Anatomy 9 & 10 Flashcards
larynx functions
- allows air passage in and out of the trachea
- protective sphincter preventing foreign bodies entering airway
- speech production (phonation)
larynx located at level
- C3-C6
- from tip of epiglottis to inferior border of cricoid cartilage
larynx anatomical relations
- superiorly opens into laryngopharynx
- epiglottis
- inferiorly continues into the trachea
main laryngeal cartilages
- epiglottis (only one elastic all others hyaline)
- cricoid cartilage (only complete ring)
- thyroid cartilage
- arytenoid cartilage
cricothyroid joint type and function
- synovial joint
- allows for rotation and gliding of thyroid cartilage
- results in changes in length of vocal folds which changes pitch
epiglottis connects/type/function
- connects to thyroid cartilage via thyro-epiglottic ligament
- connects to hyoid via hyoepiglottic ligament
- elastic cartilage
- closes airway during swallowing
arytenoid cartilage description and articulations
- paired hyaline cartilage of the larynx
- found posteriorly
- articulates with cricoid cartilage inferiorly
- apex articulates with corniculate cartilage and aryepiglottic fold
- vocal process (anterior process of the cartilage) provides posterior attachment for vocal ligament
crico-arytenoid joint function
- permit arytenoid cartilages to slide towards/away from another, tilt, and rotate
- important for tensing and relaxing vocal folds during voice production
intrinsic ligaments and membranes of the larynx
- quadrangular membrane
- cricothyroid ligament
- vocal ligament
extrinsic ligaments and membranes of larynx
- thyrohyoid membrane
- thickened anteriorly and posteriorly to form median and lateral thyrohyoid ligaments
- cricothyroid ligament
quadrangular membrane of larynx attachments/type of tissue/forms
- superiorly extends between arytenoid and epiglottis
- inferiorly extends between arytenoid and thyroid cartilage and the free inferior margin = vestibular ligament
- submucosal CT
- vestibular ligament covered loosely by mucosa to form vestibular fold
cricothyroid ligament of larynx attachments/type of tissue/forms
- from cricoid to thyroid cartilage
- from vocal process of arytenoid to thyroid cartilage
- superior free edge of cricothyroid ligament forms vocal ligament
- vocal ligament forms the submucosal part of vocal folds
what constitutes vestibular ligament and vocal ligament
- quadrangular membrane attachment from arytenoid cartilage to thyroid cartilage forms vestibular ligament
- crycothyroid ligament from vocal process of arytenoid to thyroid cartilage forms vocal ligament
describe thyrohyoid membrane
- spans the space between thyroid cartilage and hyoid bone
- thickened anteriorly and posteriorly as median and lateral thyroid ligaments
laryngeal folds
- ary-epiglottic fold
- vestibular fold
- vocal fold
- mucous membranes creating folds over free edges of ligaments/membrane
aryepiglottic fold description and function
- mucosa overlying superior free edge of quadrangular membrane
- extends from arytenoid cartilage to epiglottis
- forms the laryngeal inlet which is the protective sphincter of the larynx
vestibular fold description
space between this and laryngeal inlet called
- formed over the inferior free edge of quadrangular membrane which extends from arytenoid to thyroid cartilage
- space between vestibular fold and laryngeal inlet called vestibule
- play little or no part in voice production
vocal fold description, space between name, and function
- formed over superior free edge of cricothyroid ligament which extends from vocal process of arytenoid and thyroid cartilage
- mucous membrane overlying
- space between vocal folds called rima glottis
- rima glottis + vocal folds + vocal process = glottis
- control sound production from the larynx and serve as the main inspiratory sphincter of larynx when tightly close
intrinsic laryngeal muscles functions
- open or close the rima glottis (abductors/adductors)
- alter the tension of the vocal folds (tensors/relaxors)
- open or close the laryngeal inlet (sphincter muscles)
extrinsic laryngeal muscle functions
- infrahyoids depress the hyoid and larynx
- suprahyoids and stylopharyngeus elevate the hyoid and larynx
muscles which open and close the rima glottis
- posterior cricoarytenoid is the only muscle to abduct the vocal folds = opening the rima glottidis
- transverse arytenoid muscle and lateral crico-arytenoid muscles close the rima glottidis
muscles which alter tension of vocal fold and effect of shortening/lengthening
- cricothryoid muscle lengthens
- thyroarytenoid muscle shortens
- lengthened vocal cords = higher pitch
- shortened vocal folds = lower pitch
muscles which open/close laryngeal inlet
- closure by oblique arytenoid muscle
- opening by descent of the larynx mainly by elastic recoil
larynx motor nerve supply
- all by recurrent laryngeal nerve with one exception
