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External ear components?

- pinna, EAC, TM
- helix: outer rim of tissue and cartilage that forms C and ends at ear lobe
- external auditory meatus is opening that leads into external EAC
- the canal has glands that secrete cerumen
- at end of canal is TM, a thin dividing wall b/t external and middle ear
- mastoid process: bony projection of temporal bone that lies just behind the external ear and contains tiny cavities filled with air


Middle ear components?

- eustachian tube, tympanic cavity and its contents like ossicle muscles, ligaments, mucosal folds
- 3 tiny bones:
malleus, incus and stapes
- connected to nasopharynx by eustachian tube


Inner ear components?

- 3 fluid filled structures:
semicircular canals
- vestibule is entrance area to inner ear
- on end of vestibule becomes 3 semicircular canals
- the other end of vestibule becomes coiled cochlea


Blood supply to ear?

- 2 branches of external carotid artery: posterior auricular artery and superficial temporal artery
- accompanying veins drain into internal jugular vein by either facial or external jugular veins


Nerve supply to the ear?

- external: auriculo-temporal branch of trigeminal nerve, greater auricular nerve, lesser occipital nerve and auricular branch (arnold's branch) of vagus nerve
- middle ear: chorda tympani nerve, and tympanic plexus nerve
- inner ear: facial nerve and vestibulocochlear nerve


lymphatic drainage of the ear?

- pre auricular lymph node (anteriorly)
- post auricular lymph node (posteriorly)
- infra auricular lymph node inferiorly


2 fxns of ear?

- hearing and balance


External ear's fxn in hearing?

- pinna/aurical: concave structure that collects and directs sound waves traveling in ear canal
- ear canal: 1.25 in long, inner 2/3 ear canal embedded in temporal bone, outer 1/3 is cartilage.
Ear canal resonates sound waves and increases loudness of tones in 3000-4000 hz range
- maintains proper conditions of temp and humidity to preserve elasticity of TM
- contains glands that produce wax and contains tiny hairs which provides added protection against insects of foreign particles from damaging TM


Middle ear's fxn in hearing?

- composed of TM and cavity which houses ossicular chain
- TM: divides external and middle ear, very sensitive to sound waves and vibrates back and forth as sound waves strike it
- middle ear cavity: located in mastoid process of temporal bone, extends from TM to inner ear, cavity is an extension of nasopharynx via eustachian tube
- ossicular cahin: helps connect and transmit sound from middle to inner ear, consists of malleus, incus and stapes
- malleus: attached to TM
- incus: lies in middle b/t malleus and stapes
- stapes: footplate inserts into oval window of inner ear
- 2 tiny muscles that attach ossicles: stapedius and tensor tympanic


Fxns of ET (eustachian tube)?

- air exchange: keeping air pressure on both sides of TM equal
- excretory: drainage for middle ear
- defense: helps in preventing infection


Fxns of inner ear in hearing?

- composed of cochlea (hearing) and vestibular system (balance)
- both systems have separate fxns but are housed in same area and share same fluid
- cochlea: spiral shaped, composed of 3 fluid chambers, 2 outer chambers filled with perilymph fluid and 3rd chamber in center secretes endolymph, this area is called cochlear duct
-cochlear duct contains basilar membrane which lies organ of corti
- the pitch of the impulses relayed depends on which area of basilar membrane or which portion of organ of corti is stimulated
- apical portion (most curled) transfers lower frequencies and basal end relays higher frequencies
- CN 8 carries impulses to temporal lobe of brain to be interpreted


Inner ear's fxn in balance? 3 components?

- vestibular system:
composed of 3 semi-circular canals, helps to maintain balance regardless of head position or gravity in conjunction with eye and somatosensory input
- 3 components:
3 semi-circular canals, utricle, saccule

- semicircular canals: located at right angles to eachother and to those on opposite of the head, inside each fluid filled canal is sensory receptor (cupula) attached at its base
- head moves, fluid within canals stimulate the cupula and sends impulses to brain about direction and movement
- the utricle and saccule work in similar ways


Fxn of nose?

- part of resp tract and assists in sense of smell, conditions the air by filtering, warming, moistening, and cleans itself of fbs

- ID of odors
- passageway for inspired and expired air
- humidification, filtration, and warmth of inspired air
- resonance of laryngeal sound


Makeup of external nose?

