ENT anatomy Flashcards
What structures made up the nasal septum?
Perpendicular plate of ethmoid bone
Septal cartilage
Vomer
What 2 bones make up the floor of the nasal cavity?
Palatine bones
Palatine plate of the maxilla
What are the 4 main foramen entering each nasal cavity?
- Anterior ethmoidal foramen
- Posterior ethmoidal foramen
- Sphenopalatine foramen
- Incisive foramen (Single midline)
What is the name of the anastamoses within the nasal cavity?
Keisselbach’s plexus (Little’s area)
What is the medical term for nostril?
Nares
What is the dip connecting the lip and nose?
Philtrum
What is the name for the outer rim of the nostril?
Ala
What are the 3 sections of the external nose?
Root
Dorsum
Tip
What are the 8 main foramen of the cranial vault through which cranial nerves pass?
- Foramen magnum
- Foramen ovale
- Foramen rotundum
- Superior orbital fissure
- Jugular foramen
- Hypoglossal canal
- Internal acoustic meatus
- Cribriform plate of ethmoid bone
How many paranasal sinuses are there?
8 (4 bilateral pairs)
What type of epithelium lines the paranasal sinuses?
Respiratory epithelium
What is thought to be the function of the paranasal sinuses?
Reduce skull weight
Assist with vocal resonance
What is sinusitis?
Inflammation of the sinus mucosa
What are the 4 types of paranasal sinuses?
Frontal sinuses
Ethmoidal air cells
Sphenoid sinuses
Maxillary sinuses
Where does the sphenoid sinus drain to?
Sphenoethmoidal recess
Where do the posterior ethmoidal air cells drain into?
Superior meatus
What 2 structures are found within the middle meatus allowing sinus drainage?
- Ethmoidal bulla (Rounded projection)
- Semilunar hiatus (Curved groove surrounding the bulla)
Where do frontal sinuses drain to?
Semilunar hiatus in middle meatus
Where do maxillary sinuses drain to?
Semilunar hiatus in middle meatus
Where do anterior ethmoidal air cells drain to?
Semilunar hiatus in middle meatus
Where do the middle ethmoidal air cells drain to?
Ethmoidal bulla in middle meatus
Where does the nasolacrimal duct drain to?
Inferior meatus
What are the 2 main regions of the nasal cavity?
Nasal vestibule
Nasal cavity proper
What type of epithelium lines the nasal vestibule?
Stratified squamous epithelium (Keratinised to non-keratinised (1)
What 2 types of epithelium line the nasal cavity proper?
Respiratory epithelium (2)
Olfactory epithelium (3)
How do the concha assist with olfaction?
They create turbulence which keeps air within the top of the nasal cavity for longer
Describe the route of the olfactory pathway
- Receptor cells in the olfactory epithelium of the nasal cavity
- Pass up the crimbriform plate
- Synapse with olfactory bulb (Ganglia)
- Neurons pass along olfactory tract
- To temporal lobe and olfactory areas of the supracortex
What nerve gives general somatic sensation to the anterosuperior nasal cavity?
CN V1 (Ophthalmic division)
What nerve gives general somatic sensation to the posteroinferior nasal cavity?
CN V2 (Maxillary division
Describe the regions of the face supplied by each division of CN V
What are the 3 main arteries that enter the nose and contribute to Kiesselbach’s plexus?
Ophthalmic artery
Maxillary artery
Facial artery
What branches of the ophthalmic artery enter the nose?
- Anterior ethmoidal artery
- Posterior ethmoidal artery
What foremen does the anterior ethmoidal artery enter the nasal cavity via?
Anterior ethmoidal foramen
What foremen does the posterior ethmoidal artery enter the nasal cavity via?
Posterior ethmoidal artery
From what major artery does the ophthalmic artery arise?
Internal carotid
What are the 2 branches of the maxillary artery that enter the nasal cavity?
