Lecture 13: Brainstem, Nuclear Organization Flashcards
What is the difference of organization of spinal cord vs. brainstem?
Spinal cord has motor neurons ventrally and sensory neurons dorsally
Brainstem has motor neurons medially and sensory neurons laterally
So brainstem rotated 90 degrees
Sulcus limitans
marked the separation between motor and sensory neurons in spinal cord and brain stem
Functional columns
columns of cranial nerve nuclei in brainstem
In brainstem, how are the functional columns organized?
- 3 motor functional columns
- 3 sensory functional columns
Column 1 (most medial, GSE)
Skeletal muscle of myotomes
Exits medially
What nuclei does column 1 contain
Oculomotor nuclei
Trochlear nuclei
Abducens Nuclei
Hypoglossal Nuclei
Why are there crossed neurons coming from the oculomotor nuclei and trochlear nuclei?
The ones in oculomotor nuclei that are crossing only go to the SUPERIOR rectus
- so superior oblique and superior rectus are cross-innervated
- similarities between the two muscles
Column 2 (GVE)
PARASYMPATHETICS
exit point not touched upon in lecture
What nuclei does column 2 contain?
Edinger-Westphal nucleus (parasympathetic of oculomotor; ciliary ganglion; dilates pupil)
-functions as motor limb of light reflex and near response (accommodation)
superior salivatory nucleus = CN VII
-innervates lacrimal gland, submandibular and sublingual glands
Inferior salivatory nucleus = CN IX
-innervates parotid gland
-synapse in the otic ganglion
Dorsal motor nucleus of vagus = CN X
-responsible for innervation of thoracic and abdominal
-not involved in head and neck!
What does loss of light reflex and near response indicate?
Loss of edinger-westphal nucleus (CN III) because parasympathetics mediate the motor portion of those responses
What does loss of lacrimation mean?
Loss of Superior Salivatory nucleus, or loss of CN VII parasympathetics
What does loss of parotid gland function mean?
Hard to tell but it means a CN IX lesion
Column 3 (SVE)
muscles of facial expression and throat control; migrated medial to lateral
Exits ventrolaterally
What nuclei does column 3 contain?
motor nucleus of V (mastication)
motor nucleus of VII (facial expression)
Nucleus Ambiguus (IX, X) palate, pharynx and pharynx muscles
Parasympathetic nerves (that should be in dorsal motor nucleus of vagus) is present in nucleus ambiguous (so it has both motor and parasymp as well)
Column 4 (SVA)
Solitary Nucleus
-represents the fusion of functional columns SVA and GBA
-visceral sensory nucleus
-SVA = gustatory nucleus = taste = 7, 9, 10
-GVA = cardiorespiratory nucleus = carotid sinus, carotid body = self-regulates change blood in pressure and pH
Crosstalk to with dorsal motor nuclei in column two in order to control heart rate, etc. (since DMX controls parasympathetics of thoracic)