Neuro Exam 1

In the visual pathway, do nasal RGC fibers cross contralateral, or stay ipsilateral?

Contralateral

In the visual pathway, do tempoal RGC fibers cross contralateral, or stay ipsilateral?

Ipsilateral

If you have central vision loss in one eye and temporal visual field oss in the other eye, you most likely have

Junctional scotoma

A junctional scotoma is:

A lesion that's localized in the optic chiasm region

What is part of the CNS?

• Brain - Spinal chord - optic nerve (CN2)

What is part of the PNS?

• Cranial Nerves - Spinal nerves

How many cranial nerves and spinal nerves are there?

12/31

cranial-12

spinal-31

What can be found in the anterior cranial fossa?

• Inferior surface of frontal lobe: - Olfactory bullb/tract

What can be found in the middle cranial fossa?

• Optic chiasm - Pituitary gland - Temporal lobe

What can be found in the posterior cranial fossa?

• Brainstem - Cerebellum

What parts of the brain are inferatentorial?

Brainstem and cerebellum

What parts of the brain are supratentorial?

Everything except for brainstem and cerebellum

Which dura fold seperates the cerebellum and the cerebrum?

Tentorium cerebelli

Which dura folds seperate the 2 cranial hemispheres?

Falx cerebri

The brainstem is composed of what structures?

• Midbrain - Pons - Medulla

What is found in the telencephalon?

• Cerebral cortex - Subcortical white matter - Basal ganglia

What is found in the diencephalon?

• Hypothalmus - Midbrain - LGN

What is found in the mesencephalon?

Midbrain

What is found in the metencephalon?

• Pons - Cerebellum

What is found in the myelencephalon?

Medulla

When does neurelation occur?

3rd and 4th week (day 18-28) post-fertilization

What occurs during neurulation?

Development and closure of the neural tube

How is gestational age calculated?

Post-fertilization age + 2 weeks

The CNS is derived from what?

The neural tube

Where are ventricles developed from?

The hollow part of the neural tube

Wher is the PNS derived from?

Neural crest cells

What causes spinal bifida?

Incomplete closure of the neural tube

What's the best way to prevent spinal bifida?

Follic acid

The optic nerve and retina are derived from what brain section during development?

The diencephalon

Name the covered parts of the ventricles.

-What structures were ventricles developed from?

from the hollow part of the neural tube

Most neurons in the CNS are:

Multipolar

The olfactory receptor neurons in the olfactory epithelium are:

Bipolar

The dorsal root ganglion neurons are:

pseudounipolar

What type of cells make myelin in the CNS?

Oligodendrocytes

What type of cells make myelin in the PNS?

Schwann cells

What is the difference between nuclei and ganglia?

Nuclei - Cell bodies in the CNS (central-nuclei)

Ganglia - Cell bodies in the PNS (P-GANG)

Bundles of fibers in the brain are called

• Fasciculi - Brachium - Column - Peduncles - Lemiscus

Bundles of axons in the PNS are called

• Nerves - Nerve roots - Nerve trunk - Nerve chord - Ramus

Why doesn't the basal ganglia fit the definition of a ganglia?

"The basal ganglia is in the CNS while any other ""ganglia"" is in the PNS"

basal=the og base.

Basal ganglia in CNS= grey matter

What is white matter?

Areas of the CNS that contain myelinated axons (fibers in the inner brain)

-messengers

What is grey matter?

Areas of the CNS that mainly consists of neuron cell bodies- (outer layer of cortex)

-thinking/sends orders

Includes: thalamus, basal ganglia, cortex

How are grey matter and white matter organized in the cerebral cortex?

Grey matter on the outside, white matter on the inside

How are grey matter and white matter organized in the brainstem?

White matter on the outside and between sections of the inside

Grey matter more concentrated in chunks on the inside

How are grey matter and white matter organized in the spinal cord?

• White matter all around the outside

• Grey matter on the inside

How many cervial spinal nerves are there?

