Unit I: Nasal Cavity and Paranasal Sinuses Flashcards
Functions of the Nasal cavity
1) To provide an airway
2) Olfaction
3) Warming and moistening of inspired air
4) Cleansing of inspired air
This extends from the nostrils (nares) anteriorly to the choanae posteriorly. It is divided into left and right chambers by the nasal septum
Nasal cavity
This divides the nasal cavity into left and right chambers
Nasal septum
Contents of the External nose
1) Tip
2) root
3) nares
4) alae
This part of the external nose is the free end of the nose
Tip
This part of the external nose connects the nose to the forehead
Root
This part of the external nose is called the nostrils
Nares
This part of the external nose is bound to the nares laterally
Alae
The ROOF of the nasal cavity is formed by these bones
1) nasal bone
2) frontal bone
3) cribriform plate of the ethmoid bone
4) body of the sphenoid bone
The FLOOR of the nasal cavity is formed by these bones
1) palatine process of the maxilla
2) horizontal plate of palatine bone
The TWO bones that form the hard palate
1) palatine process of maxilla
2) horizontal plate of palatine bone
The MEDIAL wall of the nasal cavity is formed by these structures
1) Septal cartilage
2) Perpendicular plate of ethmoid bone
3) Vomer
The posterior apertures of the nasal cavity that open into the nasopharynx
Choanae
The LATERAL wall of the nasal cavity is formed by these structures
1) Nasal bone
2) Frontal process of the maxilla
3) Lacrimal bone
4) ethmoid bone
5) inferior nasal concha
6) perpendicular plate of the palatine bone
7) medial pterygoid plate of sphenoid bone
The lateral wall of the nasal cavity is formed by a series of projections that jut medially into the nasal cavity
Conchae
Conchae of the lateral wall of the nasal cavity
1) Superior nasal concha
2) Middle nasal concha
3) Inferior nasal concha (separate bone)
The superior nasal concha is formed from this bone
Ethmoid bone
The middle nasal concha is formed from this bone
Ethmoid bone
This is present ABOVE the superior nasal concha. It is also part of the ethmoid bone
Highest nasal concha
Functions of the Nasal Concha
1) INCREASES SURFACE AREA of nasal cavity and allow for moistening and warming of the air and cleaning it (more room)
2) INCREASES TURBULENCE of nasal cavity by increasing the contact with particles in the air and brings more air in contact with the oldfactory fibers
This is when the nasal septum does NOT lie in the median plane. A severe case of this can touch the lateral wall and cause breathing difficulties. It can also exacerbate snoring
Deviated septum
Causes of a deviated septum
1) Congenital malformation (rare)
2) birth injury (very delicate)
3) Postnatal trauma (breaking nose)
This is a small space located ABOVE and BEHIND the superior nasal concha. It receives the opening of the sphenoid sinus
Sphenoethmoidal recess
This is a space BELOW the superior nasal concha. It receives the opening POSTERIOR ethmoidal cells
Superior meatus
This is a space BELOW the middle nasal concha. It receives the openings of the
- frontal sinus (frontonasal duct or infundibulum)
- the maxillary sinus
- the middle ethmoidal cells
- anterior ethmoidal cells
Middle meatus
This is a rounded projection into the middle meatus. The middle ethmoidal cells open onto this structure.
Ehtmoidal bulla
A curved slit lying BELOW the ethmoidal bulla within the middle meatus. The frontonasal duct, anterior ethmoidal cells and maxillary sinus open into this slit
Hiatus semilunaris
This is the space BELOW the inferior nasal concha. It receives openings of the nasolacrimal duct
Inferior meatus
This connects the lacrimal sac of the orbit to the nasal cavity
Nasolacrimal duct
This is the area JUST inside each nostril. It contains hair, sebaceous glands, and sweat glands
Nasal vestibule
This is the LOWER two thirds of the nasal cavity
Respiratory region
This is the superior nasal concha and the upper one-third of the nasal septum, It contains fibers of the oldfactory nerve (CN I) which passes down through the cribriform plate
Oldfactory region
People over the age of 50 lose receptor cells in this area at a rate of 1% per year
Oldfactory area
Special sensory innervation to the nasal cavity
Oldfactory nerve (CN I)
General sensory innervation to the nasal cavity is from this nerve and its branches
Branches of the maxillary and opthalmic divisions of the trigeminal nerve (CN V)
Autonomic innervation (BOTH sympathetic and parasympathetic) of the nasal cavity is from this structure
Pterygopalatine ganglion
The primary blood supply to the nasal cavity if from these two arteries
1) Sphenopalatine branch of the maxillary artery (most important) [branch of external carotid]
2) anterior ethmoidal branch of the opthalmic artery [branch of internal carotid]
This is a nosebleed that is common due to the richness of blood supply. There are two forms: mild and severe
Epistaxis
This is a form of epistaxis that involves the small branches in or near the vestibule. Caused by minor trauma or low humidity
Mild form
This is a form of epistaxis that involves spurting arterial blood. Results form a rupture of the sphenopalatine artery at one of its major anastomoses. Caused by major trauma (car accident)
Severe form
Other causes for BOTH forms of epistaxis
1) Hypertension
2) blood disorders
3) cocaine abuse
Lymph from the nasal cavity drains into this structure
Deep cervical nodes
These are cavities found within the bones of the face. They develop as outgrowths of the nasal cavity. All of these open into the nasal cavity
Paranasal sinuses
These openings of the nasal cavity facilitate drainage of the sinuses
Paranasal sinuses
Formation of the paranasal sinuses is related to
1) Wolff’s law
2) decreased weight of the skull
3) can use to identify individuals after death
This paranasal sinus lies IN the frontal bone and opens into the hiatus semilunaris of the middle meatus via the frontonasal duct
Frontal sinus
The frontal sinus opens into the hiatus semilunaris of the middle meatus via this duct
Frontonasal duct
This is the LARGEST of the paranasal sinuses. It lies WITHIN the maxilla on each side lateral to the nasal cavity and inferior to the orbit.
Maxillary sinus
This paranasal sinus opens into the hiatus semilunaris within the middle meatus.
Maxillary sinus
This is the ONLY paranasal sinus that may be present at birht
Maxillary sinus
This lies within the body of the sphenoid bone and opens into the sphenoethmoidal recess
Sphenoidal sinus
This consists of several groups of ehtmoidal cells that lie within the ethmoid bone between the orbit and the nasal cavity
Ethmoidal sinus
The groups of ethmoidal cells found within the ethmoidal sinus include
1) Posterior ethmoidal cells
2) Middle ethmoidal cells
3) Anterior ethmoidal cells
Clinical significance of NASAL Cavity: A infection can spread to these regions:
1) Anterior cranial fossa
2) LACRIMAL apparatus
3) Nasopharynx
4) paranasal sinuses
5) middle ear
6) mastoid air cells
Infection can spread from the nasal cavity to the ANTERIOR CRANIAL FOSSA via this structure. It can lead to MENINGITIS
Cribriform plate where the oldfactory fibers come through
Infection can spread from the nasal cavity to the LACRIMAL APPARATUS via this structure. It can lead to conjunctivitis
Conjunctiva via the nasolacrimal duct
