Brainstem

Question 1

What are the three major regions of the brainstem, from superior to inferior?

Answer 1

Midbrain, Pons, and Medulla oblongata

Question 2

The brainstem connects which three major structures?

Answer 2

Spinal cord, Diencephalon, and Cerebellum

Question 3

What is the brainstem’s primary role regarding neural pathways?

Answer 3

Principle pathway for long descending/ascending fiber systems

Question 4

What is the brainstem the origin for?

Answer 4

Most cranial nerves (CNs 3-12) and some major tract systems

Question 5

What are the ventral/anterior structures of the Midbrain, Pons, and Medulla?

Answer 5

Midbrain: Crus cerebri/cerebral peduncle
Pons: Basal area
Medulla: Pyramids

Question 6

What is the common central region running through all three brainstem sections?

Answer 6

Tegmentum

Question 7

What is the dorsal/posterior structure of the Midbrain?

Answer 7

Tectum

Question 8

What is the dorsal/posterior structure of the Pons and Medulla?

Answer 8

The Fourth ventricle

Question 9

What fluid-filled space is located in the Diencephalon?

Answer 9

3rd ventricle

Question 10

What fluid-filled space passes through the Midbrain?

Answer 10

Cerebral aqueduct

Question 11

What fluid-filled space is located dorsally to the Pons and Upper Medulla?

Answer 11

4th ventricle

Question 12

What structure continues through the Lower Medulla and Spinal Cord?

Answer 12

Central canal

Question 13

Where are the Corticospinal tracts located within the brainstem regions (Midbrain, Pons, Medulla)?

Answer 13

Ventrally in the: Crus cerebri/cerebral peduncle (Midbrain); Basilar pons (Pons); Medullary pyramids (Medulla)

Question 14

Where does the majority of the Corticospinal tract cross over (decussate)?

Answer 14

Just inferior to the medullary pyramids (Decussation of Pyramids)

Question 15

Where does the Corticobulbar tract synapse and where does it stop?

Answer 15

Synapses bilaterally on CN nuclei (5, 7, 9-12) throughout the brainstem; stops at the medulla

Question 16

What is the function of the Pontine nuclei (in the Pons)?

Answer 16

Gives rise to transverse pontine (pontocerebellar) fibers which connect the cerebrum with the cerebellum for motor planning, learning, and coordination of fine movement

Question 17

The Inferior olivary nucleus forms which external structure on the ventral medulla surface?

Answer 17

The bilateral Olives (lateral to the pyramids)

Question 18

What is the function of the Inferior olivary nucleus?

Answer 18

Relays info from the red nucleus and spinal cord to the cerebellum to transmit afferent signals for smooth coordinated movements

Question 19

What does the DC-ML system transmit, and where do its 2nd order axons ascend in the brainstem?

Answer 19

Transmits fine touch, proprioception, and vibration (1st order neurons synapse on dorsal nuclei in the Medulla) . The 2nd order axons decussate and ascend as the Medial Lemniscus in the tegmentum of the Medulla, Pons, and Midbrain.

Question 20

What does the ALS (Anterolateral Spinothalamic System) transmit, and where do its axons ascend in the brainstem?

Answer 20

Transmits pain, temperature (cold/warmth), crude touch, tickle, and itch. Its 2nd order axons (Spinothalamic tracts) ascend anterolaterally in the Medulla and within the tegmentum of the Pons and Midbrain (where the tract is also called the Spinal Lemniscus).

Question 21

What two key structures are in the upper midbrain tegmentum and what is their general function?

Answer 21

Red Nucleus (motor coordination/rubrospinal tract) ; and Substantia Nigra (dopamine release, motor planning; pathology linked to Parkinson’s disease)

Question 22

The Red Nucleus receives projections from which structures?

Answer 22

Superior cerebellar peduncle and Inferior olivary nucleus

Question 23

What is the function of the Reticular Formation?

Answer 23

Mediates a variety of functions, including sleep/wakefulness, and sensory, motor, and autonomic functions

Question 24

What tract connects the cerebellum to the brainstem, decussates in the lower midbrain, and carries motor coordination info?

Answer 24

Superior cerebellar peduncle

Question 25

What is the collective term for the four swellings on the dorsal surface of the midbrain?

Answer 25

Corpora Quadrigemina or Tectum/Tectal plate

Question 26

What is the function of the Superior Colliculus?

Answer 26

Eye tracking movements and head & neck reflexes (projects to the tectospinal tract)

Question 27

What is the function of the Inferior Colliculus?

Answer 27

Auditory processing (acuity/discrimination) and localization of sound in space

Question 28

What structure separates the tectum and tegmentum in the midbrain and is involved in pain modulation?

Answer 28

Periaqueductal Gray matter (PAG)

Question 29

Which CN nuclei are located in the midbrain tegmentum?

Answer 29

CN III (Oculomotor nucleus and Edinger-Westphal nucleus) and CN IV (Trochlear nucleus)

Question 30

Which CN nuclei are located in the pons tegmentum?

Answer 30

CN VI (Abducens nucleus); CN VII (Facial motor nucleus, Superior salivatory nucleus) ; and CN VIII (Cochlear nuclei, Vestibular nuclei)

Question 31

The external feature called the Facial Colliculus is formed by which CN fibers looping over which nucleus?

Answer 31

Fibers from the Facial motor nucleus (CN VII) looping over the Abducens nucleus (CN VI)

Question 32

Which CN nuclei are located in the medulla tegmentum?

Answer 32

CN IX (Inferior salivatory nucleus , Solitary nucleus , Nucleus ambiguus ); CN X (Solitary nucleus, Nucleus ambiguus, Dorsal motor nucleus ); CN XII (Hypoglossal nucleus)

Question 33

What is the function of the Solitary Nucleus?

Answer 33

Receives visceral afferents (CN IX & X) and relays taste (CN VII, IX, X) to the thalamus

Question 34

Which artery supplies the inferior cerebellum, medulla oblongata, and choroid plexus of the 4th ventricle?

Answer 34

Posterior Inferior Cerebellar Artery (PICA)

Question 35

Which artery supplies the anteroinferior cerebellum and inferolateral pons?

Answer 35

Anterior Inferior Cerebellar Artery (AICA)

Question 36

Which artery supplies the pons?

Answer 36

Pontine Arteries (aa)

Question 37

Which arteries primarily supply the midbrain?

Answer 37

Superior Cerebellar Artery (SCA) (superior & dorsal cerebellum & midbrain) and Posterior Cerebral Artery (PCA) (midbrain, cerebral peduncles)