- made of bone and cartilage covered with skin
- upper bony part bridge
- rounded lower boarders called ala nasi
- anterior naris are divided by columella


Components of nasal cavity?

- nares serve as entryway which open posteriorly to nasopharynx
- walls of nasal cavity:
roof - divided into frontonasal, ethmoidal, and sphenoidal
floor - consists of palatine process of maxilla and horizontal plate of palantine bone
medial- nasal septum, ethmoid bone, vomer, nasal crest of maxillary and palatine bone
lateral - hallmarked by 3 nasal conchae, which divide nasal cavity into 4 passages that have openings to paranasal sinuses


The sinuses?

- air filled cavities lined with mucosal membrane with small openings into nasal cavity
- 4 sinuses: maxillary, frontal, sphenoidal, ethmoid


Nerve supply of nose?

- infratrochlear and external nasal branches of ophthalmic nerve, infraorbital branch of maxillary nerve (both part of CN 5)
- olfactory nerves pass through cribiform plate
- sensory innervation of nasal cavity from ophthalmic nerve and maxillary nerve


Blood supply of nose?

- branches of ophthalmic and maxillary arteries
- ala and septum by facial artery
- walls of nasal cavity, branches of maxillary artery
- sphenopalatine artery which anastomoses with branch of superior labial artery
- kiesselbach area: most common area for nose bleeds


lymph drainage of nose?

- from nasal cavity into submandibular lymph nodes and vessels drain into upper deep cervical lymph nodes


How does the nose fxn in protection?

- internal nose is covered by vascular mucous membrane that is lined with cilia and mucous secretions
- mucous contains lysozymes
- sneezing throws out particles from the nose


Fxn of olfaction?

- distinguish b/t sweet, fruity, chemical, peppermint, musky, pungnt, and putrid
- helps to ID food, sensual smells, and warnings of danger (chemicals and spoiled food)


Fxn of eustachian tube?

- permits nose to equalize pressure of air b/t external atmosphere and middle era


Fxn of drainage of nose?

- permits drainage of paranasal sinuses and nasolacrimal duct


Physiology of olfaction? (long)

- odorants are chemical compounds that are carried by inhaled air to olfactory epithelium, located in roof of 2 nasal cavities
- olfactory region in humans is small, 50 mill primary sensory receptor cells
- region consists of cilia projecting down through epithelium that is coated in layer of mucus
- mucus produced by bowmans glands that are in olfactory epithelium
- mucus helps transport odorants to olfactory receptors
- each olfactory receptor neuron has 8-20 cilia
- cilia is area where molecular reception with the odorant occurs and sensory transmission starts
- mucus layer is base and consists of basal cells
- olfactory neuron receptors turnover about q 40 days (only nerves that regenerate)
- on opp side of epithelium neuronal cells from axons that are bundled in groups of 10-100 to penetrate ehmoid cribiform plate reaching olfactory bulb - at bulb neurons converge to terminate with post-synaptic cells to form synaptic structures called glomeruli
- these converge into mitral cells
- from mitral cells response increases the sensitivity of olfactory signal to higher levels of CNS in corticomedial amygdala portion of brain


Oral cavity fxn?

- begin process of digestion
- chews food and mixes it with saliva
- taste buds on tongue provide sensaton of taste
- impt role in speech
- also used for: breathing, drinking, facial expressions, social interactions


3 major salivary glands?

- parotids
- submandibular glands
- sublingual glands


parotid gland?

- largest
- located in front of ears
- facial nerve runs through parotid, 5 branches lie within gland (temporal, zygomatic, buccal, mandibular, and cervical)
- stenson's duct - oral cavity


Submandibular gland?

- medium size gland
- located behind lower jaw, under chin and tongue
- comes out into oral cavity through wharton's duct


Sublingual gland?

- smallest
- located deep in floor of mouth
- enters mouth through small sublingual ducts


3 parts of a tooth?

- anatomic crown: portion of tooth covered by enamel
- anatomic root: lower 2/3 of tooth
- pulp cavity: houses dental pulp which includes nerves, arteries, veins and lymph channels