Anatomy Test #3 Lecture 4/5 material! Flashcards
Cranial Nerve 1 name
The olfactory nerve
Cranial 1 gives us our sense of
smell
The olfactory nerve consists of
little fascicles that pass through the cribriform plate into the cranial cavity (specifically into the olfactory bulb, which means that it is no longer the olfactory nerve)
The olfactory bulb
initiates new axons that flow posteriorly as the OLFACTORY TRACT (not the olfactory nerve)
the olfactory trigone
has medial fibers (medial striae)
and lateral fibers (lateral striae)
lateral striae of the olfactory trigone project into
the primary olfactory area on the ipsilateral side
the medial striae of the olfactory trigone
cross to the opposite side of the brain via the anterior commisure
Does one side take care of smell?
no, lateral and medial striae result in both sides taking care of smell
the fornix
part of the limbic system, part of emotional brain
lamina terminalis
marks the rostral end of the rostrum of the corpus colosseum
cranial nerve 1 function
has no motor function at all, all olfaction or smell
cranial nerve 2
optic nerve
optic nerve originates
in the eye
optic nerve is what type of fibers
all sensory
the optic nerve enters the cranial cavity through the
optic canal
the optic chiasm
where some of the fibers of the eye cross
the optic tract
after the optic chiasm, terminates into the lateral geniculate body of the thalamus
function of cranial nerve 2?
optic nerve, so vision
fibers coming from lateral retina do what
stay on the same side as the chiasm
fibers coming from medial retina do what
cross the chiasm
your lateral retina sees the
medial visual field
your medial retina sees the
lateral visual field
If you have pressure on the optic chiasm, what happens?
It prevents the medial fibers from crossing, so you won’t be able to see anything in the periphery aka the lateral visual field. So you will only see things in the medial visual field
corticoblindness
damage to occipital lobe, causes you to not be able to see
visual adnosmiam
damage to the association cortex of the occipital lobe- you might be able to see, but you won’t know what you are seeing, you wouldn’t be able to name it.
cranial nerve III name
Oculomotor Nerve
CN III emerges from
These nerves are situated on the ventral brainstem at the level of the junction between the midbrain and the pons. They may be observed emerging from the midbrain centrally in
the INTERPENDUNCULAR FOSSA
What is the name of cranial nerve IV
the trochlear nerve (the smallest of all of the nerves)
where does the trochlear nerve originate
This is the ONLY cranial nerve that is attached to the dorsal aspect of the brainstem (Netter: 115). However, it then wraps around to the ventrolateral aspect and may be observed laterally at the level of the midbrain
what is the only cranial nerve that is crossed?
the trochlear nerve! It’s fibers cross in the superior medullary velum
What is the name of cranial nerve VI
the abducens nerve
what does the abducens nerve do?
it abducts your eye
CN IV exits the skull through
superior orbital fissure to innervate one muscle.
Unique Features of trochlear nerve:
smallest cranial nerve
fibers cross in the superior medullary velum
innervates the superior oblique muscle
Trochlear nerve function - and is it motor or sensory or both
Function: Motor: This cranial nerve innervates one eye muscle, the Superior Oblique which moves the eye in a downward and outward direction.
Cranial nerve VI emerges from the junction between the
pons and the medulla (pontomedually groove)
for eyes to move normally they must
move in the same direction and distance at the same speed
conjugate extra-occular movement / conjugate deviation of the eye
eyes move in the same direction and distance at the same speed.
If your left eye looks lateral, what should right eye be doing
looking medial at the same velocity, speed and rate.
Medial Rectus
Eye rotates in
Superior Rectus
Eye rotates up
Inferior Rectus
Eye rotates down
Inferior Oblique
Eye rotates up and out. (diagonally up and out)
innervation of medial rectus, superior rectus, inferior rectus, and inferior oblique is by what nerve?
cranial nerve 3
levator palpebrae muscle function, and what innervates it?
function is to open the eyelid, and its innervated by cranial nerve 3. When the muscle contracts it opens your eye
ptosis (p is silent)
sagging of eyelid due to issues with levator palpebrae. Likely due to cranial nerve 3
Do cranial nerves have sympathetic function?
no sympathetic but yes parasympathetic
cranial nerve III has what kind of autonomic function?
parasympathetic function- it is motor to the constrictor pupillae muscle. It consists of smooth muscle fibers in the iris of the eye (the part of the eye that we look at and it’s the color of the persons eye). When it gets a parasympathetic signal, your pupil will constrict.
discuss the ciliary muscle of the eye
it’s another parasympathetic muscle innervated by cranial nerve III.
