The Nose and Paranasal Air Sinuses 2 Flashcards
In the lateral wall of the nasal cavity, there is an opening from the maxillary air sinus to …. ….
The nasal cavity.
Above the opening in the lateral wall of the nasal cavity from the maxillary air sinus to the nasal cavity, what is the lateral wall of the nasal cavity formed by?
It is formed by the ethmoid bone.
What does the cribriform plate form?
It forms the roof of the nose and the floor of the anterior cranial fossa.
What is the crista galli?
This is a midline projection of the cribriform plate.
What is the downward projection of the cribriform plate called?
It is called the perpendicular plate of the ethmoid.
What does the cribriform plate form part of?
It forms part of the midline nasal septum.
On either side, what is the cribriform plate expanded by?
It is expanded by numerous air cells.
The lateral walls of the air cells lie in the medial walls of the orbital cavities.
What do the ethmoid air cells expand into the top of the nasal cavity to form?
They form the anterior, middle and posterior groups of ethmoidal air cells or sinuses.
What are conchae?
These are bony processes in the nasal cavity that curl over the air sinuses in the lateral wall of the nose.
How many conchae are there?
3 - superior, middle and inferior.
What are the superior and middle conchae a part of?
They are a part of the ethmoid bone.
Is the inferior conchae a part of any bone?
It is a separate bone.
What do we have beneath each concha?
We have a meatus or a pocket.
Which bones form the midline nasal septum?
- above – perpendicular plate of the ethmoid
- below – a thin flat bone called the vomer
- extends from behind like a wedge between the cranial base and the floor of the nose.
- midline septum continues anteriorly as a cartilaginous septal cartilage.
What are the paranasal air sinuses lined with?
They are lined with respiratory mucous membrane.
Describe the nerve and blood supply to the paranasal air sinuses.
They have a sensory nerve supply and a rich blood supply.
What do the paranasal air sinuses open into?
They open into the cavity of the nose.
What is the shape of the maxillary air sinus?
It is pyramidal in shape.
What is the base of the maxillary air sinus?
The lateral wall of the nose.
Where is the apex of the maxillary air sinus?
Near the zygomatic bone.
What does the roof of the maxillary air sinus consist of?
It consists of the floor of the orbit.
Where does the infraorbital canal lie?
It lies in the roof of the maxillary air sinus.
Where does the anterior wall of the maxillary air sinus lie?
It lies behind the cheek.
What do we have behind the posterior wall of the maxillary air sinus?
We have the pterygomaxillary fissure and the pterygopalatine fossa.
Describe the floor of the maxillary sinus.
The tips of the roots of several teeth create irregular bumps.
What are the tooth roots embedded in?
They are embedded in the alveolar bone of the maxilla.
What happens when the maxillary air sinus becomes infected?
The respiratory mucous membrane swells and fluid can collect in the cavity which can be painful (especially when bending forwards) in the face or in the top teeth.
What is the ostium?
This is a hole through which the maxillary sinus drains.
Where is the ostium?
This is high in the lateral wall of the nose beneath the middle concha at the front of a groove called the hiatus semilunaris.
What does the hiatus semilunaris run around?
It runs around the base of a swelling that is formed by a bulging of some of the ethmoidal air cells.
What is the bulla ethmoidalis?
This is a swelling that is formed by the bulging of some ethmoidal air cells which protrudes a little into the middle meatus.
What do the air cells of the ethmoid bone drain into?
They drain into the cavity of the nose.
How do the air cells of the ethmoid bone drain into the cavity of the nose?
Through holes that open under the middle and superior meati.
What do the sphenoidal air sinuses drain into?
They drain into the nose.
How do the sphenoidal air sinuses drain into the nose?
Through 2 openings high in the roof of the nose at the back in a region called the sphenoethmoidal recess.
What does each frontal bone also contain?
It also contains an air sinus lateral to the midline.
(Sometimes there is a common sinus and sometime or another one or the other air sinus will be absent)
How does the frontal sinus drain into the nose?
It drains into the nose on either side through a funnel like opening called the infundibulum.
What does the frontal sinus empty into?
It empties into the front of the hiatus semilunaris.
What structure empties into the inferior meatus?
The nasolacrimal duct.
Where does the opening of the auditory tube lie?
It lies at the level of the floor of the nose.
What type of nerve is the trigeminal nerve?
This is a mixed cranial nerve.
What is trigeminal nerve like in size compared to other cranial nerves?
it is the largets cranial nerve.
What does the large ganglion of the trigeminal nerve contain?
It contains the cell bodies of its sensory fibres.
Where is the large ganglion of the trigeminal nerve?
This lies in the middle cranial fossa, in a depression on the apex of the petrous temporal bone.
What happens to the trigeminal nerve as it grows forward during development?
- pushes underneath the dura mater of the middle cranial fossa
- eventually the dura fuses around the trigeminal nerve
- draws a layer of the arachnoid mater with it up to the point where the dura fuses around the trigeminal nerve
What are the first part of the nerve and its sensory ganglion bathed in?
They are bathed in cerebrospinal fluid in a subarachnoid space that lies beneath the dura of the middle cranial fossa.
What is Meckel’s cave?
This is the space where the subarachnoid space lies beneath the dura of the middle cranial fossa.
What happens to the trigeminal nerve beyond its large, sensory ganglion?
It divides into 3 branches on the floor of the middle cranial fossa.
What are the 3 divisions of the trigeminal nerve?
- opthalmic division
- maxillary nerve
- mandibular division
What is the path of the opthalmic division of the trigeminal nerve?
It passes forwards through the superior orbital fissure into the orbit.
