ENT Anatomy Flashcards
Which bones do the conchae belong to?
- Superior and middle - ethmoid bone
- Inferior concha - bone in itself
Which bones form the walls the nasal cavities?
- Lateral wall: lateral cartilages, nasal, ethmoid, inferior concha, sphenoid, palatine and maxilla
- Medial wall: Septal cartilage, vomer and perpendicular plate of ethmoid
- Floor: Palatine process of maxilla and horizontal process of palatine (roof of oral cavity)
- Roof: Nasal, nasal part of frontal, ethmoid(cribriform and crista galli) and sphenoid
Which 2 Le Fort fractures can cause anosmia?
Le Fort II and III (as they can disrupt the cribriform plate). May also risk spread of infection
What is the olfactory pathway?
- 1) Odourants enter nose into receptor cells in the olfactory epithelium (1st neurons in chains)
- 2) Passes through cribriform plate with olfactory cranial nerves
- 3) Synapse onto olfactory bulb (ganglia)
- 4) Neurons pass along olfactory tract
- 5) Pass to temporal love and olfactory areas
True or False: Airflow through the nose can be impacted by engorgement of the nasal mucosa due to erectile tissue (arteriovenous). One side will be engorged then change to other side every 1-5 hours.
True
What are the paranasal sinuses lined with?
Mucous-secreting respiratory mucosa (ciliated pseudostratifed columnar epithelium with goblet cells)
What is sinusitis and how does it occur?
Inflammation of the mucosa in 1 or more of the sinuses. Can be infection, allergy or autoimmune issues, which can prevent cilia wafting mucosa towards ostia, or viral URTIs cause swelling of mucosa which can block ostia. Sinuses become filled with infected mucous and pressure builds.
What nervs provide sensation to the paranasal sinuses, and what are the clinical implications?
CN V1 and V2, which can cause referred pain e.g. toothache
Which sinus is predisposed to sinusitis and why?
Maxillary sinus, because the ostia is located superiorly in the medial wall so cilia have to work against gravity to drain the mucous
What is a oro-antral fistula and what are the clinical risks?
Communication between maxillary sinus and tooth socket. Apex of a root of a tooth can protrude through the maxillary alveolar bone. Can lead to spread of tooth infection to sinuses.
What is Kiesselbach (Little’s) area?
Anastomotic arterial blood supply from ophthalmic, maxillary and facial arteries. Common site for epistaxis.
What is the pterion?
H-shaped suture where the temporal, frontal, sphenoid and parietal bones join. Thinnest part of the skull
Which bones make up the anterior, middle and posterior cranial fossas?
- Anterior - frontal, ethmoid and sphenoid
- Middle - Sphenoid and temporal
- Posterior - temporal and occipital
What structures pass through the internal acoustic meatus?
CN VII (Facial), CN VIII (Vestibulocochlear), labyrinthine artery and vein
What does the facial nerve supply?
- Motor
- Muscles of facial expression
- Stylohyoid
- Posterior belly of digastric and stapedius,
- Special sensory
- taste to anterior 2/3rds of tongue (via chorus tympani),
- Sensory
- External ear (part of)
- Parasympathetic
- Secretorymotor to salivary glands, lacrimal gland and mucous glands of oral and nasal cavity
What type of cartilage is found in the external ear?
Elastic cartilage
Which glands produce ear wax?
Ceruminuous glands
How should the EAM be pulled in adults and children in otoscopy?
In children, posteroinferiorly (as EAM is short and straight). In adults, posterosuperiorly
What is indicated if the cone of light has moved?
That the pressure in the ear has changed
What is the innervationn of the tympanic membrane?
Internal surface - CN IX
External surface - CN V3 (auriculotemporal branch)
What does the glossopharyngeal nerve supply?
- Mucosa of middle ear
- Eustachian tube
- Nasopharynx mucosa
- Oropharynx
- Tonsils
What would happen if you clicked your fingers next to the ear of someone with Bell’s Palsy?
They may report it being very loud as their stapedius is paralysed to can’t protect against excessive noise
What is the main route of the facial nerve?
Exits the brain at the pontomedullary junction, then passes through the petrous temporal bone at the internal acoustic meatus in posterior cranial fossa then exists the skull at the stylomastoid foramen
How can you clinically test the facial nerve?
Asking the patient to make various facial expressions
What are perilymph and endolymph each similar to and how do they differ?