- cricothyroid supplied by external branch of superior laryngeal nerve
- all are branches of vagus nerve
larynx sensory nerve supply
- above the vocal folds = internal branch of superior laryngeal nerve
- below vocal folds = recurrent laryngeal nerve
- all are branches of vagus nerve
larynx role in breathing
- forced inspiration: rima glottis more wideley opened by posterior cricoarytenoid
- quiet respiration: a triangular “open” rima glottis
larynx role in speech production
- vocal folds are adducted (closed)
- rima glottis closed
- air is forced through causing vibration
larynx role in effort closure and swallowing
- vocal and vestibular folds are adducted (closed)
- rima glottis is closed
- vestibular folds which are open in speech production and inhalation also close off vestibule (extra airway protection)
- epiglottis swings down to arytenoids
valsalva manouvre
- any forced expiration against a closed airway
- cough
- sneeze
- strain during bowel movement
- weight lifting
describe the nasal cavity and its boundaries
- paired left and right nasal cavities
- separated by nasal septum
- separated from oral cavity by hard palate
- nares are anterior opening
- choanae are posterior openings which open into nasopharynx
what receptors does nasal cavity contain
olfactory receptors
what comprises the external nose
- bone
- cartilage
- muscle
bones of the external nose
- nasal bones
- frontal process of maxilla
cartilage of external nose
- septal cartilage
- major alar cartilage
- minor alar cartilage
muscles of external nose
- overlies the bone and cartilage
- nasalis
- levator labii superioris alaeque nasi
- depressor septi nasi
floor of nasal cavity formed by
- palatine process of maxilla
- horizontal plate of palatine bones
features of floor of nasal cavity
- nares
- incisive canals
- nasal crest: ridge formed at connection of paired maxilla and palatine bones and attachment of vomer
nasal septum main components
- septal cartilage
- perpendicular plate of ethmoid bone
- vomer
- forms the medial wall of the nasal cavities
septal deviation description/cause/symptoms/tx
- septum is displaced away from midline
- caused by injury or birth defect
- one side of nasal cavity obstructed
- can cause snoring, difficulty breathing through nose or nosebleeds
- corrected surgically
roof of nasal cavity formed by
- cribiform plate of ethmoid bone
- nasal bones
- nasal spine of frontal bone
- spehnoid bone
describe ethmoid bone in relation to nasal cavity
- cribiform plate in midline has many holes which allow CNI nerves into the nasal cavity from brain
- perpendicular plate also in midline which forms part of nasal septum
- left and right ethmoidal labrynth either side which has superior and middle conchae
lateral wall of nasal cavity formed by
- nasal bone
- ethmoid bone: superior and middle conchae from ethmoidal labrynth
- lacrimal bone
- maxilla
- inferior concha
- palatine bone
- sphenoid bone
what underlies nasal conchae and function
- middle, superior and inferior conchae have corresponding meatus underlying
- creates various airstreams
- increases surface area between lateral wall and respired air
- facilitates engagement with epithelium
- allows for moisturisation, purification and warming of air
nerves found/innervating nasal cavity
- olfactory nerve CNVI
- anterior ethmoidal nerve branch of opthalmic nerve CNV1
- maxillar nerve CNV2 branches: anterior superior alveolar nerve, infraorbital nerve nasal branch, nasopalatine nerve, posterior superior/inferior lateral nasal nerves
parasympathetic supply of nasal cavity
- axons from salvatory nucleus in brainstem
- carried in greater petrosal nerve of CNVII to pterygopalatine ganglion
- post-ganglionic fibres carried within maxillary nerve branches CNV2
sympathetic supply of nasal cavity
- axons from sympathetic trunk ascend in the internal carotid plexus
- travel to pterygopalatine ganglion via deep petrosal nerve
- post-ganglionic axons carried in maxillary nerve branches
arterial supply of nasal cavity
- from maxillary artery: sphenopalatine and greater palatine branches
- from facial artery: superior labial and lateral nasal branches
- from ICA/opthalmic artery: anterior ethmoidal and posterior ethmoidal branches
which area in nasal cavity susceptible to nosebleeds and why
- anterior septal region
- arterial supply of nose form many anastomoses in this region
- nosebleeds can commonly occur
venous drainage of nose
- veins that folllow maxillary artery (spehnopalatine and greater palatine) drain to pterygoid plexus
- veins that follow facial artery (superior labial and lateral nasal) drain to facial vein
- veins that follow ethmoidal arteries drain to cavernous sinus
paranasal sinuses names and epithelium
- ethmoidal cells in ethmoid labrynth
- maxillary sinus
- frontal sinus
- sphenoid sinus
- lined with respiratory epithelium (ciliated columnar)