8

C1- C8

(think of your daily schedule; starts at 8)

How many thoracic spinal nerves are there?

12

T1- T12

(lunch at 12)

How many lumbar spinal nerves are there?

5

L1- L5 spinal nerves

How do you remember the parts of the spine in order?

Come To Learn Some Chemistry

At what vertebral bones does the spinal chord end?

L1-L2 BONES

Where are lumbar punctures (spinal taps) performed and why?

Below L2 usually between L3 or L4 because they aren't part of the spinal cord

Dorsal root ganglion are part of the

PNS

(aka spinal ganglion), dorsal=on your back

The dorsal root of the spinal nerve is sensory or motor?

Sensory

(dorsal/behind)

The ventral root of the spinal nerve is sensory or motor:

Motor

(ventral=frontal)

Why is the spinal nerve considered a mixed nerve?

It has sensory, motor, and autonomic functional components

Functional components of spinal nerves:

General somatic afferent (GSA)

sensory fibers from skin, skeletal muscles, and joints to the CNS

-cell bodies in the dorsal root ganglia

Functional components of spinal nerves:

General viseral afferent (GVA)

sensory fibers from visceral organs to the CNS

-cell bodies in dorsal root ganglia

Functional components of spinal nerves:

General somatic efferent (GSE)

motor fibers to skeletal muscles

-cell bodies in the anterior horn of the spinal cord

Functional components of spinal nerves:

General visceral efferent (GVE)

autonomic motor fibers to smooth muscle, cardiac muscle, and glands

Sympathetic: T1-L2/L3;

-preganglionic neurons in the intermediolateral cell column

Parasympathetic: S2-S4;

-preganglionic neurons in sacral parasym. nucleus of the intermediate grey matter

What is referred pain?

Pain that is felt at a different location from the site of origin

Why are heart attacks considered an example of referred pain?

Because the pain from the heart attack can be felt at the left shoulder or arm as opposed to the heart itself

because of referred pain, intracranial or cervical pathological issues can present themselves as:

Eye pain

"What does ""somatic efferent"" refer to?"

Ventral horn cells/cranial nerve motor nuclei that project directly from the CNS to skeletal muscles

"What does ""autonomic efferent"" refer to?"

a 2-neuron chain that synapses in the peripheral ganglia before reaching its target organ

What are the common sympathetic functions?

Fight or flight

- Bronchodilation

- Pupil dilation(cats)

- Increased heart rate

- Digestion inhibition

- Piloerection

What part of the spinal cord is responsible for the sympathetic divisions

1. Thoracic (T1-12); sympathetic ganglia: prevertebral, paravertebral, adrenals

2. Lumbar (L1-3); Norepi & Ach

What are the common parasympathetic functions?

What a SLUD! (rest/digest=gut stuff )

• Salivation

• Lacrimation

• Urination

• Defication

• - Pupil constriction

• - Bronco-constriction

• - Slowed heart rate

What part of the autonomic nervous system is responsible for the parasympathetic division

Cranial

1. CN 3- oculomotor

2. CN 7- Facial

3. CN 9- Glossopharyngeal

4. CN 10- Vagus nerve; (parasympathetic ganglia in/near end organs)

Sacral

1. S2-4

*S4- Ach, parasym. ganglia in/near end organs

How do you find the central sulcus in MRI scans?

"Look for the superior frontal sulcus (yellow/long) and follow the ""letter T"" to the precentral sulcus (blue/short).

The sulcus immediately following the ""T"" is your central sulcus (red)

Somatosensory deficits are associated with the:

Post-central gyrus (behind=sensory)

Motor deficits are associated with the:

Pre-central gyrus (frontal=motor)

What seperates the frontal lobe and parietal lobe?

The central sulcus

What seperates the parietal lobe and the occipital lobe?

The parietal-occipital sulcus

What seperates the parietal lobe from the temporal lobe?

The lateral fissure (sylvian fissure)

What are the common motor defects?

