Nasal Cavity Anatomy

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Questions and Answers

Damage to the ethmoidal infundibulum would directly impair drainage from which of the following paranasal sinuses?

  • Sphenoid sinus
  • Frontal sinus (correct)
  • Posterior ethmoid air cells
  • Maxillary sinus

A patient presents with anosmia (loss of smell) following a head trauma. Which of the following structures is MOST likely damaged?

  • The vascular supply from the sphenopalatine artery
  • Olfactory mucosa in the roof of the nasal cavity (correct)
  • Respiratory mucosa in the inferior meatus
  • Sensory branches of the maxillary nerve (CN V2) in the posterior nasal cavity

A surgeon is performing a rhinoplasty and needs to reshape the anterior nasal septum. Which component is MOST relevant to this procedure?

  • The perpendicular plate of the ethmoid bone
  • The vomer bone
  • The nasal bone
  • The septal cartilage (quadrangular cartilage) (correct)

A patient with a severe nosebleed is found to have significant bleeding from Kiesselbach's area. Which set of arteries is MOST likely involved in this bleeding?

<p>Anastomoses of multiple arteries including the sphenopalatine, anterior ethmoidal, superior labial, and greater palatine arteries (C)</p> Signup and view all the answers

A patient undergoes a surgical procedure that inadvertently damages the nerve providing sensory innervation to the anterior nasal cavity. Which nerve branch was MOST likely affected?

<p>Ophthalmic nerve (CN V1) (B)</p> Signup and view all the answers

What is the PRIMARY function of the nasal conchae (turbinates) in the lateral wall of the nasal cavity?

<p>To increase the surface area for warming and humidifying inspired air (A)</p> Signup and view all the answers

A child is born without complete formation of the hard palate. Which structures have failed to properly fuse during development?

<p>Palatine process of the maxilla and horizontal plate of the palatine bone (A)</p> Signup and view all the answers

Which of the following BEST describes the epithelium found lining the majority of the nasal cavity responsible for conditioning the inspired air?

<p>Pseudostratified ciliated columnar epithelium with goblet cells (D)</p> Signup and view all the answers

What is the MOST significant functional consequence of a severely deviated nasal septum?

<p>Obstruction of airflow and increased susceptibility to sinusitis (C)</p> Signup and view all the answers

A patient presents with inflammation of the sphenoethmoidal recess. Drainage from which sinus would be MOST directly affected?

<p>Sphenoid sinus (C)</p> Signup and view all the answers

If a tumor were to compress the maxillary artery as it passes through the pterygopalatine fossa, which of the following arteries would MOST directly be affected, potentially leading to reduced blood supply to the nasal cavity?

<p>Sphenopalatine artery (A)</p> Signup and view all the answers

Which of the following autonomic nervous system effects would be observed during parasympathetic activation of the nasal mucosa?

<p>Dilation of blood vessels and increased mucus production (B)</p> Signup and view all the answers

During endoscopic sinus surgery, damage to which structure would MOST likely result in a cerebrospinal fluid (CSF) leak?

<p>Ethmoid bone near the cribriform plate (A)</p> Signup and view all the answers

A patient presents with recurrent sinusitis primarily affecting the maxillary sinus. Which anatomical variation would MOST likely predispose this patient to maxillary sinusitis?

<p>A narrow maxillary ostium located high on the medial wall of the sinus (A)</p> Signup and view all the answers

A surgeon is planning to perform an anterior ethmoidectomy. Which anatomical landmark is MOST critical to identify to avoid damaging the orbit?

<p>Lamina papyracea (D)</p> Signup and view all the answers

Which of the following explains why some sinus infections can cause periorbital cellulitis (infection around the eye)?

<p>The ethmoid sinuses are located adjacent to the orbit and share thin bony walls (D)</p> Signup and view all the answers

A patient presents with persistent epistaxis refractory to anterior nasal packing. Angiography reveals a bleeding vessel in the posterior nasal cavity. Which artery is MOST likely the source of the bleeding?

