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 pons_**nd 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 l**a**ndmarks 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!!!