Oral, Nasal and Pharyngeal Structure and Function Flashcards
Describe the skeleton of the external nose
From superior to inferior, the bones and cartilage that comprise the nasal skeleton include the:
- Frontal bone
- Nasal bones (paired)
- Septal cartilage
- Alar cartilages (paired)
- Maxilla (frontal process)
(insert image from notes)
Describe the skeleton and boundaries of the nasal cavity
Lateral wall of the nasal cavity:
- Alar cartilage
- Lateral cartilage
- Nasal bone
- Ethmoidal bone
- Sphenoidal bone
- Palatine bone
- Maxilla
Medial wall of the nasal cavity
- Alar cartilage
- Septal cartilage
- Cribiform plate of ethmoid bone
- Vomer bone
- Maxilla
(insert images from notes)
Discuss the implcations of the ethmoid bone becoming endangered during severe breaks of the nose
The ethmoid bone is very close in proximity to the brain; severe breaks of the nose can endager the brain and meninges directly opposed to the bone.
Particular complications include:
- Infection of the brain
- Bleeding of/into the meninges
- Rhinorrhea (leakage of CSF into the nose)
Discuss the structures and features of the medial wall of the nasal cavity
Features of the medial wall include:
-
Vestibule
* skin and hair at the entrance of the nasal cavity - Highly vascular mucous membrane
- lines the all of the nasal cavity except the vestibule (which is skin and hair)
- mucous humidifies and traps foreign particles
- most nose bleeds occur as a result of damage to this highly vascular surface
- Olfactory area
- situated at the superior border of the cavity
- lined by olfactory epithelium that contains afferent sensory nerves of the olfactory cranial nerve
-
Respiratory area
* comprised of ciliated respiratory epithelium that facilitate the process of expectoration (muco-cliary elevator) -
Nasal septum
* wall that divides the left and right nasal cavities.
Describe the features of the lateral wall of the nasal cavity
Features of the lateral nasal cavity wall include:
- Turbinate Bones
- thin, folded bones that project into the nasal cavity from the lateral -> producing concha
- superior, middle and inferior conchae
- lined by highly vascular mucosal membrane
- produce turbulance to warm and humidify incoming air before passing to the lower airways
- inflammation of the concha causes congestion and blockage of the nose
-
Vestibule
* skin and hair around the entry to the nasal cavity
What are the **meatuses **of the nasal cavity?
What are paranasal sinuses?
The meatuses of the nasal cavity represent the space between the conchi and the lateral nasal cavity wall.
The meastuses have communications to other areas - namely the paranasal sinuses.
The paranasal sinuses develop as outpouchings of the nasal cavity -> carrying respiratory epithelium with them ( thus have sensory functions) that is relevant to sinus pathologies.
What are the four main paranasal sinuses?
Describe any important structures or functions of them.
What are their innervations?
The main paranasal sinuses are the:
- Frontal sinus
- Ethmoid sinus
- Sphenoid sinus
- Maxillary sinus
The maxillary sinus is important in pathology due to the relative position of the opening (from the middle meatus) into the sinus being positioned superiorly.
- Often drainage of nasal fluid into the maxillary sinus
- Difficult to drain the maxillary sinus to clear it due to gravity - medical intervention in the form of aspiration required in certain cases
The other sinuses are less problematic as they more readily drain with gravity.
The frontal, ethmoid and sphenoid sinuses recieive innervation from the V1 branch of the trigeminal nerve
The maxillary sinus recieves innervation from the V2 branch of the trigeminal nerve.
Where does the nasolacrimal duct enter the nasal cavity?
The oriface of the nasolacrimal duct is positioned within the inferior meatus of nasal cavity.
The nasolacrimal duct connects the lacrimal gland (superior to the orbit) to the nasal cavity.
The purpose of this duct is to remove excess tear production (when someone is crying they tend to get a runny nose)
Describe the arterial supply of the nasal cavity!
The blood supply of the nasal cavity can be divided into quadrants (where both the lateral and septal walls of the nasal cavity - except the anterior quadrant)
Posterior Quadrant = Sphenopalatine artery
Superior Quadrant = Anterior + Posterior Ethmoidal Arteries
Inferior Quadrant = Greater Palantine Artery
Anterior Quadrant = where the lateral and septal wall of the nasal cavity have different arterial supplies:
- Septal wall: Superior labial arteries
- Lateral wall: Lateral nasal branches of the facial artery
Discuss the nerve supply of the nasal cavity
The nerve supply of the nasal cavity is divided into two halves:
Anterosuperior half: Branches of ethmoidal nerves (V1)
Posteroinferior half:
Lateral Wall: Branches of greater and lesser palatine nerves (V2)
Septal Wall: Nasopalantine nerve (V2)
Describe the structure of the pharynx
The pharynx is the continuation of the nasal and oral cavities to the larynx.
The pharynx spans from the inferior border of the skull to the C6/Lower border of the cricoid cartilage.
There are three sub-regions of the larynx:
Nasopharynx, Oropharynx and Laryngopharynx
The posterior border of the larynx is formed by a series or sling of constrictor muscles to close off the pharynx. These constrictor muslces contract sequentially on swallowing to propell contents. These constrictor muscles meet their paired contralateral equivalent in the midline Median of Raphe.
The constrictor muscles include: Superior, Middle and Inferior Constrictor Muscles
Describe structures present in the nasopharynx
Superficially:
-
Opening of the auditory tube
- Communicates with the middle ear - facilitates the equalisation of pressure in the middle ear so as too not damage the tympanic membrane
- Tubal elevation (structural protruberance around opening of the auditory tube)
-
Pharyngeal tonsil
- Aggregations of lymphoid tissue susceptible to inflammation
- **Salpingopharyngeal fold **
- Uvula
Deep:
- Cartilagenous Auditory Tube
-
Salpingopharyngeus Muscle
- a muscle contracted to alter the area around the auditory tube - this can unblock any occlusions in the auditory tube so that middle ear equalisation can be achieved.
