L 33 Nasal Cavity & Pterygopalatine Fossa – Vocabulary Flashcards

Pterygopalatine Fossa

  • Small, inverted-tear–shaped space
    • Inferior to the orbit
    • Posterior to the maxilla
    • Medial (deep) to the infratemporal (IT) fossa
  • Functions as:
    • Location of pterygopalatine ganglion (PPG)
    • Distribution hub for maxillary nerve (CN V2)
    • Termination site of the 3rd part of the maxillary artery

Borders & Corresponding Openings

  • Anterior (post. surface of maxilla)
    • Inferior orbital fissure → floor of orbit (V2 & infraorbital vessels leave; infraorbital a. enters)
    • Posterior superior alveolar foramina → maxillary sinus (post. sup. alveolar nn./aa.)
  • Medial (lat. surface palatine bone)
    • Sphenopalatine foramen → lateral nasal wall (post. sup. nasal nn.; sphenopalatine a.)
  • Lateral
    • Pterygomaxillary fissure → IT fossa (maxillary a. enters; V2 communicates)
  • Posterior (pterygoid process, sphenoid)
    • Pterygoid canal → middle cranial fossa (nerve & artery of pterygoid canal)
    • Foramen rotundum → middle cranial fossa (maxillary n. exits)
    • Pharyngeal canal → nasopharynx (pharyngeal n./a.)
  • Roof – body of sphenoid
  • Floor – opening of greater palatine canal → bony palate (greater/lesser palatine nn./aa.)

Pterygopalatine Ganglion (PPG)

  • Suspended from CN V2 by ganglionic branches
  • Fiber types traversing ganglion
    • Preganglionic parasympathetic (CN VII via greater petrosal) – synapse
    • Postganglionic sympathetic (deep petrosal, from sup. cervical ganglion) – pass through
    • Somatic sensory (from CN V2) – pass through
  • Nerve of the pterygoid canal (Vidian n.) = union of
    • Greater petrosal n. (preganglionic para-symp., CN VII, origin: geniculate ganglion)
    • Deep petrosal n. (postganglionic symp.)
  • Postganglionic fibers distribute via V2 branches to:
    • Lacrimal gland (via zygomatic → lacrimal n.)
    • Mucosal glands of nasal cavity, paranasal sinuses, nasopharynx
    • Palatal & gingival glands of upper jaw

Maxillary Nerve (CN V2)

  • Purely somatic sensory; exits cranial cavity through foramen rotundum → enters PPF
  • Picks up post-ganglionic para- & sympathetic fibers from PPG
  • Leaves fossa via inferior orbital fissure as infra-orbital n.

Branches within PPF & Destinations

  • Greater palatine n.
    • Descends palatine canal → greater palatine foramen → hard palate
    • Gives posterior inferior nasal branches in canal
  • Lesser palatine n. → soft palate (lesser palatine foramen)
  • Nasopalatine n.
    • Through sphenopalatine foramen → nasal septum → incisive canal → anterior palate
  • Zygomatic n. → orbit
    • Zygomaticofacial & zygomaticotemporal branches supply skin of cheek, temple
    • Carries secretomotor fibers to lacrimal gland
  • Posterior superior nasal nn. → lateral nasal wall (via sphenopalatine foramen)
  • Pharyngeal n. → nasopharynx (via pharyngeal canal)
  • Posterior superior alveolar n. → molar teeth, maxillary sinus
  • Infra-orbital n. (continuation of V2)
    • Gives middle & anterior superior alveolar nn. (premolars, canines, incisors, sinus)
    • Emerges infra-orbital foramen → cheek, ala nasi, lower lid, upper lip

Maxillary Artery – 3rd (Pterygopalatine) Part

  • Enters PPF via pterygomaxillary fissure; branches parallel those of CN V2
  • Infra-orbital a.
    • Course identical to infra-orbital n.; gives anterior superior alveolar aa.
  • Posterior superior alveolar a. → posterior teeth, sinus
  • Descending palatine a. → palatine canal
    • Splits into greater & lesser palatine aa.
  • Sphenopalatine a. (terminal branch)
    • Through sphenopalatine foramen → lateral & septal walls; forward via incisive canal to palate
  • Additional minor branches: artery of pterygoid canal, pharyngeal a.

Nose – Overview & Functions

  • Two wedge-shaped nasal cavities extending from nares to choanae → nasopharynx
  • Superior 13\frac{1}{3} = olfactory region (CN I)
  • Inferior 23\frac{2}{3} = respiratory region (warming, humidifying, filtering air; drainage of secretions)
  • Connected to paranasal sinuses (air-filled extensions of nasal cavity)

External Nose & Skeletal Framework

  • Dorsum: root → apex
  • Nares (nostrils); vestibule just internal (vibrissae present)
  • Alae: lateral soft tissue walls of nares
  • Septum divides cavities; external framework includes:
    • Bones: paired nasal bones (superior dorsum); contributions from frontal & maxilla
    • Cartilages:
    • Lateral cartilages (paired) – dorsum
    • Alar cartilages (paired, U-shaped) – nares
    • Septal cartilage (single) – inf. part of septum

