Temporal & Infratemporal Fossae – Comprehensive Study Notes

Overview

• The lecture focuses on two adjacent regions on the lateral aspect of the skull:
  • Temporal fossa (superficial compartment)
  • Infratemporal fossa (deep compartment, inferior to the zygomatic arch)
• Key skeletal landmarks: zygomatic arch, superior & inferior temporal lines, infratemporal crest, pterygomaxillary fissure, foramina (ovale, spinosum), and pterygopalatine fossa.
• Clinical significance: origin & insertion for muscles of mastication, major neurovascular crossroads (maxillary artery, V-nerve branches), pathways for infection spread, venous communications with cavernous sinus.

Temporal Fossa

Bony Landmarks

• Superior & inferior temporal lines
  • Begin as a single ridge on the posterior edge of the zygomatic process of the frontal bone, then diverge posteriorly.
  • $\textbf{Superior\ temporal\ line}$
  • Continues as a broad arch on frontal ➔ parietal bones.
  • Provides attachment for the temporal fascia.
  • $\textbf{Inferior\ temporal\ line}$
  • Runs roughly parallel & ends at the supramastoid crest of the temporal bone.
  • Marks the uppermost limit of the temporalis muscle.
• Zygomatic arch: anatomically separates temporal fossa (above) from infratemporal fossa (below).

Boundaries

• Above & posterior: superior and inferior temporal lines.
• Below: zygomatic arch.
• Anterior: frontal process of zygomatic bone + zygomatic process of frontal bone.
• Floor (bony): frontal bone, parietal bone, squamous part of temporal bone, and temporal surface of the greater wing of sphenoid.

Contents (from superficial ➔ deep)

• Temporalis muscle (covered by temporal fascia).
• Neurovascular structures running on or through the temporalis:
  1. $\textbf{Deep\ temporal\ nerves}$ (motor, from $V_3$).
  2. $\textbf{Deep\ temporal\ arteries}$ & veins (from maxillary vessels) – supply temporalis.
  3. Zygomaticotemporal nerve (sensory, from $V_2$).
  4. Auriculotemporal nerve (sensory, from $V_3$).
  5. Temporal branch of facial nerve (motor supply to frontalis, orbicularis oculi, etc.).
  6. Superficial temporal artery & vein (terminal branch of external carotid; scalp supply).
  7. Middle temporal artery (pierces temporal fascia to reach temporalis).

Temporalis Muscle (detailed)

• Origin: entire temporal fossa up to inferior temporal line + temporal fascia.
• Insertion: passes deep to zygomatic arch ➔ tendon attaches to coronoid process & anterior border of mandibular ramus.
• Actions:
  • Elevation (closes jaw).
  • Posterior (horizontal) fibers ➔ retraction of mandible.
• Innervation: deep temporal nerves (branches of $V_3$).
• Blood supply: deep temporal arteries/veins.

Infratemporal Fossa

Position & General Description

• A wedge-shaped space inferior & deep to the zygomatic arch, medial to the ramus of mandible, and lateral to the lateral pterygoid plate. Lies below the infratemporal crest of the greater wing of sphenoid.

Boundaries

• Roof: infratemporal surface of the greater wing of sphenoid (houses foramen ovale & spinosum).
• Lateral wall: ramus of mandible (including mandibular condyle & TMJ capsule).
• Medial wall: lateral pterygoid plate of sphenoid; posteriorly related to pharynx.
• Anterior wall: posterior (infratemporal) surface of maxilla (maxillary tuberosity).
• Posterior wall (sometimes described): tympanic plate & styloid process of temporal bone.

Key Foramina & Fissures in/around Roof & Walls

• $\textbf{Foramen\ ovale}$: transmits mandibular nerve ($V_3$), accessory meningeal artery, emissary vein → cavernous sinus.
• $\textbf{Foramen\ spinosum}$: middle meningeal artery & vein, meningeal branch of $V_3$.
• $\textbf{Gap\ deep\ to\ zygomatic\ arch}$: communicates superiorly with temporal fossa.
• $\textbf{Pterygomaxillary\ fissure}$ (vertical slit between maxilla & lateral pterygoid plate): leads medially to pterygopalatine fossa.
• $\textbf{Inferior\ orbital\ fissure}$: anterior–superior communication to orbit.
• $\textbf{Sphenopalatine\ foramen}$ (within the pterygopalatine fossa): final doorway into nasal cavity.

Communications Summary

• Temporal fossa ⇄ infratemporal fossa (via gap under zygomatic arch).
• Pterygopalatine fossa (medial) via pterygomaxillary fissure.
• Orbit (anterosuperior) via inferior orbital fissure.
• Nasal cavity (indirect) via sphenopalatine foramen.

Contents of Infratemporal Fossa

Muscles

• Inferior portion of temporalis.
• Lateral pterygoid (two heads; attaches to TMJ articular disc & pterygoid fovea of mandibular neck).
• Medial pterygoid (deep & superficial heads; mirror image of masseter).

