What forms the skeleton of the external nose?
Nasal bones forming the bridge of the nose, articulating with frontal bone above and frontal process of maxilla laterally. Lateral, septal and alar cartilages form the rest of the anterior projection.
What do the septal cartilages do?
Project into nasal cavity, separating it into two halves.
What comprises the lateral wall of the nasal cavity?
What comprises the medial wall of the nasal cavity?
Maxilla, nasal bone, frontal, ethmoid, septal cartilage and vomer.
What sits at the front and back of the nasal cavity?
Anterior and posterior nares.
What is the structure of the ethmoid bone?
One horizontal plate in anterior cranial fossa by cribriform plate and downwards projections making the medial wall/septum and two lateral walls.
What can happen in a bad fracture of the ethmoid bone?
Can injure the cribriform plate and potentially allow infections in, bleeds into the meninges or produce subdural haemorrhages or rhinorrhoea, which is leakage of CSF from the subarachnoid space out into the nasal cavity.
What is the medial wall of the nasal cavity lined by?
Almost entirely by highly vascular mucous membrane.
What is the function of the mucous membrane of the nasal cavity?
Helps warm and humidify air before it enters lower airways
Helps prevent spasms of small muscles around bronchioles
Mucous partly humidifies but also traps foreign particles, prevents them entering the lower airways.
What is the nasal vestibule lined by?
Skin and hair - no vascular mucous membrane.
What is within the upper one third of the medial and lateral nasal walls?
Olfactory epithelium containing primary afferent olfactory neurons projecting up into the cribriform plate into the olfactory bulb.
What is within the lower two-thirds of the medial and lateral nasal walls?
Respiratory (pseudostratified squamous) epithelium that is ciliated, beating to encourage mucus towards the oral or nasal cavity.
What are the conchae?
Turbinate bones projecting off the lateral nasal wall into the nasal cavity - superior, middle and inferior.
What lines the conchae?
Highly vascular mucosa
What are the meatus?
The space between the conchae and the lateral wall or the concha above and the below.
What exists within the meatus?
Openings of sinuses into nasal cavity
What are the paranasal sinuses?
Frontal, ethmoid, sphenoid and maxillary sinuses.
How do the paranasal sinuses develop?
As outpouchings of the nasal cavity, dragging mucosa along with it, hence they too are lined by mucosa.
Why is drainage of the maxillary sinus difficult?
Because it, unlike the other sinuses, drains superior.
Which nerves innervate the paranasal sinuses?
CNV1: Frontal, ethmoid and sphenoid sinuses
CNV2: Maxillary sinus
Where does the nasolacrimal duct open?
Into inferior meatus
What does the nasolacrimal duct do?
Drains tear fluid produced in lacrimal gland in superolateral part of orbit.
What supplies blood to the superior quadrant of the nasal cavity?
Anterior and posterior ethmoidal arteries.
What supplies blood to the inferior quadrant of the nasal cavity?
Branches of greater palatine arteries that come in through the mouth and into the nose through a hole in the floor of the nasal cavity.
What supplies blood to the anterior quadrant of the nasal cavity?
Lateral: nasal branches of facial artery Medial: labial arteries
What supplies blood to the posterior quadrant of the nasal cavity?
Sphenopalatine artery (branch of external carotid).
What is the nerve supply to the nasal cavity?
Superior half: ophthalmic division of trigeminal (branches of anterior ethmoidal nerves)
Inferior half: maxillary division of trigeminal nerve (greater and lesser palatine nerves)
Where does the pharynx extend between?
From base of skull all the way down to the lower border of the cricoid cartilage.
Which muscles comprise the pharynx?
Superior, middle and inferior constrictors
What are the attachments for the constrictor muscles of the pharynx?
Lateral aspects of nasal and oral cavities, hyoid bone and larynx. Attach to one another via median raphe.
What are the boundaries of the nasopharynx?
Soft palate inferiorly, nasopharynx posteriorly and ethmoid superiorly.
What lies in the nasopharynx?
Pharyngeal tonsils - adenoids
Opening of auditory tube.
Salpingopharyngeus: one of the muscles of the pharynx attaching to auditory tube.
Contraction pulls on opening of auditory tube, opening it just enough to release pressure.
