Brain stem and spinal cord

Question 1

Describe the gross anatomy of the spinal cord.

Answer 1

(brain stem) –> cervical enlargement –> lumbosacral enlargement –> cauda equina –> filum terminale

Question 2

Describe the internal anatomy of the spinal cord.

Answer 2

White matter (outer): dorsal column, lateral column and ventral column
Gray matter (inner, “butterfly”): dorsal- and ventral horn

Question 2

What are the four segments of the spinal cord called?

Answer 2

Cervical-, thoracic-, lumbar- and sacral segments

Question 3

How many of the different segments are there?

Answer 3

C8, T12, L5, S5

Question 4

How does the white:gray matter ratio differ thorughout the segments?

Answer 4

More gray the further down the spinal cord

Question 5

What is Rexed’s ten laminae, and what does it reflect?

Answer 5

A division of the gray matter of the spinal cord, reflecting the functional aspects, e.g., VII = autonomic NS, VIII + IX = motor system

Question 6

What is the dorsal root vs the ventral root (sensory/motor)?

Answer 6

Dorsal: sensory (afferent)
Ventral: motor (efferent)

Question 7

What lies in the very middle of the spinal cord?

Answer 7

The central canal, which is the caudal part of the ventricular system

Question 8

How does the motor neurons differ from the sensory neurons?

Answer 8

They are bigger

Question 9

How many of the cranial nerves originate or terminate in the brain stem?

Answer 9

10: NIII-NXII

Question 10

Describe the cranial nerve I (NI).

Answer 10

Name: olfactory nerve
S/M: sensory
Major function: sense of smell
Connection to the brain: telencephalon

Question 11

Describe the cranial nerve II (NII).

Answer 11

Name: optic nerve
S/M: sensory
Major function: vision
Connection to the brain: diencephalon

Question 12

Describe the cranial nerve III (NIII).

Answer 12

Name: Oculomotor nerve
S/M: motor
Major function: eye movements, pupilary constriction
Connection to the brain: mesencephalon

Question 13

Describe the cranial nerve IV (NIV).

Answer 13

Name: trochlear nerve
S/M: motor
Major function: eye movements
Connection to the brain: mesencephalon

Question 14

Describe the cranial nerve V (NV).

Answer 14

Name: trigmental nerve
S/M: motor and sensory
Major function: somatic sensation from face, mouth, muscles of mastication
Connection to the brain: pons

Question 15

Describe the cranial nerve VI (NVI).

Answer 15

Name: abducens nerve
S/M: motor
Major function: eye movenments
Connection to the brain: pons

Question 16

Describe the cranial nerve VII (NVII).

Answer 16

Name: facial nerve
S/M: motor and sensory
Major function: controls muscles of facial expression, taste, lacrimal and salivary glands
Connection to the brain: pons

Question 17

Describe the cranial nerve VIII (NVIII).

Answer 17

Name: auditory nerve
S/M: sensory
Major function: hearing, sense of balance
Connection to the brain: pons and medulla oblongata

Question 18

Describe the cranial nerve IX (NIX).

Answer 18

Name: glossopharyngeal nerve
S/M: motor and sensory
Major function: taste
Connection to the brain: medulla oblongata

Question 19

Describe the cranial nerve X (NX).

Answer 19

Name: vagus nerve
S/M: motor and sensory
Major function: autonomic
Connection to the brain: medulla oblongata

Question 20

Describe the cranial nerve XI (NXI).

Answer 20

Name: spinal accessory nerve
S/M: motor
Major function: neck movements
Connection to the brain: medulla oblongata and spinal cord

Question 21

Describe the cranial nerve 12 (NXII).

Answer 21

Name: hypoglossal nerve
S/M: motor
Major function: tounge movements
Connection to the brain: medulla oblongata

Question 22

Where does the cranial nerves of the brain stem originate or terminate?

Answer 22

In cranial nerve nuclei

Question 23

How does the ventral vs. dorsal surface of the brain stem differ in structure?

Answer 23

Ventral: Mesencepahlon with cerebral peduncle, pons, medulla oblongata with pyramid and olives
Dorsal: Mesencepahlon with superior and inferior colliculus, pons with rhomboid fassa, medulla oblongata (open superior, closed inferior)

Question 24

What is the rhomboid fossa?