Vessels

• Maxillary artery & its three parts:
  1. \textbf{Mandibular\ (1^{st})\ part} – posterior to neck of mandible.
  2. \textbf{Pterygoid\ (2^{nd})\ part} – between heads of lateral pterygoid.
  3. \textbf{Pterygopalatine\ (3^{rd})\ part} – enters pterygopalatine fossa.
• Major branches (by part):
  • 1st: deep auricular, anterior tympanic, middle meningeal, accessory meningeal, inferior alveolar, mylohyoid.
  • 2nd: deep temporals, pterygoid branches, masseteric, buccal.
  • 3rd: posterior superior alveolar, infraorbital, artery of pterygoid canal, pharyngeal, greater palatine, sphenopalatine.
• Pterygoid venous plexus (between pterygoid muscles & temporalis).

Nerves & Ganglia

• Mandibular nerve divisions (after passing through foramen ovale):
  • Motor branches to muscles of mastication.
  • Sensory branches:
    • Inferior alveolar nerve → lower teeth; gives mental & mylohyoid branches.
    • Lingual nerve → general sensation anterior $\frac{2}{3}$ tongue; joined by chorda tympani (taste + parasymp.).
    • Buccal nerve → cheek mucosa & skin.
    • Auriculotemporal nerve → TMJ, parotid capsule, scalp anterior to ear; conveys glossopharyngeal parasymp. from otic ganglion to parotid.
• Otic ganglion: parasympathetic relay (preganglionic IX via lesser petrosal; postganglionic hitch-hike on auriculotemporal to parotid).
• Chorda tympani (CN VII) traverses the fossa to join lingual nerve.

Other Structures

• Temporomandibular joint (TMJ) articular capsule & disc (superolateral corner of fossa).

Clinical / Applied Points

• Inferior alveolar nerve block: anesthetic deposited near mandibular foramen within the infratemporal fossa.
• Middle meningeal artery: vulnerable to fracture at pterion; epidural hematoma.
• Pathways for spread of infection / tumor: pterygoid plexus → cavernous sinus (via emissary veins) or facial vein (via deep facial v.).

Maxillary Artery (Detailed)

• Origin: one of two terminal branches of external carotid artery (other = superficial temporal).
• Course subdivided by lateral pterygoid muscle:
  • $1^{st}$ part (mandibular): deep to condylar neck; branches enter foramina.
  • $2^{nd}$ part (pterygoid): muscular; supplies muscles of mastication.
  • $3^{rd}$ part (pterygopalatine): inside pterygopalatine fossa; chiefly branches to nasal cavity, palate, orbit.
• Important branch list (mnemonic: “DAM I AM P M B” for 1st/2nd):
  • Deep auricular, Anterior tympanic, Middle meningeal, Inferior alveolar, Accessory meningeal, Mylohyoid…
  • Pterygoids (lateral/medial), Masseteric, Buccal…
  • 3rd-part highlight: posterior superior alveolar, infraorbital, sphenopalatine, greater palatine.

Pterygoid Venous Plexus

• Location: between medial & lateral pterygoid muscles and between lateral pterygoid & temporalis.
• Drains: nasal cavity; teeth & gums; muscles of mastication; paranasal sinuses; nasopharynx; roof & lateral wall of oral cavity.
• Communications:
  • Cavernous sinus (emissary veins) – clinical link to intracranial spread of infection.
  • Facial vein via deep facial vein.
  • Inferior ophthalmic vein via inferior orbital fissure.
  • Pharyngeal venous plexus.
• Mainly empties into maxillary vein → joins superficial temporal vein in parotid gland to form retromandibular vein.

Mandibular Nerve ($V_3$) & Branches (Functional Focus)

• Mixed nerve (motor + sensory) entering fossa through foramen ovale.
• Motor supply: four muscles of mastication + mylohyoid & anterior belly of digastric.
• Sensory branches (outlined above) + meningeal branch.
• Clinical correlations:
  • Lingual nerve easily injured in dental procedures (loss of tongue sensation ± taste depending on site).
  • Auriculotemporal nerve carries glossopharyngeal parasymp. → Frey’s syndrome if mis-rewiring after parotid surgery (gustatory sweating).

Muscles of Mastication (Grouped)

• $\textbf{Masseter}$: obvious external muscle (not in fossae).
• $\textbf{Temporalis}$: occupies temporal fossa; inserts on coronoid.
• $\textbf{Medial\ pterygoid}$: mirror image of masseter on inner ramus; elevates & protrudes.
• $\textbf{Lateral\ pterygoid}$: only one that depresses (opens) mandible; protrusion & side-to-side grinding.

Key Images / Mental Maps Presented in Slides

• Diagram showing cranial fossae division by zygomatic arch (temporal vs infratemporal).
• Composite schematic identifying: ① pterygomaxillary fissure → ② pterygopalatine fossa → ③ sphenopalatine foramen.
• Layered dissection highlighting branches of maxillary artery, pterygoid muscles, deep temporal nerves/arteries, TMJ disc.

Source Acknowledgement

• Anatomical facts cross-checked with “Gray’s Anatomy for Students, $3^{rd}$ Edition (Drake, Vogl & Mitchell, 2014)”.

These bullet-point notes fully integrate structural details, neurovascular contents, boundaries, and clinical perspectives for efficient exam revision on the temporal and infratemporal fossae.