Pterygopalatine Fossa - Easy Diagrams for University Exams

Diagram 1: Boundaries of the PPF (Box Diagram - Easiest to Draw)

          ROOF
    (sphenoid body + palatine bone - orbital process)
         ┌─────────────────────────────┐
         │                             │
POSTERIOR│  PTERYGOPALATINE FOSSA      │ANTERIOR
(pterygoid│                             │(posterior wall of
 process +│                             │ maxillary antrum)
 greater  │     Inverted teardrop       │
 wing of  │         shape               │
 sphenoid)│                             │
         └─────────────────────────────┘
          FLOOR
    (apex - opens into palatine canal)
    MEDIAL: palatine bone / nasal mucoperiosteum
    LATERAL: open → pterygomaxillary fissure → infratemporal fossa

Fig. 8.156 from Gray's Anatomy for Students - Anterolateral (A) and lateral (B) views showing the PPF with its bounding bones and key foramina

Diagram 2: Communications / Gateways of the PPF (Spider/Wheel Diagram - Most Exam-Favourite)

                  Middle Cranial Fossa
                  ↑ Foramen Rotundum (V2 enters)
                  ↑ Pterygoid Canal (nerve of pterygoid canal)

        Nasal Cavity         ┌──────────────┐      Infratemporal Fossa
        ← Sphenopalatine     │              │ ← Pterygomaxillary Fissure
          Foramen            │     PPF      │     (maxillary artery enters;
                             │    (centre)  │      post. sup. alveolar N. exits)
        Orbit               └──────────────┘
        ↑ Inferior                 │
          Orbital Fissure          ↓
                           Palatine Canal
                           (greater & lesser palatine N. + A.)
                                   │
                             Roof of Mouth (Hard Palate)

                             Palatovaginal Canal → Nasopharynx

Fig. 8.158 from Gray's Anatomy for Students - Gateways of the PPF with each opening and its destination

Diagram 3: Contents of the PPF

┌─────────────────────────────────────┐
│         CONTENTS OF PPF             │
│                                     │
│  1. MAXILLARY NERVE (V2)            │
│     - enters via foramen rotundum   │
│     - purely sensory                │
│     - exits as infra-orbital N.     │
│       via inferior orbital fissure  │
│                                     │
│  2. PTERYGOPALATINE GANGLION        │
│     (= sphenopalatine ganglion)     │
│     - largest parasympathetic       │
│       ganglion in head              │
│     - hangs off V2 by 2 roots       │
│                                     │
│  3. MAXILLARY ARTERY (3rd part)     │
│     - enters via pterygomaxillary   │
│       fissure                       │
│     - terminal part of ext. carotid │
└─────────────────────────────────────┘

Diagram 4: The Pterygopalatine Ganglion - Roots & Branches (High-Yield Nerve Diagram)

1. Sensory root - 2 ganglionic branches from V2 (pass through without synapsing)
2. Parasympathetic root - greater petrosal nerve (from geniculate ganglion of VII) + deep petrosal nerve (sympathetic, from internal carotid plexus) → unite = Nerve of Pterygoid Canal → SYNAPSE occurs here (preganglionic → postganglionic parasympathetic)
3. Sympathetic root - deep petrosal nerve fibers (postganglionic from superior cervical ganglion, T1 origin) - pass through without synapsing

Fig. 8.160 from Gray's Anatomy for Students - Complete autonomic pathway: geniculate ganglion → greater petrosal nerve + deep petrosal nerve → nerve of pterygoid canal → pterygopalatine ganglion → distribution

Fig. 8.157 from Gray's Anatomy for Students - Sphenoid bone (anterior + posterosuperior views) showing foramen rotundum and pterygoid canal

Diagram 5: Maxillary Artery in the PPF (3rd Part)

