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What does the metencephalon of the rhombencephalon become?
pons and cerebellum
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What is the appearance of the cerebellum?
laminated, layered appearance
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What are the folds of the cerebellum called?
folia
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What does the cerebellum overlie?
posterior aspect of pons and medulla
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Where does the cerebellum sit?
posterior cranial fossa
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What covers and protects the cerebellum?
tentorium cerebella
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What separates the right and left hemispheres of the cerebellum?
falx cerebelli
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What connects the right and left hemispheres of the cerebellum?
vermis
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What connects the cerebellum to the brainstem?
- superior peduncle
- middle and inferior peduncles
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What does the superior peduncle connect the cerebellum to?
midbrain
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What does the middle peduncle connect the cerebellum to?
pons
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What does the inferior peduncle connect the cerebellum to?
medulla
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What type of structure is the superior peduncle?
predominately an efferent structure of cerebellum (sends out cerebellar messages)
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What type of structures are the middle and inferior peduncles?
predominately afferent structures (take info into cerebellum)
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What are the 3 lobes of the cerebellum?
- anterior lobe
- posterior lobe
- flocculonodular
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What are the parts for the anterior lobe of the cerebellum?
spinocerebellum/paleocerebellum
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What does the anterior lobe do?
- muscle tone maintenance (hypotonia)
- maintenance of posture
- gross voluntary movement (gait)
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What are the the parts of the posterior lobe?
- middle lobe
- pontocerebellum
- neocerebellum
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What does the posterior lobe do?
coordination of fine voluntary movements
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What does damage to the posterior lobe of the cerebellum do?
ataxia and intentional tremor
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What is the largest lobe of the cerebellum?
posterior lobe
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What is the name for the flocculonodular lobe?
archicerebellum
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What does the flocculonodular lobe do?
maintenance of equilibrium
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Where is the flocculonodular lobe?
most inferior portion of the cerebellum
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Do the fibers of the cerebellum project directly from the cerebellum to the spinal cord?
no, therefore, if cerebellum is damaged, the person won't be paralyzed
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What type of matter makes the cerebellar cortex?
gray matter
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How many types of cells are in the cerebellar cortex?
5
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What are the layers of the cerebellar cortex (superficial to deep)?
- molecular
- perkinje
- granular
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What type of matter makes the cerebellar cortex?
white matter
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Are the deep cerebellar nuclei bilateral or unilateral?
bilateral
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What are the deep cerebellar nuclei of the cerebellar cortex (medial to lateral)?
- fastigal
- globose
- emboliform
- dentate nuclei
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Which of the deep cerebellar nuclei of the cerebellar cortex deals with equilibrium?
fastigal
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In the cerebellar cortex, where does information travel?
from cortex to nuclei
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Afferent cerebellar input is primarily via:
middle and inferior peduncles
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What does the cerebellum need to carry out functions?
- constant proprioceptive info
- equilibrium states
- muscle tone in body
- skeletal muscle activity
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What is proprioceptive info?
position sense from mm spindles
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Where is equilibrium state processed?
semi-circular canals
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Where does skeletal muscle activity of the cerebellum come from?
corticospinal and corticobulbar
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Corticospinal:
- cortex to spinal cord
- tell LMN what to do
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Where do the functions of the cerebellum occur?
medial and inferior peduncles
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What do the deep cerebellar nuclei do?
make decisions -send info- from various sources
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What are the efferent cerebellar peduncles?
- superior cerebellar peduncle
- fastigial efferent connections
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Are the superior cerebellar peduncles afferent or efferent?
efferent
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Where does most of the information from cerebellar nuclei pass to leave cerebellum?
superior cerebellar peduncles
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Where does most of the efferent info from the superior cerebellar peduncle go to?
red nucleus in midbrain
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Where is the information in the superior cerebellar peduncle come from?
