Gimme answer for 15m of posterior wall of nose

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The visual is a two-part educational material focusing on nasal anatomy and clinical nasopharyngeal swab procedures. Image A is a sagittal anatomical diagram of the human head and neck, illustrating key landmarks for swab insertion. Labeled structures include the tip of the nose (1), nasal vestibulum (2), anterior part of the inferior turbinate (3), posterior part of the inferior turbinate (4), and the posterior nasopharyngeal wall (5). An asterisk (*) highlights the mid-turbinate region, a critical landmark for specimen collection. Image B is a clinical photograph depicting the procedural setup for endoscopically guided nasopharyngeal swab measurement. A healthcare worker in personal protective equipment (PPE), including a face shield and gloves, is shown using a flexible endoscope on a seated participant. A monitor in the background displays a real-time endoscopic view of the nasal cavity and the tip of a swab. This composite image is designed for medical training to standardize insertion depths and ensure accurate anatomical positioning during respiratory pathogen testing, such as for SARS-CoV-2.

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Here is a complete 15-mark answer on the Posterior Wall (and full anatomy) of the Nose / Nasal Cavity, structured the way ENT exams expect it:

Posterior Wall of Nose (Nasal Cavity Anatomy) - 15 Marks

1. Introduction

The nasal cavity is a paired, air-filled space lying above the hard palate and below the anterior cranial fossa. It opens anteriorly through the nares (nostrils) and posteriorly through the choanae into the nasopharynx. Each nasal cavity has four walls: roof, floor, medial (septal) wall, and lateral wall. The posterior opening is the choana (posterior nasal aperture).

2. Walls of the Nasal Cavity

(a) Roof

Three parts (anterior to posterior):

Frontonasal part - sloping upward (nasal bones + frontal process of maxilla)
Ethmoidal part - horizontal, formed by the cribriform plate of ethmoid (site of olfactory nerve filaments passing through)
Sphenoidal part - sloping downward (body of sphenoid/anterior wall of sphenoid sinus)

(b) Floor

Formed by:

Palatine process of maxilla (anterior 3/4)
Horizontal plate of palatine bone (posterior 1/4)

(c) Medial Wall (Nasal Septum)

Perpendicular plate of ethmoid (posterosuperior)
Vomer (posteroinferior)
Septal cartilage (anterosuperior)
Columella (anteroinferior, membranous/mobile septum)
Keystone area = junction of nasal bones, perpendicular plate of ethmoid, upper lateral cartilage (ULC), and cartilaginous septum

Kiesselbach's plexus (Little's area): Anteroinferior septum - most common site of epistaxis; formed by:

Posterior septal branch of sphenopalatine artery (SPA)
Anterior ethmoidal artery (AEA)
Greater palatine artery
Alar branch of superior labial artery

3. Lateral Wall of Nose (Most Important / High-Yield)

This is the most complex wall and the main focus in exams. It bears the turbinates (conchae) and the meati.

Bones forming the lateral wall:

Nasal bone (anterosuperior)
Frontal process of maxilla (anterior)
Lacrimal bone
Ethmoid (labyrinth - main contributor)
Inferior turbinate bone (separate bone)
Perpendicular plate of palatine bone (posterior)
Medial pterygoid plate of sphenoid (most posterior)

Turbinates (Conchae):

Turbinate	Origin	Meatus Below It
Inferior	Separate bone (largest)	Inferior meatus
Middle	Ethmoid bone	Middle meatus
Superior	Ethmoid bone	Superior meatus
Supreme (Santorini)	Ethmoid (inconsistent)	Supreme meatus

Meati and Their Openings:

Inferior Meatus:

Between inferior turbinate and nasal floor
Opening of nasolacrimal duct (under the anterior end - Hasner's valve)
Preferred route for nasal airway devices (widest meatus)

Middle Meatus:

Between middle and inferior turbinates
Contains the ostiomeatal complex (OMC)
Structures seen here:
- Uncinate process (UP) - sickle-shaped bony projection
- Ethmoid bulla (EB) - most prominent anterior ethmoid cell
- Hiatus semilunaris - 2D crescent-shaped gap between UP (anteriorly) and EB (posteriorly)
- Ethmoid infundibulum - 3D trough bounded by UP medially, lamina papyracea laterally, EB posterosuperiorly
Sinus drainage into middle meatus:
- Maxillary sinus
- Frontal sinus (via frontonasal recess)
- Anterior ethmoidal sinuses

Superior Meatus:

Between superior and middle turbinates
Drains: posterior ethmoidal sinuses

Sphenoethmoidal Recess:

Above and behind the superior turbinate
Drains: sphenoid sinus

Important Structures on Lateral Wall:

Sphenopalatine foramen - within superior meatus, between basal lamella of middle turbinate and superior turbinate; transmits the sphenopalatine artery and nerve
Eustachian (pharyngotympanic) tube orifice - on lateral wall of nasopharynx
Fossa of Rosenmüller (pharyngeal recess) - posterosuperior to ET orifice; common site of nasopharyngeal carcinoma

4. Posterior Wall of Nose - Choana

The choana (posterior nasal aperture) is the opening connecting the nasal cavity to the nasopharynx.

Bony Margins of the Choana:

Border	Bone
Superior	Body of sphenoid (+ root of medial pterygoid plate)
Medial	Vomer (+ ala of vomer superiorly)
Inferior	Horizontal plate of palatine bone (+ posterior nasal spine)
Lateral	Perpendicular plate of palatine bone + medial pterygoid plate of sphenoid

The pterygoid canal (Vidian canal) is visible in the root of the medial pterygoid plate.

