L4 Brainstem Structure and Function/Intro to Cranial Nerves

Question 1

Patterns of development in Spinal Cord vs. Brain Stem?

Answer 1

Dorsal/Lateral pattern in Spinal Chord

Anterior/Posterior pattern in Brain Stem

Question 2

Neural tube expands outwards stretching the roof plate out into a broad membrane (_________)

Brings the SENSORY nuclei (_______) to lie lateral to the MOTOR regions (_______)

Some ________ plate neurons migrate ventrally to form special nuclei in the base of the pons and medulla

Answer 2

Neural tube expands outwards stretching the roof plate out into a broad membrane (EPENDYMA)

Brings the sensory nuclei (ALAR) to lie lateral to the motor regions (BASAL)

Some ALAR plate neurons migrate ventrally to form special nuclei in the base of the pons and medulla

Question 3

Functions of the Brainstem? (3)

Answer 3

1. Passage for ascending/descending tracts connecting spinal cord to higher centers
2. Reflex Centers associated w/ control of Respiration, Cardiovascular Systems, and Consciousness
3. Contains Nuclei of Cranial Nerves III to XII (I and II come off of forebrain)

Question 4

Anterior Surface Features of the Medulla?

Answer 4

Pyramids (Assc with pyramidal tract, aka corticospinal tract. leave primary motor cortex to influence lower motor neurons)

Olives (lateral swellings to pyramids)

Decussation of the Pyramids

Cranial Nerves (Lower 4: Nerves IX-XII)

Question 5

Posterior Surface Features of the Medulla?

Answer 5

Median Sulcus (continuous w/ that of spinal cord)

Dorsal Columns carrying first order sensory neurons form Elevations (TUBERCLES):

• Fasciculus Gracilis (Gracile Tubercule) => continues to Nucleus Gracilis (MORE MEDIAL)
• Fasciculus Cuneatus (Cuneate Tubercule) => Continues to Nucleus Cuneatus (MORE LATERAL)

Question 6

Descending motor tracts enter the brainstem via the CEREBRAL PEDUNCLES, pass through the ______ into the _______ where they are grouped together close to the surface forming _________

Answer 6

Descending motor tracts enter the brainstem via the CEREBRAL PEDUNCLES, pass through the PONS into the MEDULLA where they are groups together close to the surface forming PYRAMIDS

Question 7

Pons:

• Dominated by Transverse Fibers (______________ Fibers);
• Neurons arise in ______________ and travel back to the cerebellum (via _________ Cerebellar Peduncle) relaying information from the cerebral cortex

Answer 7

Pons:

• Dominated by Transverse Fibers (Pontocerebellar Fibers);
• Neurons arise in Pontine Nuclei and travel back to the cerebellum (via Middle Cerebellar Peduncle) relaying information from the cerebral cortex

Question 8

Midbrain:

• Huge column of descending fibers on either side - Cerebral peduncles (________________) separated by __________________
• ________________(located in interpeduncular fosssa)

Answer 8

Midbrain:

• Huge column of descending fibers on either side - Cerebral peduncles (Crura Cerebri) separated by Interpeduncular Fossa
• Mamillary bodies (located in interpeduncular fosssa)

Question 9

Posterior Surface of Pons/Midbrain?

Answer 9

_

Question 10

Internal Features of the Midbrain and their Functions? (3 Parts)

Answer 10

_

Question 11

________________:

• Posterior/Roof of Midbrain
• 2 Superior Colliculi (_______)
• 2 Inferior Colliculi (________)

Answer 11

Tectum (Tectal Plate):

• Posterior/Roof of Midbrain
• 2 Superior Colliculi (VISUAL)
• 2 Inferior Colliculi (AUDITORY)

Question 12

___________________:

• Mid part of Midbrain
• Upper part contains paired RED NUCLEI: involved in motor control

Answer 12

Tegmentum:

• Mid part of Midbrain
• Upper part contains paired RED NUCLEI: involved in motor control

Question 13

__________________:

• Subdivision of Mibrain
• Composed of CRUS CERIBRI [_____________])
• Contains Substantia Nigra. Role/pathology?

Answer 13

Basal Portion:

• Subdivision of Mibrain
• Composed of CRUS CERIBRI [cerebral peduncles])
• Contains Substantia Nigra: pigmented (melanin) mass of neurons with a role in muscle tone/activity. Degeneration is associated with Parkinson’s disease

Question 14

Where do Cranial Nerves arise?

Answer 14

FOREBRAIN (I &II)

BRAINSTEM (III-XII)

Question 15

______________and _____________ leave the MIDBRAIN

Answer 15

Oculomotor (III) and Trochlear (IV) nerves leave the MIDBRAIN

Question 16

_________________ leaves in the groove between MEDULLA and PONS

Answer 16

Abducens Nerve (IV) leaves in the groove between MEDULLA and PONS

Question 17

_______________leaves the side of the PONS via two roots

Answer 17

Trigeminal Nerve (V) leaves the side of the PONS via two roots (MOTOR and SENSORY)

Question 18

__________________leaves the UPPER MEDULLA via two roots

Answer 18

Facial Nerve (VII) leaves the UPPER MEDULLA via two roots

Question 19

____________________ exits the LATERAL UPPER MEDULLA

Answer 19

Vestibulocochlear (Auditory) Nerve (VIII) exits the LATERAL UPPER MEDULLA

Question 20

__________________ and _________________ Leave MEDULLA Dorsal to the Olive

Answer 20

Glossopharyngeal (IX) and Vagus Nerves (X) Leave MEDULLA Dorsal to the Olive

Question 21

______________ and _________________ leave between the PYRAMIDS and OLIVES by many roots

Answer 21

Spinal Accessory Nerve (XI) and Hypoglossal Nerve (XII) leave between the PYRAMIDS and OLIVES by many roots