- Sphenopalatine artery
- Greater palatine artery
Describe the route of the sphenopalatine artery in the nasal cavity
Pierces through the sphenopalatine foramen and covers a large area of the vomer and covers the lateral wall
Describe the route of the greater palatine artery in the nasal cavity
Descends to the hard palate, anteriorly and then up through the incisive foramen to Keisselbachs plexus
From what major artery does the maxillary artery branch off?
External carotid artery (Just anterior to the external ear)
What are the 3 main branches of the facial artery?
- Superior labial artery → Septal branch
- Inferior labial artery
- Lateral nasal artery
Describe the route of the facial artery and its branches entering the nasal cavity
The facial artery curves up from the mandible and courses through the upper lip and gives off the lateral nasal artery which moves up into the lateral nasal wall
The facial artery then gives off the superior labial artery which continues through the midline to the septum where it gives off the septal branch of the superior labial artery
Describe the route of CN V1 into the nasal cavity
CN V1 branches into the anterior ethmoidal nerve which passes through the anterior ethmoidal foramen into the roof of the nasal cavity which passes into the anterosuperior area
Describe the route of CN V2 into the nasal cavity
CN v2 branches into the nasopalatine nerve which passes through the sphenopalatine foramen into the floor of the nasal cavity
It then travels down the incisive foramen to the hard palate, supplying somatic sensation to the roof of the mouth
Through which skull foramen does CN V1 pass through?
Superior orbital fissure
Through which skull foramen does CN V2 pass through?
Foramen rotunda
What type of nerves synapse from the pterygopalatine ganglion?
Parasympathetic, motor
Where does the pterygopalatine ganglion sit?
It sits in the pterygopalatine fossa, which is a recess between the sphenoid bone and maxilla
What nerves pass through, but do not synapse at the pterygopalatine ganglion?
Cranial nerve V2 and and deep petrosal nerves
What are some of the types of nerves contained in the facial nerve?
- Parasympathetic secretomotor supply
- Special sensation (Taste)
- Somatic motor
- General sensory
Where does the facial nerve supply parasympathetic secretomotor supply?
Lacrimal gland
Sublingual and submandibular salivary glands
Minor glands of the nasal cavity, palate and nasopharynx
Where does the facial nerve supply taste sensation to?
Tastebuds of the anterior 2/3rds of the tongue
Where does the facial nerve supply somatic motor sensation to?
Muscles of facial expression
What are the 3 main branches of the facial nerve that leave the facial nerve in the temporal bone?
Greater petrosal nerve
Nerve to stapedius
Chorda tympani
Describe the course of the facial nerve branching to the greater petrosal nerve
Leaves CNS at pontomedullary junction
Through internal acoustic meatus
Genticulate ganglion
Branch to form greater petrosal
Back up to the middle cranial fossa
Synapses with the pterygopalatine ganglion
Joined by the deep petrosal nerve (post-ganglionic sympathetic fibres) from internal carotids
Forms the vidian nerve which passes through the pterygoid canal to the lacrimal and minor glands
Describe the route of the chord tympani branch of the facial nerve
Leaves CNS at pontomedullary junction
Through internal acoustic meatus
Genticulate ganglion
Through tympanic cavity
Between malleus and incus
Through petrotympanic fissure
Joins lingual nerve of CN V3
Passes to the tongue to supply taste (Lingual branch of V3 supplies general sensation), sublingual and submandibular salivary glands
How many branches does the facial nerve split into to supply the muscles of facial expression?
6
Describe the structures of the pinna
- Helix
- Anti-helix
- Tragus
- Anti-tragus
- Concha
- Lobe
What is the name given to the opening of the ear canal?
External acoustic meatus
What nerve causes the tickling sensation in the back of the throat when the each is itched with cotton buds?
Cranial nerve X
What type of cartilage makes up the ear?
Elastic cartilage
Where does the posterior region of the pinna drain its lymph to?
Posterior auricular and mastoid lymph nodes
Where’d does the anterior region of the pinna drain its lymph to?
