Anatomy of the Head and Neck

lecture 17

Abbas A. A. Shawka

Medical student

2nd stage

Subjects

Nasal cavity

Paranasal sinuses

Nasal cavities :-• Two cavities ..

• The smaller anterior regions of the cavities are enclosed by the external nose, whereas the larger posterior regions are more central within the skull.

1. The anterior apertures of the nasal cavities are the nares , which open onto the inferior surface of the nose.

2. The posterior apertures are the choanae, which open into the nasopharynx.

• The nasal cavities are separated !!!

1. from each other by a midline nasal septum.

2. from the oral cavity below by the hard palate.

3. from the cranial cavity above by parts of the frontal, ethmoid, and sphenoid bones.

Lateral wall • Characterized by having three bony

structures ( the chonchae )

• Conchae project medially and inferiorly across the nasal cavity

• Anterior, posterior and medial margin of each choncha are free.

• From this division we will have 4 pathways for air stream …

1. Spheno-ethmoidal recess

2. Superior meatus

3. Middle meatus

4. Inferior meatus

Lateral wall

• This division increase the contact area between the air and the lateral wall WHY ?!!

• Lateral wall of nasal cavity also have

1. Opening of paranasal sinuses in lateral wall and roof ..

2. Opening of nasolacrimal duct ..

Regions of Nasal Cavity

1. Nasal vestibule

2. Respiratory region

3. Olfactory region

Skeletal framework • Bones that contribute to the skeletal framework of the nasal cavities include:

1. the unpaired ethmoid, sphenoid, frontal, and vomer.

2. the paired nasal, maxillary, palatine, and lacrimal bones and inferior conchae.

• Of all the bones associated with the nasal cavities, the ethmoid is a key element !!!

Ethmoid bone

External nose

• Like posterior regions of nasal cavity, the anterior opening are held open by skeletal framework …

• The bony parts are where the nose is continuous with

1. the skull-here the nasal bones and parts of the maxillae and frontal bones provide support.

2. by cartilages , and on each side, support is provided by septal cartilage, lateral processes of septal cartilages and alar cartilage.

alar

Paranasal sinuses

• All of the paranasal sinuses:

₋ are lined by respiratory mucosa, which is ciliated and mucus secreting.

₋ open into the nasal cavities.

₋ are innervated by branches of the trigeminal nerve [V] .

Frontal sinuses • Located in frontal bone

• Triangular in shape

• The base of each triangular sinus is oriented vertically in the bone at the midline above the bridge of the nose and the apex is laterally approximately one-third of the way along the upper margin of the orbit.

• Each frontal sinus drains onto the lateral wall of the middle meatus via the frontonasal duct, which penetrates the ethmoidal labyrinth and continues as the ethmoidal infundibulum at the front end of the semilunar hiatus.

• The frontal sinuses are innervated by branches of the supra-orbital nerve from the ophthalmic nerve [V1 ] .

• Their blood supply is from branches of the anterior ethmoidal arteries .

Ethmoidal sinuses • Each cluster of cells in the

ethmoidal labrunith is separated from the orbit by the thin orbital plate of the ethmoidal labyrinth, and from the nasal cavity by the medial wall of the ethmoidal labyrinth.

• Ethmoidal air cells are divided into anterior, middle, and posterior ethmoidal cells based on the location of their apertures on the lateral wall of the nasal cavity.

• Anterior ethmoidal cells frontonasal duct

infundibulum

• Middle ethmoidal cells ethmoidal bulla

• Posterior ethmoidal cells lateral wall of superior nasal meatus

• Ethmoidal air cells are innervated by :-

1. the anterior and posterior ethmoidal branches of the nasociliary nerve from the ophthalmic nerve [V1].

2. the maxillary nerve [V2] via orbital branches from the pterygopalatine ganglion.

• The ethmoidal cells receive their blood supply through branches of the anterior and posterior ethmoidal arteries.

Maxillary sinuses • In maxillary bone ( body )

• Pyramidal in shape

• Each is pyramidal in shape with the apex directed laterally and the base deep to the lateral wall of the adjacent nasal cavity.

• The medial wall or base of the maxillary sinus is formed by the maxilla, and by parts of the inferior concha and palatine bone that overlie the maxillary hiatus.

• The opening of the maxillary sinus is near the top of the base, in the center of the semilunar hiatus, which grooves the lateral wall of the middle nasal meatus .

• Relationships of the maxillary sinus are as follows:

1. The superolateral surface (roof) is related above to the orbit.

2. The anterolateral surface is related below to the roots of the upper molar and premolar teeth and in front to the face.

3. The posterior wall is related behind to the infratemporal fossa.

• The maxillary sinuses are innervatedby infra-orbital and alveolar branches of the maxillary nerve [V2].

• receive their blood through branches from the infra-orbital and superior alveolar branches of the maxillary arteries.

