Anatomy 3 - Brain Stem Flashcards
What brain vesicle does the medulla make up?
Myelencephalon
T/F: The spinal cord structural orientation is maintained in the medulla
True
What secondary brain vesicles make up the brain stem?
What is not a part of the brain stem in the area?
- Myelencephalon (medulla oblongata)
- Metencephalon (pons, cerebellum)
- Mesencephalon (midbrain)
- > The cerebellum is NOT a part of the brain stem
T/F: The medulla contains ascending (sensory) and descending (motor) fiber tracts that are continuous with ascending/descending fiber tracts of the spinal cord.
True
What does the inferior cerebellar peduncle carry? And what two things does it connect?
- Carries fibers
- Connects cerebellum to spinal cord (body below neck)
The pyramids on the anterior surface of the medulla continue as?
What type of nerve if found here? (Sensory/motor)
- corticospinal tracts
- Somatomotor
What is the decussation of the pyramids? (90%/10%)
- Where 90% of corticospinal tracts from cerebrum will cross and form the lateral corticospinal tract on the contralateral side
- 10% of corticospinal tracts do not cross and form the medial corticospinal tract
Which cranial nerves emerge from the spinal cord in the medulla region?
CN6-12
What region is the inferior olivary nucleus found in?
What type of relay center does it act as?
- Found on the anterior surface of the medulla
- Cerebella relay center for the perception of time
Posterior medulla you will find: (Fasciculus gracilis/cuneatus)
_____ medial
_____lateral
They are associated with that rostral enlargements?
- Fasciculus gracilis medial
- Fasciculus cuneatus lateral
- Nuclei Cuneatus and Gracilis
The open part of the medulla os associated with which ventricle?
4th
What is the area postrema in the medulla?
The floor of the fourth ventricle leading to opening of the central canal
- Vomit center
What do you find in the white matter of the medulla?
ascending and descending tracts of myelinated axons continuous with tracts of the spinal cord
What do you find in the gray matter of the medulla?
Nuclei
What do you find in the caudal half of the medulla? (also called what?)
- Also called the closed medulla
- Find central canal, continuation of spinal cord and has much of the dorsal/ventral organization of the spinal cord white mater
What are the three levels of the medulla cross section anatomy?
- Level of pyramidal decussation
- Level of medial lemniscus decussation
- Rostral half = open medulla
What will you find in the pyramid (cortiospinal) fiber tracts at the level of decussation of the medulla?
Efferent voluntary motor from cerebral cortex to muscles of trunk and appendiges
What will you find in the fasciculus gracilis fiber tracts at the level of decussation of the medulla?
Sensory touch and proprioception from the legs (have not crossed yet)
What will you find in the fasciculus cuneatus fiber tracts at the level of decussation of the medulla?
Sensory touch and proprioception from the arms (have not crossed yet)
What will you find in the spinothalamic tracts fiber tracts at the level of decussation of the medulla?
Sensory pain and temperature from trunk and appendiges
What will you find in the anterior spinocerebellar fiber tracts at the level of decussation of the medulla?
sensory from thoracolumbar ventral horn to cerebellum
What will you find in the posterior spinocerebellar fiber tracts at the level of decussation of the medulla?
sensory from legs to cerebellum
What will you find in the CN 5 spinal trigeminal fiber tracts at the level of decussation of the medulla?
- Nucleus and a tract of CN V
- continuation of spinal cord, dorsal horn, substantia gelatinosa
- Afferent pain and temp of head
What will you find in the decussation of the medial lemniscus of the medulla?
Crossover point for ascending fibers for proprioception and tactile sensation from the nuclei gracilis and cuneatis (dorsal column tracts)
If you have a lesion in the right pyramid at the level of the medial lemniscus decussation of the medulla, will you have motor issues on the RIGHT or LEFT side of the body?
Left Side (the pyramids have crossed already)
What will you find in the medial longitudinal fasciculus (MLF) at the level of the medial lemniscus decussation of the medulla?
- Afferent ascending sensory from vestibular nucleus (balance)
- Descending motor medial vestibulospinal tract
- Tectospinal tract
Name 4 fiber tracts that are continuous from the level of decussation of the pyramids
- CN5 Spinal Tract
- Ant spinocerebellar
- Post Spinocerebellar
- Spinothalamic tracts
What will you find in the accesory cuneate nucleus at the level of the medial lemniscus decussation of the medulla?
associated with the cuneocerebellar (arms) tract
What will you find in the reticular formation at the level of the medial lemniscus decussation of the medulla?
