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Jugular spine

The jugular spine is a small, pointed bony projection located on the inferior surface of the petrous part of the temporal bone, forming part of the anterior boundary of the jugular foramen. It separates the pars nervosa (anteromedial compartment) from the pars vascularis (posterolateral compartment) of the jugular foramen, thereby playing an important role in organizing the passage of neurovascular structures at the skull base.

It is an important landmark in skull base imaging and surgery, particularly in evaluating lesions involving the jugular foramen, such as schwannomas, paragangliomas, and meningiomas.

Synonyms

  • Spina jugularis
  • Jugular process of temporal bone

Location and Structure

  • Position: Inferior aspect of the petrous temporal bone, at the anterior margin of the jugular foramen
  • Shape: Small, sharp, triangular or spine-like projection
  • Composition: Dense cortical bone with minimal cancellous component
  • Anatomical role: Divides the jugular foramen into functional compartments

Relations

  • Anteriorly: Internal carotid artery (petrous segment)
  • Posteriorly: Jugular bulb and internal jugular vein
  • Medially: Inferior petrosal sinus (pars nervosa)
  • Laterally: Vagus nerve and accessory nerve (pars vascularis)
  • Superiorly: Petrous temporal bone and inner ear structures
  • Inferiorly: Jugular foramen opening

Attachments

  • Provides attachment for fibrous septa dividing compartments of the jugular foramen
  • Supports dural reflections associated with venous sinuses and cranial nerve passages

Function

  • Structural partition: Separates neural and vascular compartments within the jugular foramen
  • Stabilization: Supports dural and venous structures at skull base
  • Landmark: Critical for radiological localization and skull base surgical approaches

MRI Appearance

T1-weighted images:

  • Cortical bone: Very low signal (black)
  • Adjacent marrow (petrous apex): May show limited bright signal if fatty marrow present
  • Surrounding structures:
    • Jugular bulb: intermediate-to-low signal depending on flow
    • Dura: low signal
  • Jugular spine appears as a sharp, low-signal bony projection

T2-weighted images:

  • Bone: Low signal (dark)
  • Adjacent vascular structures: Variable signal depending on flow
  • Jugular spine remains a distinct dark structure against brighter surrounding soft tissues

STIR:

  • Normal bone: Low signal
  • Surrounding soft tissue: Intermediate-to-dark unless fluid present
  • Jugular spine remains hypointense, clearly delineated from adjacent structures

CT Appearance

Non-Contrast CT:

  • Bone: High attenuation, sharply defined cortical projection
  • Clearly visualized as a pointed bony spine separating compartments of the jugular foramen
  • Excellent for evaluating anatomical variation and bony detail

Post-Contrast CT:

  • Bone itself does not enhance
  • Adjacent venous structures (jugular bulb) enhance, improving contrast with the jugular spine

MRI image

Jugular spine mri axial image