• Paralysis/-plegia - Paresis - Palsey - Para - Quadri- or teta-

What does paralysis/-plegia mean?

No movement

What does paresis mean?

Weakness (partial paralysis)

What does palsey mean?

Weakness or no movement

"What does ""para"" mean?"

Both legs

"What does ""quadri"" or ""tetra"" mean?"

All four limbs

What are common sensory pathway deficits?

• Sensory loss - Paresthesias

What are paresthesias?

False feelings of pain, burning, tingling, etc.

What brodmann area is the primary visual cortex?

Brodmann Area 17 (aka striate cortex)

(17= “ see-teen”)

Why is the primary visual cortex also called the striate cortex?

The presence of the line of gennari

Summary:

(Brodmann Area 17 = Primary visual cortex = Striate cortex)

“At age 17, I got my FIRST pair of Striate glasses to VISUALIZE the world."

What is the line of Gennari?

The dense axonal input from the thalamus to layer 4 of the visual cortex

Broadmans areas 18 and 19 are known as:

The extrastriate cortex

What are the Main Long Tracts and what are they responsible for

1. Posterior column-medial Lemiscus Pathway (sensory): vibration, joint position, fine tactile discrimination (poke w/2 needles; what’s the diff?)

2. Anterolateral Pathway (sensory): pain, temp, crude touch (non-discriminative; something is touching me but idk what is it)

3. Lateral corticospinal Tract (motor): voluntary movement of the extremities

If you have a cortical lension, it'll present itself as

A contralateral deficit

What type of pathway is the medial lemniscus pathway? What is it for?

Sensory - Vibration - Joint position (proprioception) - Fine tactile descrimination

What type of pathway is the anterolateral pathway? What is it for?

Sensory - Pain - Temperature - Crude touch

What type of pathway is the lateral corticospinal pathway? What is it for?

Motor - Voluntary movement of extremities

Recite the medial lemniscus pathway

Primary sensory neuron

- Input goes to the spinal cord via the dorsal root ganglion

- Dorsal root ganglion -> Posterior (dorsal) columns - Up the spine via posterior (dorsal) columns -> medulla

Secondary sensory neuron (Medial lemniscus)

- *Contralateral crossover in medulla via internal arcuate fibers

- Up the medulla -> VPL in Thalmus

Tertiary sensory neuron

- VPL in thamlus -> Primary somatosensory cortex

Recite the anterolateral (spinothalmic) pathway

Primary Sensory Neuron

- Input enters spinal chord via dorsal root ganglion - Dorsal root ganglion -> Dorsal/posterior horn (synapse)

Secondary Sensory Neuron

- Crossover to contralateral side in spinal chord

- Up the spinal chord via the anterolateral pathway (spinothalmic tract)

- Synapse in the VPL of thalamus

Tertiary Sensory Neuron

- VPL -> primary somatosensory cortex

Recite the corticospinal pathway (pyramidal tract)

Upper motor neuron

- Precentral gyrus in brain -> Medulla

- Crossover to contralateral side via pyramidal decussation

- Medulla -> Spine via lateral corticospinal tract (synapse)

Lower Motor Neuron

- Spine -> Skeletal muscle

If you have a hemi-chord lesion, what do you expect to happen?

• Ipsilateral loss of motor control segments below the lesion

• - Ipsilateral loss of medial lemniscus senses below the lesion

• - Contralateral loss of spinothalamic senses below the lesion

• - No loss of function above the lesion

cortical lesions cause what type of deficits?

contralateral

The precentral gyrus is also known as the:

Primary motor cortex

The postcentral gyrus is also known as the:

Primary somatosensory cortex

The pre/postcentral gyri (homunculus) dictate the _____ side of the somatosensory and motor functions

Contralateral

Somatotopic organization in primary somatosensory & primary motor cortex using homunculi:

FAT

Face (lateral bottom)

Arm (middle)

Trunk (top & into the (butt) crack)

The medial inter-hemispheric region of the homunculus controls what area of the body?

Legs (trunk)