- Modulates sensory signaling to cortex
- Modulates motor signaling (reticulospinal tracts)
- Autonomic activity
- sleep/wake
- emotions
What will you find in the inferior olivary nuclei at the level of the medial lemniscus decussation of the medulla?
Associated with cerebellum (time perception)
What will you find in the nucleus ambiguous at the level of the medial lemniscus decussation of the medulla?
CN 9/10 for swallowing (motor)
The canal is replaced by what at the open medulla/rostral half of the medulla?
Replaced by the 4th ventricle
As you move rostrally from the spinal cord,
____ is continuous of the ventral horn
____ is continuous of the dorsal horn
- Basal plate is continuous from the ventral horn (contains motor nuclei)
- Alar plate is continuous with the dorsal horn (contains sensory nuclei)
What sulcus splits the Alar and the basal plates?
Sulcus limitans
What CN is in the most medial basal plate nucleus?
Hypoglossal nucleus: CN 12 - somatomotor to skeletal muscle of tongue
What CN is in the second most medial basal plate nucleus?
Nucleus ambiguous - CN 9/10
special visceral efferent to skeletal m of larynx and pharynx for swallowing
What is the most lateral basal plate nucleus?
Dorsal motor nucleus:
CN10 = parasympathetic
Inferior salivatory nucleus (CN 9 to parotid parasympathetic)
What is the floor of the 4th ventricle laterally?
Alar plate containing sensory nuceli (vestibular and solitary nuclei)
What is the most medial alar plate?
Solitary nucleus:
- viscerosensory from CN 9/10 for cardiovascular and respiratory input (carotid body and sinus)
- special sensory for taste cn 7, 9, 10
what is the second most medial alar plate?
Spinal nucleus of CN 5 - general somatic afferent for somatosensory (pain and temp) of head
what is the second most lateral alar plate?
Vestibular nuclei of CN 8 (inferior and medial)
- special sensory afferent for balance
What is the most lateral alar plate?
Cochlear Nucleus of CN 8
- Special sensory afferent for auditory
What will you find in the inferior cerebellar peduncle of the open medulla?
Afferent to cerebellum from spinal cord and medulla oblongata
What will you find in the medial longitudinal fasciculus (with the tectospinal tract) of the open medulla?
Coordinates movement of eyes and body with vestibular input for overall balance/equilibrium
What will you find in the medial lemniscus of the open medulla?
Cuneatus and gracilis have merged
What will you find in the inferior olivary nucleus of the open medulla?
Involved in relaying signals to cerebellum
What is the ventral surface of the pons called?
Basilar Pons
What is the dorsal surface and floor of 4th ventricle called?
Pontine tegmentum
What will you find in the transverse pontine (pontocerebella) of the basilar pons?
Relay afferent signals to cerebellum via middle cerebellar peduncle
What will you find in the corticospinal and corticobulbar fiber tracts of the basilar pons?
Corticospinal - somatomotor from precentral gyrus to body
Corticobulbar - somatomotor from precentral gyrus to head
What will you find in the facial colliculus of the tegmental pons?
CN 7 fibers
What will you find in the superior cerebellar peduncle of the tegmental pons?
efferent fibers from cerebellum to brain stem and cortex
What will you find in the middle cerebellar peduncle of the tegmental pons?
afferent fibers from cortex
What will you find in the inferior cerebellar peduncle of the tegmental pons?
afferent fibers from medulla and spinal cord to brain stem
What will you find in the trigeminothalamic of the tegmental pons?
afferent somatosensory from head to cortex
What will you find in the lateral lemniscus of the tegmental pons?
auditory relay circuit to inferior colliculus for auditory reflex movement of head
What will you find in the rubrospinal tract of the tegmental pons?
efferent motor to arms
What will you find in the tectospinal tract of the tegmental pons?
efferent motor to neck/shoulders
What will you find in the spinal nucleus tract of CN 5 of the tegmental pons?
descending limbic and hypothalamic fibers to autonomic control centers in medulla and spinal cord
Nuclei of the caudal pons:
Facial nucleus CN 7
muscles of facial expression
Nuclei of the caudal pons:
abducens nucleus CN 6
eye muscles (lateral rectus)
Nuclei of the caudal pons:
Spinal trigeminal nucleus cn 5
pain/temp from face
Nuclei of the caudal pons:
superior olivary nucleus
relay in auditory pathway
Nuclei of the caudal pons:
trapezoid body
relay in auditory pathway
Nuclei of the caudal pons:
medial/inferior vestibular nucleus (also found where?)