External carotid artery
        ↓
   Maxillary artery
        ↓ (enters via pterygomaxillary fissure)
   ┌─── PPF (3rd part of maxillary artery) ───┐
   │                                           │
   ├──→ Posterior superior alveolar A.         │
   │    (exits via pterygomaxillary fissure)   │
   ├──→ Infra-orbital A.                       │
   │    (exits via inferior orbital fissure)   │
   ├──→ Greater palatine A.                    │
   │    (exits via palatine canal)             │
   ├──→ Sphenopalatine A.                      │
   │    (exits via sphenopalatine foramen)     │
   ├──→ Artery of pterygoid canal              │
   └──→ Pharyngeal A.                          │
        (exits via palatovaginal canal)        │

Quick Exam Tips

1. Shape of PPF: Inverted teardrop / pyramid - narrow inferiorly, wide superiorly
2. The only truly "open" wall is the lateral one (pterygomaxillary fissure) - all others are bony walls with specific foramina
3. V2 is purely sensory - it does NOT synapse in the pterygopalatine ganglion; only preganglionic parasympathetics synapse there
4. Pterygopalatine ganglion = sphenopalatine ganglion (same structure, two names)
5. Largest parasympathetic ganglion in the head (the other three are ciliary, otic, submandibular)
6. Lacrimation pathway: VII → geniculate ganglion → greater petrosal N. → nerve of pterygoid canal → PPF ganglion → zygomatic N. (V2) → zygomaticotemporal N. → lacrimal N. (V1) → lacrimal gland - damage anywhere = dry eye

Endoscopic Approaches to the Pterygopalatine Fossa

Overview of Approaches

1. Standard Endoscopic Endonasal Approach (EEA) to PPF

Indications

• Posterior epistaxis (sphenopalatine artery ligation)
• Medial PPF tumors (V2 schwannoma, nerve sheath tumors)
• Pterygopalatine ganglion block / neurolysis
• Biopsy of PPF masses

Surgical Steps

1. Positioning & prep: Patient supine, head elevated 15-20°. Decongestion with adrenaline-soaked pledgets. 0° and 30° endoscopes.
2. Uncinectomy + maxillary antrostomy: Wide middle meatal antrostomy to expose the posterior wall of the maxillary sinus. The posterior fontanelle is the key landmark.
3. Identify crista ethmoidalis: This bony ridge on the posterior lateral nasal wall marks the sphenopalatine foramen - the gateway to the PPF.
4. Sphenopalatine foramen dissection: Elevate mucosa posterior to the crista ethmoidalis. The sphenopalatine artery (and its branches) exits here. For epistaxis, this is where ligation/clips are placed.
5. Enter PPF: The periosteum of the PPF is incised. The first structure encountered is fat, then the vascular plexus (distal branches of maxillary artery - Vidian, descending palatal, palatovaginal branches), and deepest are the neural structures (V2, Vidian nerve, pterygopalatine ganglion).

Fig. 47.14 from Cummings Otolaryngology - Schematic of the right maxillary artery within the PPF and the sphenopalatine artery exiting the sphenopalatine foramen. Note the crista ethmoidalis as the key landmark.

Nasal mucosa → crista ethmoidalis → sphenopalatine foramen
→ PPF periosteum → PPF fat → maxillary artery branches
→ pterygopalatine ganglion → V2 (maxillary nerve)
→ Vidian nerve (deepest, most medial, at pterygoid canal)

2. Endoscopic Transmaxillary Approach (Maxillary Artery Ligation)

Steps (from Cummings Otolaryngology)

1. Wide maxillary antrostomy exposing the full posterior wall of the maxillary sinus.
2. Strip mucosa from the posterior wall.
3. Drill/Kerrison the posterior maxillary bone - preserve the periosteum underneath.
4. Electrocauterize periosteum to expose the PPF fat.
5. The maxillary artery is visible as a pulsatile structure traveling lateral to medial in the fat.
6. Use a blunt probe to isolate the main trunk, dissect circumferentially.
7. Place two clips proximally, one distally; apply bipolar between clips, then transect.
8. Pack with dissolvable hemostatic material.