What structures contribute to the formation of the roof of the mouth?
From anterior to posterior:
- Alveolar arches
- Palatine process of maxilla
- Horizontal process of palatine bone
- Soft palate
- Uvula
What structures contribute to the floor of the mouth?
The mylohyoid muscle is a diaphragmatic muscle that forms the diaphragm that is the floor of the mouth.
This floor provides points of attachment for a number of other muscles - particularly muscles of the tongue and the digastric muscle
The geniohyoid muscle lies on top/superior to the mylohyoid muscle (floor) - it spans from the hyoid bone to the mandible
Describe the surface anatomy of the tongue
The tongue can be divided into an anterior 2/3rd that sits within the oral cavity and posterior 1/3rd that sits in the oropharynx cavity.
The sulcus terminalis is a ‘v-shaped’ depression at the interfact between the anterior and posterior parts of the tongue. It also demarcates the beginning of the lingual tonsils posterior to it beneath the surface mucosa.
At the apex of the sulcus terminalis is the foramen caecum. This is a reminant of the duct of the thyroid gland. The thyroid gland develops as a diverticulum that invaginated/outpouched from the tongue. The foramen caecum is where this diverticulum closes off.
Papillae are small groove in the mucosa that increase the surface area of the tongue to facilitate better taste and secretion. There are three types of papillae on the surface of the tongue:
1. Fungiform papillae
- round and small in shape, they occupy the majority of the anterior 2/3 of the tongue
2. Foliate Papillae
- linear grooves positioned laterally on the tongue at the interface between anterior and posterior tongue
3. Valate papillae
- 8 to 12 vallate papillae in a single V-shaped line immediately anterior to the terminal sulcus of the tongue - these are the largest papillae
The tongue also gives rise to the palatoglossal arch ( anterior arch formed by mucosa overlying the palatoglossal muscle) and palatopharyngeal arch (posterior arch formed by mucosa overlying palatopharyngeus muscle)
Discuss the position, function and innervation of the extrinsic muscles of the tongue!
The extrinsic muscles of the tongue are responsible for altering the position of the tongue.
Each of the muscles are in pairs (L&R)
Genioglosis = protrudes the tongue forward
- deficiencies lead to a deviated tongue towards the side of deficiency
Styolglossus = retracts the tongue
Palatoglossus = elevates the tongue
Hyoglossus = depresses the tongue
All of the extrinsic muscles of the tongue are innervated by hypoglossal nerve** (CN XII) - except for palatoglossus which is supplied by the pharyngeal branch of **vagus nerve.
What structures are located within the oropharynx?
Strucutres include:
- Palatoglossal arch (anterior arch)
- mucosa overlying the palatoglossal muslce
- Palatopharyngeal arch (posterior arch)
- mucosa overlying the palatopharyngeal muscle
- Palatine tonsil
- located between the two oropharynx arches
- can become chronically inflammed and are generally removed
- thought to play a role in priming the immune system early in development
- Uvula
- posterior apex of the soft palate that contributes to sealing off the nasal cavity during swallowing, coughing and sucking.
- Epiglottis
- Superior constrictor
- underlying constrictor muscle enclosing the posterior aspect of the oropharynx
What structures contribute to the soft palate?
What is the purpose of the soft palate?
The soft palate is important in sealing either the nasal or oral cavities off from the pharynx during specific actions:
It seals the nasal cavity during swallowing, coughing and sucking
Seals the oral cavity to allow unimpeded breathing during chewing
View the image attached to view the structures associated
What is meant by Waldeyer’s Ring?
Waldeyer’s Ring refers to the incomplete ring of lymphoid tissue that is organised around the oro- and naso-pharynx.
It includes the pharyngeal, tubal, palatine and lingual lymphoid tissues
Provide an overview of the laryngeal skeleton
Hyoid bone provides attachment to inferior strucutres; ensuring continuity with the head/skull/oral cavity. Connected to thyroid cartilage inferiorly via the thyrohoid membrane
Thyroid cartilage contains the vocal ligaments and is open posteriorly. It articulates inferiorly via cricothyroid ligament/membrane from its inferior horn to the cricoid cartilage below.
Cricoid cartilage is closed posteriorly and deficient anteriorly. It gives rise to the arytenoid cartilages that take attachment from the vocal cords.
The epiglottis originates from the internal angle of the thyroid cartilage and projects upwards posterior to the tongue. Boluses of food push the epiglottis down to prevent food from entering the airways - deflecting it into the oesophagus
What are the intrinsic muscles of the larynx?
What are their effects on the vocal cords?
See the images attached
Outline the blood supply to the larynx
Blood supply is provided to the larynx from both above and below.
The superior and inferior laryngeal arteries supply the majority of blood to the larynx
The superior laryngeal artery originates from the superior thyroid branch of the external carotid artery and enters the larynx with the internal branch of the superior laryngeal nerve through the lateral aperture of the thyrohyoid membrane.
The inferior laryngeal artery originates from the inferior thyroid branch
Superior and inferior laryngeal veins drain the larynx and share the same course as the arteries
Outline the motor supply to the pharynx
How do these muscles contribute to a diagnostic reflex?
See the attached image
Note: all muscles are supplied by the vagus nerve (except stylopharygeus which receives innervation from CN IX)
