Lecture 13- Brainstem 1 Flashcards
What are the 3 parts of the brainstem?
medulla, pons, midbrain
What are the two parts of the metencephalon?
cerebellum and pons
What is the mesencephalon?
midbrain
What is the myelincephaon?
Medulla
What is the tegmentum?
the core of the brainstem made of small nucleui and tracts
Where do norepinephric fibers to the cortex originate?
locus coeruleus
Where is the locus coeruleus found?
in the pontine reticular formation
Where do serotonergic fibers from the brainstem originate?
raphe nuclei
What are the external bulges caused by the nucleus cuneatus and gracilis called?
tuberculum gracilis and tuberculum cuneatus
Where is the olive seen on the exterior?
rostral medulla
What internal structure causes the lateral protusion called the olive found at the rostral medulla?
inferior olivary nucleus
Where do the pontine nuclei project?
to the cerebellum (pontocerebellar tract) via the middle cerebellar peduncle
What fibers travel in the middle cerebellar peduncle?
pontocerebellar fibers traveling from the pontine nuclei to the cerebellum
What is found on the dorsal side of the midbrain?
superior and inferior colliculi (the tectum)
What is found on the ventral side of the midbrain?
cerebral peduncles
What types of fibers are found in the cerebral peduncles?
descending motor fibers of the corticospinal and corticobulbar tracts
What is the function of the thalamus?
to relay somatosensory, visual and auditory information to the cortex
What type of information does the medial geniculate body/nucleus receive?
auditory fibers from the inferior colliculus
What type of information does the lateral geniculate body/nucleus receive?
visual from the superior colliculus
Where does the medial lemniscus terminate?
Ventral posterolateral Nucleus of the thalamus
Where does the Ventral Posteromedial (VPM) Nucleus receive information from?
somatosensory info from the face (trigeminal nerve)
What does the central canal of the spinal cord become in the medulla?
fourth ventricle
What passageway connects the third and fourth ventricles?
cerebral aqueduct
How does CSF pass through the midbrain?
via the cerebral aqueduct
What does the fourth ventricle become in the midbrain?
cerebral aqueduct
What are the 3 tracts associated with cranial nerve nuclei in the brain stem?
Tractus Solitarius
Spinal (Descending Tract of V)
Mesencephalic Tract of V
What are the 3 cranial nerves associated with Tractus Solitarius?
VII- Facial
IX- Glossopharyngeal
X- Vagus
What are the 4 brain stem nuclei associated with the trigeminal nerve?
Motor Nucleus of V
Main Sensory Nucleus of V
Spinal (descending) Nucleus of V
Mesencephalic Nucleus of V
What is unique about the mesencephalic nucleus of V in comparison to the 3 other brain stem nuclei associated with CN V?
it is a 1st order nucleus where as the others are 2nd order nuclei receiving input from the trigeminal ganglion
What 3 brainstem nuclei are associated with the vagus nerve (CN X)?
Dorsal Motor Nucleus of X
Ventral Motor Nucleus of X (Nucleus Ambiguus)
Nucleus of Tractus Solitarius
What muscle is controlled by the abducens nerve (VI)?
lateral rectus
What muscle is controlled by the trochlear nucleus?
superior oblique muscle
Which nuclei is associated with the function of the jaw muscles?
Motor nucleus of V
What nucleus is associated with pain and temperature in the face?
Spinal Nucleus of V
What parasympathetic nucleus is associated with control of the constrictor pupillage muscle of the iris?
Edinger-Westphal Nucleus (CN III)
What is the purpose of the mesencephalic nucleus of V?
muscle sense of jaw muscles-neurons innervation muscle spindles
Which Cranial Nerves do NOT arise from the brainstem?
I- Olfactory
II- Optic
Which cranial nerve exits from the walls of the interpeduncular fossa between the two cerebral peduncles?
