H and N 1.9 Flashcards
What is the size of the parotid gland?
The parotid salivary gland is the largest of the 3 paired salivary glands
What is the journey of the parotid gland?
The parotid duct passes horizontally from the gland, pierces the buccinator muscle, and enters the oral cavity opposite the 2nd maxillary molar tooth
Where does the fascial nerve exit?
The facial nerve (CN VII) exits through the stylomastoid foramen, passes through the parotid gland, and distributes its 5 terminal branches over the face
What are the 5 terminal branches of the facial nerve?
- Temporal
- Zygomatic
- Buccal
- Marginal Mandibular
- Cervical branches
Why is surgery of parotid gland dangerous?
Surgery involving the parotid gland (tumor resection) or trauma to this region of the face places the terminal motor branches of the facial nerve (CN VII) in jeopardy, which could result in paralysis or weakness to 1 or more of the facial muscles.
What can a stone cause?
A stone (calculus) may occlude the parotid (Stensen’s) duct, necessitating its removal
What is the parotid gland innervate by?
innervated by the glossopharyngeal nerve (CN IX) via preganglionic parasympathetic fibers that course to the otic ganglion via the lesser petrosal nerve, synapse in the ganglion, and send postganglionic fibers to the gland via the auriculotemporal branch of CN V3
What does the lacrimal apparatus consist of?
lacrimal glands, which secrete tears, and a system of collection ducts
What do lacrimal ducts do?
Lacrimal ducts convey tears from the glands to the conjunctival sac, and the lacrimal canaliculi drain them into the lacrimal sac
Where to tears drain?
drain down the nasolacrimal duct and empty into the inferior nasal meatus behind the inferior nasal concha
How are tears produced?
- Under parasympathetic autonomic control exerted by nerve fibres that originate in the facial nerve (CN VII)
- And ultimately reach the glands via the lacrimal nerve a brach of the ophthalmic division of the trigeminal nerve
What is the plica semilunaris?
The human plica semilunaris is our remnant of the nictitating membrane (a 3rd eyelid that is transparent), seen in many other vertebrates, especially birds, reptiles, and some mammals
What do tears contain?
- albumins
- lactoferrin
- lysozyme
- lipids
- metabolites
- ectrolytes
- provide a protective layer of fluid that helps keep the cornea moist and protected from infection
What is dry eye?
Dry eye (insufficient tear production) is not uncommon and can be treated with lubricating moisturizing eyedrops or systemically with prescription medications
What are the three layers of the eyeball?
- an external fibrous layer consisting of the sclera and transparent cornea
- a middle vascular pigmented layer consisting of the choroid, ciliary body, and iris;
- an internal neural layer, the retina
What is the fovea centralis?
- The fovea centralis, a central depression in the macula, is an avascular region that contains cones but no rods
- This area provides the most acute vision.
How does light travel?
Light passes to the retina through the refractive media of the eye, which consists of the cornea, aqueous humor, lens, and vitreous humor
What is cataract?
- An opacity of the lens
- treatment involves surgically removing the lens and implanting a plastic lens and then correcting the vision with glasses
What is glaucoma?
- An increase in ocular pressure usually due to poor reabsorption fo aqueous humour
- This increased pressure may damage the retina
What is the region of the eyeball (globe) between the zonular fibres and the iris?
The posterior chamber
How does the posterior chamber communicate?
by an opening in the iris (the pupil), with the anterior chamber lying between the iris and the cornea
What does. the. aqueous humour do?
Aqueous humor, continuously produced by the ciliary process of the ciliary body, fills these 2 chambers and is absorbed into the trabecular meshwork and scleral venous sinus.
What do the dilator and sphincter muscles (smooth muscles) of the iris do?
Account for dilation and constriction of the pupillary opening
What does contraction of the ciliary muscles (circular fibres) do?
Contraction of the ciliary muscle (circular fibers) has a sphincteric action on the ciliary body such that the zonular fibers relax and the elastic lens becomes more rounded in shape, leading to accommodation for focusing on objects close to the eye.
What is the machoism of glaucoma?
- An increase in ocular pressure above normal limits can lead to glaucoma
- This condition usually results from increased resistance to outflow of the aqueous humor via the scleral venous sinus (canal of Schlemm).
