Week 1: Brain and Spinal Cord

Question 1

Coronally, the white matter is organized ___ the grey matter, more “____” the brain.

The white matter tracts in the spinal cord are on the “___,” (Ie, they switch organizations), with grey matter in the ___ surface.

Answer 1

Coronally, the white matter is organized below the grey matter, more “inside” the brain.

The white matter tracts in the spinal cord are on the “outside,” (Ie, they switch organizations), with grey matter in the interior surface.

Question 2

homunculus:

feet and legs are represented medially next to the ___ __ fissure. Theb bodies are represented on the superior-medial surface, and the hands are __ to that, the face is also __. The pharyngeal structures are inferior, near the __ __.

Answer 2

feet and legs are represented medially next to the longitudinal cerebral fissure. Theb bodies are represented on the superior-medial surface, and the hands are lateral to that, the face is also lateral. The pharyngeal structures are inferior, near the sylvian fissure.

Question 3

these two arrows make up the

Answer 3

diencephalon

Question 4

Answer 4

Question 5

what consists of the limbic system

Answer 5

cingulate gyrus, fornix, hippocampus and amygdala

Question 6

two componens of the diencephalon

Answer 6

thalamus and hypothalamus

Question 7

three components of hindbrain

Answer 7

cerebellum, pons and medulla oblongata

Question 8

three components of the midbrain

Answer 8

superior and inferior colliculus and tegmentum

Question 9

Answer 9

Question 10

Answer 10

Question 11

two layers of the dura

Answer 11

endosteal (connects to the skull)

meningeal (connects to the arachnoid mater

Question 12

the later with a webby appearance, named for spider web. Overlays the cerebral arteries and veins, and cerebral gyri and sulci.

Answer 12

arachnoid mater

Question 13

There are ___ vertebrae in the vertebral column, divided into 5 regions; cervical, thoracic, lumbar, sacral and coccygeal.

Answer 13

There are 33 vertebrae in the vertebral column, divided into 5 regions; cervical, thoracic, lumbar, sacral and coccygeal.

Question 14

The atlas has a superior articular surface facet that articulates with the __ __ of the skull

Answer 14

The atlas has a superior articular surface facet that articulates with the occipital condyles of the skull

Question 15

The spinal cord has ___pairs of spinal nerves. Each with ___ motor fibers and ___ sensory fibres composed of multiple rootlets.

Answer 15

The spinal cord has 31 pairs of spinal nerves. Each with anterior motor fibers and posterior sensory fibres composed of multiple rootlets.

Question 16

The cord itself ends around L1-l2, called the ___ ___. Below the level of T12, the spinal nerves form a region called __ __.

Answer 16

The cord itself ends around L1-l2, called the conus medullaris. Below the level of T12, the spinal nerves form a region called cauda equina.

Question 17

meningeal layer:

Arachnoid is the middle layer and held against the dura by ___ from the __

Answer 17

Arachnoid is the middle layer and held against the dura by pressure from the CSF

Question 18

Answer 18

Question 19

• the __ __ houses the cell body of the sensory neurons. It’s also called the dorsal/posterior root ganglion/sensory root ganglion.

Answer 19

• the spinal ganglion houses the cell body of the sensory neurons. It’s also called the dorsal/posterior root ganglion/sensory root ganglion.

Question 20

which pathway is in each segment of the spinal cord

Answer 20

Question 21

how many neurons in a somatic motor pathway

Answer 21

somatic motor pathway ie/ corticospinal or corticobulbar. There are 2 parts; UMN and LMN

In the corticospinal pathway: info goes from the CNS out to the body

In the corticobulbar pathways; fibers carry infro from the CNS to the face structures, involving the cranial nerves.

There are horizontal pathways, both from the cerebellum and from the basal ganglia to modulate the main pathways

Question 22

Corticospinal Pathway

__ is where the cell bodies of the UMN of the corticospinal paths originate. From these cell bodies, axons descend into the cortex, where they converge to form the _- __, and pass through the __ __ of the internal capsule inferiorly.

the UMN then moves towards the __ __/crus cerebri, doesn into the __, and then to the ___ __, where the UMN __.

The UMN continues to move down to the __ __, and it SYNAPSES with the LMN in the __ __

Answer 22

PMC is where the cell bodies of the UMN of the corticospinal paths originate. From these cell bodies, axons descend into the cortex, where they converge to form the corona radiata, and pass through the posterior limb of the internal capsule inferiorly.

the UMN then moves towards the cerebral peduncles/crus cerebri, doesn into the pons, and then to the mmedullary pyramids, where the UMN DECUSSATES.

The UMN continues to move down to the spinal cord, and it SYNAPSES with the LMN in the ANTERIOR HORN

Question 23

outline the different aspects of the internal capsule

Answer 23

posterior capsule; contains corticospinal lumb fibers (descending)

Genu; carries cortical bulbar tract spinals

Anterior limb fibers (cognitive processes, probably discussed in course

Question 24

Outline the corticobulbar pathway

Answer 24

There fibers can be traced inferiorly from the corte, to the internal capsule (travelling through the genu of the internal capsule), and then down to the brainstem, where they synapse to a bunch of cranial nerves (or decussate before synapsing to cranial nerves)

At the cranial nerve level, they exit to innervate the head and neck structures.

