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Pharyngeal tubercle

The pharyngeal tubercle is a small midline bony prominence located on the inferior surface of the basilar part of the occipital bone, anterior to the foramen magnum. It serves as the primary attachment point for the pharyngeal raphe, anchoring the superior constrictor muscle and contributing to the structural support of the posterior pharyngeal wall.

It is an important landmark at the craniovertebral junction, positioned between the clivus and the upper cervical spine, and plays a role in stabilizing the upper aerodigestive tract.

Synonyms

  • Tuberculum pharyngeum
  • Pharyngeal spine (less commonly used)

Location and Structure

  • Position: Midline on the inferior surface of the occipital bone, anterior to the foramen magnum
  • Shape: Small, rounded or slightly elongated bony elevation
  • Surface: Roughened for fibrous attachment
  • Bone type: Dense cortical bone with minimal underlying cancellous marrow
  • Forms part of the clival region of the skull base

Relations

  • Superiorly: Clivus and posterior cranial fossa
  • Inferiorly: Posterior wall of the nasopharynx
  • Anteriorly: Pharyngeal mucosal space
  • Posteriorly: Foramen magnum and upper cervical spinal canal
  • Laterally: Basilar part of occipital bone and attachments of longus capitis muscle

Attachments

  • Pharyngeal raphe: Main fibrous attachment anchoring the posterior pharyngeal wall
  • Superior constrictor muscle: Indirect attachment via the pharyngeal raphe
  • Fibrous tissues: Contribute to stabilization of the pharyngeal wall at the skull base

Function

  • Structural support: Anchors the pharyngeal wall to the skull base
  • Swallowing mechanics: Provides a stable attachment for pharyngeal constrictor muscles during deglutition
  • Airway stability: Maintains posterior pharyngeal wall alignment
  • Anatomical landmark: Important reference point in skull base and nasopharyngeal imaging

MRI Appearance

T1-weighted images:

  • Cortex: Very low signal (dark)
  • Underlying marrow: Minimal but may appear faintly bright if fatty marrow is present
  • Adjacent soft tissues:
    • Pharyngeal wall: intermediate signal
    • Fat planes: bright
  • Appears as a small low-signal midline bony prominence along the inferior clivus

T2-weighted images:

  • Cortex: Low signal (dark)
  • Marrow: May appear intermediate to slightly bright, depending on fatty content
  • Adjacent mucosa and soft tissue: Intermediate-to-bright signal
  • Maintains a well-defined low-signal outline against surrounding soft tissues

STIR:

  • Normal bone: Intermediate-to-dark signal
  • Cortex: Remains dark
  • Adjacent soft tissues: Suppressed fat signal with clearer delineation of pharyngeal wall
  • Tubercle appears as a dark focal bony landmark against suppressed background fat

CT Appearance

Non-Contrast CT:

  • Cortex: High-attenuation, sharply defined bony prominence
  • Structure: Small midline projection on inferior surface of occipital bone
  • Clearly visualized on sagittal and axial reconstructions
  • Appears as a dense, well-circumscribed tubercle anterior to the foramen magnum
  • Surrounding soft tissues of the nasopharynx are lower attenuation

Post-Contrast CT (standard):

  • Bone: No intrinsic enhancement
  • Soft tissues: Pharyngeal mucosa and surrounding tissues may show mild enhancement

MRI image