5 - Brainstem Structure and Cranial Nerve Nuclei

Question 1

Name each blackened label?

Answer 1

Question 2

What are the three general areas of the brainstem in a cross-section?

Answer 2

The portion posterior to the ventricular space (blue)

The portion anterior to the ventricular space (green)

Additional structures on the anterior surface (red)

Question 3

What are the three functions of the brain stem?

Answer 3

Integrative functions

Cranial nerve functions

Conduit functions

Question 4

Describe the integrative funcitons of the brainstem?

Answer 4

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.

Question 5

Describe the conduit function of the brainstem?

Answer 5

It serves as a conduit for ascending sensory and descending motor tracts.

Question 6

What is the motor funciton of the brainstem? What tract does this?

Answer 6

Corticosplinal tract (green) - voluntary movement of limbs

Question 7

What are the sensory functions of the brainstem? What tracts do this?

Answer 7

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

Question 8

What are the cranial nerve functions of the brainstem?

Answer 8

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.

Question 9

Describe the developent of the brainstem nuclei?

Answer 9

1. NS developes from neural tube
2. Neural tube has basal plate (motor) and alar plate (sensory) divided by sulcus limitans
3. Brainstem development is similar to spinal cord development

Question 10

How does the NS develop from the neural tube?

Answer 10

Neural folds come up to make neural crests that eventually meet to form a neural tube that extends.

Question 11

What are the sensory and motor portions of the spinal cord derived from?

Answer 11

The basal plate (motor) and the alar plate (sensory), which is divided by the sulcus limitans.

Question 12

Describe the brainstem development?

Answer 12

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.

Question 13

Where are the motor and sensory nuclei each found in the brainstem?

Answer 13

Motor is medial

Sensory sides

Question 14

Which cranial nerves emerge form the midbrain and above?

Answer 14

Cranial nerves 1-4

Question 15

What cranial nerve emerges at the mid-pons level?

Answer 15

The trigeminal nerve (V)

Question 16

Which cranial nerves exit at the level of the pons?

Answer 16

Cranial nerves 5-8

Question 17

Which cranial nerves exit at the level of the medulla?

Answer 17

Cranial Nerves 9-12.

Question 18

What are cranial nerve nuclei?

Answer 18

Clusters of cell bodies WITHIN the brainstem (bilaterally)

Question 19

Where would you find the nuclei of somatic motor neurons?

Answer 19

Motor neurons are in the medial portion of brainstem (red portions).

Question 20

Where would you find nuclei of visceral motor neurons in the brainstem?

Answer 20

Near the medial portion of the brainstem (yellow).

Examples include: edinger-wesphal nucleus, salivatory nucleus, and dorsal motor nucleus of X.

Question 21

Where would you expect to see visceral sensory, somatic sensory, and special sensory nuclei in the brainstem?

Answer 21

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.

Question 22

Which cranial nerve is located within the interpeduncular fossa?

Answer 22

CN III - oculomotor

Question 23

What is located within the midbrain?

Answer 23

Tectum, tegmentum, cerebral aqueduct, CN III, and CN IV

Question 24

Label the parts of the midbrain

Answer 24

Question 25

Label each nucleus

Answer 25

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

Question 26

What structure is circled and what runs through it?

Answer 26

The red nucleus, and strands of what will make up the oculomotor nerve run through it.

Question 27

What structures are located in the pons?

Answer 27

The middle cerebellar peduncle 4th ventricle CNs V, VI, VII, and VIII

Question 28

What is each pathway depicted here with color?

Answer 28

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

Question 29

What structures / spaces are located near the medulla?

Answer 29

The 4th ventricle Olives Medullary pyramids (CST) CNs IX, X, XI, and XII

Question 30

What nucleiu is associated with each color?

Answer 30

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

Question 31

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?

Answer 31

PCA Weber's syndrome

Question 32

What is the blood supply to the medial pons? What syndrome is associated with a lesion or loss of blood flow to this area?

Answer 32

Basilar artery Medial pontine syndromes

Question 33

What is the blood supply to the lateral pons? What syndrome is associated with a lesion or loss of blood flow to this area?

Answer 33

Superior cerebellar artery (rostral) or AICA (caudal) Lateral pontine syndromes

Question 34

What is the blood supply to the medial medulla? What syndrome is associated with a lesion or loss of blood flow to this area?

Answer 34

Vertebral artery or anterior spinal artery. Medial medullary syndrome.

Question 35

What is the blood supply to the lateral medulla? What syndrome is associated with a lesion or loss of blood flow to this area?

Answer 35

The vertebral artery or PICA. Lateral medullary syndrome.

Question 36

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?

Answer 36

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).