ethmoidal cells drain to
- anterior cells drain into infundulum in middle meatus (opening of frontonasal duct)
- middle cells drain into middle meatus
- posterior cells drain into superior meatus
maxillary sinus drains to
- middle meatus
- at semilunar hiatus
frontal sinus drains to
- middle meatus
- at infundulum (continuation of frontonasal duct)
sphenoid sinus drains to
- sphenoethmoidal recess
- superiorly/posteriorly in nasal cavity
- only sinus not to drain into lateral wall
upper respiratory infections symptoms suggesting paranasal sinus involvement
- discomfort
- headaches
- radiating pain into maxillary teeth
teeth and maxillary sinus clinical context
- maxillary molar teeth in close relation to maxillary sinus
- extraction could lead to oro-antral communication
- infection could case toothache sensation as mucous membrane in maxillary sinus and maxillary teeth have same innervation
margin of the orbit formed by
- frontal bone superiorly
- zygomatic bone laterally
- maxilla inferomedially
Bones of the orbit
-frontal
-lacrimal
-maxilla
-ethmoid
-zygomatic
-greater and lesser wing of sphenoid
-palatine bone
Openings into the orbit
-optic canal
-superior orbital fissure
-inferior orbital fissure
-nasolacrimal canal
What goes into optic canal and inferior orbital fissure
Optic canal- optic nerve and ophthalmic artery
Inferior orbital fissure- inferior opthalmic vein
What goes into superior orbital fissure
-superior opthalmic vein
-CNIII superior and inferior branch
-CNIV
-CNV1 frontal, lacrimal and nasociliary branch
-CNVI
What is name of fat in orbit and function
-retrobulbar fat
- supporting the eyeball
Optic nerve course and clinical relevance
-optic tract meet and form optic chiasm
- optic chiasm lies superior and anterior to pituitary gland
- enters optic canal
- expansion of pituitary (tumour etc) presses of optic chiasm causing visual filed defects such as tunnel vision
Structures of the optic nerve
-meninges: dura, arachnoid and pia mater which extend to sclera
- central retinal artery and vein
- subarachnoid space filled with CSF
Clinical relevance of optic nerve
-central retinalmartery can become occluded causing amaurosis fugax (temp loss of vision) sometimes permanent
- increased intracranial pressure slows retinal venous drainage via central retinal vein and can cause papilloedema
What is papilloedema/cause/appearance
-swelling of the optic disc (which attaches CNII to eyeball)
- caused by increased intracranial pressure which slows venous drainage via central retinal vein
- through ophthalmoscope retina looks fuzzy and fluffy aka lack of clear outlines
Visual field defect affecting the optic nerve on one side
-sight to that eye will be lost
-other eye works fine
Visual field defect issue at optic chiasm
-tunnel vision
- fibres which cross over here supply lateral vision to contralateral eye
- lateral side of each visual field is lost
- only medial sides of visual field function
-called bitemporal hemianopia
Visual field defect lesion at optic tract
-medial side of the affected side loss of vision
-lateral side of contralateral side affected
-another form of hemianopia
Orbicularis oculi actions/innervation/malfunction leads to
-close eyelids gently/involuntarily (palpebral part)
-close eyelids tightly/voluntarily (orbital part)
-innervated by temporal and zygomatic branches of CNVII
-malfunction leads to sagging of lower eyelid, inability to blink so tears cannot be spread over eyelid
-leakage of tears and dry eyes can potentially cause ulceration
Lacrimal apparatus location and tear production
-lacrimal gland in upper lateral corner of the orbit
- tears secreted into conjunctival sac and continually washed across the eye by blinking of the eyelids
- blinking by orbicularis oculi so function of CNVII essential to keep corners and conjunctiva moist
Describe drainage of tears
- pool at the medial angle of the eye where lacrimal caruncle lies
- drain via lacrimal puncta (two little holes in both superior and inferior eyelids)
- drain into canaliculi and then to lacrimal sac to nasolacrimal duct
-nasolacrimal duct drains into inferior nasal meatus
Lacrimal gland parasympathetic supply
- preganglionic parasympathetic fibres from CNVII
- travel in greater petrosal nerve and then nerve of pterygoid canal to reach pterygopalatine ganglia
- postganglionic fibres travel with zygomatic branch of CNV2 to reach lacrimal gland
Extraocular muscles
-superior, medial, lateral and inferior rectus
-superior and inferior oblique
-levator palpebrae superioris
levator palpebrae superioris function and muscle fibre types
-allows us to open eyelid and keep it open
-smooth and striated muscle fibres
Superior oblique attaches to eye via
-tendon
-tendon changes direction and is at an angle to actual muscle
-runs through a pulley called trochlea
4 recti of the eye functions
-medial rectus pulls eye medially