Nasal Cavity Boundaries

  • Septum (~3 equal parts)
    • Septal cartilage (ant./inf.)
    • Vomer (post./inf.)
    • Perpendicular plate of ethmoid (post./sup.)
    • Minor floor contributions: maxillae & palatine bones
  • Floor
    • Ant.: palatine process of maxilla
    • Post.: horizontal plate of palatine
  • Roof (ant.→post.)
    • Nasal & septal cartilages → nasal bones → frontal → ethmoid (cribriform) → sphenoid
  • Lateral Wall Bones
    • Inferior nasal concha (independent bone)
    • Nasal, frontal, maxilla, ethmoid, sphenoid, palatine
  • Choanae – posterior apertures to nasopharynx

Conchae (Turbinates) & Meatuses

  • 3 mucosa-covered shelves ↑ surface area
    • Superior & middle = parts of ethmoid; inferior = separate bone
  • Conchae divide cavity into channels (meatuses) with sinus & duct openings

Meatuses & Key Openings

  • Inferior meatus (below inferior concha)
    • Nasolacrimal duct drains tears here
  • Middle meatus (between inf. & middle conchae)
    • Semilunar hiatus (crescent groove)
    • Openings: frontal sinus, maxillary sinus, anterior ethmoidal cells
    • Ethmoidal bulla (rounded elevation)
    • Opening: middle ethmoidal cells
  • Superior meatus (between middle & superior conchae)
    • Posterior ethmoidal cells
  • Spheno-ethmoidal recess (above sup. concha, beneath roof)
    • Sphenoidal sinus opening

Paranasal Sinuses

  • Pneumatized cavities in four bones (frontal, ethmoid, sphenoid, maxilla) – present only in mammals & archosaurs
  • Lined by respiratory mucosa; innervated by branches of CN V
  • Sinus drainage:
    • Frontal → semilunar hiatus (middle meatus)
    • Ethmoidal air cells
    • Anterior → semilunar hiatus
    • Middle → ethmoidal bulla
    • Posterior → superior meatus
    • Sphenoidal → spheno-ethmoidal recess
    • Maxillary (largest)
    • Ostium high on superolateral wall → semilunar hiatus (middle meatus); difficult to drain clinically

Neurovasculature of Nasal Cavities

Arterial Supply

  • Internal carotid system
    • Anterior & posterior ethmoidal aa. (from ophthalmic a.)
    • Branch into anterior lateral & anterior septal branches
  • External carotid system
    • Sphenopalatine a. (terminal maxillary)
    • Posterior lateral nasal & posterior septal branches
    • Greater palatine a. (from descending palatine)
    • Enters via incisive canal; anastomoses in septum (Kiesselbach area)
    • Facial a. contribution: superior labial a. → anteroinferior septum, nares

Venous Drainage

  • Dense plexus paralleling arteries – thermoregulation
  • Drains via:
    • Sphenopalatine v. → pterygoid plexus → retromandibular/facial vv.
    • Facial v. → internal jugular v.
    • Ophthalmic v. → cavernous sinus (clinically relevant route for infection spread)

Innervation

  • Olfactory n. (CN I) – special sensory in olfactory epithelium; axons pass through cribriform plate to olfactory bulb
  • Ophthalmic division (CN V1) – anterosuperior cavity
    • Anterior & posterior ethmoidal nn. (nasociliary branch)
    • Anterior ethmoidal: major sensory supply; gives external nasal n. to tip of nose
    • Both also innervate frontal, ethmoidal, sphenoidal sinuses
  • Maxillary division (CN V2) – posteroinferior cavity & autonomics
    • Nasopalatine n. → septum, anterior palate
    • Posterior inferior nasal branches (from greater palatine) → lateral wall
    • Posterior superior nasal branches → lateral wall
    • Pharyngeal n. → nasopharynx

Clinical Correlation – Epistaxis (Nosebleed)

  • Thin mucosa + extensive anastomoses → frequent bleeding site
  • Kiesselbach (Little’s) area on anterior septum = convergence of:
    • Septal branch of sphenopalatine a.
    • Septal branch of anterior ethmoidal a.
    • Greater palatine a.
    • Superior labial a.
  • Common causes: hypertension, dry air, trauma (digital/nasal picking). Traumatic bleeds often venous.

Study Guide – Key Questions for Review

  1. Define all six boundaries of the PPF, list every opening, its communicating space, and the neurovascular structures transmitted.
  2. Enumerate fiber types in the PPG; name nerves conveying each type; indicate which fibers synapse; list all target organs.
  3. List major V2 branches, course, and sensory/autonomic territories.
  4. Draw/trace the third part of the maxillary artery with all named branches.
  5. Itemize bones & cartilages of (a) lateral nasal wall, (b) septum, (c) external nose.
  6. Name paranasal sinuses and specify exact meatal drainage site.
  7. Compare/contrast arterial, venous, and neural supply of nasal septum vs. lateral walls.