Anatomy theme 8 Flashcards
What does the external ear consist of ?
auricle , ext. auditory meatus and tympanic membrane
What does the middle ear consist of ?
ossicles and the muscles (stapedius and tensor tympani)
What is the epitympanic recess ?
small part of of the inner ear extends above the tympanic membrane as the epitympanic recess
Where is the tensor tympani muscle ?
in part of the pharyngotympanic tube
What are the ossicles ?
malleus , incus and stapes
Where is the inner ear found ?
medial to the tympanic cavity in the petrous temporal bone
What is the embryonic derivation of the tubotympanic recess ?
1st pouch
What is the embryonic derivation of malleus and incus ?
meckels cartilage - 1st pharyngeal, arch
What is the embryonic derivation of stapes ?
reicherts bar - 2nd pharyngeal arch
What are the 4 parts of the temporal bone ?
petromastoid part
squamous part
tympanic ring
styloid process
What is contained in the petromastoid portion ?
middle and inner ear
Where is the tympanic ring ?
the external part of the ext.auditory tibe
What are the formaina in the temporal bone ?
jugular fo carotid canal stylomastoid fo internal auditory meatus greater and lesser petrosal hiatus
What are the 4 walls of the middle ear ?
anterior
posterior
lateral
medial
What are the 2 openings on the anterior wall ?
pharyngotympanic tube - bigger
opening for the tensor tympani
What are the features of the medial wall of middle ear ?
promantory - formed from the undelrying cochlea
round window
oval window
Which opening is occupied by the footplate of the stapes ?
oval window (fenestra vestibuli)
What are the features of the posterior wall of the middle ear ?
the pyramid - contains the stapedius - attached the Stapes
What are the features of the lateral wall of the middle ear ?
tympanic membrane and the epitympanic recess
What are the features of the malleus ?
Consists of a round head in the epitympanic recess
long process in the tympanic membrane
facet for the incus
Where does the tensor tympani insert ?
into the long process (manubrium) of the malleus
What are the features of the incus ?
long process
short process
facets for malleus and incus
What are the features of the stapes ?
head - facet for the incus
arch and flat oval base which occupies the oval window
Where does the stapedius muscle insert ?
tendon for the stapedius muscle inserts into the neck of the stapes
How do the ossicles enable us to hear ?
sound is funneled by the auricle and the external auditory meatus.
increases air pressure over the tympanic membrane
manubrium moves medially
head moves in antero-posterior direction
base of stapes pushes on the oval window
What are the functions of the ossicles ?
act as an impedance matching device
apply pressure to the oval window
work in a lever action
protect against loud sounds
What are the functions of tensor tympani and stapedius ?
modulate the frequency response
protect against loud sounds
The facial nerve leaves the brainstem as which 2 branches ?
nervus intermedius
motor root
How do the 2 roots enter the skull ?
they fuse and enter the petrous temporal bone through the internal auditory meatus
What does the facial nerve do in the petrous temporal bone ?
it travels in the facial canal
and bends at the epitympanic recess to give the geniculate ganglion
What are the branches of the geniculate ganglion ?
greater petrosal nerve
What does the greater petrosal nerve do ?
contains parasympathetic secretomotor axons to the pterygopalatine ganglion
What does the pterygopalatine ganglion supply ?
nasal lacrimal and palatine mucous glands
What does the greater petrosal nerve do ?
travels in the hiatus of the greater petrosal nerve and joins the deep petrosal nerve to form the nerve of the pterygoid canal which enters the pterygopalatine fossa
What is the deep petrosal nerve a branch of ?
the superior cervical ganglion
What is the lesser petrosal nerve a branch of ?
glossopharyngeal
What does the lesser petrosal nerve do ?
joined by the tympanic branch of the IX to supply parasympathetic secretomotor axons to the parotid gland
What joins the lesser petrosal nerve at the tympanic plexus ?
a small branch from the geniculate ganglion joins the LPN at the promantory
How does the lesser petrosal nerve travel ?
