Case 4 anatomy Flashcards
petrous and what part of temporal bone?
squamous
what makes up the auricle?
made of elastic cartilage and covered by a layer or perichondrium and skin
external auditory meatus - bone or cartilage?
- The outer third is cartilaginous which, like the auricle, is covered by perichondrium and skin
- The inner two thirds are formed by bone covered by periosteum and skin
what produces ear wax?
ceruminous glands
which part of the tympanic membrane is pulled inwards by the tensor tympani muscle?
pars tensa
what are the different parts of the tympanic membrane?
- Umbo = the depression which marks the site of the handle of the malleus
- Pars flaccida = the thin part of membrane which is located superior to the lateral process of the malleus between the mallear folds
- Pars tensa = forms the majority of the membrane, it is pulled inwards by the tensor tympani muscle
- Anterior & posterior mallear folds = fibrous thickenings that extend from the lateral process of the malleus to the tympanic bone
what proivdes sensory innervation to the outer surface of the tympanic membrane? inner surface?
auricotemporal nerve (a branch of V3) with supplementation from the auricular branch of the vagus MANDIBULAR
Glossopharyngeal nerve provides sensory innervation to the internal surface of the tympanic membrane
what does the tympanic cavity consist of?
two parts; the tympanic cavity proper which lies medial to the tympanic membrane and the epitympanic recess that lies superior to the membrane
what connects the tympanic cavity and the mastoid air cells?
mastoid antrum
what forms the roof of the tympanic cavity?
tegmen tympani
(plate of thin bone (part of temporal bone)), separates the middle ear from the meninges & temporal lobe
what is the promontory?
formed by the basal turn of cochlear
where’s the carotid canal?
just anterior to the jugular foramen
what is the opening to the mastoid atrum called?
aditus
what’s in the anterior and posterior walls of the tympanic cavity?
anterior wall:
- opening of pharyngotympanic tube
- hole for tensor tympanic muscle
posterior wall:
- aditus for mastoid antrum
- pyramid for tendon of stapedius
where does the tensor tympani originate and insert?
originates from the auditory tube and attaches to the handle of malleus, pulling it medially when contracting
what innervates the tensor tympani muscle?
tensor tympani nerve, a branch of the mandibular nerve
what are the tensor tympani and chorda tympani branches of?
chorda tympani - facial nerve
tensor tympani - mandibular - trigeminal
where does the stapedius muscle originate and insert?
arises from the posterior wall of tympanic cavity and attaches on the stapes
what innervates the stapedius muscle?
facial nerve
what type of joints between the ossicles?
synovial
what is the purpose of the ear muscles?
damped down high frequency vibrations
what forms the eustachian tube?
posterolaterally the skeleton of the tube is formed by bone but the anterior two-thirds are cartilaginous
which muscles attach to the cartilaginous portion of the auditory tube? what do they do?
- levator veli palatini
- tensor veli palatini
they are actively involved in opening it
where are tubal tonsils found and what is there purpose?
under the mucosa that surrounds the opening of the auditory tube in the nasopharynx
to prevent infection spreading from the nasopharynx to the middle ear
where is the facial canal? what runs through it?
Z-shaped canal running though the temporal bone from the internal acoustic meatus to the stylomastoid foramen
- Facial nerve enters the facial canal and runs laterally above the inner ear
- Expands to from the geniculate ganglion
- Turns sharply to run in a posterior directly along the medial wall of the tympanic cavity
- Turns downwards and descends along the posterior wall of the tympanic cavity
- Exits the skull through the stylomastoid foramen
within the temporal bone, what are the three main branches that the facial nerve gives off? describe course of each nerve and what it does.
greater petrosal, nerve to stapedius, chorda tympani
- Greater petrosal = arises at the geniculate ganglion, contains preganglionic parasympathetic fibres which pass to pterygopalatine ganglion
- Nerve to stapedius = arises from the facial nerve as it descends behind the pyramid, contains motor fibres
- Chorda tympani = arises just above the stylomastoid foramen, contains preganglionic parasympathetic fibres that pass to the submandibular ganglion and sensory fibres for taste from the anterior two-thirds of tongue
describe the orientation of the semicircular canals in terms of the long axis of the petrous temporal bone
- Superior/anterior = vertical and placed at right angles to the long axis of the petrous bone
- Posterior = vertical and placed parallel with the long axis of the petrous bone
- Lateral = horizontal and lies in the medial wall of the aditus of the mastoid antrum
where is the vestibule located in relation to the semicircular canals and cochlear?
anterior to the semi-circular canals and posterior to the cochlear
what does the oval window lead from and to?
middle ear to vestibule
what is the central pillar of the cochlea called? and what passes through it?
modiolus, through which branches of the cochlear nerve pass
what is the spiral lamina?
a ledge of bone spirals around the modiolus, this ledge is termed the spiral lamina (bony ledge which projects from the modiolus into the interior of the canal) – it projects into the bony canal
what does the basilar membrane extend from and to?
from the spiral lamina to the bony wall of the canal
what is superior scala tympani or scala vestibuli?
scala vestibuli (think about it like endolymph comes from the vesibule and then goes round to the scala tympani)
the semicircular ducts open into the utricle through how many openings?