- 3 of the 4 deep cerebellar nuclei
- dententate
- globose
- emboliform
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What is the red nucleus involved with?
motor tone, influences skeletal mm
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Is the fastigial efferent connection part of superior peduncle?
no, exits by itself
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What uses the fastigial efferent connections?
fastigial nuclei
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What is the fastigial efferent connection?
group of neurons located below superior cerebellar peduncle
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What do fastigial efferent neurons project to?
vestibular nuclei in pons
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What is the vestibular nuclei in the pons involved with?
equilibrium issues
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All information enters cerebellum through:
two peduncles
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What makes decisions in the cerebellum?
cortex and deep cerebellar nuclei
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What sends out info from the cerebellum?
peduncles
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Afferent cerebellar input primarily via middle and inferior peduncles --> cerebellar cortex --> deep cerebellar nuclei --> efferent cerebellar output
- 1. superior cerebellar peduncle
- 2. fastigial efferent projections
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What does the myelencephalon of the rhombencephalon become?
medulla oblongata
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Where is the medulla oblongata?
most caudal portion of brain stem
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What is the medulla oblongata?
rostral continuation of spinal cord
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What is the point that distinguishes the medulla from the spinal cord?
anything above magnum foramen is medulla
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The medulla forms part of the floor of:
4th ventricle
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The medulla is divided into columns by:
anterior and posterior median fissures
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What is the obex?
- on dorsal aspect of medulla
- V-shaped structure formed where 4th ventricle narrows into central canal of spinal cord
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What is the anterolateral sulcus?
- marks lateral limits of the pyramides
- seen as 4 of the CNs associated w/ medulla
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What CNs are associated with the medulla?
- Glossopharyngeal (IX)
- Vagus (X)
- Spinal Accessory (XI)
- Hypoglossal (XII)
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What are the contents of the medulla?
- cranial nerve nuclei
- nucleus gracilis and nucleus cuneatus
- ascending sensory tracts
- descending motor tracts
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Name the cranial nerve nuclei of the medulla oblongata:
- spinal nucleus of V
- inferior salivatory nucleus
- nucleus ambiguus
- dorsal motor nucleus
- hypoglossal motor nucleus
- solitary nucleus
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Is the spinal nucleus of V motor or sensory?
sensory
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Which CN is CN V?
trigeminal
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The spinal nucleus of V descends from which structure?
pons
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What structure does the nucleus of V go into?
medulla
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The spinal nucleus of V is shared by how many CN?
4
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The 4 CN of the spinal nucleus of V all have what in common?
general sensation capabilities
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What CN share the spinal nucleus of V?
- trigeminal
- facial
- glossopharyngeal
- vagus
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Is the inferior salivatory nucleus motor or sensory?
motor
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Which NS is the inferior salivatory nucleus involved with?
parasympathetic system
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Which CN share the inferior salivatory nucleus?
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What is contained within the inferior salivatory nucleus?
preganglionic parasympathetic nuerons involved w/ innervating salivary and mucus glands
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Is the nucleus ambiguus motor or sensory?
motor
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What does the nucleus ambiguus contain?
cell bodies of LMN involved w/ innervation of pharynx, larynx, and soft palate
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Which CN share the nucleus ambiguus?
- glossopharyngeal
- vagus
- spinal accessory
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Is the dorsal motor nucleus motor or sensory?
motor
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Which CN does the dorsal motor nucleus belong to?
vagus
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What does the dorsal motor nucleus contain?
cell bodies of preganglionic parasympathetic neurons involved with innervating visceral structures of thorax, abdomen, and pelvis (lungs, GI, gallbladder, etc)
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What does visceral structures mean?
those with smooth muscle
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Which CNs have:
parasympathetic function
involve motor nuclei
preganglionic parasympathetic neurons?
CN 3, 7, 9, 10
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Is the hypoglossal motor nucleus motor or sensory?
motor
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Which CN is the hypoglossal motor nucleus associated with?
hypoglossal (XII)
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What does the hypoglossal motor nucleus contain?
cell bodies of LMN involved w/ innervating intrinsic and extrinsic mm of tongue
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Is the solitary nucleus motor or sensory?
sensory
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Which CNs is the solitary nucleus involved w/?