in the petrous temporal bone and emerges at the hiatus of the lesser petrosal nerve to enter the FO.Ovale to provide preganglionic axons to the otic ganglion
Where does the nerve to stapedius emerge ?
arises distal to the geniculate ganglion and travels to stapedius
Where is the chorda tympani given off ?
in the petrous temporal bone
Where does the chorda tympani pass ?
over the tympanic membrane and ossicles to the infratemporal fossa
joins the lingual nerve
How does the chorda tympani enter the infratemporal fossa ?
through the petrotympanic fissure
What does the chorda tympani contain ?
parasympathetic preganglionic secretomotor axons to the submandibular ganglion
taste fibres for the anterior two thirds of the tongue
Where does the facial nerve emerge from the skull ?
the stylomastoid foramen
What branches does the facial nerve give off before passing into the parotid gland ?
branches to Post. Digastric and Stylohyoid
What does the facial nerve do in the parotid gland ?
gives off the temporal , zygomatic , buccal , mandibular and cervical branches to the muscles of facial expression
What does the inner ear do ?
concerned with reception of sound and balance
Where is the inner ear found ?
medial to the middle ear in the petrous temporal bone
What does the inner ear consist of ?
bony (osseous) labyrinth and a membranous labyrinth
What is the bony labyrinth ?
an interconnecting system of twisted canals filled with peri-lymph
What does the bony labyrinth do ?
consists of the vestibule , cochlea and the semilunar canals
What does the vestibule do ?
communicates with the round and oval windows
What is the cochlea ?
hearing organ
What are the semi-lunar canals ?
anterior , posterior and lateral
What is the membranous labyrinth ?
suspended in peri-lymph
What is the superior margin of the orbit made of ?
orbital plate of the frontal bone
What are the lateral margins of the orbit made of ?
zygomatic bone
What are the inferior margins of the orbit made of ?
zygomatic bone and maxilla
What are the medial margins of the orbit made of ?
frontal process of the maxilla and posteriorly the lacrimal bone
Which bone is the optic canal in ?
lesser wing of sphenoid
What does the optic canal transmit ?
optic nerve and the opthalmic artery
What is the superior orbital fissure ?
a cleft between the greater and lesser wings of sphenoid
What structures are transmitted by the superior orbital fissure ?
lacrimal nerve frontal nerve trochlear nerve superior oculomotor nasociliary inferior oculomotor abducent
What is the inferior orbital fissure a cleft between ?
the greater wing of sphenoid
maxilla
What does the inferior orbital fissure transmit ?
opthalmic vein
orbital branch of the middle meningeal
What do the anterior and posterior ethmoidal foramina do ?
transmit the anterior and posterior ethmoidal nerves to the ethmoidal air sinuses
What are the attachments of levator palpebrae superioris ?
attaches to the roof of the orbit and the skin of the upper eyelid
What is the action of LPS ?
elevation of the upper eyelid
What muscle opposes the action of LPS ?
orbicularis oculi
What is the innervation of LPS ?
oculomotor
What are the attachments of superior rectus ?
arises from the tendinous ring and and inserts into the superior aspect of the eyeball
What are the actions of superior rectus ?
elevation
adduction
inward rotation at extreme adduction
What is the innervation of superior rectus ?
oculomotor
What are the attachments of inferior rectus ?
Arises from the tendinous ring and inserts into the posteroinferior aspect of the eyeball
What are the actions of inferior rectus ?
depression
adduction - towards the midline
outward rotation at extreme adduction
What is the innervation of inferior rectus ?
oculomotor
What are the attachments of lateral rectus ?
Arises from the tendinous ring and inserts into the lateral aspect of the eyeball
What are the actions of lateral rectus ?
abduction - away from the midline
What is the innervation of lateral rectus ?
abducens
What is the attachments of superior oblique ?