What forms the roof of the mouth?
Hard and soft palate
What forms the hard palate?
Palatine process of maxilla and horizontal process of palatine bone.
What hangs off the horizontal process of the palatine bone?
What forms the floor of the mouth?
Mandible and diaphragm made from mylohyoid muscle.
What are the attachments of the mylohyoid muscle?
Mandible to hyoid bone.
What anchors to the mylohyoid muscle?
What separates the anterior 2/3 and posterior 1/3 of the tongue?
Sulcus terminalis with apex pointing posteriorly.
What is the foramen caecum?
The remnant duct from which the thyroid gland develops, sitting in apex of sulcus terminalis.
What lines the entire tongue?
What lines the anterior 2/3 of the tongue?
Where are the valate/circumvalate papillae?
Directly anterior to the sulcus terminalis
Where are the foliate papillae?
Posterolateral surface of tongue
Where are the taste buds?
Embedded in the walls of the papillae
What is located on the posterior 1/3 of the tongue?
Rough and nodulated due to lymphoid nodules sitting just below the mucosa – these are the lingual tonsils
What are the extrinsic muscles of the tongue?
What is genioglossus important for?
Protruding (sticking out) the tongue - both must be working at the same time.
What innervates the extrinsic muscles of the tongue?
All are innervated by CNXII, except palatoglossus, which is innervated by pharyngeal branch of vagus.
What will damage of the hypoglossal nerve result in?
Deviation of the tongue on protrusion to the side of the lesion.
What do the intrinsic muscles of the tongue do?
Changes shape of the tongue
What are the intrinsic muscles of the tongue?
Superior longitudinal, inferior longitudinal, transverse and vertical muscles.
What nerve innervates the intrinsic muscles of the tongue?
What provides general and special sensory innervation to the posterior third of the tongue?
What provides general and special sensory innervation to the anterior two-thirds of the tongue?
General sensory: trigeminal nerve
Special sensory: chorda tympani (CNVII)
What does chorda tympani travel with to the tongue?
Which nerve forms the afferent arc of the gag reflex?
Which nerve supplies the upper teeth?
Superior alveolar nerve (maxillary division of CNV)
Which nerve supplies the lower teeth?
Inferior alveolar nerve (mandibular division of CNV)
Where will the upper teeth refer pain through?
Maxillary branch of CNV
Where will the lower teeth refer pain to?
Other areas innervated by mandibular division of CNV, e.g. external auditory meatus.
How many salivary glands are there?
3 pairs on each side
What are the 3 salivary glands?
Parotid, submandibular and sublingual glands
What is the parotid gland?
Sits superficial to ramus of mandible, has a duct projecting anteriorly to masseter, opens into vestibule between lip and gum opposite upper 2nd molar tooth
What is the submandibular gland?
2 parts: below the mylohyoid muscle, therefore outside oral cavity
Part above, therefore inside oral cavity
Wraps around free posterior edge of mylohyoid
Duct takes origin from internal portion
Projects up lateral to lingual frenulum
What is the sublingual gland?
Lateral to tongue in floor of mouth
Directly under mucosa
Has openings directly into mucosa in floor of mouth lateral to tongue
What forms the oropharynx?
Posterior to alveolar arches
Back of tongue with lingual tonsil sits anteriorly
Roof formed by soft palate
Walls: palatoglossal and palatopharyngeal arches
What forms the palatoglossal and palatopharyngeal arches?
Folds of mucosa over underlying muscle
What does palatoglossus do?
What does palatopharyngeus do?
What sits between the two palatine arches?
What is the function of the palatine tonsils?
Primes the immune system in early life
What does the soft palate do?
Seals off nasal cavity during coughing, swallowing and suction – through elevation
Seals off oral cavity by being depressed to allow unimpeded breathing while chewing
What is musculus uvulae connected to?
Palatine aponeurosis, which attaches it to the palatine bone.
Which 5 muscles support the structure of the soft palate and make it move?
Tensor veli palatini
Levator veli palatini
What innervates the 5 muscles that support the soft palate?
All muscles are innervated by pharyngeal branches of vagus except for tensor veli palatini (CNV)
Which muscles open the auditory tube?
Tensor veli palatini
Levator veli palatini
What is Waldeyer's ring?
