Intro to Brainstem II Flashcards
The Rule of 4 of the brainstem
?
General guides for localization of brainstem lesions
The long tracts serve as “meridians of longitude” whereas the cranial nerves serve as “parallels of latitude”.
Your goal is to establish where they intersect on your patient.
Most long tract lesions in brainstem will be contralateral; most cranial nerve signs will be ipsilateral to the lesion.
Your patient presents with contralateral weakness and contralateral loss of vibration/proprioception in arms and legs.
You suspect:
brainstem lesion but this could be anywhere in brainstem above caudal medulla. It doesn’t tell you midbrain, pons or rostral medulla.
Check cranial nerves for leve
Midbrain: 3, 4
Pons: 5, 6, 7, 8
Medulla: 9,10,11,12
Midbrain CN
3, 4
Pons CN
5, 6, 7, 8
Medulla CN
9,10,11,12
Cranial nerve NUCLEI locations in the brainstem
Midbrain
III
edinger westphal nucleus
IV
Cranial nerve NUCLEI locations in the brainstem
Pons
V Mesencephalic nucleus of V Primary Motor Nucleus of V Main Sensory nucleus of V Spinal nucleus of V (at caudal pons) VI VII VIII (cochlear nucleus and vestibular nucleus at pontomedullary junction)
Cranial nerve NUCLEI locations in the brainstem
Medulla
IX (nucleus of solitary tract)
X (nucleus of solitary tract, dorsal motor nucleus of vagus and ventral motor nucleus of vagus aka nucleus ambiguous)
XII (hypoglossal nucleus)
(Spinal nucleus of V is here too)
(LR6SO4)3
CN 3 does everything but
Lateral Rectus
Superior oblique
CN 3 is between
superior cerebellar (below) and posterior cerebral arteries
Uncus herniation hurts
CN 3
Cranial nerve NUCLEI
collection of neurons (gray matter) in the brain stem that is associated with one or more cranial nerves.
Axons carrying information to and from the cranial nerves form a synapse first at these nuclei.
Lesions occurring at these nuclei can lead to effects resembling those seen by the severing of nerve(s) they are associated with.
All the nuclei except that of the trochlear nerve (CN IV) supply nerves of the same side of the body.
All the nuclei except that of the ______ supply nerves of the same side of the body.
trochlear nerve (CN IV)
Mesencephalic nucleus of V
Primary Motor Nucleus of V
Main Sensory nucleus of V
Spinal nucleus of V (at caudal pons)
Trigeminal Nerve
The _______ is involved with proprioception of the face, that is, the feeling of position of the muscles.
mesencephalic nucleus