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Pterygomaxillary fissure

The pterygomaxillary fissure is a vertical slit-like opening located deep within the face, forming a key communication between the infratemporal fossa and the pterygopalatine fossa. It lies between the posterior surface of the maxilla and the pterygoid process of the sphenoid bone.

This fissure serves as an important anatomical gateway allowing the passage of neurovascular structures from the infratemporal region into the pterygopalatine fossa. Its location makes it a critical landmark in maxillofacial imaging, skull base anatomy, and surgical approaches to the deep face.

Synonyms

  • Pterygomaxillary cleft

  • Posterior maxillary fissure

Location and Structure

  • Position: Posterior to the maxilla, anterior to the pterygoid process of the sphenoid

  • Orientation: Vertically oriented slit-like gap

  • Boundaries:

    • Anteriorly: Posterior surface of the maxilla

    • Posteriorly: Pterygoid process of the sphenoid

    • Superiorly: Inferior orbital fissure (via pterygopalatine fossa)

    • Inferiorly: Opens into the infratemporal fossa

  • Shape: Narrow, elongated fissure best appreciated on coronal imaging

Relations

  • Anteriorly: Maxillary sinus posterior wall

  • Posteriorly: Lateral pterygoid plate

  • Medially: Pterygopalatine fossa

  • Laterally: Infratemporal fossa

  • Superiorly: Inferior orbital fissure

  • Inferiorly: Posterior maxillary region

Contents

  • Maxillary artery (terminal part)

  • Posterior superior alveolar nerve

  • Posterior superior alveolar vessels

  • Venous connections to the pterygoid venous plexus

Function

  • Acts as a communication pathway between infratemporal and pterygopalatine fossae

  • Allows passage of neurovascular structures supplying maxilla, nasal cavity, and orbit

  • Serves as a surgical landmark in endoscopic and maxillofacial procedures

Clinical Importance

  • Key landmark in skull base and maxillofacial surgery

  • Essential reference point in endoscopic sinus surgery

  • Important for assessing spread pathways between deep facial spaces

  • Routinely evaluated in CT and MRI of the midface

MRI Appearance

T1-weighted images:

  • Appears as a linear low-signal gap between maxilla and pterygoid process

  • Surrounding fat in the pterygopalatine fossa shows bright signal, helping delineate the fissure

  • Vascular structures appear as flow voids within or adjacent to the fissure

T2-weighted images:

  • Fissure margins remain low signal due to cortical bone

  • Adjacent fat appears bright, improving contrast

  • Flowing blood within vessels may appear as signal voids

STIR:

  • Surrounding fat signal is suppressed, making the fissure appear as a dark linear space

  • Neurovascular structures appear as low-to-intermediate signal against suppressed background

T1 Fat-Saturated Post-Contrast:

  • Normal vessels within the fissure show enhancement

  • Surrounding fat remains suppressed, allowing clear visualization of fissure boundaries

  • No intrinsic enhancement of bone margins

CT Appearance

Non-Contrast CT:

  • Best modality for visualization

  • Appears as a sharp vertical bony cleft between the posterior maxilla and pterygoid process

  • Cortical margins are well-defined and high density

  • Maxillary sinus posterior wall and pterygoid plates are clearly outlined

  • Thin-slice coronal and axial reconstructions provide optimal depiction

Post-Contrast CT (standard):

  • Bony margins remain sharply defined

  • Normal vascular structures may enhance within adjacent soft tissues

  • Useful for confirming anatomical relationships rather than soft-tissue detail

X-Ray Appearance

  • Limited visualization due to deep location and superimposed structures

CT images

Pterygomaxillary fissure sinus CT anatomy labelled image-img-00000-00000