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