Posterior view through choanae shows:

Inferior nasal concha
Middle nasal concha
Ethmoidal bulla
Uncinate process

Mucosal Landmarks Behind the Choana (Nasopharynx):

Posterior pharyngeal wall
Uvula
Soft palate (inferior boundary between nasopharynx and oropharynx)
Pharyngeal tonsil (adenoids) - in roof/posterior wall of nasopharynx

Source: Color Atlas of Human Anatomy Vol.2, p.185-187

5. Blood Supply of Nasal Cavity

Arterial Supply (two main sources):

A. Internal Carotid Artery (via ophthalmic artery):

Anterior ethmoidal artery (AEA) - exits orbit via anterior ethmoidal foramen, supplies anterosuperior septum and lateral wall
Posterior ethmoidal artery (PEA) - exits ~12 mm posterior to AEA, 6 mm anterior to optic canal; supplies posterior nasal cavity

B. External Carotid Artery (via internal maxillary artery - IMA):

Sphenopalatine artery (SPA) - main artery of the nasal cavity; enters via sphenopalatine foramen in superior meatus
- Posterior septal branch - courses along sphenoid rostrum; supplies nasal septum (forms pedicle of nasoseptal flap)
- Posterior lateral nasal branch - supplies middle and inferior turbinates
Descending palatine → greater palatine artery - supplies anteroinferior nasal cavity and septum (via incisive foramen)
Pharyngeal branch of IMA (palatovaginal artery) - courses through pharyngeal canal from posterior wall of pterygopalatine fossa; supplies posterosuperior nasal cavity and nasopharynx

From facial artery: Superior labial artery → alar branch → nasal vestibule and anterior nasal cavity

Vascular Plexuses:

Kiesselbach's plexus (Little's area) - anteroinferior septum; most common site of anterior epistaxis
Woodruff's plexus - posteroinferior meatus (posterior lateral nasal + pharyngeal branch of IMA); previously thought arterial, now known to be venous; site of posterior epistaxis

6. Venous Drainage

Anterior/posterior ethmoidal veins → superior ophthalmic vein → cavernous sinus
Sphenopalatine vein → pterygoid plexus
Diploic veins of Breschet → communicate with cavernous and superior sagittal sinuses
Valveless system - allows retrograde intracranial spread of infection

7. Nerve Supply

Sensory Innervation:

Ophthalmic (V1):

Internal nasal branch of anterior ethmoidal nerve - anterosuperior septum and lateral wall
Posterior ethmoidal nerve - posterior nasal cavity

Maxillary (V2):

Sphenopalatine (nasopalatine) nerve - posterior nasal cavity and septum
Anterior superior alveolar nerve - anterior nasal cavity and floor

Autonomic Innervation (via Vidian nerve - nerve of pterygoid canal):

Sympathetic (vasoconstriction): preganglionic from sympathetic chain → superior cervical ganglion → deep petrosal nerve → joins GSPN → Vidian nerve → nasal mucosa (without synapsing in SPG)
Parasympathetic (vasodilation + secretion): preganglionic from superior salivary nucleus (CN VII) → nervus intermedius → GSPN → Vidian nerve → sphenopalatine ganglion (synapse) → postganglionic fibers with branches of V2 to nasal mucosa

Olfactory:

Olfactory nerve (CN I) - filaments pass through cribriform plate of ethmoid to upper nasal cavity (superior turbinate and upper third of septum)

Summary Table - Quick Revision

Feature	Details
Choana borders	Superior: sphenoid body; Medial: vomer; Inferior: palatine bone; Lateral: palatine + medial pterygoid plate
Main artery	Sphenopalatine artery (branch of IMA)
Anterior epistaxis site	Kiesselbach's plexus / Little's area
Posterior epistaxis site	Woodruff's plexus
NLD opens into	Inferior meatus (Hasner's valve)
Sphenoid sinus drains into	Sphenoethmoidal recess
Posterior ethmoid drains into	Superior meatus
Middle meatus drains	Maxillary, frontal, anterior ethmoid sinuses
Olfactory area	Superior concha + upper 1/3 septum
Vidian nerve formed by	Greater superficial petrosal nerve (GSPN) + deep petrosal nerve

Sources: K.J. Lee's Essential Otolaryngology; Color Atlas of Human Anatomy Vol.2; Scott-Brown's Otorhinolaryngology; Gray's Anatomy for Students

Gimme a diagram of posterior wall of nose

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Detailed anatomical diagram of the posterior wall of the nose (posterior nasal apertures / choanae), as seen from a posterior view. The diagram should clearly label all bony borders: Superior border - body of sphenoid bone and root of medial pterygoid plate; Medial border - vomer (vertical midline bone) and ala of vomer; Inferior border - horizontal plate of palatine bone and posterior nasal spine; Lateral border - perpendicular plate of palatine bone and medial pterygoid plate of sphenoid. Also label the two choanae (left and right posterior nasal apertures), the pterygoid canal (Vidian canal), the inferior nasal concha, the middle nasal concha, the nasal septum, and the soft palate below. Use clean medical illustration style with clear labels and arrows, white background, professional ENT anatomy diagram quality.

Here's the diagram showing the posterior wall of the nose (posterior view of the choanae). Key structures labeled:

Bony borders of each choana:

Superior - body of sphenoid + root of medial pterygoid plate (with pterygoid/Vidian canal)
Medial - vomer (the vertical midline divider between the two choanae)
Inferior - horizontal plate of palatine bone + posterior nasal spine
Lateral - perpendicular plate of palatine bone + medial pterygoid plate of sphenoid

Structures visible through the choanae:

Inferior nasal concha
Middle nasal concha
Soft palate (below)

Quick memory tip: "SVP LaMP"

Sphenoid (superior) | Vomer (medial) | Palatine - horizontal plate (inferior) | Lateral - palatine perpendicular plate + Medial Pterygoid plate

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