5 - Brainstem Structure and Cranial Nerve Nuclei Flashcards
Name each blackened label?
What are the three general areas of the brainstem in a cross-section?
The portion posterior to the ventricular space (blue)
The portion anterior to the ventricular space (green)
Additional structures on the anterior surface (red)
What are the three functions of the brain stem?
Integrative functions
Cranial nerve functions
Conduit functions
Describe the integrative funcitons of the brainstem?
They’re performed by a diffuse nucleus within the core of the brainstem - the reticular formation (yellow) ; this helps to regulate consciousness and contain respiratory and CV centers.
Describe the conduit function of the brainstem?
It serves as a conduit for ascending sensory and descending motor tracts.
What is the motor funciton of the brainstem? What tract does this?
Corticosplinal tract (green) - voluntary movement of limbs
What are the sensory functions of the brainstem? What tracts do this?
Spinothalamic tract (red) - transmits pain and temp information to the brain
Posterior column / Medial Lemniscus (pink) - transmits touch, vibration, pressure, and proprioception to the brain
What are the cranial nerve functions of the brainstem?
Cell bodies of neurons clustered in “nuclei” throughout the brainstem which serve as the origins of motor CNs or as the terminations of sensory CNs.
Describe the developent of the brainstem nuclei?
- NS developes from neural tube
- Neural tube has basal plate (motor) and alar plate (sensory) divided by sulcus limitans
- Brainstem development is similar to spinal cord development
How does the NS develop from the neural tube?
Neural folds come up to make neural crests that eventually meet to form a neural tube that extends.
What are the sensory and motor portions of the spinal cord derived from?
The basal plate (motor) and the alar plate (sensory), which is divided by the sulcus limitans.
Describe the brainstem development?
It’s similar to the development of the spinal cord.
Instead of maintaining the tube-like structure like the sp cd, it opens up and unfolds.
Basal plate stays medial and sensory (alar) plate goes more laterally.
Where are the motor and sensory nuclei each found in the brainstem?
Motor is medial
Sensory sides
Which cranial nerves emerge form the midbrain and above?
Cranial nerves 1-4
What cranial nerve emerges at the mid-pons level?
The trigeminal nerve (V)
Which cranial nerves exit at the level of the pons?
Cranial nerves 5-8
Which cranial nerves exit at the level of the medulla?
Cranial Nerves 9-12.
What are cranial nerve nuclei?
Clusters of cell bodies WITHIN the brainstem (bilaterally)
Where would you find the nuclei of somatic motor neurons?
Motor neurons are in the medial portion of brainstem (red portions).
Where would you find nuclei of visceral motor neurons in the brainstem?
Near the medial portion of the brainstem (yellow).
Examples include: edinger-wesphal nucleus, salivatory nucleus, and dorsal motor nucleus of X.
Where would you expect to see visceral sensory, somatic sensory, and special sensory nuclei in the brainstem?
More laterally within the brain stem (green, blue, purple).
Examples include the rostral and caudal nucleus solitarius (gustatory), the trigeminal nuclei, the cochlear nuclei, and the vestibular nuclei.
Which cranial nerve is located within the interpeduncular fossa?
CN III - oculomotor
What is located within the midbrain?
Tectum, tegmentum, cerebral aqueduct, CN III, and CN IV
Label the parts of the midbrain
Label each nucleus
Oculomotor nucleus (red) - medial for motor on the top picture
Trochlear nucleus (red) - medial for motor on bottom picture
Edinger Westphal nucleus (yellow) - medial for motor
Corticospinal tract (green) - located in the crus cerebri
Medial lemniscus (pink) - sides for sensory
Spinothalamic tract (red) - sides for sensory
What structure is circled and what runs through it?
The red nucleus, and strands of what will make up the oculomotor nerve run through it.
What structures are located in the pons?
The middle cerebellar peduncle
4th ventricle
CNs V, VI, VII, and VIII
What is each pathway depicted here with color?
Corticospinal tract (green) - broken into clusters anteriorly
Medial lemniscus (pink) - medial
Spinothalamic tract (red) - lateral (top picture)
Abducens nucleus (red) - medial motor (bottom picture)
Facial nucleus (orange) - medial motor
Lateral vestibular nucleus (purple) - sides sensory
What structures / spaces are located near the medulla?
The 4th ventricle
Olives
Medullary pyramids (CST)
CNs IX, X, XI, and XII
What nucleiu is associated with each color?
Corticospinal tract (green) - medullary pyramids
Medial lemniscus (pink)
Spinothalamic tract (red) - lateral cornor of tegmentum
Hypoglossal nucleus (red) - medial motor
Dorsal motor nucleus of X (yellow)
Nucleus ambiguous (glossopharyngeal and stuff for pharynx/larynx) (organge)
Vestibular nuclei (purple) - sensory sides
What is the blood supply to the midbrain cerebral peduncle? What syndrome is this associated with if there’s a loss of blood flow or a lesion to this region?
PCA
Weber’s syndrome
What is the blood supply to the medial pons? What syndrome is associated with a lesion or loss of blood flow to this area?
Basilar artery
Medial pontine syndromes
What is the blood supply to the lateral pons? What syndrome is associated with a lesion or loss of blood flow to this area?
Superior cerebellar artery (rostral) or AICA (caudal)
Lateral pontine syndromes
What is the blood supply to the medial medulla? What syndrome is associated with a lesion or loss of blood flow to this area?
Vertebral artery or anterior spinal artery.
Medial medullary syndrome.
What is the blood supply to the lateral medulla? What syndrome is associated with a lesion or loss of blood flow to this area?
The vertebral artery or PICA.
Lateral medullary syndrome.
A patient presents with paralysis and impaired sensation from the left side of her body. These problems do not affect her face. Ultimately she exhibits paralysis and atrophy of the right half of her tongue. Explain where her lesion is and what artery probably had an infarct?
Problem with her tongue indicates a defect in the nuclei of the hypoglossal nerve, which would be located within the medulla.
Sure enough, this patient has a lesion of her right medulla from an infarct in her anterior spinal artery that caused her symptoms on the contralateral side (because the decussation already occured).
