Cranial Nerve Nuclei
Cranial Nerve Nuclei
CHAPTER OBJECTIVES
To learn the basic information regarding the motor and sensory nuclei of the cranial nerves, including their locations and central connections
A forty-nine-year-old man wakes up one morning to find the right side of his face paralyzed. When examined by his local medical practitioner, he is found to have complete paralysis of the entire right side of the face. He is also found to have severe hypertension. The patient talks with slightly slurred speech. The physician tells the patient that he has suffered a mild stroke, and he is admitted to the hospital.
The patient is later seen by a neurologist who disagrees with the diagnosis. The original physician grouped together the facial paralysis, the slurred speech, and the hypertension and, in the absence of other findings, made the incorrect diagnosis of cerebral hemorrhage. A lesion of the corticonuclear fibers on one side of the brain
CRANIAL NERVES
CRANIAL NERVES
The twelve pairs of cranial nerves leave the brain and pass through foramina and fissures in the skull. All the nerves are distributed in the head and neck, except cranial nerve ten, which also supplies structures in the thorax and abdomen. The cranial nerves are named as follows:
One. Olfactory
Two. Optic
Three. Oculomotor
Four. Trochlear
Five. Trigeminal
Six. Abducens
Seven. Facial
Eight. Vestibulocochlear
Nine. Glossopharyngeal
Ten. Vagus
Eleven. Accessory
Twelve. Hypoglossal
See Atlas Plates one, six, and eight.
Understand the functional ramifications of lesions to cranial nerve nuclei versus damage of the cranial nerve proper will cause paralysis only of the muscles of the lower part of the opposite side of the face. This patient has complete paralysis of the entire right side of the face, which could only be caused by a lesion of the lower motor neuron. The correct diagnosis was Bell palsy, an inflammation of the connective tissue sheath of the facial nerve, which temporarily interfered with the functions of the axons of the right facial nerve. This case provides a good example of how knowledge of the central connections of a cranial nerve enables a physician to make the correct diagnosis.
The cranial nerves are commonly damaged by trauma or disease, and testing for their integrity forms part of every physical examination.