Perilymph like extracellular fluid, endolymph like intracellular fluid. Difference in ionic content between the two: Perilymph is high in potassium, while endolymph is very low
What type of acceleration do the semicircular canals detect?
Rotational acceleration
What is the process of sound transmission in the internal ear?
- Sound waves make tympanic membrane vibrate
- Vibrations transmitted through ossicles
- Base of stapes vibrates in oval window
- Vibration of stapes creates pressure waves in perilymph
- Hair cells in the cochlea are moved, neurotransmitter is released, APs stimulated and conveyed to brain by cochlear nerve
- Pressure waves descend and become vibrations again
- Pressure waves are dampened at the round window
What are the receptor cells of the cochlea and where are they located?
Organ of corti, located on the basilar membrane of the cochlear duct
What is the cochlear canal divided into?
Scala vestibuli, scala tympani and cochlear duct
What marks the posterior boundary of the oral cavity, and the anterior boundary of the pharynx?
Folds of the palatine tonsils
Oral cavity proper
Between behind the teeth and the pharynx
Oral vestibuel
Between the teeth and the lips
What is the sublingual fold?
Layer of mucosa overlying the sublingual glands
What is the innervation of the muscles of the floor of the mouth?
- Mylohyoid - CN V3
- Geniohyoid - C1 (which piggy backs on hypoglossal n.)
Where does parotid gland enter the oral cavity?
By Upper 2nd molar
What is the innervation of the sublingual and submandibular glands, and how does it get there?
chorda tympani n, and it piggy backs on the lingual branch of V3
What is the innervation of the parotid gland and how does it get there?
Secretomotor innervation from CN IX (Glossopharyngeal), and it piggy backs on auriculotemproal branch of V3
What does the thyroid descend through when developing?
Foramen caecum of the tongue
What is the innervation of the tongue?
- Anterior 2/3rds
- General sensory - CN V3 (via Lingual nerve)
- Special sensory - CN VII (via chorda tympani)
- Posterior 1/3rd
- Both - CN IX (glossopharyngeal)
- Motor - CN XII Hypoglossus (except Palatoglossus which is Vagus)
What acts as the boundary between the anterior and posterior parts of the tongue?
Sulcus terminalis
What are the 4 differernet types of papillae on the tongue, and which have taste buds?
- Foliate
- Vallate
- Fungiform
- Filiform (only ones which do not have taste buds)
What is the function of the intrinsic and extrinsic muscles of the tongue?
- Extrinsic - change position of the tongue
- Intrisnic - change shape fo the tongue
What are the four extrinsic muscles of the tongue and their attachments?
- Palatoglossus (palate)
- Hyoglossus (hyoid)
- Styloglossus (styloid process)
- Genioglossus (mental spine)
Which nerve innervates all of the muscles of the tongue, and what is the one exception?
CN XII (Hypoglossus), except palatoglossus which is CN X (Vagus)
What is the course of the hypglossal n. (CN XII)?
- Connects to CNS via many rootlets at medulla oblongata
- Intracranial: passes forwards to hypoglossal canal through posterior cranial fossa
- Exits skull via hypoglossal canal in occipital bone (anterior wall of foramen magnum)
- Extracranial: descends in neck lateral to carotid sheath, then at level of hyoid bone it passes anteriorly towards the lateral aspect of the tongue
How would you clinically test the hypoglossal n. (CN XII) and what do the results mean?
Ask the patient to stick their tongue out.
- If both CN XIIs are functioning normally the tongue tip remains in the MIDLINE upon protrusion
- In unilateral CN XII damage the tongue tip will POINT TOWARDS the side of the injured nerve
Which artery supplies the tongue and when it is often damaged?
Lingual artery mostly (from anterior division of ECA) - also contributions from facial a., and is often damaged during seizures
What is the relationship between arteries and nerves, and hyoglossus m.?
- Arteries pass medial to hyoglossus
- Nerves pass laterally
What is the vermillion border?
The often well-demarcated border between the lips and the normal skin around them
Where are the palatine tonsils found?
Between the pharyngeal arches
What forms the anterior and posterior arches of the oral cavity?
- Palatopharyngeus makes up the posterior arch
- Palatoglossus forms the anterior arch
What is the motor nerve supply to the palatine muscles?
All CN X (Vagus) except for tensor veli palatini which is CN V3
How do you clinically test CN X (Vagus) and CN V3?
