Organization of the CNS

What 2 things make up the CNS

brain and spinal cord

What makes up the PNS

nerves and ganglia

3 divisions of the brain

forebrain, midbrain, hindbrain

Divisions of the **forebrain**

telencephalon, diencephalon

Divisions of the **midbrain**

mesencephalon

divisions of the **hindbrain**

metencephelon, myelencephalon

What structures come from the telencephalon

cerebral cortex, basal ganglia, hippocampus, amygdala

What structures come from the diencephalon

thalamus, hypothalamus

What structures come from the mesencephalon

tectum, tegmentum

What structures come from the metencephalon

pons, cerebellum

What structures from the myelencephalon

medulla

embryonic origin of the forebrain

prosencephalon

embryonic origin of the midbrain

mesencephalon

embryonic origin of the hindbrain

rhomboncephalon

cephalic flexure

forebrain forms a bend with the spinal cord

spinal column length in males and females

males: 18”

females: 17”

what are the two enlargements of the spine

cervical enlargement and lumbar enlargement

what is the film terminale

terminal point of the spine

How many bones make up the human spinal column?

33 bones

What attaches the dura mater to the arachnoid mater?

denticulate ligaments

How many bones of the spine are articulating/moving?

24 bones

How many curves are there in the spine, what are there names?

4 curves: cervical, thoracic, lumbar, spinal

why is there restriction of the spine

prevents cutting of the spinal column (deficits in motor/sensory function)

where do blood vessels enter the spinal column

intervertebral foramina

how many **segments** does the spinal cord have? what do they correspond to?

31 segments, anterior and posterior rootlets

where do the rootlets of the spinal cord exit through? what do they pass with?

intervertebral foramen, pass with blood vessels that serve spinal cord

where does the spinal cord terminate near?

around L2

what is found between the pia mater and arachnoid mater?

CSF - cerebrospinal fluid

What is the central canal of the spinal cord continuous with? What is found in it?

continuous with the ventricles, contains CSF

cervical and lumbar enlargement **measurements**

0\.25 inches enlarges to 0.50 inches

which of the roots (anterior or posterior) has a ganglion

posterior

conus medullaris

tapered end of the spinal column

cauda equina

bundle of nerve roots at the base of spinal column; AKA horse tail

Where do all synapses occur in the spinal cord?

gray matter

What does information does the posterior/dorsal gray horn pass?

sensory information

What type of signals does the dorsal gray horn pass sensory information by?

ascending/up signals

What would damage of the dorsal gray horn cause?

interference with interpretation of sensory information

What does the anterior/ventral gray horn carry in the spinal cord?

motor information

What type of signals does the ventral gray horn of the spinal cord carry?

descending/down signals

Where do the descending signals of the ventral gray horn go?

autonomic nerves

If there is damage to the ventral gray horn, what would this interfere with?

motor information (ie: paralysis, tingling, muscle weakness)

What does spinal white matter consist of?

Axons coated with myelin

What does myelin do?

mixture of proteins and lipids that promotes signal strength conduction and protect the axons

What happens if there is damage to the white spinal matter?

* deficits in reflex actions


* affects the persons ability to move, use sensory information

What do the axons in spinal white matter connect to?

different parts of the gray spinal matter

Gray and White matter forms…?

spinal tracts

What information is converted through the posterior tract?

pressure, touch, and vibration

What information is conveyed through the spinothalamic tract?

pain and temperature

What is conveyed through the corticospinal tract?

motor signals/movements

afferent

towards the brain, UP/ascending

efferent

via spinal cord to target, DOWN/descending

What are the 3 somatosensory pathways?