3. Endoscopic Endonasal Transpterygoid Approach (EETPA)

Indications

• Petrous apex lesions (cholesterol granuloma, chondrosarcoma)
• Lateral clivus / inferior cavernous sinus
• Meckel's cave (trigeminal schwannoma)
• Jugular foramen tumors
• Deep infratemporal fossa tumors

Key Anatomic Landmarks (the "three foramina" of EETPA)

┌─────────────────────────────────────────────┐
│         POSTERIOR WALL OF PPF               │
│                                             │
│  FORAMEN ROTUNDUM (superolateral)           │
│    → V2 enters from middle cranial fossa    │
│                                             │
│  VIDIAN (PTERYGOID) CANAL (medial)          │
│    → nerve of pterygoid canal               │
│    → KEY landmark: identifies floor of      │
│      sphenoid sinus + ICA position          │
│                                             │
│  PALATOVAGINAL CANAL (inferomedial)         │
│    → pharyngeal branch to nasopharynx       │
└─────────────────────────────────────────────┘

Procedural Steps (Finger et al., Operative Neurosurgery 2023)

1. Maxillary antrostomy - standard wide exposure
2. Posterior wall of maxillary sinus opened - exposes PPF
3. Sphenopalatine artery cauterized at sphenopalatine foramen (prevents bleeding; destroys ipsilateral nasal septal flap reconstructive option - plan reconstruction BEFORE this step)
4. PPF contents mobilized - fat, vessels, and pterygopalatine ganglion retracted to expose the pterygoid process
5. Identify Vidian canal - this is the crucial landmark. The Vidian nerve runs medially at the floor of the sphenoid sinus and guides safe drilling toward the petrous ICA
6. Drill pterygoid process stepwise between the Vidian canal (medially) and foramen rotundum (superolaterally) to expose deeper targets
7. Variants depending on target:
   • Extended PPF: remove pterygoid plate for lateral sphenoid recess
   • Petrous apex: follow Vidian canal posteriorly
   • ITF: drill lateral to foramen rotundum

4. Prelacrimal Recess Approach vs. Denker's Approach

Prelacrimal Recess Approach

• A mucosal incision is made anterior to the inferior turbinate, preserving the nasolacrimal duct
• The anteromedial maxillary wall is dissected subperiosteally, gaining access to the anterior face of the PPF and lateral ITF without removing the anterior maxillary wall
• Advantage: Preserves nasolacrimal system; avoids facial incisions; good for moderate lateral extension
• Disadvantage: Limited field of view compared with Denker's; steep instrument angle

Denker's Approach (Modified Medial Maxillectomy / Extended Medial Maxillectomy)

• The anterior wall of the maxillary sinus is removed endoscopically to create a wide window
• Provides the broadest lateral exposure of any purely endonasal approach
• Used for large JNAs (Stage III-IV), large PPF/ITF schwannomas, or malignancies
• Advantage: Maximum lateral exposure, allows two-handed dissection, excellent for JNA
• Disadvantage: Loss of anterior maxillary wall support, epiphora risk, greater mucosal disruption

5. Stepwise Endonasal Approach: The 5-Step Protocol (Plzák et al., PMC 5629706)

Outcomes & Evidence (2025 Systematic Review)

• Most common histotypes: JNA (36%), malignancies (26%), chordomas (14%)
• Gross total resection: 88% of PPF/ITF tumors
• Most common complication: V2 hypoesthesia (facial numbness) - 10 cases (10%), with 3 being transient
• Factors predicting incomplete resection: tumor extension into the temporo-masseteric zone or tubo-pharyngeal space - these areas are beyond the reach of pure EEA and may require combined open approaches

Indications for Open vs. Endoscopic Approaches

Common Pitfalls & Complications

1. V2 injury (most common) - facial and palatal numbness; avoid by identifying V2 at foramen rotundum before dissecting laterally
2. Vidian nerve sacrifice - dry eye (decreased lacrimation); the nerve lies medially at the pterygoid canal floor
3. ICA injury - rare but catastrophic; always identify Vidian canal as ICA marker before deep drilling
4. Ipsilateral nasal septal flap unavailable - the EETPA requires sphenopalatine artery cauterization, which devascularizes the Hadad-Bassagaisteguy flap; plan skull base reconstruction with contralateral flap or free flap
5. JNA recurrence - failure to drill the Vidian canal root; tumor nidus sits at the junction of the pterygoid canal and the sphenopalatine foramen