Answer 24

The connection between the brainstem and the cerebellum

Question 25

Where is the 4th ventricle located?

Answer 25

On the dorsal side of the brainstem, between the brainstem and the cerebellum

Question 26

Describe the internal structure of the brainstem.

Answer 26

Complex. Gray matter: cranial nerve nuclei + other nuclei Whiter matter: ascending and descending tracts + tracts within the brainstem Reticular formation

Question 27

How are the motor nuclei generally located compared to the sensory nuclei?

Answer 27

Medial

Question 28

What does the internal structure of the closed part of the medulla oblongata resemble?

Answer 28

The internal structure of the spinal cord

Question 29

What nuclei are located in the closed part of the medulla oblongata?

Answer 29

Dorsal column and trigmental sensory

Question 30

What tracts are located in both the closed and open part of the medulla oblongata?

Answer 30

Medial lemniscus (sensory) and corticospinal (motor)

Question 31

What nuclei are located in the open part of the medulla oblongata?

Answer 31

Inferior olivary, sensory cranial (nucleus of the solitary tract, trigmenial sensory nucleus) and motor cranial (dorsal motor nucleus of vagus, hypoglossal nucleus, nucleus ambiguus)

Question 32

How does the hypoglossal nerve and the vagus nerve differ from each other?

Answer 32

Hypoglossal: one nucleus, one function Vagus: several nuclei (trigmenial sensory, ambigus, solitary tract, dorsal motor), several functions

Question 33

Describe the structure of the ventral surface of pons.

Answer 33

Crossing fibers (to cerebellum)

Question 34

What nuclei and tracts are located in the caudal part of the pons?

Answer 34

Nuclei: facial Tracts: medial lemniscus + corticospinal

Question 35

What nuclei and tracts are located in the upper part of the pons?

Answer 35

Nuclei: trigminal nerve (head) Tracts: medial lemniscus + corticospinal

Question 36

What structure lies dorsal to the mesencephalon?

Answer 36

The cerebral aqueduct

Question 37

What are the superior colliculus function?

Answer 37

Visual system

Question 38

What structure is also found in the upper part of the mesencephalon, and what function?

Answer 38

Substansia nigra, motor system

Question 39

What nuclei are located in the mesencephalon?

Answer 39

Oculomotor, trochlear and abducens

Question 40

What are the difference between descending and ascending tracts?

Answer 40

De: down A: up

Question 41

Which tracts are found in the white matter of the spinal cord?

Answer 41

De: corticospinal tract (for voluntary movements) A: spinothalamic tract (for pain and temp.), dorsal column (for touch and proprioception)

Question 42

Describe the pyramidal tract system.

Answer 42

Main motor tracts controlling voluntary movements Cortex --> brain stem: corticobulbar tract Brain stem --> spinal cord: corticospinal tract

Question 43

How many neurons are there in the pyramidal tract system?

Answer 43

2: - upper motor: cellbody in cortex, axon decends in the pyramidal system and crosses the midline - lower motor: cellbody in the ventral horn or motor cranial nerve nuclei, axon reaches skeletal muscle via a peripheral nerve

Question 44

Where does the fibers of the corticospinal tract cross, and where does these crossing fibers end?

Answer 44

On the ventral surface of medulla oblongata, ends in the lateral corticospinal tract. The non-crossing fibers end in the ventral

Question 45

What are the two main sensory pathways?

Answer 45

1) Dorsal column-medial lemniscal pathway: touch and proprioception 2) Spinothalamic tract: temp and pain

Question 46

How many neurons are there in the sensory systems?

Answer 46

3: - 1st neuron: cellbody in spinal ganglion - 2nd neuron: cellbody in the spinal cord or brain stem --> axon crossed midline - 3rd neuron: cellbody in thalamus --> axon projects to the cerebral cortex

Question 47

Describe the dorsal-medial lemniscus pathway.

Answer 47

1st neuron: spinal ganglion --> posterior collumn (spinal cord) --> 2nd neuron: dorsal column nuclei --> medial lemniscus (brain stem) --> 3rd neuron: thalamus --> cerebral cortex

Question 48

Describe the spinothalamic tract pathway.

Answer 48

1st neuron: spinal ganglion --> 2nd neuron: dorsal horn (spinal cord) --> spinothalamic tract (spinal cord and brain stem)--> 3rd neuron: thalamus --> cerebral cortex