CN VII, IX, and X
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What sensory function is the solitary nucleus involved w/?
taste
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Where are the nucleus gracilis and nucleus cuneatus?
- pass through pons and tegmentum as medial lemniscus
- inferior medulla
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Where are 2nd order sensory neurons located?
tegmentum of medulla
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Are the nucleus gracilis and nucleus cuneatus bilateral or unilateral?
bilateral
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What are contained in the inferior medulla?
cell bodies of 2nd order sensory neurons which form medial lemnisci
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What function are the nucleus gracilis and nucleus cuneatus a part of?
conscious proprioception pathway (dorsal column)
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Where do all ascending sensory tracts originate?
spinal cord and medulla
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What do the ascending sensory tracts from the spinal cord and medulla pass through?
tegmentum of medulla
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What are the portions of the ascending sensory tracts (discussed in relation to tegmentum of pons and midbrain)?
- spinal lemniscus
- medial lemniscus
- trigeminal lemniscus
- medial longitundinal fasciculus
- anterior and posterior spinocerebellar tracts
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What do the anterior and posterior spinocerebellar tracts do?
bring unconscious proprioception to cerebellum
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Where do the anterior and posterior spinocerebellar tracts run?
from spinal cord to cerebellum
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What info do the anterior and posterior spinocerebellar tracts conduct?
proprioception (body position sense)
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Where do descending motor tracts go?
spinal cord and medulla
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What do descending motor tracts pass through?
medulla
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Where may the descending motor tracts stop?
at midbrain, pons, or medulla
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What are the major descending motor tracts?
- corticospinal
- corticobulbar
- rubrospinal
- reticulospinal
- corticospinal decussation
- decussation of medial lemniscus
- medullary reticular formation
- inferior cerebellar peduncle
- inferior olivary nuclear complex
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Where does the corticospinal tract begin?
precentral gyrus of cortex w/ UMN
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What does the corticospinal tract pass through?
medulla
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Where does the corticospinal tract go?
ventral horns of spinal cord
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Corticobulbar:
- UMN descend and enter brain stem and stop at some point at a motor nucleus
- mm of head, neck, and face
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Where does the rubrospinal tract run?
from red nuclei into ventral horns of spinal cord
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What is the rubrospinal tract involved with?
skeletal muscle activity
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Is the reticulospinal tract motor or sensory?
both motor and sensory function
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Is the reticulospinal tract mainly motor or sensory?
motor
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Where do the neurons of the reticulospinal tract come from?
reticular formation of brainstem
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Where is the reticular formation?
midbrain, pons, and medulla
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Where does the reticulospinal tract descend to?
spinal cord
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Where does the R/L corticospinal tract decussation occur at?
pyramids in medulla (ventral surface)
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Decussation of medial lemniscus:
where 2nd order sensory neurons originating from nuclei cuneatus and nuclei gracilis decussate (cross over) and form medial lemniscus (ascending)
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What is the medullary reticular formation?
small diffuse nuclei full length of brainstem
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What is the medullary reticular formation a part of?
overall reticular formation associated w/ tegmentum of brain stem
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Inferior Cerebellar peduncle:
- structure which attaches cerebellum to the brainstem
- contains afferent and efferent fibers
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What is the olivary nuclear complex?
large nuclear complex involved w/ cerebellar coordination activities
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What type of fibers does the inferior olivary nuclear complex contain?
both afferent and efferent fibers
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What is the major function of the inferior olivary nuclear complex (motor or sensory)?
motor
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Specific area w/in the medullar are involved with what?
regulation of major physiological activities
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What are the major physiological activities that specific areas w/in the medulla are involved with?
- respiratory center
- cardiovascular center
- vomiting
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respiratory center:
instigates phrenic nn to control diaphragm
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cardiovascular center:
- controls heart rate and blood pressure
- -receives info from multiple system including endocrine system
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Vomiting:
reverse peristalisis
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