- This increase in intraocular pressure can damage the optic disc where axons are passing from retinal ganglion cells through the optic nerve to the brainstem.
What does the external ear consist of?
- The auricle
- The external acoustic meatus
What does the middle ear consist of?
-The tympanic cavity and its 3 ossicles
What is the lateral wall of the tympanic cavity formed by?
-The tympanic membrane (eardrum)
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What is the medial wall of the tympanic cavity?
The medial wall contains the oval and round windows
What are the auditory ossicles?
The auditory ossicles include the malleus (hammer), incus (anvil), and stapes (stirrup)
What does the middle ear connect to?
The middle ear connects to the nasopharynx by the auditory (eustachian) tube
What can happens via the auditory tube?
air may enter or leave the middle ear cavity and equalize middle ear pressure with atmospheric pressure
What does the inner ear consist of?
the cochlea and the vestibular apparatus
What is the acoustic and vestibular apparatus inverted by?
CN VIII the vestibulocohlear nerve
What is the external ear innervated by?
by sensory branches from CN V3, CN VII, and CN X
What is the middle ear innervated by?
by the glossopharyngeal nerve (CN IX)
What is acute otitis externa?
Acute otitis externa, better known as swimmer’s ear, is an inflammation or infection of the external ear
What is acute otitis media?
Acute otitis media (earache) is an inflammation of the middle ear and is common in children younger than age 15
What is the eardrum attached to?
The lateral wall of the tympanic cavity shows the eardrum attached to the handle of the malleus, the tensor tympani muscle, which dampens excessive vibration of the malleus, and the pharyngotympanic (auditory, eustachian) tube
What does the pharyngotympanic (auditory, eustachian) tube permit?
air to enter or leave the middle ear cavity and aids in the equalization of the air pressure within the middle ear
How can very loud sounds damage the ear?
Very loud sounds may damage the ear. In part, the tensor tympani muscle and stapedius muscle (not shown) help to mitigate excessive vibrations of the ear ossicles
What is the lateral nasal wall characterised by?
3 nasal turbinates (called concha if not covered by mucosa)
What is the space beneath each turbinate?
the meatus
Where does the nasolacrimal duct open into?
The inferior nasal meatus
Where does the frontal sinus and maxillary sinus open into?
The middle nasal meatus
Where does the anterior and middle ethmoidal sinuses open on?
the ethmoidal bulla, beneath the middle nasal turbinate
Where does the posterior ethmoidal sinus open in?
the sphenoidal sinus opens in the sphenoethmoidal recess
Where is the vascular supply of the lateral wall of the nasal cavity by?
The vascular supply of this region is via branches of the sphenopalatine artery (from the maxillary artery)
What is the innervation to the nasal cavity lateral wall by?
the innervation is from the maxillary nerve or CN V2 (general sensation), CN I (olfaction), and CN VII (secretomotor fibers to the mucous glands via the pterygopalatine ganglion)
What is rhinosinutis?
- Rhinosinusitis is an inflammation of the paranasal sinuses, especially the ethmoid and maxillary sinuses, and nasal cavity.
- This infection usually results from a respiratory virus or secondary bacterial infection.
- Nasal congestion, facial pain and pressure, discharge, fever, headache, painful maxillary teeth, and halitosis are some of the signs and symptoms.
Where does the parotid gland empty?
empties into the oral cavity via the parotid duct
Where does the submandibular gland empty?
empties into the floor of the mouth via the submandibular duct, which lies beneath the oral mucosa in close relationship to the lingual nerve
Where does the sublingual salivary gland open?
he sublingual salivary gland opens through several small ducts beneath the anterior tongue
What is the parotid gland like?
The parotid gland is a totally serous gland
What is the submandibular salivary gland like?
mostly serous and partially mucous
What is the sublingual salivary gland like?
almost completely mucous
Where do minor salivary glands exist?
in the mucosa of the hard palate, cheeks, tongue, and lips
Where can calculus exist?
Sometimes a small calculus (stone) can obstruct a parotid or submandibular salivary gland duct
Where can tumour exist?
- both glands may harbor a tumor, necessitating their resection
- In the case of the parotid gland, great care must be taken by the surgeon to spare the terminal branches of the facial nerve, which passes through the parotid gland after its exit from the stylomastoid foramen