Doesn’t arise from the common tendinous ring - comes from a tendon above the common tendinous ring
passes through the trochlea
inserts into superoposterolateral aspect of eyeball
What are the actions of superior oblique ?
depression
abduction
inward rotation at extreme abduction
What is the innervation of superior oblique ?
trochlear
What are the attachments of inferior oblique ?
arises from the floor of the orbit and inserts into the psoteroinferolateral aspect of they eyeball
What are the actions of inferior oblique ?
elevation
abduction
outward rotation at extreme abduction
What is the innervation of inferior oblique ?
oculomotor
What are the 3 terminal branches of the opthalmic divsion of the trigeminal ?
nasociliary
lacrimal
frontal
What does the lacrimal nerve do ?
passes to the lateral wall of the orbit and picks up postsynaptic fibres from the pterygopalatine ganglion and the zygomatic nerve.
goes to the lacrimal gland
What does the frontal nerve do ?
It lies on LPS and divides into the supraorbital and the supratrochlear nerves
How does the nasociliary nerve pass ?
passes anteromedially
What are the branches of the nasociliary nerve ?
ganglionic branches long ciliary nerve posterior ethmoidal nerve infratrochlear nerve anterior ethmoidal nerve
What are the terminal branches of the nasociliairy nerve ?
infratrochlear and anterior ethmoidal nerves
What does the anterior ethmoidal nerve do ?
supply the anterior ethmoidal cells
emerges as the external nasal nerve
What are the 3 coats of the eyeball ?
fibrous coat
vascular coat
neural coat
What does the fibrous coat consist of ?
sclera and the cornea
What does the vascular coat consist of ?
choroid- venous/arterial
ciliary body- suspends the lens via the suspensory ligament and contains the ciliary muscle
iris
What are the muscles found in the irris ?
constrictor pupillae
dilator pupillae
What is the innervation of the constrictor pupillae ?
parasympathetic fibres of Oculomotor - from ciliary ganglion
What is the innervation of dilator pupillae ?
sympathetic fibres
What does the neural coat consist of ?
nervous layer - macula
What is the lacrimal gland ?
a serous gland wrapped around the free border of the LPS creating 2 lobes
How do tears wash over the eyelid and where do they go ?
tears drain medially and into the lacrimal sac and then the nasolacrimal duct and the inferior meatus
Where does the parasympathetic supply to the lacrimal gland come from ?
from the pterygopalatine ganglion
the greater petrosal nerve and the deep petrosal nerve fuse to form the nerve of the pterygoid canal. Postganglionuc fibres enter the orbit though the inferior orbital fissure as the zygomatic nerve
Where does the zygomatic nerve pass ?
through the inferior orbital fissure
What does the ciliary ganglion do ?
provides innervation to the dilator and constrictor pupillae
What is the parasympathetic root of the ciliary ganglion ?
from the oculomotor nerve to the constrictor pupillae
What is the sympathetic root of the ciliary ganglion ?
arises from the internal carotid and opthalmic artery plexus and supplies the dilator pupilale muscle
What is the sensory root of the ciliary ganglion ?
from the nasociliary nerve and the iris and the cornea and the long ciliary nerves
What are the branches of distribution of the ciliary ganglion ?
short ciliary nerves
What is intramembranous ossification ?
mesoderm to bone
What is endochondral ossification ?
cartilage to bone
How does the cranial vault form ?
intramembraneous ossification
How does the cranial base form ?
endochondral ossification
What is the boundary between the anterior and middle cranial fossa ?
lesser wings of sphenoid
anterior clinoid processes
jugum sphenoidale
What are the boundary between the middle and posterior cranial fossae ?
superior border of the petrous temporal bone
posterior clinoid processes
dorsum sellae
What are the features of the anterior cranial fossa ?
crista galli
cribriform plate
orbital plate of frontal bone
What are the features of the middle cranial fossa ?
Jugum sphenoidale sella turcica pituitary fossa optic canal Fo. Lacerum Superior orbital fissure Fo.Rotundum Fo. Ovale Fo.Spinosum Hiatus for the greater and lesser petrosal nerves
What are the features of the posterior clinoid fossa ?
Clivus Fo. Magnum Hypoglossal canal jugular Fo Internal auditory meatus Internal occipital protuberance
Which cranial nerves emerge in the anterior cranial fossa ?
olfactory
Which cranial nerves emerge in the middle cranial fossa ?
optic oculomotor trochlear trigeminal abducens
Which cranial nerves emerge from the posterior cranial fossa ?