Question 25

where do cranial nerves decussate

Answer 25

note that most cranial nerves are part of the corticobulbar pathway. most decussate as a LMN at the brainstem level exceptions are: 1, 2, 4 (decussates at midbrain), 7 (partial ipsilateral innervation)

Question 26

Primary visual cortex; visual info projects specific on PVC in relation to the __ \_\_. This retinotopic organization makes it so that nuclei that are __ to the calcarine sulcus are from ___ visual fields, where as nuclei inferior to the calcarine sulcus receive info from the ___ visual field (it is thus flipped around)

Answer 26

Primary visual cortex; visual info projects specific on PVC in relation to the **calcarine** **sulcus**. This retinotopic organization makes it so that nuclei that are **superior** to the calcarine sulcus are from **inferior** **visual** **fields**, where as **nuclei** **inferior** to the calcarine sulcus receive info from the **superior** **visual** **field** (it is thus flipped around)

Question 27

rupturing of the meningeal artery causes bleeding in the ____ space

Answer 27

epidural space/Arterial blood escapes into the extradural space (between dura and bone)

Question 28

Answer 28

Question 29

Pterion: the craniometric point near the sphenoid fontanelle of the skull. Point of convergence of the sutures between the \_\_, \_\_, __ and __ temporal bones. It is the thinnest point of the skull that often can get fractured.

Answer 29

Pterion: the craniometric point near the sphenoid fontanelle of the skull. Point of convergence of the sutures between the **frontal, sphenoid, parietal and squamous temporal bones.** It is the thinnest point of the skull that often can get fractured.

Question 30

Where does the corticospinal tract decussate?

Answer 30

corticospinal tract decussates in the medullary pyramids

Question 31

where does the corticospinal tract synapse?

Answer 31

On the spinal cord section: the black lateral dots are the descending motor r axons of the upper motor neurons. These UMNs continue to descend in these lateral black bundles until they get to the level of the organ they innervate, at which point they cross the grey matter, go into the anterior horn (ventral root colun), and synapse with a second order neuron (LMN) Therefore, for the motor corticospinal tract, the cortical axons move from corona radiata → internal capsule → cerebral peduncle area → pons → then cross over happens at the medullary pyramid→ descend down the lateral aspect of the spinal cord → **and the synapse to the LMN happens at the ventral root horn.**

Question 32

A young woman presents with weakness of the left side of her face, left arm, and left leg. She has no sensory deficit or headache. Where is the most likely location of the lesion?

Answer 32

This individual likely has a lesion in the **posterior limb of the internal capsule** near the genu, on the right side. Note that the age of this individual and her lack of vascular risk factors indicate that multiple sclerosis may be the cause, rather than the infarct. The fibers in the internal capsule are very densely packed into one spot. They are supplied by a **common vascular (Lacunar arteries) system.** If you damage the internal capsule, both sensory and motor function can be compromised, since chances are more than one type of fiber is nicked.

Question 33

Name the analog of the corticospinal tract that supplies the head. Through which specific region of the internal capsule do upper motor neurons from this tract travel?

Answer 33

Yellow fibers are the corticobulbar axons, innervating the face. You can tell that they are corticobulbar based on their projections-- recall that the face part of the homunculus is superior-lateral. Moves through corona radiata, internal capsule (genu), cerebral peduncles, THEN THEY DON'T GO TO THE SPINAL CORD (SINCE THEY ARE MEANT FOR THE FACE). They decussate at the brainstem, cross the midline through the pons or medulla, and the LMN exits at that level to innervate the face.

Question 34

why are grey matter horns wider in the cervical portion of the spinal cord

Answer 34

The grey matter horns look wider in the neck, because all the descending axons and sensory axons are in there-- there's a tremendous amount of neural tissue.

Question 35

what is the black region of the cervical spinal cord

Answer 35

the corticospinal tract. recall that the UMN of the corticospinal motor tract descend down the spinal cord on the lateral aspects vThe black regions are fibers of the corticospinal tract, which are motor axons that originated in the cortex, and are descending to join with LMNs to initiate movement.

Question 36

corticospinal tract These fibers descend through the corona radiata, through the internal capsule, through cerebral \_\_\_, \_\_\_, to the \_\_\_, where they **decussate**. They cross the midline, and descend into the contralateral spinal cord \_\_\_. When they reach the level, the axon travels into the **\_\_\_ ____ matter**, synapses with the LMN, and the LMN exits to innervate the muscle.

Answer 36

These fibers descend through the corona radiata, through the internal capsule, through cerebral peduncles, pons, to the medulla, where they **decussate**. They cross the midline, and descend into the contralateral spinal cord laterally. When they reach the level, the axon travels into the **ventral grey matter**, synapses with the LMN, and the LMN exits to innervate the muscle.

Question 37

An elderly individual with a history of hypertension presents with sudden onset left arm and leg ataxia, unsteadiness, slurred speech, nausea and vomiting. Where is the most likely location of the lesion?

Answer 37

this person has dysarthria, and poor coordination of left limbs - dysarthria= vermis left limbs = left cerebellar hemisphere (recall that the cerebellum is already ipsilatearl)

Question 38

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Question 39

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Question 40

Answer 40

Question 41

_The cerebellar peduncles connect it to the brain stem:_ Superior cerebellar peduncle; connect cerebellum to the \_\_\_. Middle cerebellar peduncle: connects cerebellum to the \_\_ Inferior peduncle; connects cerebellum to the \_\_.

Answer 41

_The cerebellar peduncles connect it to the brain stem:_ **Superior** cerebellar peduncle; connect cerebellum to the **midbrain**. **Middle** cerebellar peduncle: connects cerebellum to the **pons** **Inferior** peduncle; connects cerebellum to the **medulla**.