QUIZ 4 Flashcards
cranial nerves
- peripheral nerves of the brain
- 12 paired cranial nerves
- directly comes off the brain (not spinal cord)
- numbered by emergence (forebrain to hindbrain) (rostral to caudal)
numbered cranial nerves
1 olfactory 2 optic 3 oculomotor 4 trochlear 5 trigeminal 6 abducent 7 facial 8 vestibulocochlear 9 glosophyaryngeal 10 vagus 11 accessory 12 hypoglossal
purely special somatic sensory nerves cranial nerves
- olfactory (1)
- optic (2)
- vestibulocochlear (8)
motor cranial nerves
- oculomotor (3)(parasympathetic)
- trochlear (4)
- abducent (6)
- accessory (11)
- hypoglossal (12)
mixed cranial nerves
- trigeminal (5)
- facial (7) (parasympathetic)
- glossophyaryngeal (9)(parasympathetic)
- vagus (10) (parasympathetic)
oculomotor nerve
-movement of the eye
cranial nerve pathway
starts in brain -> ganglion -> synapse with new neuron -> postganglion -> target organ
anterior cranial fossa
- frontal
- ethmoid
- sphenoid
middle cranial fossa
- sphenoid
- parietal
- temporal
posterior cranial
- holding cerebellum
- occipital
cranial foramina
- cribriform plate -> olfactory
- optic canal -> optic
- superior orbital fissure -> ophthamic, trochlear, oculomotor, abducens
- foramen rotundum- maxillary
- foramen ovale- mandibular
- internal acoustic meatus- facial, vestibulocochlear
- jugular foramen- glosopharyngeal, vagus, accessory
- hypoglossal canal- hypoglossal
trigeminal
- mandibular
- mylohyoid
- lingual
olfactory nerve (1)
- special somatic sensory
- goes through cribriform plate of the ethmoid bone (top of nasal cavity)
- many of them
- synapse of the olfactory bulb
- post synapse -> olfactory tract to cerebral cortex
- anterior cranial fossa
- olfactory bulb is inferior to the frontal lobe
- bipolar neurons
- skip the thalamus* (unlike other somatic sensory)
- go directly to the temporal lobe and limbic system
dog olfactory bulb
- much larger
- rely more on smell
optic nerve (2)
- special somatic sensory
- transmit signals from retina
- enters the skull through the optic canal of the sphenoid
- round foramina (medial superior)
- comes in form the front to the back
- chiasm- neurons meet
- nerve becomes a tract in CNS
- light will come in through eye -> hit retina (rod and cones) -> transmission -> optic nerve -> optic chiasm
- visual field of left eye hits the right side of the retina (right occipital cortex) vice versa
- thick -> many neurons
lateral geniculate body is a nucleus that relays optic sensory information from the eye towards the visual cortex of the cerebrum. given what you know about brain region function where is the lateral geniculate body found
- thalamus
- diencephalon that is receiving somatic sensory signals from most somatic sensory information (not olfactory) -> then sent to cerebrum (occipital lobe)
vestibulocochlear nerve
- special somatic sensory of balance and hearing
- two branches: vestibular branch and cochlear branch
- vestibular branch:
- balance (knowing where your body is in space)
- 3 semicircular canals -> help you orient your body
- transmits signals from semicircular canals -> through internal auditory canal -> goes out to the brain stem
- cochlear branch:
- comes from cochlea
- cochlea- snail shaped, hearing, vibrations
- auditory auricles- pick up vibrations through hairs
- go to thalamus -> cerebrbum
peripheral nerves
- come out from the brain
- numbers from anterior to posterior
visceral efferent
- motor
- pre and post ganglion
accessory nerve (CN XI)
- somatic motor
- two roots:
- cranial root- medulla oblongata
- *spinal root- spinal cord C1-C5 -> enters via foramen magnum
- two branches:
- cranial branch- accessory (runs next to) to vagus
- spinal branch- innervates trapezius and sternocleidomastoid -> exits via jugular foramen
hypoglossal nerve (CN XII)
- somatic motor
- innervates the tongue
- intrinsic tongue
- extrinsic tongue:
- hyoglossus
- genioglossus
- styloglossus
- NOT palatoglossus
- does NOT contribute to the ansa cervicalis
- C1 spinal nerve simply runs along it for a bit
- goes from the medulla oblongata through a very thin foramen -> hypoglossal canal
trochlear nerve (CN IV)
- only has somatic motor
- only innervates one muscle:
- superior oblique muscle
- movement of the eye
- attaches at the orbit (back) and goes through a pulley-like sling called the trochlea
- ligaments attached to lateral superior side
- passed from inside of the skull to the eye orbit through the superior orbital fissure of sphenoid
superior orbital fissure of sphenoid
- where the trochlear nerve passes through to go from inside skull to eye orbit
- space between the lesser wings (superior cranial fossa) and greater wings (middle cranial fossa)
- abducens nerve goes through here too
- trochlear
- oculomotor
- opthalmic
abducens nerve (CN VI)
- somatic motor
- innervated lateral rectus muscle
- abducts the eye
- from back to lateral side
- pull from the lateral side of the eye -> abducts laterally
- goes through the superior orbital fissure of the sphenoid
oculomotor nerve (CN III)
- visceral efferent: parasympathetic (involuntary)
- somatic motor (voluntary)
- ciliary ganglion
- somatic motor muscle that it innervates:
- levator palpebrae superioris (opens eyelid)
- superior oblique
- superior rectus
- inferior rectus
- medial rectus
- lateral rectus
- inferior oblique (medial, rotation)
- Parasympathetic muscles it innervates (involuntary):
