Exam 1: Brainstem 2: Pons and Trigeminal Sensory System + some of midbrain (CN nuclei origins diagrams for pons included in Brainstem 1 deck)

Question 1

Identify the landmark or structure

Answer 1

Pyramid

Question 2

Identify the landmark or structure

Answer 2

Decussation of Pyramids*

*At the caudal medulla, where the corticospinal tracts decussate!

Question 3

Identify the landmark or structure

Answer 3

Dorsal root of spinal nerve

Question 4

Identify the landmark or structure

Answer 4

Gracile fasciculus

Question 5

Identify the landmark or structure

Answer 5

Spinal accessory nucleus (CN XI)

Question 6

Identify the landmark or structure

Answer 6

Medial motor nuclei

Question 7

How far down does the trigeminal tract go?

What is it analogous with?

Answer 7

the trigeminal tract goes all the way into the spinal cord

it becomes analogous with Lissauers tract

Question 8

Identify the landmark or structure

Answer 8

Solitary nucleus (CN VII, IX, X)

Question 9

Identify the landmark or structure

Answer 9

Spinal trigeminal nucleus (CN V, VII. IX, X)

Question 10

Identify the landmark or structure

Answer 10

Solitary nucleus (CN VII, IX, X)

Question 11

Identify the landmark or structure

Answer 11

Spinal trigeminal nucleus (CN V, VII. IX, X)

Question 12

What does the red line represent?

What nuclei are found lateral to the line? medial?

Answer 12

The red line is the sulcus limitans

Lateral to the sulcus limitans are the sensory nuclei

Medial to the sulcus limitans are the motor nuclei

Question 13

Identify the landmarks or structures of the Pons marked by the red and yellow stars

Answer 13

The red star is the basal portion of the pons

The yellow star is the Tegmental portion (ventral to the 4th ventricle)

Question 14

Identify the landmark or structure

Answer 14

Facial colliculus

Question 15

What are the Major Longitudinal Regions of the Pons (“Bridge”)

Answer 15

Basal Pons (Basis Pontis)

and

Pontine Tegmentum

Question 16

What are the major components of the Basal Pons (Basis Pontis)

Answer 16

• Corticospinal and corticobulbar tracts (descending)
• Pontine nuclei (cerebellar circuitry)

Question 17

What are the major components of the Pontine Tegmentum

Answer 17

• Is separated from cerebellum via 4th Ventricle
• Cranial nerve nuclei
• Reticular formation
• Medial lemniscus (ascending pathway heading to VPL of thalamus)
• MLF (mostly ascending here; keeps dorsomedial position)

Question 18

Whats unique about the Pons?

• Reticular formation in medulla and caudal pons involved in _____ and _____ functions.
• Large, lateral connections with cerebellum via superior and middle _____ _____
• Shares vestibular nuclei of CN VIII with medulla (at _____ junction)
• Nuclei of CN ___, ___, and ___

Answer 18

Whats unique about the Pons?

• Reticular formation in medulla and caudal pons involved in motor** and **autonomic functions (also sleep, wakefullness, conciousness).
• Large, lateral connections with cerebellum via superior and middle cerebellar peduncles (hence, “bridge”)
• Shares vestibular nuclei of CN VIII with medulla (at pontomedullary junction)
• Nuclei of CN VII, VI, V

Question 19

Identify the landmark or structure

Answer 19

Corticospinal and corticobulbar tracts

Question 20

Identify the landmark or structure

Answer 20

Medial longitudinal fasciculus (MLF)

NOTE: medial longitudinal fasiculus, connects vestibular and cochlear nuclei to nearby nuclei controlling extraocular muscles (III, IV, VI)

Question 21

Identify the landmark or structure

Answer 21

Facial colliculus

Question 22

Identify the landmark or structure

Answer 22

Nucleus of abducent nerve

Question 23

Identify the landmark or structure

Answer 23

Motor nucleus of facial nerve

Question 24

Identify the landmark or structure

Answer 24

Facial nerve

Question 25

Identify the landmark or structure

Answer 25

Abducent nerve

Question 26

Identify the landmark or structure

Answer 26

Transverse pontine fibers

Question 27

Study the cross section of the rostral to mid ponsnd be able to recognize the major landmarks and structures

Answer 27

Study the cross section of the rostral to mid pons and be able to recognize the major landmarks and structures

Question 28

Study the cross section of the Pontomesencephalic Junction and be able to recognize the major landmarks and structures