WHEN YOU BRING SOMETHING CLOSE TO YOUR EYE YOUR CILIARY MUSCLE CONTRACTS CAUSING THE LENS TO THICKEN (LENS TO THICKEN IS BC OF PARASYMPATHETIC SYSTEM AND THIS IS CALLED DISTANCE ACCOMMODATION,
further information:
The dark spot in your eye is the pupil. It allows light rays into your eyes so you can see. Right behind pupil is your lens. Your lens allows the light rays to be focused on the retina. So it’s a built in pair of glasses. When you take an object away from the eye, it relaxes, and the lens thins. Results in
function of the trochlear nerve
extra-occular movement only!
superior oblique: eye turns diagonally DOWN and OUT
cranial nerve VI extra ocular movement function
lateral rectus of the eye- abduction - eye turns out
Annulis of zinn
a cartilaginous layer that surrounds the optic canal, connects to the rim of the optic canal. all extra ocular muscles except for inferior oblique originate here.
so: the superior oblique the superior rectus the lateral rectus the medial rectus the inferior rectus all original here!!
the inferior oblique originates where?
the medial orbital surface!
the oculomotor nerve enters the orbit through the
superior orbital fissure
as soon as CN III enters the orbit it divides into
an upper division and lower division
what does the upper division of cranial nerve III innervate?
innervates upper muscles that are supplied by the oculomotor nerve
so:
1. levator palpabrae superioris
2. superior rectus
what does the lower division of cranial nerve III innervate?
all muscles that are not upper supplied by the oculomotor nerve so: 1. the medial rectus 2. the inferior rectus 3. the inferior oblique
What division of Cranial Nerve III has the parasympathetic functions?
the lower division:
- papillary constriction
- lens thickening
medial/ internal strabismuss
cross eyed
if you’re crossed, what nerve would be effected?
cranial nerve III. Because it’s pulling your eye in. This is also because cranial nerve 6 is not innervating your lateral rectus.
your occulomotor nerve is sandwiched between
your superior cerebellar artery and your posterior cerebral artery
cardinal eye movements
Cranial nerve III, IV and VI exam
allows a person to track an object moving infront of their eyes- have patient track object with eyes moving left to right, up and down, and diagonally in and out.
direct and consensual light reflex
optic nerve III
- shine a light in someones eyes and the pupil on the ipsilateral side will obviously constrict, but this reflex causes the contralateral side to also constrict
cranial nerve 5 name
trigeminal nerve
what’s the biggest cranial nerve in terms of mass and size?
the trigeminal nerve
origination of trigeminal nerve
comes from your ventrolateral pons
trigeminal ganglion
the thick portion of trigeminal nerve which house the sensory nerve bodies for this nerve
distal to trigeminal ganglion are the divisions of the trigeminal nerve. Name them
there are three divisions called the
- ophthalmic divison (V1)
- maxillary divison (V2)
- mandibular division (V3)
the three divisions of the trigeminal nerve are all for
sensory of the face
the ophthalmic division of the trigeminal nerve
ONLY SENSATION it gives general sensation to
- forehead and scalp, back to the vortex (where we have our crown of head)
- anterior nose, upper eyelid, and your conjunctiva (mucus membrane of eye) + sclera of the eye (the white capsule that encloses your eye)
the maxillary division of the trigeminal nerve
ONLY SENSATION gives general sensation to
- the middle face, ant temple, sides (alae) of the nose, and upper lip
- nasopharynx and nasal cavity
- soft and hard palate
- upper row of teeth and gums
the mandibular division of the trigeminal nerve sensory functions
gives general sensation to
- post. temple, skin over chin and jaw + lower lip
- ant 2/3d’s of of tongue (gen sensation)
- lower row of teeth + gums
- TMJ