- ciliary muscle (shapes lens -> oval to round shape)
- synapse at the ciliary ganglion
- constrictor pupillae (constricts pupil depending on light)
oculomotor palsy
- oculomotor palsy -> weak muscle function for muslces innervated by the oculomotor (in the eye)
- lateral palpebrae superioris- weakened -> ptosis of eyelid (drooping)
- parasympathetic issues would involve weakening of the pupillary constriction (constrictor pupillae)
- lack of direct and consensual pupillary reflexes (light)
- when you shine light in one eye you expect pupil reflex in both eyes -> this wont happen if there is oculomotor palsy
- lack of accommodation reflex (close vision) -> speed at which your lens can change shape (influenced by ciliary muscle)
- long distance to short distance
- lens shape modification (ciliary muscle)
abducens palsy
- limited ocular movement
- abduction of eye is lacking
- somatic motor only
- only one eye can abduct
- both can adduct
- lazy eye
trigeminal nerve (CN V)
-3 branches: ophthalmic (superior orbital fissure), maxillary (foramen rotundum), mandibular (foramen ovale)
-provides general somatic innervation to face, dura, jaws, and tongue
-motor innervation to mastication muscles
-travels along postganglionic neurons (parasympathetic)
-
trigeminal nerve (CN V): somatic face
Sensory: -eyeball (ophthalmic ->pain) -skin of nose (ophthalmic) -skin of forehead (ophthalmic) -maxillary teeth (maxillary -> pain) -skin of cheeks (maxillary) -mandibular teeth (V3) -skin of lower jaw (V3) -oral mucosa (V3) -tongue anterior 2/3 (not taste -> its touch) (V3) Motor: -masticatory muscles (V3)
foramen rotundum
-round shape
trigeminal nerve: ophthalmic division (CN V1)
- Somatic Sensory:
- eyeball
- skin of nose
- skin of forehead
- enters through superior orbital fissure
- exits from orbit through supraorbital notch (forehead)
trigeminal nerve: maxillary division (CN V2)
- Somatic Sensory
- maxillary teeth
- skin of cheeks
- foramen rotundum
- exits from maxilla from the infraorbital foramen (below orbit)
trigeminal nerve: mandibular division (CN V3)
- Somatic Sensory:
- mandibular teeth
- skin of lower jaw
- oral mucosa
- tongue anterior 2/3 (not taste)
- Somatic Motor:
- masticatory muscles (temporalis, masseter, pyerygoids)
- leaves skull through foramen ovale
- goes into mandible through mandibular foramen
- exits through the mental foramen (chin)
masseter
- muscle of mastication
- zygomatic arch of the cheek bone to the mandible
- innervated by the trigeminal mandibular division (V3)
temporalis
- between the skull and the zygomatic arch of the cheek bone to the mandible
- muscle of mastication
- innervated by the trigeminal mandibular division (V3)
- contract on sides of head when you clench your teeth
pterygoids
- muscle of mastication
- innervated by the trigeminal mandibular division (V3)
- from back of palate to the mandible
facial nerve (CN VII)
- exits through the internal acoustic meatus
- somatic sensory taste
- general somatic auricle (floppy bit around the ear)
- somatic motor facial expressions muscles
- parasympathetic innervation of the lacrimal gland (tear gland) and submandibular, sublingual glands (salivary)
- three branches: greater petrosal (parasympathetic to lacrimal gland), chorda tympani (parasympathetic to salivary glands: special sensory taste), and facial nerve (somatic motor to facial expression)
- Special Sensory:
- taste (anterior 2/3 of tongue)
- Somatic Motor:
- facial expression muscles
- Parasympathetic: lacrimal gland
- salivary glands (submandibular, sublingual)
facial nerve: greater petrosal (CN VII)
- solely parasympathetic to lacrimal gland
- in internal acoustic meatus
- greater petrosal branch branches out after the facial nerve enters the temporal bone through the internal acoustic meatus
- greater petrosal branch exits via the hiatus of facial canal
- goes back towards the orbit through the foramen lacerum
- preganglionic neurons will synapse at the pterygopalatine ganglion
- postganglion parasympathetic neurons travel along the branches of trigeminal maxillary nerve (V2)
- postganglionic parasympathetic innervation goes to the lacrimal glands
facial nerve: chorda tympani (CN VII)
- parasympathetic to salivary glands: special sensory taste
- goes through the petrotympanic fissure
- goes through the internal acoustic meatus
- chorda tympani branch goes through the petrotympanic fissure at the temporal bone
- merges with trigeminal mandibular (V3)
- receives taste from the anterior 2/3 from the tongue
- provides parasympathetic innervation to salivary glands
- parasympathetic preganglion will synapse at the submandibular ganglion
- postganglionic neurons will travel to submandibular and sublingual glands
facial nerve: facial nerve (CN VII)
- third branch
- (somatic motor to facial expression
- passes through the stylomastoid foramen
- goes through the internal acoustic meatus
- leaving the temporal goes through the stylomastoid foramen
- branches again into 5 branches -> go in different directions to innervate different somatic motor facial expression muscles
lacrimal gland
- found lateral superior to each eyeball
- produces tear fluid
- lubricates the eye
- moves from the lateral superior across the eyeball towards the lacrimal duct -> goes into the nasal duct
- innervation by the greater petrosal branch of the facial nerve
where is the sublingual gland found
-deep to tongue