5
what connects the utricle and saccule?
utriculo-saccular duct
what connects the saccule to the cochlea?
ductus reuniens
what does the utriculo-saccular duct give rise to? what does this do?
- The utriculo-saccular duct gives rise to the endolymphatic duct which passes through the vestibule and bone to enter the posterior cranial fossa
- It is expanded at its end to form the endolymphatic sac which lies beneath the dura mater on the posterior surface of the temporal bone
- The endolymphatic sac stores excess endolymph
where are the sensory receptors of the utricle and saccule found?
in areas of specialised epithelium called maculae
where is the macula in the utricle and saccule located?
floor of utricle and medial wall of saccule
where are the sensory receptors of the semicircular ducts found?
ampulla on a transverse crest called the crista
the cochlear duct is enclosed between which two membranes?
basilar and tectorial membranes
what is the spiral organ?
organ of Corti
what do the different sensory receptors respond to?
- Crista of semi-circular ducts respond to kinetic balance
- Maculae of utricle and saccule respond to static balance
- Spiral organ of cochlear duct responds to sound
what is the nasopharynx lined by?
respiratory epithelium
what is located in the nasopharynx?
pharyngeal and tubal tonsils and ostium of auditory tube
what is the nasopharynx located posterior to?
the nasal choanae
where does the oropharynx extend from and to?
from soft palate to tip of epiglottis
what is located in the oropharynx?
- Contains the palatopharyngeal folds (horizontal fold of pharyngeal mucosa that passes from the soft palate and joins with its opposite fold over the entrance to the oesophagus)
- Contains the palatoglossal folds (thick fold of tissue passing from the soft palate to the lateral border of the tongue)
- Site of palatine (ones you see when open mouth) and lingual (at back of base of tongue) tonsils
where does the laryngopharynx extend from and to? where does it terminate?
from epiglottis to oesophagus
- terminates at C6
what does the laryngopharynx contain?
piriform recess
what does the wall of the pharynx consist of?
3 layers:
• Innermost – mucosal layer = the type of epithelium is dependent on location
• Middle – fibromuscular layer = comprised of the pharyngobasilar fascia, pharyngeal raphe (where each muscle joins its fellow of the opposite side in a fibrous midline) and muscles
• Outermost – the buccopharyngeal fascia = contains nerves and vessels
what is the external layer of muscles of the pharynx?
circular:
• Superior constrictor – located in oropharynx
• Middle constrictor – located in laryngopharynx
• Inferior constrictor – located in laryngopharynx
(none in the nasopharynx)
what is the inner layer of muscles of the pharynx?
longitudinal:
• Stylopharyngeus
• Salpingopharyngeus (arises from eustachian tube – opens to equalise pressure in middle ear)
• Palatopharyngeus
which is the innervation of the pharyngeal muscles?
all vagus except stylopharyngeus innervated by glossopharyngeal nerve
where do the longitudinal muscles originate and insert onto?
stylopharyngeus - styloid process to pharynx
salpingopharyngeus - eustachian tube to pharynx
palatopharyngeus - hard palate of oral cavity to pharynx
what goes through the superior and middle constrictor muscles?
stylopharyngeus muscle
what forms passavant’s ridge?
some of the upper fibres of the superior constrictor muscle combine with fibres of the palatopharyngeal muscle to form this
what does the palatopharyngeus muscle do to the oropharyngeal isthmus during swallowing?
widens it
what does the salpingopharyngeus do?
elevates the pharynx and assists in opening the auditory tube
what does the inferior constrictor consist of?
the thyropharyngeus and the cricopharyngeus which attach anteriorly to the thyroid and cricoid cartilages respectively
what is the pharyngeal plexus?
network of nerves that is located in the buccopharyngeal fascia on the posterior aspect of the pharynx – it contains the following fibres:
• Motor fibres from vagus
• Sensory fibres from glossopharyngeal
• Parasympathetic fibres from glossopharyngeal
• Sympathetic fibres from superior cervical ganglion
what does the layrngeal skeleton consist of?