<p>Sphenopalatine artery (D)</p> Signup and view all the answers

A previously healthy individual develops a benign tumor within the nasal cavity that obstructs the natural drainage pathway of the maxillary sinus. What is the MOST likely long-term consequence of this obstruction if left untreated?

<p>Chronic maxillary sinusitis (A)</p> Signup and view all the answers

During development, which of the paranasal sinuses is typically the LAST to develop, often appearing after the age of two years?

<p>Frontal sinus (B)</p> Signup and view all the answers

Damage to which structure could lead to impaired tear drainage, causing excessive tearing (epiphora)?

<p>Inferior meatus (B)</p> Signup and view all the answers

Flashcards

Nasal Cavity Function

Proximal part of the respiratory tract that filters, warms, and humidifies air; involved in olfaction and speech resonance.

Paranasal Sinuses

Air-filled extensions of the nasal cavity located in the frontal, ethmoid, maxillary, and sphenoid bones.

Nasal Cavity Extent

The anterior boundary is the nostrils (nares) and the posterior boundary is the choanae, which open into the nasopharynx.

Nasal Septum

Divides the nasal cavity into right and left halves.

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Nasal Cavity Roof

Formed by the nasal, frontal, ethmoid, and sphenoid bones.

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Nasal Cavity Floor

Formed by the hard (palatine process of maxilla and horizontal plate of palatine bone) and soft palates.

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Nasal Septum Composition

Composed of the perpendicular plate of ethmoid, vomer bone, and septal cartilage.

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Nasal Conchae (Turbinates)

Superior, middle, and inferior bony projections on the lateral wall of the nasal cavity.

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Meatus

The space below each concha.

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Respiratory Mucosa

Pseudostratified ciliated columnar epithelium with goblet cells.

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Olfactory Mucosa

Located in the roof of the nasal cavity and contains olfactory receptors.

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Main Arterial Supply to Nasal Septum

Sphenopalatine artery (from the maxillary artery).

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Kiesselbach's Area

Anterior nasal septum; common site of nosebleeds due to anastomosis of several arteries.

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Sense of Smell Innervation

Olfactory nerves (CN I).

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General Sensory Innervation of Nasal Cavity

Branches of the trigeminal nerve (CN V).

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Frontal Sinuses

Located in the frontal bone, superior to the orbits, and drain into the middle meatus.

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Maxillary Sinuses

Located in the maxillary bones, lateral to the nasal cavity, and drain into the middle meatus.

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Sinusitis

Inflammation of the paranasal sinuses, often due to infection or allergies.

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Nasal Polyps

Benign growths in the nasal cavity or paranasal sinuses.

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Deviated Nasal Septum

Can obstruct airflow and contribute to sinusitis.

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Study Notes

  • The nasal cavity is the proximal part of the respiratory tract
  • The nasal cavity filters, warms, and humidifies air
  • It is involved in olfaction and speech resonance
  • The paranasal sinuses are air-filled extensions of the nasal cavity located in the frontal, ethmoid, maxillary, and sphenoid bones

Boundaries of the Nasal Cavity

  • The nasal cavity extends from the nostrils (nares) to the choanae
  • The choanae open into the nasopharynx
  • The nasal septum divides the nasal cavity into right and left halves
  • The roof is formed by the nasal, frontal, ethmoid, and sphenoid bones
  • The floor is formed by the hard (palatine process of maxilla and horizontal plate of palatine bone) and soft palates

Nasal Septum

  • The nasal septum is composed of bone and cartilage
  • The perpendicular plate of the ethmoid bone forms the superior part
  • The vomer bone forms the inferior and posterior part
  • The septal cartilage (quadrangular cartilage) forms the anterior part
  • The nasal septum is often deviated to one side

