Discuss the anatomy and physiology of the brain and brain stem. Explain the function of the twelve cranial nerves
Crani al Nerv
e Function Sign of Dysfunction
I Olfactory: sensory, carries impulses for sense and smell
...
Discuss the anatomy and physiology of the brain and brain stem. Explain the function of the twelve cranial nerves
Crani al Nerv
e Function Sign of Dysfunction
I Olfactory: sensory, carries impulses for sense and smell Loss or disturbance in the sense of
smell.
II Optic: Sensory, carries impulses for vision decreased visual acuity and contrast sensitivity, impaired color vision, and
an afferent pupillary defect. (blindness)
III Oculomotor: Contains motor fibers to interior oblique and to superior, inferior, ad medial rectus extraocular muscles that direct eye ball; levator muscles of eyelid; smooth muscles of iris and ciliary body; and proprioception (sensory) to brain from
extraocular muscles Drooping of the eyelid, eyeball moves outward, dilation of the pupil, double vision.
IV Trochlear: Propioceptor and motor fibers for superior oblique
muscle of eye (extraocular muscles) Rotation of eyeball upward and
outward, double vision
V Trigenimal: (facial muscles including chewing, facial sensation) This is the largest cranial nerve
Both motor and sensory for face; conducts sensory impulses from mouth, nose, surface of eye, and dura mater; also contains motor fibers that stimulate chewing muscles Sensory root – Pain or loss of sensation in the face, forehead, temple and eyes. Motor root – affecting the jaw, trouble chewing
VI Abducems: Moves the eyeballs outwards by sending nerve
impulses to the lateral rectus muscles Deviation of the eyes outward; double
vision
VII Facial: (taste, tears, saliva and facial expressions); Mixed: 1. Supplies motor fibers to muscles of facial expression and to the lacrimal and salivary glands. 2. Carries sensory fibers from taste
buds of anterior part of tongue Paralysis of all the muscles in one side of the face, inability to wrinkle the forehead, close the eye, whistle,
deviation of the mouth. Bell’s Palsy
VIII Vestibulocochlear: (acoustic) auditory: Purely sensory;
vestibular branch transmits impulses for sense of equilibrium,
cochlear branch transmits impulses for sense of hearing Deafness or ringing in the ears, dizziness, nausea and vomiting
IX Glossopharyngeal: (swallowing, saliva, taste) Mixed: 1. Motor fibers serve pharynx and salivary glands. 2. Sensory fibers carry impulses from, pharynx, posterior tongue, and pressure
receptor of carotid artery (blood pressure) Disturbance of taste; Difficulty in swallowing
X Vagus: (control of PNS: smooth muscles of GI tract); Sensory and motor impulses for pharynx; a large part of this nerve is parasympathetic motor fibers, which supply smooth muscles of abdominal organs Hoarseness and difficulty swallowing and talking.
This nerve also regulates the heart, blood vessels and digestion
resulting in irregular heartbeat and lowered blood pressure. It regulates the stomach telling it to move food through the digestive system, thus damage can result in decreased digestion and thus
nausea, bloating and vomiting.
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