Parotid gland and its associated lymph nodes
Pre-auricular lymph nodes
Where does the ear lobe drain its lymph to?
Superficial cervical lymph nodes
What are some structures that pass close to the pinna?
The auriculotemporal nerve (V3) passes up near the tragus of the ear to the temporalis muscle
The superficial temporal artery also passes close to the tragus of the ear
The posterior auricular vein, lymph nodes and artery pass behind the ear
Describe the structures of the tympanic membrane
What condition is shown?
Glue ear (Otitis media with effusion)
What condition is shown?
Acute otitis media (Bulging)
What is shown?
Gromit used in treatment of glue ear
What condition is shown?
Perforation
What are the 3 bones of the middle ear?
- Malleus - Hammer
- Incus - Anvil
- Stapes - Stapes
What is the function of the bones of the middle ear?
They conduct sound waves from the tympanic membrane to the inner ear
These go from larger to smaller, amplifying the sound waves
This is the bone conduction mechanism of hearing
How does the tympanic cavity facilitate and control the movement of the bones of the middle ear?
- Air within the cavity
- Synovial joints
- 2 skeletal muscles
What are the 2 main regions of the tympanic cavity?
Tympanic cavity proper
Epitympanic recess
What is the name of the hole in the epitympanic recess?
Mastoid adieus
What is the name of the bulge on the medial wall of the tympanic cavity?
Promontory
Where does the malleus attach to the tympanic membrane?
Umbo
What is the name of the joint between the malleolus and incus?
Malleoincal joint
What is the name of the joint between the incus and stapes?
Pedioincal joint
What suspends the malleus and incus bones?
Ligaments form the tegmen tympani
Where does the stapes attach to medially?
The oval window of the otic capsule
What are the 2 skeletal muscles found within the middle ear?
- Tensor tympani
- Stapedius
Where does the tensor tympani run?
From the cartilaginous portion of the eustacian tube to the handle of the malleus
What is the function of the tensor tympani?
Dampens sound by reducing vibrations of the tympanic membrane
Reduces noises from chewing (Both innervated by CN V3)
What nerve innervates the tensor tympani?
CN V3
What causes the rumbling sound during yawning?
CN V3 also innervates the muscles opening and closing the mouth
This may cause rubbing together of the tensor tympani fibres, leading to rumbling
Where does the stapedius run?
From the pyramidal eminence (Out of the temporal bone) to the neck of the stapes
Where is the muscle belly of the stapedius found?
In the temporal bone
What is the function of the stapedius?
This dampens sound by reducing vibrations of the stapes on the oval window and is innervated by CN VII, playing a role in the acoustic reflex to loud sounds
What can be caused by dysfunction of the muscles of the middle ear?
Hyperacousis - Over-interpretation of sound
How does pressure in the middle ear compare to outside pressure normally?
It is usually equal, allowing for efficient oscillation of the tympanic membrane
What occurs when atmospheric pressure increases (E.g. in water)?
The tympanic membrane pushes in, therefore decreasing ability to oscilate, causing muffling of sound
What occurs when atmospheric pressure decreases (E.g. altitude)?
The tympanic membrane bulges out, therefore decreasing the ability to oscilate, causing muffling of sound
What can occur due to unbalanced pressure within and outside of the ear?
Barotrauma to the tympanic membrane
How can the air pressure within the middle ear be equalised?
By opening the eustachian tube
What muscles open the eustachian tube?
Palatine muscles
Why are children more at risk of otitis media?
They have a much shorter eustachian tube, so infection can more easily enter the middle ear
What nerve supplies the walls of the tympanic cavity?
CN IX (Glossopharyngeal)
How does the glossopharyngeal innervate the structures of the middle ear?
Some nerve fibres from the pharynx pass up into the eustachian tube
It also forms the tympanic branch, which enters the middle ear and forms a plexus over the promontory
This coalesces into the lesser petrosal nerve passing out and to the parotid gland
What is infection of the mastoid air cells known as?
Mastoiditis
How does mastoiditis occur?
