Ch. 14 - Brain and Cranial Nerves III Flashcards
some say marry money, but my brother says big brains matter more
to remember which nerves are sensory/mixed/both!
oh once one takes (the) ana-tomy final, very good vacations start happening
olfactory, optic, oculomotor, trochlear, abducens, trigeminal, facial, vestibulocochlear, glossopharyngeal, vagus, spinal accessory, hypoglossal
What kind of neurons are olfactory receptors? What is their function?
bipolar neurons (axons); relays olfactory info
What is the pathway of the olfactory nerve? (CN I)
extends from olf mucosa of nasal cavity –> olf bulb –> olf tracts –> primary olf area in temporal lobe
What is the pathway of the optic nerve? (CN II)
retinal cell axons form optic nerve –> merge and some axons cross in optic chiasm –> optic tracts –> thalamus/midbrain –> prim visual area in cerebral cortex
What is the function of the oculomotor, trochlear, and abducens nerves? (CN III, IV, VI)
synapse with muscles for moving the eyeballs & upper eyelid
What other movement can the CN III perform?
autonomic movement to constrict pupils
What is strabismus?
misalignment of the eyes caused by weak muscles
What are the 3 branches of the trigeminal nerve?
ophthalamic, maxillary, mandibular
Two portions of the trigeminal portion (CN V):
SENSORY - pain, touch, temperature, receptors of face and oral cavity
MOTOR - muscles of mastication
Where does the facial nerve arise from?
the pons
Two portions of the facial nerve (CN VII):
SENSORY - taste buds on ant 2/3 of tongue
MOTOR - produce facial expressions, salivary/nasal/lacrimal glands
What is Bell’s palsy?
facial droop/loss of muscle tone in the face due t odamage to CN VII
What are the 2 branches of the vestibulocochlear nerve (CN VIII) ?
V - carries impulses for equilibrium
C - carries impulses for hearing
Two portions of the glossopharyngeal nerve (CN IX):
SENSORY - taste buds from post 1/3 of tongue, proprioceptors of swallowing muscles, baroreceptors in carotid sinus, chemoreceptors in carotid artery
MOTOR - swallowing muscles (som), saliva secretion (auto)
What would damage to CN IX lead to?
problems swallowing, dry mouth (less activation of salivary glands)
Two portions of vagus nerve (CN X)
SENSORY - external ear, baro & chemo receptors, sensation from visceral organs
MOTOR - muscles of pharynx, larynx, soft palate for swallowing/vocalization/coughing, autonomic output to visceral organs
Where does the accessory nerve arise from (CN XI)
originates from spinal nerves C1-C5, passes through foramen magnum up to brain
Where does the output from CN XI go to?
sternocleidomastoid and trapezius muscles to control head movements
Where does the hypoglossal nerve (CN XII) arise from?
medulla
What does CN XII control?
muscles of tongue during speech and swallowing
How does lidocaine HCl function in pain control?
- stabilizes neuronal membrane by inhibiting ionic fluxes required for initiation/conduction of impulses
- these affects local anesthetic action
How do opioids (particularly morphine) affect pain control?
act on receptors on neuronal cell membranes
- presynaptic action of opioids inhibit NT release to produce analgesic response
How does aspirin and other non-steroid anti-inflammatory drugs (NSAIDs) affect pain control?
inhibit activity of cyclooxygenase (COX) which leads to formation of prostaglandins (PGs) that cause inflammation, swelling, pain, and fever
How does fentanyl control pain?
- induces opening of G-protein-coupled + blocks opening of N-type voltage gated Ca2+ channels, resulting in hyperpolarization + reduced neuronal excitability
- it selectively binds to mu-receptor in CNS mimicking effects of endogenous opiates
- this stimulates the exchange of GTP for GDP on the G-protein complex, inhibiting adenylate cyclase
- results in a decrease in intracellular cAMP; reduces release of substance P, GABA, dopamine, ACh, NE