CN III- Oculomotor
What are the 4 voluntary muscles innervated by the oculomotor nerve?
inferior oblique, medial, inferior and superior oblique
What is the only cranial nerve to emerge from the dorsal aspect of the brainstem?
trochlear nerve (CN IV)
What cranial nerve exits just caudal to the inferior colliculus at the junction of the pons and midbrain?
trochlear nerve (CN IV)
What would a lesion in the nucleus of the trochlear nerve result in?
loss of function of the superior oblique in the CONTRALATERAL eye
What type of nerurons does the motor nucleus of V contain?
alpha motor neurons
What happens to fibers after exiting the main sensory nucleus of V?
cross the midline to join the medial edge of the medial lemniscus and project to the VPM of the thalamus
Where are the motor nucleus and main sensory nucleus of V located?
pons
Where is the nucleus of the spinal (descending) tract of V?
pons, rostral and caudal medulla
What type of information does the spinal nucleus of V receive?
pain and temp from face (project to contralateral VPM)
What does Lissauer’s tract merge with at the spinomedullary junction?
spinal (descending) tract of V
Which cranial nerve nuclei is found in the lateral wall of the rostral 4th ventricle and cerebral aqueduct?
mesencephalic tract of V
Where do the central axons from the neurons of the mesencephalic nucleus of V project?
motor nucleus of V (also to spinal nucleus of V)
Which cranial nerves emerge from the midbrain?
III- oculomotor (ventrally)
IV- trochlear (dorsally)
Where does cranial nerve V emerge from the brainstem?
rostral pons
What 3 cranial nerves emerge from the pontomedullary junction?
VI- Abducens
VII- Facial
VIII- Vestibulocochlear
Where is the abducens nucleus located?
caudal pons (superiolateral to MLF)
Where is the motor nucleus for the facial nerve located?
caudal pons (inferiolaterally to spinal nucleus and tract of V)
What is unique about the fibers that emerge from the motor nucleus of the facial nerve?
they run dorsally and loop around the nucleus of VI before running ventrolaterally to exit at the pontomedullary junction just lateral to CN VI
What is the name of the tract that fibers from the cochlear nucleus run to the superior olivary nucleus?
trapezoid body
Which cranial nerve exits medially on the ventral side of the medulla between the pyramids and the olive?
hypoglossal (XII)
Which 4 cranial nerve exit the medulla?
IX- Glossopharyngeal
X- Vagus
XI- Accessory
XII- Hypoglossal
Where is the nucleus of the solitary tract located?
rostral medulla
What information does the nucleus of the solitary tract receive?
taste- VII, IX, X
GVA- IX, X
Where do the fibers of the nucleus of the solitary tract project?
- taste to the thalamus
- GVA info to dorsal motor of X (visceral reflexes)
Which nucleus contains preganglionic parasympathetic neurons that innervate the heart?
dorsal motor nucleus of X (vagus)
What is the function of the fibers that exit the ventral motor nucleus of X (nucleus ambiguous)?
innervate muscles of the larynx, pharynx and the soft palate
Where is the hypoglossal nucleus located?
rostral medulla
Which three nuclei are found in the caudal medulla?
nucleus gracilis, nucleus cuneatus, external cuneate nucleus
Where does the external cuneate nucleus receive input from?
cuneocerebellar tract, afferents from DRG that innervate muscle spindles and golgi tendon organs above C8
Where do the neurons of the interior olivary nucleus receive input from?
red nucleus and spinal cord
Where do the neurons of the inferior olivary nucleus project?
to the cerebellum via the inferior cerebellar peduncle
Where do neurons of the pontine nuclei send their projections?
to the contralateral cerebellar hemisphere via the middle cerebellar peduncle
What is the name of the the tract that is formed by fibers emerging from the superior olivary nucleus projecting to the inferior colliculus?
lateral lemniscus
Where is the substantia nigra located?
midbrain just internal of the fibers of the cerebral peduncle
Where do fibers of the inferior colliculus project? What type of information do they contain?
Medial geniculate nucleus/ body (hear ME)
auditory information
What CN has fibers that terminate in the superior colliculus?
optic nerve (CN II)
Where is the red nucleus located?
midbrain
Where in the brain stem does CN terminate?
superior colliculus (midbrain)