-lateral rectus pulls eye laterally
-superior rectus pulls eye upwards and medially
-inferior rectus pulls eye downwards and medially
2 obliques of the eye function
-superior oblique pulls eye downwards and outwards
-inferior oblique pulls eye upwards and outwards
Motor nerve supply of extraocular muscles
-LR6 lateral rectus abducens CNVI
-SO4 superior oblique trochlear CNIV
-all others occulumotor CNIII
Occulomotor nerve branches and muscles supplied
-superior branch supplies levator palpebrae superioris, SR
-inferior branch supplies MR, IR, IO
-carries parasympathetic fibres for pupil constriction
-carries sympathetic fibres to smooth muscle component of levator palpebrae superioris
CNIII palsy leads to
-dilated pupil (as CNIII carries parasympathetic fibres for pupil constriction)
-ptosis due to complete loss of levator palpebrae superioris (dropping of eyelid)
-eye is turned downwards and outwards due to SO and LR still in tact
Iris contains
-sphincter pupillae under parasympathetic supply CNIII
- dilator pupillae under sympathetic supply
Humour secreted by/absorbed by and clinical importance
- aqueous humour secreted by ciliary body
- absorbed by scleral venous sinus
- if issue with drainage of humour can lead to build up of drainage and pressure and may cause glaucoma
Describe lens accomodation
-in absence of parasympathetic nerve stimulation ciliary muscle is relaxed and zonular fibres under tension which stretches lens to refract light for distant vision
-parasympathetic stimulation causes ciliary muscle to contract and zonular fibres relax so lens becomes more spherical to refract light for near vision
osteology of the ear
- petrous temporal bone
- internal acoustic meatus
- stylomastoid foramen
- external acoustic meatus
what separates external ear from middle ear
tympanic membrane
external ear overview
composition/function
- auricle and external acoustic meatus
- composed of cartilage and bone
- leads sound waves to tympanic membrane
middle ear overview
function and connection
- ossicles mechanically transmitting sound
- connected to pharynx by auditory tube
internal ear overview of function
- semi-circular canals for motion
- cochlea for hearing
- converting mechanical signals to electrical to be carried by CNVIII
auricle of ear composition/function/other name
- composed of elastic cartilage
- catches and funnels sound into external acoustic meatus
- sometimes called the pinna
external ear nerve supply
- greater auricular nerve supplies helix, antihelix and lobule
- auriculotemporal nerve supplies tragus and crus of antihelix
external acoustic meatus length/composition/epidermis/dermis
- 2.5cm long
- cartilagenous lateral 1/3 and bony medial 2/3
- epidermis is stratified squamous epithelium
- dermis contains hair follicles, glands, ceruminous glands that secrete ear wax, blood vessels and nerves
tympanic membrane location/held by
- in external ear separating external ear from middle ear
- held within temporal bone by fibrocartilgenous ring
tympanic membrane clinical considerations
- examined with otoscope
- presence of cone of light means no fluid accumulation or similar pathology behind tympanic membrane
- light caused by light from otoscope
middle ear location/contains/relations/muscles
- in pterous part of temporal bone
- contains ossicles of the ear
- relations with chorda tympani and nasopharynx
- 2 muscles: tensor tympani and stapedius
ossicles name/function
- malleus
- incus
- stapes
- increase force and decrease amplitude of vibrations from tympanic mebrane
- mechanically transmit sound
middle ear anatomical relations and clinical relevance
- thin roof of bone between middle ear and middle cranial fossa so risk of infection spread
- chorda tympani
- ICA
- IJV
middle ear infections name/cause/clinical implications
- otitis media
- often caused by obstructions to auditory tube
- chronic infections may damage ossicles resulting in conductive deafness
- infection may spread to mastoid air cells causing mastoiditis…can be quite painful
pathology of vestibulocochlear nerve effect on CNVII
- may require surgery at internal acoustic meatus which potentially endangers CNVII
- example: scwannoma benign tumour of nerve cell effecting CNVIII
stapedius function
dampens the movement of the stapes
what constitutes bony labrynth of middle ear
- vestibule
- cochlea
- semicircular canal
- contaaining fluid called perilymph and endolymph
vestibulocochlear nerve divisions and function
- vestibular part for sensation of motion/equilibrium/balance
- cochlear part for the sensation of hearing
damage to cochlear part of CNVIII vs damage to mechanical transmission
- neural hearing loss
- damage to mechanical transmission = conductive loss
damage to vestibular part of CNVIII signs/symptoms
- ataxia: poor muscle control causing clumsy movements
- vertigo: sensation that you or envirionment is moving or spinning
- nausea