1. dorsal column medial lemniscal pathway
2. spinothalamic pathway
3. spinocerebellar pathway

what type of muscle weakness would you experience with an upper motor neuron lesion

paralysis that affects a **whole** **movement system**

what type of muscle weakness would you experience with a lower motor neuron

individual muscle groups paralyzed

what type of muscle wasting would there be with an upper motor neuron lesion

wasting only due to disuse

what type of muscle wasting would there be with a lower motor neuron lesion

pronounced wasting

what type of muscle tone would there be with an upper motor neuron lesion

hypertonic, rigidity

what type of muscle tone would there be with a lower motor neuron lesion

hypotonic, flaccid

what type of tendon reflexes would there be with an upper motor neuron lesion

hyper-reflexia

what type of tendon reflexes would there be with a lower motor neuron lesion

hypo-reflexia

what type of sensory loss would there be with an upper motor neuron lesion

cortical sensory loss

what type of sensory loss would there be with a lower motor neuron lesion

peripheral sensory loss

what type of EMG would there be with an upper motor neuron lesion

normal nerve conduction

what type of EMG would there be with a lower motor neuron lesion

abnormal nerve conduction

what type of babinski reflex would there be with an upper motor neuron lesion

positive

what type of babinski reflex would there be with an lower motor neuron lesion

negative

What composes the somatic sensory nervous system?

12 cranial nerves, 31 spinal nerves

What are the 2 divisions of the PNS?

somatic nervous system, ANS

What nervous system are CN I and CN II apart of?

CNS

what spinal roots arise above the intervertebral foramina?

8 cervical roots

what spinal roots arise from below the corresponding vertebra?

12 thoracic

5 lumbar

5 sacral

1 coccygeal

how many spinal nerve pairs are there?

31 pairs, one on each side of the spinal column

where do the spinal nerve pairs arise from?

plexus of nerve roots at the spinal cord

dorsal root carrries information where?

info TO the brain, afferent

ventral root carries information where?

info FROM the brain, efferent

what makes up the brachial plexus?

C5-8, T1

what makes up the lumbosacral plexus?

S1-3

what does the dorsal root ganglion contain?

cell bodies of sensory neurons known as **first-order neurons**

what is the dorsal root ganglion responsible for?

experiencing pain induced by mechanical, thermal, chemical and noxious smell

What are the 5 components of a reflex arc?

1. receptor
2. sensory neuron
3. interneuron
4. motor neuron
5. effector

What 3 neurons found in a reflex arc?

* sensory **neuron**
* inter**neuron**
* motor **neuron**

balance between the parasympathetic and sympathizers system =

homeostasis

parasympathetic AKA

rest and digest

sympathetic AKA

fight or flight

how do cranial preganglionic fibers of the parasympathetic nervous system travel?

via CN 3, 7, 9, 10

how do the sacral preganglionic fibers of the parasympathetic nervous system travel?

spinal nerves

where do the preganglionic fibers of the parasympathetic system travel to?

terminal ganglia **close to effector organ**

where are preganglionic neurons located in the parasympathetic system?

nuclei of brainstem and lateral horn of sacral spinal cord

parasympathetic: preganglionic fibers are __, postganglionic fibers are __

1. long
2. short

what is the preganglionic transmitter and most common post-ganglionic transmitter in the parasympathetic system?

acetylcholine

neurotransmitters in the parasympathetic system are mostly __

cholinergic

sympathetic AKA

fight or flight

A single preganglionic neuron in the sympathetic nervous system may have how many targets?

10-20

What is the sympathetic chain?

network of sympathetic spinal ganglia

Central neuron in the lateral horn of spine projects via __, to what?

ventral spinal roots, to the **thoracic-lumbar** column

Describe preganglionic fibers of the sympathetic system:

* axon from the central neuron to the sympathetic ganglion
* **short** distance and **myelinated**

Describe postganglionic fibers of the sympathetic system

* ganglion to target effector
* **long** distance and **unmyelinated**

Where does the central neuron originate (sympathetic)

spinal cord

Where does the central neuron pass signals to? (sympathetic) where will they synapse?

2 sympathetic chains on either side of the spinal column, and **may synapse higher or lower**

How many ganglia are on the sympathetic chain? How many in each section of the spine?

* 23 ganglia pairs
* 3 cervical ganglia
* 12 thoracic ganglia
* 4 lumbar ganglia
* 4 sacral ganglia