Facial vestibulocochlear glossopharyngeal vagus spinal accessory hypoglossal
What are the 3 layers of the meninges ?
dura mater
arachnoid mater
pia mater
What are the 4 parts of the dura mater ?
falx cerebri
falx cerebelli
diaphragma sella
tentorium cerebelli
What does the falx cerebri do ?
hangs down into the cranial cavity and separates the 2 cerebral hemispheres
What does the falx cerebelli do ?
separates the right and left cerebellar hemispheres
What is the diaphragma sellae do ?
a small fold between the anterior and posterior clinoid processes
What are the 2 spaces between the meningeal layers ?
extradural space
subarachnoid space
What is the extradural space ?
space between the dura and the bone
What is the subarachnoid space ?
below the arachnoid mater and is filled with CSF
Do venous sinuses contain valves?
no
What do the dural venous sinuses do ?
drain blood from the brain into the internal jugular vein and the jugualr foramen
What does the superior sagittal sinus drain into ?
the confluence
What does the inferior sagittal sinus do ?
turns into the straight sinus as it approaches the tentorium cerebelli
What is the transverse sinus ?
passes laterally from the confluence and becomes the sigmoid sinus as it passes to the petrous temporal bone
What is the sigmoid sinus ?
continues medially from the petrous ridge to the jugular fo. All blood drains into the sigmoid sinus
What are the cavernous sinuses ?
lie in the body of the sphenoid on either side of the sella tursica - draineed by the superior and inferior petrosal sinuses
What does the superior petrosal sinus do ?
drains into the cavernous sinus
What does the inferior petrosal sinus do ?
drains directly into the internal jugular vein
What is the arterial supply of the brain ?
vertebral and the internal carotid arteries
How does the internal carotid artery enter the posterior cranial fossa ?
through the carotid canal
How does the vertebral artery enter the posterior cranial fossa ?
foramen magnum
What are the structural buttresses of the skull ?
ares of bone that are the most structurally stable and are the least likely to break
What does the buttress system do ?
absorbs and transmits forces applied to the facial skeleton to protect fragile bony areas
What does the CSF do ?
supports the brain and absorbs the energy of impact
What do the dural reflections do ?
support the brain and transmit the wieght of the rbain to the skull
What do the dural venous sinuses do ?
involved in temperature regulation by cooling arterial blood and protects against transient changes in venous pressure
What are the 4 types of haemorrhages ?
extradural
subarachnoid
subdural
intracerebral
What are extradural haemorrhages ?
between the dura mater and the bone - rupturing of the middle meningeal artery
What are subdural haemorrhages ?
bleeding into the subdural space - rupturing of the superior cerebral veins
What are subarachnoid haemorrhages ?
bleeding into the subarachnoid space such as aneurysms and angiomas
What are intracerebral haemorrhages ?
bleeding into the brain itself - eg . middle cerebral artery
What are typical routes of infection spread ?
tissue planes
venous
lymphatic
direct erosion
What are some of the spaces that infection either intraoral or extraoral can spread to from a 3rd man molar ?
sublingual space submental space submandibular space pterygomandibular space peritonsillar space parotid space
Describe the route of infection spread from a 3rd mandibular molar ?
periapical abcess - in the roots of molar
breaks through on the lingual side
enters the sublingual space
spread backward - ludwigs angina
What can infections erode ?
basiocciput
enter the mediastinum
What is the second route of infection spread ?
from submandibular space
into lateral pharyngeal space
retropharyngeal space
What are the severe consequences of infection if left untreated ?
airways obstruction
intracranial spread
septicaemia
Describe a route of infection spread from the cavernous sinus ?
from the cavernous sinus into the emissary veins and the into the infraorbital vein into the facial vein
Describe a second route of infection from the cavernous sinus ?
from the cavernous sinus into the pterygoid plexus of veins and into the RM vein
What bones does the orbital plate of the zygomatic bone articulate with ?
frontal bone
zygomatic process of the temporal bone
maxilla
greater wing of sphenoid
Name the foramina located in the greater wing of sphenoid ?
foramen ovale , rotundum and spinosum
What bones does the maxilla articulate with ?
zygomatic bone palatine bone ethmoid bone inferior concha frontal bone lacrimal bone nasal bone
Which extraocular muscles dont arise from the common tendinous ring ?
