Head and Neck LO5 Nerves

What’s a neuron?

functional cellular component of nervous system

What’s a nerve?

a bundle of neural processes outside the CNS and in the PNS

What’s the synapse?

junction between two neurons or between a neuron and an effector organ; where neural impulses are transmitted

What’s a ganglion?

a accumulation of neuron cell bodies outside the CNS

What’s an afferent nerve?

AKA sensory nerve carries information from the periphery of the body to the brain (or spinal cord)

What kind of sensory information does the afferent nerve carry?

taste, pain, proprioception to the brain

What’s an efferent nerve?

AKA motor nerve. Carries info away from the brain to the periphery of the body

Where do efferent nerves carry info to?

muscles

What’s resting potiential?

the difference in charges from the fluid outside the membrane (positive charge) and the fluid inside (negative charge)

What’s an action potiential?

temporary reversal of the electric potential along the membrane for a brieg period

What’s the refractory period?

membrane cannot be stimulated in this period

What are neurotransmitters?

how the nerve crosses synapse

3 layers of the CNS

Dura mater, arachnoid mater, pia materW

What’s dura mater?

outermost membrane, supports the large venous channels, carrying blood from the brain toward the.heart such as the cavernous sinus.

What’s the archnoid mater?

middle layer, underneath space contains cerebrospinal fluid

What’s pia mater?

innermost membrane, delicate and highly vascularized

What are the major divisions of the brain?

cerebrum, cerebellum, brainstem, diencephalon; thalamus and hypothalamus

What’s the largest part of brain?

cerebrum

3 parts of brainstems?

medulla, pons and midbrain

What’s the thalamus?

central relay point for incoming nerve impulses

What’s the hypothalamus?

regulates homeostasis

Where’s the medulla?

closest to spinal cord

What’s the pons?

connects the medulla with the cerebellum and with higher brain centers

What’s the midbrain?

includes relay stations for hearing, vision, and motor pathways

2 divisions of PNS

afferent and efferent

What’s the afferent NS?

sensory; carries info from receptors ti brain/spinal cord

What’s efferent NS?

motor; from brain/spinal cord to muscles or glands

What’s the Somatic NS?

subdivision of PNS; controls muscular system and external sensory receptors-involves both receptors and effectors

What’s the ANS(autonomic nervous system)?

operates without any conscious control, efferent nerves, two nerve chains

What’s sympathetic NS?

“fight-or-flight”

What’s the Parasympathetic NS?

“Rest-or-digest”

What’s cranial nerve I?

olfactory; afferent; nasal mucosa (transmits smell)

Where does cranial nerve I enter?

cribriform plate of ethomoid bone to join olfactory bulb

What’s cranial nerve II?

Optic; afferent; transmits sight from the retina of the eye to the brain

Where does cranial nerve II enter?

optic canal of the sphenoid bone on its way to retina

What’s cranial nerve III?

Oculomotor; efferent; eye muscles that move eyeball

Where does the cranial nerve III enter?

lies in cavernous sinus and exits through the superior orbital fissure of sphenoid bone

What’s cranial nerve IV?

Trochlear; efferent; one eye muscle

Where is the cranial nerve IV?

runs in cavernous sinus and exits the skull through the superior orbital fissure of sphenoid bone

What’s the cranial nerve V?

trigeminal; efferent & afferent

What does the efferent branch of cranial nerve V innervate?

muscles of mastication & other cranial muscles

What does the afferent branch of cranial nerve V innervate?

face & head skin, teeth, oral cavity, most general sensation of tongue

2 roots of the trigeminal nerve

sensory (largest) and motor

3 divisions of trigeminal root?

opthalmic, maxillary, and mandibular

Where does the ophthalmic nerve division innervate?

sensation to upper faceand scalp

Where does the maxillary and mandibular nerve divisions innervate?

provide sensation to middle and lower face

What’s cranial nerve VI?

abducens; efferent; one eye muscleWhe

Where’s cranial nerve VI?

exits the skull through the superior orbital fissure

What’s cranial nerve VII?

facia; efferent

What does the cranial nerve VII innervate?

muscles of facial expression and other cranial muscles, lacriminal gland, submandibular, sublingual and minor salivary glands

Where is the facial nerve (VII)?

leaves cranial cavity by passing through internal acoustic meatus, exits the skull by the stylomastoid foramen of temporal bone

What’s cranial nerve VIII?

vestibulocochlear; afferent; inner ear hearing and balance

Where is the cranial nerve VIII?

enters the cranial cavity through the internal acoustic meatus of the temporal bone and exits the skull by the stylomastoid foramen

What’s cranial nerve IX?

glossopharyngeal; efferent & afferent

What does the efferent part of cranial nerve IX innervate?

stylopharingeus muscle, parotid salivary gland, mucous glands of pharynx

What does the afferent part of cranial nerve IX innervate?

skin around ear, mucosa of pharynx and middle ear, taste and general sensation for posterior tongue, afferent limb of the gag reflex.

What is cranial nerve X?

Vagus; efferent and afferent

What does the efferent branch of cranial nerve X innervate?

most muscles of the soft palate, pharynx, larynx, thoracic and abdominal organs

What does the afferent branch of cranial nerve X innervate?

skin around ear, taste sensation for epiglottis

What’s cranial nerve XI?

spinal accessory; efferent; muscles of neck and soft palate and pharynx

Where’s cranial nerve XI?

jugular foramen

What’s cranial nerve XII

hypoglossal; efferent; muscles of the tongue

Wheres cranial nerve XII?

hypoglossal canal

What’s V1 of the Trigeminal Division?

ophthalmic; afferent; sensory; forehead, skull, nose

Wheres V1 of the Trigeminal Division?

superior orbital fissure

What’s V2 of the Trigeminal Division?

maxillary; afferent; sensory; cheeks, upper jaw, teeth

Wheres V2 of trigeminal division

foramen rotundum

What’s V3 of trigeminal division?

mandibular; efferent/afferent; motor/sensory; lower jaw, teeth, muscles of mastication

Where’s V3 of the trigeminal divison?

foramen ovale

Where is the entire efferent part of the trigeminal nerve

V3 mandibular nerve

Wheres the buccal nerve?

level of the occlusal plan of most distal molar of mand arch; nerve crosses anteriorly to the anterior border of the ramus, which is a landmark for buccal block

What’s crossover innervation?

incisive nerve merges with the mental nerve, posterior to the mental foramen, where it’s anesthetized by incisive nerve block

What kind of nerves does the facial nerve carry?

efferent and afferent

What’s the greater petrosal nerve?

branch off the facial nerve, carries efferent to lacriminal glands

afferent to palate for taste sensation

What’s the chords tympani nerve

branches off facial and crosses medial surface of tympanic membrane then travels lingual nerve to floor ofmouth

What does the efferent part of Chorda tympani do

submandibular and sublingual salivary glands

What does the afferent part of Chorda tympani do

taste sensation for body of tongue