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