LPS and superior oblique
Why does swallowing help reduce pressure difference?
pain develops on either side of the tympanic membrane
swallowing is accompanied by contraction of salpingopharyngeus
this opens the auditory tube
equalises the pressure on either side of the tympanic membrane
What are the functions of the mandibular division of the trigeminal nerve ?
motor to the muscles of mastication tensor veli palatini tensor tympani anterior belly of digastric mylohyoid. Sensory to the skin over the cheek and parotid gland and the lingual gingivae
What does the superior sagittal sinus drain into ?
transverse sinus and the confluence of sinuses
Where is the cavernous sinus located ?
in a groove in the body of sphenoid
What artery passes medial to the cavernous sinus ?
internal carotid artery
Which cranial nerves run close to the internal carotid artery ?
oculomotor abducens opthalmic maxillary trochlear
What would damage to the facial nerve cause ?
facial paralysis
loss of taste sensation in the anterior 2/3 of the tongue
loss of the stapedius relfex
loss of lacrimal gland secretion
Between which meningeal layers does CSF flow ?
between the arachnoid and the pia mater
What are the roles of the CSF ?
transmit some of the weight of the brain to the skull
shock absorber
What do the posterior ethmoidal air cells drain into ?
superior meatus
Where does the frontal sinus drain into ?
superior meatus
What blood vessels does the superior orbital fissure transmit ?
orbital branch of the middle meningeal
superior opthalmic vein
What are the boundaries between the anterior and middle cranial fossa ?
lesser wings of sphenoid
anterior clinoid prcoesses
jugum sphenoidale
What are the boundaries between the middle and posterior cranial fossa ?
superior borders of the petrous ridge
posterior clinoid processes
dorsum sellae
What bones forms the floor of the middle cranial fossa ?
temporal and sphenoid
What is medial to the cavernous sinus ?
internal carootid artery
abducnets
What is lateral to the cavernous sinus ?
oculomotor
trochlear
opthalmic
v2
What is superior to the tentorium cerebelli ?
occipital lobe
cerebellum
What is inferior to the tentorium cerebelli ?
brainstem
What are the 4 types of intracranial haemorrhage ?
extra dural
sub dural
sub arachnoid
intra cerebral
What forms the superior margin of the orbit ?
orbital plate of the frontal bone
lesser win og sphenoid
What forms the inferior margin of the orbit ?
orbital plate of the maxilla
zygomatic bone
small part of paaltine bone
What forms the medial margin of the orbit ?
lacrimal bone
ethmoid bone
body of sphenoid
What is the posterior wall of the orbit made from ?
body and greater wing of sphenoid
What is the action of LPS ?
closes the upper eyelid
What is the action of superior rectus ?
Elevation
adduction
inward rotation at extreme adduction
What is the action of inferior oblique ?
Elevation
abduction
outward rotation at extreme abduction
What is the action of superior oblique ?
depression
abduction
inward rotation at extreme abduction
What is the action of superior oblique ?
depression
abduction
inward rotation at extreme abduction
What is the action of laterla rectus ?
abduction
What is the action of superior rectus ?
elevation
adduction
inward rotation at extreme adduction
What is the action of inferior rectus ?
deprssion
adduction
outward rotation at extreme adduction
Which of the branches of V1 is medial ?
nasocilairy
Obliques tend to ?
abduct
Rectuses tend to ?
adduct except LR- abduction
How can infection spread to the cranium from a maxillary canine ?
erode maxilla
superior opthalmic vein
cavernous sinus
What do the parasympathetic postganglionic axons of the ciliairy ganglion supply ?
constrictor pupillae
ciliary muscle- alter the shape of the lens