Answer 28

Study the cross section of the Pontomesencephalic Junction and be able to recognize the major landmarks and structures

Question 29

Identify the landmark or structure

Answer 29

Cerebral aqueduct

Question 30

Identify the landmark or structure

Answer 30

Pontine nuclei

Question 31

Identify the landmark or structure

Answer 31

Pontocerebellar fibers

Question 32

Identify the landmark or structure marked by the red star

Answer 32

Tectum

Question 33

Identify the landmark or structure

Answer 33

Tegmentum

Question 34

Identify the landmark or structure

Answer 34

Oculomotor nerve

Question 35

Identify the landmark or structure

Answer 35

Cerebral aqueduct

Question 36

Which section of the brain stem is between the red dotted lines?

Answer 36

Midbrain

Question 37

Identify the landmark or structure

Answer 37

Superior colliculus*

*note there are 2 Superior colliculi and 2 Inferior colliculi; together the 4 colliculi are collectively called corpora quadrigemina (four bodies)

Question 38

Identify the landmark or structure

Answer 38

Inferior colliculus*

*note there are 2 Superior colliculi and 2 Inferior colliculi; together the 4 colliculi are collectively called corpora quadrigemina (four bodies)

Question 39

Identify the landmark or structure

Answer 39

Trochlear nerve (CN IV)

Note: The trochelar nerve is the only CN that exits the brain stem dorsally!

Question 40

Identify the landmark or structure

Answer 40

Crus cerebri

Question 41

Identify the landmarks or structures marked by the red and yellow stars

Answer 41

The yellow star is Tectum

The red star is Tegmentum

Question 42

The Trigeminal Ganglia consist of primary _____ neurons, with one exception:

_____ is both motor and sensory

Answer 42

The Trigeminal Ganglia* consist of primary sensory neurons, with one exception:

V₃ mandibular is both motor and sensory

Question 43

Review the functions of V₁, V₂, amd V₃!!!

What else does CN V provide sensation for?

Answer 43

Review the functions of V₁, V₂, amd V₃!!!

CN V also provides sensation for supratentorial dura!

Question 44

What else does CN IX provide sensation for?

Answer 44

CN IX also provides sensation for the middle ear, posterior 1/3 tongue, and pharynx.

Question 45

What else does CN X provide sensation for?

Answer 45

CN X also provides sensation for infratentorial dura and probably pharynx, too

Question 46

What are the 3 Trigeminal Nuclei in the brainstem?

Answer 46

Trigeminal Nuclei:

1. Mesencephalic
2. Chief or (Principal)
3. Spinal

Question 47

Trigeminal Nuclei:

• the spinal trigeminal nucleus runs in the same column as the _____ _____ of the spinal cord.
• Trigeminal sensory “column” is analogous to _____ and _____ “systems” of the spinal cord.

Answer 47

Trigeminal Nuclei:

• the spinal trigeminal nucleus runs in the same column** as the **dorsal horn of the spinal cord.
• Trigeminal sensory “column” is analogous to DC-ML and anterolateral “systems” of the spinal cord.

Question 48

General somatic sensory mainly from _____ and a little from ___, ___, and ___

Answer 48

General somatic sensory mainly from CN V and a little from VII, IX, and X (at ear).

Question 49

Where does brainstem fit into 3-neuronal sensory pathway???

Answer 49

Where does brainstem fit into 3-neuronal sensory pathway???

Question 50

Know and understand this chart

Answer 50

Know and understand this chart

Question 51

Mesencephalic Trigeminal Nucleus:

• Here’s the exception: _____ _____ nucleus is located in the CNS/brainstem.
• Receive _____ input from muscles of mastication, tongue, extraocular muscles
• Clinical Relevance: Involved in _____ _____ reflex

Answer 51

Mesencephalic Trigeminal Nucleus:

• Here’s the exception: Primary sensory nucleus is located in the CNS/brainstem.
• Receive proprioceptive input from muscles of mastication, tongue, extraocular muscles
• Clinical Relevance: Involved in _jaw jerk reflex*_
• In this reflex, there are fibers that run from the mesencephalic nucleus DOWN to the pons to the MOTOR NUCLEUS of V (that ultimately innervate muscles of mastication via the mandibular division of V3)
• Other roles of this nucleus are “under investigation”

Question 52

Note DECUSSATION in Secondary Neurons!!!

Answer 52

Note DECUSSATION in Secondary Neurons!!!