Also in medulla
Nuclei of the caudal pons:
superior salavatory nucleus
fibers are part of cn 7 to lacrimal, submandibular, and sublingual salivary glands
Nuclei of the rostral pons:
main sensory nucleus of CN 5 (continuation of what)
continuation of spinal trigeminal nerve
Nuclei of the rostral pons:
motor nucleus of CN 5
to muscles of mastication
Nuclei of the rostral pons:
mesencephalic nucleus CN 5
proprioception of jaw
Nuclei of the rostral pons:
locus ceruleus
part of reticular formation (Norepinephrine)
pain modulation
Nuclei of the rostral pons:
raphe nucleus
part of reticular formation (serotonin)
pain modulation
Lateral lemnicus, medial lemniscus, trigeminothalamic, and spinothalamic merge where and go where?
Merge at the rostral pons and carry somatosensory to post central gyrus
What are the 3 layers of the midbrain (mesencephalon)?
Dorsal = tectum intermediate = tegmentum ventral = crus cerebri
The cerebral peduncles are a combination of what two layers of the midbrain?
Cerebral peduncles = crus + tegmentum
What layer of the midbrain is the superior colliculi found and what does it do?
- Dorsal layer (tectum)
- Visual reflex (head turn)
What layer of the midbrain is the inferior colliculi found and what does it do?
- Dorsal layer (tectum)
- Auditory head turn
T/F the corpora quadrigemina is found in the dorsal layer (tectum) of the midbrain
True
T/F the Tegmentum is continuous of the pontine tegmentum
True
What do you find in the crus cerebri, the ventral layer of the midbrain?
Somatomotor
Corticobulbar and spinal tracts
What connects the 3rd and 4th ventricles?
Cerebral aqueduct
What is the tectum mostly composed of?
Corpora quadrigemina
What is the posterior commissure located in the tectum layer of the midbrain?
Posterior commissure - located rostral by CN 3 nuclei
- Coordinates eye movements
What two tracts end when moving from the tegmentum at the level of the inferior colliculus to the level of the superior colliculus?
- Decussation superior cerebellar peduncle
- Lateral lemniscus (afferent to inferior colliculus for auditory reflex)
T/F the crus cerebri at the level of the inferior colliculus is equal to the level of the superior colliculus
True
What do you find in the most lateral segment of the crus cerebri of the midbrain?
Parietal, temporal, and occipital cortex to pontine nuclei/cerebellum
What do you find in the most medial segment of the crus cerebri of the midbrain?
Frontal lobe to pontine nuclei/cerebellum
What segment is the 2nd most lateral segment of the crus cerebri of the midbrain?
Corticospinal tract
What segment is the 2nd most medial segment of the crus cerebri of the midbrain?
corticobulbar tract
What do you find in the inferior colliculus of the tectum of the midbrain?
Auditory reflex
Afferent input - cochlear, superior olivary, trapezoid nuclei via lateral lemniscus
Efferent output - to thalamus via brachium of inferior colliculus
What do you find in the superior colliculus of the tectum of the midbrain?
Visual reflex
Afferent - from retina
Efferent - to cervical spine via tectospinal for head turning and tracking
What do you find in the pretectal region of the tectum of the midbrain?
Located rostral to superior colliculus
- papillary light reflex
What do you find in the substantia nigra of the tegmentum of the midbrain at the level of the inferior colliculus?
Substantia nigra - part of basal ganglia (motor)
What do you find in the periaquiductal gray (PAG) of the tegmentum of the midbrain at the level of the inferior colliculus?
PAG - Autonomic regulation, emotion, and modulation of pain
What do you find in the trochlear nerve nuclear CN 6 of the tegmentum of the midbrain at the level of the inferior colliculus?
Eye movement superior oblique muscle (down and medial)
What do you find in the reticular formation of the tegmentum of the midbrain at the level of the inferior colliculus?
Including raphe nuclei
What do you find in the occulomotor n nucleus CN 3 of the tegmentum of the midbrain at the level of the superior colliculus?
Somatomotor - superior rectus, medial rectus, inferior rectus, and inferior oblique (lavator palpebrae)
Autonomic motor - iris constriction, ciliary muscle for accommodation
What do you find in the red nucleus of the tegmentum of the midbrain at the level of the superior colliculus?
Motor modulation flexor muscles via rubrospinal tract
What do you find in the ventral tegmental area of the tegmentum of the midbrain at the level of the superior colliculus?
Part of basal ganglia motor modulators