back of the head sensation is through
the dorsal primary ramus of C2 AKA your greater occipital nerve
the mandibular division of the trigeminal nerve motor functions
4 Muscles of Mastication (chewing)
2 Suprahyoid Muscles (muscles above hyoid bone)
Tensor Tympani (Middle Ear)
Tensor Veli Palatini (Palate)
4 Muscles of Mastication
- temporalis
- masseter- strongest muscle in body. comes from zygomatic arch, insert on lateral aspect of mandible
- medial pterygoid insert onto mandible on medial side- elevates jaw
- lateral pterygoid - inserts at head of mandible- slides jaw forward and unlocks it which allows us to open it
muscles used to close the jaw
masseter, temporalis, and medial pterygoid
muscle used to open the jaw
lateral pterygoid
cranial nerve 5- soft palate
tenses the soft palate- tensor veil palatini. Necessary for us to do in order to swallow
Tensor Tympani
DAMPENS THE VIBRATIONS TO THE MALLEUS- PREVENTS HYPERACUSIS (innervated by V3(
- runs parallel with Eustachian tube
- attaches to the malleus (1 of the three ossicles of the ear)
- malleus attaches to ear drum, so that when we pick up a sound, it goes through the tensor tympani to the malleus
- when sound vibrates to the malleus it then goes to 2 other ossicles of the ear, and that’s how we hear. If it was not for the sensory tympani, our ossicles would over vibrate and lead to Hyper Acoustics. So the sound would be so loud, we wouldn’t want to hear.
other than malleus, what are the other two ossicles of the middle ear
incus (anvil) and stapes (stirrup)
cranial nerve 7 is named
the frontal nerve
cranial nerve 7 emerges
lateral to cranial nerve 6 (the abducens nerve) in the PONTOCEREBELLAR ANGLE
three main parts of cranial nerve 7
- somatic portion - supplies muscles of fascial expression (allow you to smile, frown, furrow your brow,. It also supplies the stapedius
- Chorda Tympani-Sensory
- Greater Petrosal
the somatic portion of cranial nerve 7 exits the skull through
the stylomastoid foramen, where it then enters your parotid gland and branches off to 5 branches
5 branches of cranial nerve 7 after parotid gland
- temporal branch
2.zygomatic branch - buccal
- mandibular
- cervical
To Zanzibar By Motor Car
thumb to temple, pinky facing down towards chin
Stapedius innervated by what? and what is it?
(CN VII) Attaches to the Stapes Dampens vibrations Prevents hyperacusis smallest muscle
Chorda Tympani-Sensory innervated by what? what is it
CN VII
Taste to anterior 2/3 of tongue
Chorda Tympani-Motor innervated by what? what is it?
CN VII
Parasympathetic to submandibular & sublingual glands
Increases secretion in these glands
Greater Petrosal innervated by what and what is it?
CN VII
Parasympathetic to the lacrimal gland (tears) & mucus glands of nasal cavity (runny nose)
Increases secretion in these glands
Bell’s Palsy and it’s nerve
CN VII
paralysis of ipsilateral muscles of facial expression
cranial nerve VIII name (8)
Vestibulocochlear Nerve
cranial nerve VIII origin
just lateral to CN VII, right out of the pontocerebellar angle
Vestibulocochlear Nerve 2 parts
Cochlear portion-Audition
Vestibular portion-Balance and Equilibrium
Vestibular portion of Vestibulocochlear nerve consists of
3 Semicircular Canals (Superior, Horizontal, Posterior) ((more for monititering angular movements of head), cochlea, and between them there’s the vestibule (more for static positioning)
Cranial Nerve IX name (9)
Glossopharyngeal Nerve
Cranial Nerve IX emerges
as several rootlets dorsal to the Olive
Cranial Nerve IX functions
- General Sensation-Middle Pharynx (Oropharynx)
-area just behind mouth, where you have a sore throat - Gen. Sensation & Taste-Post. 1/3 Tongue
- Carotid Branch that Monitors:
- Motor-Stylopharyngeus
- Autonomic-Motor
Parasympathetic to the Parotid Gland
Carotid Branch of IX that Monitors:
Blood O2 Level
Blood Pressure
Autonomic-Motor of cranial nerve IX?