- Consists of 3 unpaired (thyroid, cricoid, epiglottis) and 3 pairs (arytenoid, corniculate, cuneiform) cartilages
- Hyoid bone is also considered to be part of the laryngeal framework
describe the thyroid cartilage
- Lamina
- Angle/prominence (adam’s apple)
- Superior thyroid notch (above the prominence), superior & inferior cornu (horn)
describe the cricoid cartilage - whats anterior and posterior
- Lamina (posterior – unlike thyroid)
* Arch
describe the arytenoid cartilages
- Apex
- Base
- Muscular process (lateral)
- Vocal process (anterior)
how are the thyroid and epiglottis orientated with each other?
cup both hands together - one horizontal one vertical
what sits on top of the arytenoid cartilage?
corniculate cartilage
where are the cuneiform cartilages?
in the aryepiglottic folds
which spinal levels hyoid bone, thyroid and cryoid cartilages lie opposite?
- Hyoid bone lies opposite C2
- Thyroid cartilage lies opposite C4
- Cricoid cartilage lies opposite C6
what are the three membranes of the larynx?
- thyrohyoid
- cricothyroid
- ariepiglottic
where does the thyrohyoid membrane extend from and to? what does it form?
extends from the thyroid cartilage to the hyoid bone and is thickened medially and laterally to form the medial and lateral thyrohyoid ligaments respectively
where does the cricothyroid membrane extend from and to? what does it form?
- The cricothyroid (cricovocal) membrane attaches inferiorly to the upper border of the cricoid cartilage
- Anteriorly, in the midline, it is attached to the inferior border of the thyroid cartilage (cricothyroid ligament)
- Posteriorly, it is attached to the vocal processes of the arytenoid cartilages
- Vocal fold formed by the free upper border of the cricothyroid membrane
where does the aryepiglottic membrane extend from and to? what does it form?
- The aryepiglottic (quadrangular/quadrate) membrane attaches posteriorly to the body and apex of the arytenoids and superiorly to the sides of the epiglottis
- Aryepiglottic fold is formed by the free upper border of the aryepiglottic membrane
what folds are there in the larynx? going lateral to medial
aryepiglottic fold, ventricular fold (false), vocal fold (true)
what is the ventricle of the larynx?
the recess that extends laterally between the vestibular and vocal folds
what is the saccule of the larynx?
an outpouching of the mucous membrane from the ventricle which contains many mucosal glands
what are the muscles of the larynx?
extrinsic (suprahyoid and infrahyoid) and intrinsic
what do the intrinsic muscles of the larynx do?
control the position and tension of the vocal and aryepiglottic folds, thereby modifying the shape of the airway
name the intrinsic muscles of the larynx
- cricothyroid
- transverse arytenoid
- oblique arytenoid
- posterior cricoarytenoid
- lateral cricoarytenoid
- thyroarytenoid
- aryepiglotticus
how many muscles attach onto the arytenoid?
all of them apart from cricothyroid
cricothyroid - origin, insertion and action
- origin - anterolateral aspect of cricoid cartilage
- insertion - lower border of inferior horn of thyroid cartilage
- action - increases length & tension of vocal cords and therefore raises the pitch
transverse arytenoid - origin, insertion and action
- origin - one arytenoid
- insertion - other arytenoid
- action - adducts the arytenoids. so closes the rima glottidis
oblique arytenoid - origin, insertion and action
- origin - muscular process of one arytenoid
- insertion - apex of contralateral arytenoid
- action - adducts the arytenoids, so closes the rima glottidis
posterior cricoarytenoid - origin, insertion and action
- origin - posterior surface of cricoid lamina
- insertion - muscular process of arytnenoid
- action - rotates arytenoids backwards, so abducts vocal cords & opens glottis
lateral cricoarytenoid - origin, insertion and action
- origin - lateral aspect of cricoid cartilage
- insertion - muscular process of arytenoid cartilage
- action - adducts vocal cords
thyroarytenoid - origin, insertion and action
- origin - posterior surface of thyroid cartilage
- insertion - vocal process and body of arytenoid
- action - relaxes the vocal cords
aryepiglotticus - origin, insertion and action
- origin - apex of arytenoid
- insertion - side of epiglottis
- action - narrows laryngeal inlet
what is the arterial supply of the larynx? which veins?
via laryngeal branches of the superior and inferior thyroid arteries
laryngeal veins drain into the superior and middle thyroid veins
what innervates the larynx?
two important branches of the VAGUS nerve:
- superior laryngeal nerve (internal and external branches)
- recurrent laryngeal nerve
- internal branch - sensory innervation to mucosa of larynx above vocal cords
- external branch - motor innervation to cricothyroid muscle
- recurrent laryngeal - sensory innervation to mucosa below vocal cords & motor innervation to all intrinsic muscles except cricothyroid