Lateral Wall of the Nasal Cavity

  • The lateral wall has three bony projections called the superior, middle, and inferior nasal conchae (turbinates)
  • The conchae increase the surface area of the nasal cavity, facilitating warming and humidification of air
  • The space below each concha is called a meatus
  • The superior meatus receives drainage from the posterior ethmoidal air cells
  • The middle meatus receives drainage from the frontal, maxillary, and anterior ethmoidal sinuses via the ethmoidal infundibulum and hiatus semilunaris
  • The inferior meatus receives drainage from the nasolacrimal duct

Nasal Mucosa

  • The nasal cavity is lined with respiratory mucosa, except for the vestibule and olfactory region
  • The respiratory mucosa is pseudostratified ciliated columnar epithelium with goblet cells
  • The olfactory mucosa is located in the roof of the nasal cavity and contains olfactory receptors
  • The nasal mucosa is highly vascular, which helps to warm the inspired air

Vasculature of the Nasal Cavity

  • The nasal cavity receives arterial supply from branches of both the internal and external carotid arteries
  • The sphenopalatine artery (from the maxillary artery) is the main arterial supply to the nasal septum and lateral nasal wall
  • The anterior and posterior ethmoidal arteries (from the ophthalmic artery) supply the anterior and posterior parts of the nasal cavity, respectively
  • The greater palatine artery (from the maxillary artery) and the superior labial artery (from the facial artery) also contribute to the blood supply
  • Kiesselbach's area (Little's area) in the anterior nasal septum is a common site of epistaxis (nosebleed) due to the anastomosis of several arteries

Innervation of the Nasal Cavity

  • Olfactory nerves (CN I) provide the sense of smell
  • General sensory innervation is provided by branches of the trigeminal nerve (CN V)
  • The ophthalmic nerve (CN V1) provides sensory innervation to the anterior part of the nasal cavity
  • The maxillary nerve (CN V2) provides sensory innervation to the posterior part of the nasal cavity
  • Autonomic innervation (sympathetic and parasympathetic) controls the blood flow and secretions of the nasal mucosa

Paranasal Sinuses

  • The paranasal sinuses are air-filled extensions of the nasal cavity located in the frontal, ethmoid, maxillary, and sphenoid bones
  • They are lined with respiratory mucosa and drain into the nasal cavity
  • They lighten the skull, provide resonance for speech, and may act as shock absorbers in head trauma
  • The frontal sinuses are located in the frontal bone, superior to the orbits
  • They drain into the middle meatus via the frontonasal duct and ethmoidal infundibulum
  • The ethmoid sinuses (ethmoid air cells) are located in the ethmoid bone between the nasal cavity and the orbit, divided into anterior, middle, and posterior groups
  • The anterior ethmoid air cells drain into the middle meatus via the ethmoidal infundibulum
  • The middle ethmoid air cells drain directly into the middle meatus
  • The posterior ethmoid air cells drain into the superior meatus
  • The maxillary sinuses are located in the maxillary bones, lateral to the nasal cavity
  • They drain into the middle meatus via the maxillary ostium, which opens into the hiatus semilunaris
  • The sphenoid sinuses are located in the sphenoid bone, posterior to the ethmoid sinuses
  • They drain into the sphenoethmoidal recess

Development of Paranasal Sinuses

  • The paranasal sinuses develop as outgrowths from the nasal cavity during fetal development and childhood
  • The maxillary and ethmoid sinuses are present at birth
  • The frontal sinuses usually develop after age 2
  • The sphenoid sinuses develop around age 5

Clinical Considerations

  • Sinusitis is inflammation of the paranasal sinuses, often due to infection or allergies
  • Nasal polyps are benign growths in the nasal cavity or paranasal sinuses
  • A deviated nasal septum can obstruct airflow and contribute to sinusitis
  • Epistaxis (nosebleed) is common due to the rich vascular supply of the nasal cavity
  • Fractures of the facial bones can involve the nasal cavity and paranasal sinuses
  • Tumors can arise in the nasal cavity and paranasal sinuses, and can be benign or malignant

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