Ask patient to say “Aahh”
- if the nerves are functioning normally the uvula should lift straight up in the MIDLINE
- if there is unilateral nerve pathology the uvula will be pulled AWAY FROM the non-functioning side by the normal side
What is contained within the pretracheal fascia?
- the strap muscles
- thyroid gland
- trachea & larynx
- oesophagus & pharynx
- recurrent laryngeal nerves
What are the strap muscles and what are their function?
Infrahyoid muscles. Function as:
- accessory muscles of breathing
- Help move the larynx
True or False: larynx is in close contact with the contents of the carotid sheath (internal jucular, common carotid, vagus and deep cervical nodes)
True
Since the oropharynx and laryngopharynx are common to both respiratory and digestive tracts, there is a risk of pulmonary aspiration. What protective features are in place to prevent this?
- Raising of the larynx towards to oesophagus reduces the chance of aspiration
- If it does occur, then the cough reflex engages.
- Epiglottis moves posteriorly aiding closure of laryngeal inlet
How does the larynx protection the respiratory tract?
- Maintains patency of URTI (cartilages)
- Prevents foreign bodies entering the LRT (vocal folds and cough reflex)
What makes up the cricothyroid joint?
Joins the cricoid and thyroid cartilages.
Between inferior horn of the thyroid attaching onto the superior facet of the cricoid.
What is cricoid pressure and why is it used clinically?
- Press on the cricoid cartilage
- Lamina of the cricoid cartilage compresses the oesophagus against the C6 vertebral body
- Oesophagus is closed but the larynx/airway is open
- This prevents regurgitation / aspiration but allows ventilation
Label these features
What is the route of passage for endotracheal tubes?
- Mouth/nasal cavity
- Oropharynx
- Laryngeal inlet and rima glottis of the larynx
- Trachea
Where is the laryngoscope inserted?
Into the vallecula (space between the tongue and epiglottis)
What is the aryepiglottic fold?
Superior border of the quadrangular membrane
Label these features
How does the mucociliary escalator work in the larynx?
- Mucous glands secrete mucous onto the epithelial surface
- Cilia beat to sweep the mucous (plus any foreign bodies stuck in the mucous) superiorly, towards the pharynx, to be swallowed
What forms a tight closure of airway sphincter?
Contraction of transverse and oblique arytenoids, plus cricothyroid
What are the components of sound production?
- Inspiration - diaphragm and/or intercostal muscles
- Controlled expiration
- contraction of anterolateral abdominal wall muscles
- helps build pressure in respiratory tree inferior to larynx
- pressure required depends on vocal task (whisper, normal speech, shouting)
- Phonation - producing a sound in the larynx
- expire a stream of air across vocal cords
- Depends on shape of rima glottis and tension of vocal cords
- Articulation - producing a recognisable sound within the oral or nasal cavities
- Oral sounds
- soft palate tenses (CN V3) and elevates (CN X) to close off entrance into nasopharynx
- directs stream of air through oral cavity
- sound interrupted by the tongue (CN XII) and the teeth/lips (CN VII) to produce most vowels and consonants in English language
- Nasal sounds
- soft palate tenses (CN V3) and descends (CN X) to close off entrance into oropharynx
- directs stream of air through nasal cavities
- produces one of three sounds: “m”, “n” or “ing” depending on position of tongue (CN XII), teeth and lips (CN VII
- Oral sounds
How would you clinically test the sensory and motor action of the vagus nerve in the palate, pharynx and larynx?
- ask patient to swallow small sip of water
- watch larynx move up and down
- do they ‘splutter’?
- listen to patient speak
- is voice hoarse?
- ask patient to cough
- is cough normal and powerful?
What kind of mucosa lines the middle ear?
Columnar epithelium
What is Schneiderian epitheliuma and where is it founf?
- Identical to respiratory mucosa – pseudostratified ciliated columnar with sero-mucinous glands (snot production).
- Lines nasal cavity (respiratory area) and sinuses
What kind of epithelium covered the vocal cords?
Squamous epithelium
What kind of acceleration do the utricle and saccule detect?
linear acceleration
(utricle - horizontal, saccule - vertical)
Where does submandibular gland enter the oral cavity?
Via the lingual caruncle
How does the sublingual gland enter the oral cavity?
Lies in the floor of the mouth and secretes superioly
