Internal Anatomy of the Medulla Flashcards
What nuclei and nerves are found in the medulla?
Neural circuits regulating respiration, blood pressure, and cardiac rhythm, as well as nuclei of CN 8 - 12. The spinal nucleus of the trigeminal nerve also receives sensory information from the head via several cranial nerves (CN 5, 7, 8, 10)
The Medial longitudinal fasciculus runs throughout the brainstem, what are its functions?
It coordinates eye and head movements. It interconnects the superior colliculus, vestibular nuclei, CN 3,4,6 and the cervical spinal cord.
The spinal nucleus of the trigeminal nerve (CN5) is present in what structures of the brain?
Both Medulla and pons. The caudal portion in the medulla is related to pain, temperature and touch from the head.
There is a large motor crossing in the medulla at the pyramidal decussation, what do these axons continue as? Damage rostral to the decussation would cause what? Caudal to the decussation?
They descend as the lateral corticospinal tract. Rostral damage would result in contralateral motor loss while caudally it would be ipsilateral.
What are symptoms of damage to the corticobulbar tract?
Contralateral effects (in the medulla the major example is the projection to CN XII)
The gracile and cuneate fasciculi synapse in their respective nuclei and then cross the midline, after crossing the midline what are they called?
The medial lemniscus.
Does the medial lemniscus have somatotopy? What does damage to the medial lemniscus cause?
Yes, the neck to foot somatosensory information is mapped from dorsal to ventral within the medial lemniscus. Damage results in epicritic deficits on the opposite side of the body.
The cerebellar peduncle is in the medulla, what would damage to this structure cause?
(an infarct of the PICA could cause this) Ataxia and intention tremor of the extremities on the ipsilateral side of the body. Patients lean to the side of lesion and have clumsiness and a tremor while using the ipsilateral hand
The nucleus ambiguous is a long thin column of motor neurons that occurs at most levels of the medulla, what are the symptoms of a lesion in this structure?
Unilateral damage to this nucleus will result in hoarseness, impaired swallowing, and asymmetry of the soft palate. Bilateral paralysis (as in ALS) will prevent closure of the trachea and result in choking and aspiration of fluid in the lungs.
At the transition between the pons and medulla are the dorsal and ventral cochlear nuclei on the external cerebellar peduncle. What would damage to these structures cause?
Damage to these nuclei or to the auditory portion of CN8 result in deafness of the ipsilateral ear. Damage to the vestibular nuclei or nerve results in nystagmus, vertigo, and problems with balance.
What does damage to the dorsal and ventral cochlear nuclei cause?
Damage to these nuclei or to the auditory portion of CN8 result in deafness of the ipsilateral ear.
What does damage to the vestibular nuclei or nerve cause?
Nystagmus, vertigo, and problems with balance.
What cranial nerves are most diagnostic for pathology of the medulla?
CN 8 -12
In the medulla what would a lesion to CN 8 cause?
Deafness in the ipsilateral ear, nystagmus, vertigo, and problems with balance
In the medulla what would a lesion to CN 9 cause?
Loss of the gag reflex on the side of the oropharynx of the nerve injury (afferent loss to the solitary nucleus)