An incomplete ring of lymphoid tissue around the oral and nasal cavities:
Pharyngeal tonsils at roof of nasopharynx
Tubal tonsils over auditory tube
Palatine tonsils between palatal arches
Inferiorly, lingual tonsils under posterior 1/3 of tongue
Where does the larynx extend?
From epiglottis to C6/lower border of cricoid cartilage
What 3 structures comprise the laryngeal skeleton?
Hyoid bone, thyroid and cricoid cartilage.
Where is the thyroid cartilage open?
Where in the laryngeal skeleton is the laryngeal inlet?
In the thyroid cartilage, forming a posterior opening into the airways.
What bridges the space between the thyroid cartilage and hyoid bone?
What is the cricothyroid cartilage?
The cartilage bridging the space between the cricoid and thyroid cartilage
What does the cricoid cartilage articulate with?
Inferior horn of thyroid cartilage
Where are the arytenoid cartilages located?
On posterior aspect of cricoid
What do the vocal ligaments attach to?
Anterior vocal processes of arytenoid cartilages.
What do the muscular processes of the arytenoid cartilages do?
Form attachment for intrinsic muscles of the larynx.
These move move the arytenoids, which swivel and slide, allowing for phonation and respiration.
Where does the epiglottis take origin from?
Posterior angle of thyroid cartilage and projects into laryngeal inlet.
What are the attachments of the vocal ligaments?
Two vocal ligaments, each attached to the vocal process of one of the arytenoid cartilages
What covers the vocal ligaments?
What are the two folds in the larynx?
Superior mucosal fold (false vocal cord) and inferior mucosal fold (true vocal cord)
What is first seen when looking down the larynx?
Superior vocal fold (false vocal cord)
What must happen to the vocal ligaments for phonation?
They must be adducted.
What must happen to the vocal ligaments for inspiration?
They must be abducted.
What do the intrinsic muscles of the larynx alter?
Position of vocal ligaments
Which muscle abducts the vocal ligaments?
What are the 2 main nerves supplying the larynx?
Superior and recurrent laryngeal nerve.
What does the superior laryngeal nerve supply?
Splits into two:
Internal: breaks through hole in membrane to supply vocal ligaments
External: innervates cricothyroid (if damaged, difficulty with higher pitched sounds or changing voice)
What does the recurrent laryngeal nerve supply?
Supplies all muscles of the larynx except cricothyroid
Also supplies mucosa below vocal ligaments
What will damage to the recurrent laryngeal nerve result in?
Hoarse voice and stridor.
How does the larynx get its blood supply?
Comes from above and below:
Above: branches of superior thyroid vessels, enter through thyrohyoid membrane
Below: Inferior thyroid veins and arteries, sit in front of cartilage (danger for tracheotomy)
What part of the larynx should be punctured in a tracheotomy?
Why is the cricothyroid membrane best for membrane puncture?
Because there are no main blood vessels in the midline and less likely to drown someone.
What will help make the intubation process easier?
Hyperextension of the head/neck
What do the aryepiglottic folds define?
The lateral borders of the laryngeal inlet
What occurs in the laryngopharynx when swallowing?
Epiglottis closes over laryngeal inlet and larynx is elevated to form proper seal.
What provides sensory innervation to the pharynx?
Mostly from pharyngal branches of glossopharyngeal nerve
Afferent arc of gag reflex
Reinforced by branches of trigeminal and vagus
What forms the afferent arc of the gag reflex?
Pharyngeal branches of glossopharyngeal nerve
What provides motor nerve supply to the pharynx?
Mostly from pharyngeal branches of vagus (CNX), except for stylopharyngeus (CNIX)
What are the steps involved in swallowing/deglutation?
Bolus shaped and pushed by tongue to palate.
Soft palate descends and palatal arches are approximated to grip and push the bolus into the oropharynx.
Soft palate elevated and tightened to prevent bolus entering nasal cavity.
Larynx and pharynx elevated to bring bolus closer to oesophagus.
Laryngeal inlet closed to prevent bolus from entering the trachea.
Bolus is pushed down the oropharynx and over the epiglottis.
Bolus forced down through laryngopharynx and into oesophagus.
Larynx depressed to return to normal position (mainly by elastic recoil).