Essay Physio: Cranial Nerves and Sensory Impulses

Submitted By pto614
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| Function | Pathway/ homeostatic imbalance | 1. OlfactorySensory (smell) | Purely sensory, carry afferent impulses for sense of smell.- tiny sensory nerves of smell which run from the nasal mucosa to synapse with the olfactory bulb | - Olfactory nerve fibers arise from the nasal cavity and pass through the cribriform plate to the synapse in olfactory bulb. Fibers of olfactory bulb neuron extends posteriorly to the frontal lobe to enter the cerebral hemisphere.- broken ethmoid bone or lesion of olfactory fibers= partial or total loss of smell also known as ansomia | 2. OpticSensory (vision) | Purely sensor, carry afferent impulses for vision | - Fibers come from the retina of the optic nerve which then passes through the optic canal. The nerve then converges to form the optic chiasm where the fibers and continue on the optic tracts to the thalamus and is synapse there. The thalamic fibers tthe occipital cortex where visual interpretation takes place- damage of the optic nerve may result in blindness, damage to visual pathway beyond the optic chiasm= partial loss, visual defects= anopisias | 3. OculomotorMotor | Chiefly motor nerves; contain a few proprioceptive afferents each nerve includes:- Somatic motor fibers -Parasympathetic autonomic fibers t-Sensory afferents which run from the same four extrinsic eye muscles to the brain | means eye mover, this nerve supplies four of the six extrinsic muscles that moves the eye- ( inferior oblique and superior, inferior, and medial rectus muscle) * Levator palpebrae= lifts eye lids/ sphincter puppillae= contracts pupil, lenses focusFibers extend from ventral midbrain and pass through bony orbit via superior orbital fissure to eye.- eye cannot be moved up down inward and at rest the eye rotates laterally because the action of the two extrinsic eye muscles not served by cranial nerves are unopposed, upper eyelid droops, and have double vision and trouble focusing on close objects | 4. TrochlearMotor | - supply somatic motor fibers to one of the extrinsic eye muscle, the superior oblique muscle | -fibers emerge dorsal midbrain, ventrally around the midbrain to enter orbit through superior orbital fissure along/ with 3.- trauma/paralysis = double vision and reduced ability to rotate eye infer laterally | 5. TrigeminalSensory (general sensation) | 1. ophthalmic: fiber runs from face to pons via superior orbital fissure2. maxillary division: fibers run from face to pons via foramen rotundum 3. mandibular: passé through skull via foramen ovale- loss of sensation- | three branches spring from this, the largest of the cranial nerves, it supplies sensory fibers to the face and motor fibers to the chewing muscle1. conveys sensory impulses from skin of anterior scalp, upper eyelid, and nose from nasal cavity mucosa, cornea and lacrimal gland 2. Conveys sensory impulses from nasal cavity mucosa, palate, upper teeth, ski of cheek, upper lip, lower eyelid 3. Anterior tongue except taste buds, lower teeth, skin of chin, temporal region of scalp. Supplies motor fibers, muscles of mastication. Stabbing pain from sec- minutes | 6.AbducensMotor | Supply somatic motor fibers to lateral rectus muscle and extrinsic muscle eye, convey proprioceptor impulses from the same muscle to the brain | Fibers leave inferior pons and enter orbit via superior orbital fissure to eyenerve controls the extrinsic eye muscles that abducts the eyeballs or turn it laterally – eye cannot be moved laterally, at rest affects eyeball rotates medially internal strabismus | 7.FacialSensory(Taste)/ Motor | Mixed nerves in charge of the face which has 5 major branches: temp. zy. Buccal, mandi., and cervical.- Conveys motor impulses f skeletal muscles except for chewing- transmit parasympathetic autonomic motot mpulses to lacriminal, nasal, palatine, submandibular, sublingual glads | A large nerve that innervates muscles of facial expressionFibers issues from pons- lateral of the nerve 6- enter temporal bone via…