Peripheral and Autonomic Nervous System
Damage to CN 5 would produce what injury?
Inability to masticate (chew food (trigeminal)).
Damage to CN 12 would produce what injury?
Inability to move the tongue (hypoglossal)
Damage to CN 2 would produce what injury?
Inability to see (optic)
Damage to CN 9 and 10 would produce what injury?
Inability to swallow (glossopharyngeal and vagus).
CN VIII: Vestibulocochlear nerve
-Equilibrium (vestibular branch); hearing (cochlear branch) -Sensory
CN III: Oculomotor nerve
-Motor to four of six extraocular muscles and the upper eyelid; changes the diameter of the pupil; changes the shape of the lens. -Motor
CN V: Trigeminal nerve
-Motor to muscles of mastication; sensory to the face. -Both sensory and motor
CN XI: Accessory Spinal nerve
-Motor to muscles that move the head and shoulders; motor to muscles of swallowing. -Motor
CN VI: Abducens nerve
-Motor to the lateral rectus muscle -Motor
CN IV: Trochlear nerve
-Motor to the superior oblique muscle -Motor
CN XII: Hypoglossal nerve
-Movement of the tongue during speech and swallowing. -Motor
CN I: Olfactory nerve
-Sense of smell -Sensory
CN X: Vagus nerve
-Swallowing and speech; taste to pharynx; parasympathetic innervation to viscera. -Both sensory and motor
CN IX: Glossopharyngeal nerve
-Taste to posterior third of the tongue; motor to muscles of swallowing and speech; stimulates salivation -Both sensory and motor
CN VII: Facial nerve
-Taste to the anterior half of the tongue; motor to the muscles of facial expression; stimulates lacrimal and salivary glands. -Both sensory and motor
CN II: Optic nerve
-Vision -Sensory
Sometimes the terms "neuron" and "nerve" are mistakenly used interchangeably. Explain the difference between the two structures.
A neuron is a cell that communicates with other cells via action potentials propagated down their axons. A nerve is a bundle of axons and surrounding connective tissue sheaths.
Which cranial nerve is a purely motor nerve?
Hypoglossal nerve.
The herbal supplement bitter orange, also known as synephrine, mimics the effects of the neurotransmitters of the SNS on the heart and blood vessels serving the abdominal viscera and skin. What effect do you think this would have on blood pressure? Considering this, do you think this drug should be given to people with hypertension (high blood pressure)?
Synephrine causes an increase in the rate and force of contraction of the heart and constriction of the blood vessels supplying the abdominal viscera and skin. This raises blood pressure, and so would not be recommended for people with hypertension.
Your patient, Mr. Pratchett, is unable to open his eyelid. On examination, you find that his pupil is dilated, and he is unable to move his affected eye in any direction except laterally and downward, indicating that only his lateral rectus and superior oblique extrinsic eye muscles are functioning. Based on this information, which cranial nerve do you think is involved in Mr. Pratchett's condition? Explain your reasoning.
The cranial nerve likely involved is cranial nerve III, the oculomotor nerve. This nerve innervates the four extrinsic eye muscles that are not functioning, and it also innervates the muscle that constricts the pupil, which could explain why his pupil is dilated.
Dave was playing a hockey game when he was hit in the face by a puck. He suffered a broken nose during the injury and now finds that his sense of smell has diminished. What is likely causing this?
The fracture likely affected the cribriform plate, through which the fibers of CN I pass on their way to synapse on the olfactory bulb. The fracture of the plate likely damaged some of the axons of CN I, which has resulted in his diminished sense of smell.
What are the three branches given off by a spinal nerve, and where do they travel?
The posterior rami serve the skin, joints, and musculature of the posterior trunk. The meningeal branches serve the spinal structures in the vertebral cavity. The anterior rami travel anteriorly to supply the trunk and upper and lower limbs.
The structure where the optic nerves meet and partially exchange axons is called the...
optic chiasma.