Sphenoid sinuses • The sphenoidal sinuses, one on

either side within the body of the sphenoid, open into the roof of the nasal cavity via apertures on the posterior wall of the spheno-ethmoidal recess.

• The apertures are high on the anterior walls of the sphenoid sinuses.

• The sphenoidal sinuses are related:

• above to the cranial cavity, particularly to the pituitary gland and to the optic chiasm,

• laterally, to the cranial cavity, particularly to the cavernous sinuses.

• below and in front, to the nasal cavities.

• Innervation of the sphenoidal sinuses is provided by:

• the posterior ethmoidal branch of the ophthalmic nerve [V1].

• the maxillary nerve [V 2] via orbital branches from the pterygopalatine ganglion.

• The sphenoidal sinuses are supplied by branches of the pharyngeal arteries from the maxillary arteries .

• PITUITARY GLAND CAN BE SURGICALLY APPROACHED THROUGH NASAL CAVITY AND SPHENOID SINUSES !!!

Medial wall

• Nasal Septal cartilage

• Perpendicular plate of ethmoid bone

• Vomer

• Nasal crest of maxilla and palatine

• Incisor crest ( of maxilla )

Floor of the nasal cavity • The floor of each nasal cavity is

smooth, concave, and much wider than the roof.

• Composed of :-

1. soft tissues of the external nose, and

2. the upper surface of the palatine process of the maxilla and the horizontal plate of the palatine bone, which together form the hard palate.

• The naris opens anteriorly into the floor, and the superior aperture of the incisive canal is deep to the mucosa immediately lateral to the nasal septum near the front of the hard palate.

Roof of the nasal cavity

• Formed by :-

1. Cribriform plate of ethmoid

2. Frontal bone

3. Nasal bone

4. Processes of septal cartilage and major alar cartilage

5. Sphenoid bone

6. Vomer

7. Palatine bone

NOTE :- BONES IN THE LATERAL WALL MAKE A SMALL CONTRIBUTE TO THE FORMATION OF THE ROOF !!

Lateral wall of nasal cavity

• Formed by

1. Ethmoidal labrynith

2. Palatine bone ( vertical plate )

3. Maxillary bone

4. Lacrimal bone

5. Sphenoid bone ( medial pterygoid plate )

Openings in roof and lateral wall

1. Spheno-ethmoidal recess :- opening for the sphenoid sinuses

2. Lateral wall of superior meatus :-opening for the posterior ethmoidal cells

3. Ethmoidal bulla :- opening for the middle ethmoidal cells

4. Semilumar hiatus contains openings for :-

- Frontonasal duct : drain the frontal sinuses and anterior ethmoidal sinuses

- In the floor of semilunar hiatus there is opening for maxillary sinuses

5. Lateral wall of inferior meatus :-opening for the nasolacrimal duct

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Choanae

Demonstrate the margins from the schematic diagram ?!

Arterial supply 1. Sphenopalatine artery :- ( terminal

branch of max. a. in pterygopalatine fossa. gives :-a. posterior lateral nasal branch b. Posterior septal branch

2. greater palatine artery :- ( orginate from max. artery in pterygopaatine fossa )

3. Superior labial a. and lateral nasal artery :- which are a branches from fascial a.

4. Anterior and posterior ethmoidal arteries :- orginate in orbit from ophthalamic a. then ascend to cranial cavity and enter the nasal cavity through cribriform plate

Venous drainage of nasal cavity

Innervation • Opthalamic nerve branches :- ( all are

nasociliary nerve branches )

1. Anterior ethmoidal nerve

2. Posterior ethmoidal nerve ( NOT SHOWN )

• Maxillary nerve branches :-

1. Posterior superior lateral nasal nerve

2. Posterior inferior medial nasal nerve

3. Nasopalatine nerve

4. Posterior inferior nasal nerve ( orginate from the great palatine nerve )

5. Nasal branch anterior superior alveolar branch infraorbital nerve

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Innervation • Opthalamic nerve branches :- ( all are

nasociliary nerve branches )

1. Anterior ethmoidal nerve

2. Posterior ethmoidal nerve ( NOT SHOWN )

• Maxillary nerve branches :-

1. Posterior superior lateral nasal nerve

2. Posterior inferior medial nasal nerve

3. Nasopalatine nerve

4. Posterior inferior nasal nerve ( orginate from the great palatine nerve )

5. Nasal branch anterior superior alveolar branch infraorbital nerve

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Lymphatic drainage • Lymph from anterior regions of the

nasal cavities drains forward onto the face by passing around the margins of the nares.

• These lymphatics ultimately connect with the submandibular nodes.

• Lymph from posterior regions of the nasal cavity and the paranasal sinuses drains into upper deep cervical nodes. Some of this lymph passes first through the retropharyngeal nodes .