Parasympathetic to the Parotid Gland
-Increases secretions in this gland
mumps and cranial nerve 9 and 7 relationship
it leads to the parotid gland swelling bc of cranial nerve 9 increasing secretions. This causes the parotid gland to squish cranial nerve 7, which deals with the facial expressions
Cranial Nerve X name
Vagus nerve
Cranial Nerve X emerges
as several rootlets dorsal to the Olive & caudal to CN IX
vagus nerve innervates
Motor to Pharyngeal Muscles (Except Stylopharyngeus-CN IX)
Motor to Soft Palate Muscles (1 exception-Tensor Veli Palatini-V3)
Motor to Laryngeal Muscles
Sensory-Larynx
Sensory-Lower Pharynx (Laryngopharynx)
Sensory Ext. Auditory Canal
Motor (Parasympathetic)- Thoracic & Abdominal Viscera to the Left Colic Flexure
Sensory-Abdominal & Thoracic Viscera
Cranial Nerve VI name
Spinal Accessory Nerve
Why does Dr. Thomas not call Cranial Nerve VI a cranial nerve?
because it does not come off the brain, it comes off your upper cervical spinal cord segments. the root goes up through the foramen magnum
Cranial Nerve VI innervates
trapezius and sternocleidomastoid
sternocleidomastoid where? and what does it do?
runs from manubrium up to mastoid process. It helps you turn your head left and right (right turns your head left, and visa vera). When both contract it flexes your neck and extends head at Atlanta occipital joint. Also can help you breathe
Cranial VII name
Hypoglossal Nerve
Hypoglossal Nerve originates
between the Olive & Pyramids
Hypoglossal Nerve leaves skull through
Hypoglossal canal
Hypoglossal Nerve function / innervation
Motor Innervation to Muscles of the Tongue
Exception: Palatoglossus (Vagus)
- so a patient with tongue issues, including speech sometimes, is because of this nerve
Parasympathetic-Feed and Relax cranial nerves
(CN’s III, VII, IX & X)
parasympathetic and sympathetic are what kind of systems?
only motor, no sensory
TMJ joint is the articulation between
mandibular fossa of temporal bone with the head of the mandible (mandibular condyle)
what protects TMJ joint
articular joint
what kind of joint is TMJ
hinge joint (opens and shuts) ; ball & socket (protrude, retracts, and goes side to side) ; gliding joint (u have to slide the jaw forward to open it)
insertion always moves ___ the origin
towards
The TMJ muscles all act around the temporomandibular joint (TMJ), so that any time the jaw is opened, two things always occur:
- The condyle is displaced anteriorly, thus the jaw actually partially dislocates itself to open;
- The mandible is depressed.
4 main muscles of TMJ
masseter
temporalis
medial pterygoid
lateral pterygoid
need lateral ptergoid to…
to help slip the jaw forward and unlock the TMJ
to open jaw from a closed position what has to happen
the condyle/ disk slips forward to unlock the mandible, and then the mandible is depressed
supra hyoid muscles
above the hyoid bone
- support the hyoid and allow it to free flow in the neck
- aid in swallowing and mandibular depression
Other muscles assisting in depression of the mandible include the suprahyoid group, which are:
- Mylohyoid (innervation - V3) (Netter: 53);
- Anterior belly of the digastric (innervation - V3)
- Geniohyoid (innervation - C1 which piggybacks via the hypoglossal nerve, so its not the hypoglossal nerve its C1) (Netter: 53).
Ligamentum supports of TMJ
- Articular capsule (membrane)- thick, tough, yet pliable
- Articular disc
- Temporomandibular Ligament- 2 short ligaments that prevent posterior displacement of the jaw
- Stylomandibular ligament - prevent mandibular depression
- Sphenomandibular ligament- also prevents mandibular depression
Articular Capsule of TMJ
rim of the mandibular fossa to the neck of the mandibular condyle
Temporomandibular ligament
zygomatic arch to the neck of the mandibular condyle.
Stylomandibular ligament
styloid process to the angle of the mandible.
Sphenomandibular ligament
spine of the sphenoid to the medial side of the mandibular ramus at the lingula. Medial side of mandible.
