assessing ossified or calcified variants contributing to nerve compression.

MRI image

Inferior transverse scapular ligament cor cross sectional anatomy 3T MRI AI enhanced radiology image -img-00000-00000

MRI image

Inferior transverse scapular ligament mri axial image