Skull Anatomy Quiz: Nasal Structures

Overview of the Nasal Cavity

• Located between the external nares (front) and choanae (back).
• Divided into two cavities by the nasal septum which has a medial wall (nasal septum), lateral wall, inferior wall (nasal floor/palate), and superior wall (nasal roof/skull base).
• Lined with pseudostratified columnar ciliated epithelium with goblet cells, known as respiratory epithelium, which is highly vascular.

Structure of the Nasal Cavity

• Floor: Formed by the hard palate; anteriorly made up of the palatine process of the maxilla and posteriorly by the horizontal plate of the palatine bone.
• Roof: Composed of the cribriform plate of the ethmoid, frontal, nasal, and sphenoid bones.
• Choanae: Also known as posterior nasal apertures, they connect the nasal cavity to the nasopharynx.

Nasal Septum

• Separates the nasal cavity into two nostrils.
• Made up of paired bones (nasal, maxillary, palatine) and unpaired bones (ethmoid, vomer) along with septal and greater alar cartilages.
• Deviated nasal septum (DNS) is common, often causing nasal obstruction, especially in males.

Lateral Wall of the Nasal Cavity

• Comprised of three pairs of scroll-like structures called conchae (superior, middle, inferior).
• Conchae direct airflow and increase surface area for mucosal coverage.
• Beneath each concha are corresponding meatuses (passages) that allow drainage of sinus cavities.

Meatuses

• Inferior Meatus: Largest and located under the inferior concha, drains nasolacrimal duct.
• Middle Meatus: Under the middle concha, includes the ethmoidal bulla and hiatus semilunaris, drains frontal, maxillary, and middle ethmoidal sinuses.
• Superior Meatus: Smallest, situated below the superior concha, drains posterior ethmoidal sinuses.
• Sphenoethmoidal Recess: Located above the superior concha, drains the sphenoidal sinus.

Clinical Significance

• DNS can lead to breathing difficulties, sinusitis, snoring, and may require surgical correction.
• The nasal caity has a rich vascular supply which assists in humidifying air.

Vasculature of the Nasal Cavity

• Vascular supply helps regulate temperature and humidity of inspired air.
• Venous drainage is unique, involving the facial vein and cavernous sinus, which can spread infections to the brain, causing serious conditions.

Nerve Supply

• Olfactory Nerve: Responsible for the sense of smell.
• General Sensation: Supplied by the ophthalmic and maxillary divisions of the trigeminal nerve, providing sensations like touch and pain.
• Innervation includes branches from the anterior ethmoidal nerve (from the ophthalmic division) and various maxillary nerves.

Important Pathways

• Cribriform Plate: Allows olfactory nerve fibers to pass through from the olfactory bulb to the nasal cavity.
• Sphenopalatine Foramen: Connects the nasal cavity to the pterygopalatine fossa for vascular and nerve passage.
• Incisive Canal: Links the nasal cavity with the oral cavity, allowing connection for nerves and vessels.

Conclusion

• The nasal cavity plays a crucial role in respiratory function, and understanding its anatomy is essential for recognizing the implications of obstructions and infections in this area.

Test your knowledge on the bony structures of the nasal cavities in human skull anatomy. This quiz covers key components such as nasal bones, the vomer, and the internal nasal septum. Discover how these bones interact and their significance in the skeletal system.