2.2 and 2.3- Spinal Cord and Somatic Nervous System and Intro to the visceral nervous system

brain and spinal cord

Anatomical division of the CNS

nerves that emanate from the CNS

Anatomical division of the PNS

12

How many pairs of cranial nerves are there?

Foramina of the skull

What do the cranial nerves pass through?

Spinal nerves

carry impulses to and from the spinal cord, # can change species to species

Intervertebral foramina

openings providing for exit of spinal nerves

Sensory and motor pathways

Two MAIN divisions of the PNS

somatic and autonomic

two divisons of the PNS motor pathways

sympathetic and parasympathetic

two divisions of the autonomic nervous system

afferent

Is sensory information afferent or efferent

efferent

Is motor information afferent of efferent

SAME

pneumonic to remember direction of sensory vs. motor

Sensory neurons

- Cell bodies found in the dorsal root ganglia

- Sensory axons travel down the dorsal root

- receive sensory input from the external environment

Somatic motor neurons

- Cell bodies found in the ventral horn

- Axons leave via the ventral root

- Provide voluntary motor control over skeletal muscle

Spinal nerve

What is created when there is a mix of sensory and motor axons in the are just distal to the dorsal root ganglion

Epaxial muscles

-Dorsal musculature

-Makes up the intrinsic back muscles

Dorsal rami

What innervates the epaxial muscles (intrinsic back muscles)

Hypaxial muscles

Muscles that lie ventral to the vertebral column, can include limb muscles

Dermamyotome

becomes the dermis and musculature of the back, ribs, and limbs - provides motor innervation to its muscle portion and sensory innervation to its skin portion

Gray matter

Brain and spinal cord tissue that appears gray with the naked eye; consists mainly of neuronal cell bodies (nuclei) and lacks myelinated axons.

White matter

Whitish nervous tissue of the CNS consisting of neurons and their myelin sheaths.

Conus medullaris

end of spinal cord that varies in legnth across mammal species

Fetuses and infants

In what point in a mammals life is the vertebral column and the spinal cord the same length

The spinal cord and vertebral column don't grow at the same rate

Why don't the spinal nerve levels and vertebral levels not match

Cauda Equina

The extension of the dorsal and ventral roots to the same numbered vertebral level

C7 and above

What part of the spinal cord has the matching spinal nerve coming out above the vertebra

Example: Spinal nerve C1 lies right above vertebra C1

T1 and down

What part of the spinal cord has the matching spinal nerve coming out below the vertebra

Example: spinal nerve T1 lies right below vertebra T1

Meninges

Made up of connective tissues to support and protect

Dura mater

- thick external meningeal layer

- Tough and thick

- Continuous with the dura of the brain

- Surrounded by extradural fat in the epidural space

- Extends laterally onto the proximal spinal nerves

Arachnoid mater

- Just deep to the dura mater

- Thin and delicate

- Encloses the subarachnoid spaces

- continuous with the subarachnoid space around the brain

Pia mater

- innermost meningeal layer

- Completely adherent to the spinal cord

- Creates denticulate ligaments that anchor the the spinal cord to the dura

Smooth muscle, cardiac muscle and glands

What does the autonomic nervous system innervate

sympathetic nervous system

active during moments of great effort, hyperarousal, and acute stress (fight or flight)

parasympathetic nervous

active during moments of energy intake and relates to aspects of everyday life (rest and digest)

Body wall

Where are parasympathetics not present in the body

Lateral horn

In the sympathetic nervous system, what houses the pre-ganglionic sympathetic cell bodies

T1-L4

What spinal cord levels are pre-ganglionic cell bodies found in

paravertebral ganglion

What holds the post-ganglionic cell bodies in the sympathetic nervous system

prevertebral ganglia

The paravertebral ganglion typically holds the post-ganglionic cell bodies in the sympathetic nervous system

BUT what is the exception that holds the post-ganglionic cell bodies whenever they are going to the body cavity caudal to the diaphragm

Sympathetic chain

the lineup of paravertebral ganglia

Sympathetic pathways

Which nervous system have these pathways:

- To the body wall and limbs

- To the body cavity cranial to the abdominal diaphragm

- To the body cavity caudal to the abdominal diaphragm

Parasympathetic pathways

Which nervous system have these pathways:

- Head and neck

- Body caudal to the neck including ONLY the thorax, foregut, and midgut

- Body caudal to the neck including ONLY the hindgut and pelvic viscera

White ramus communicons

Since the preganglionic sympathetic axons only enter from T1-L4, what connects the spinal nerves tot he sympathetic trunk

At all levels

What level can these be found on:

- Somatic motor cell bodies in the ventral horn

- Autonomic and somatic sensory cell bodies in the dorsal root ganglion

- A postganglionic sympathetic cell body in the paravertebral ganglion

- A gray ramus communicon

- A connection to the paravertebral ganglion above and below

From T1-L4

What levels can this be found on:

- preganglionic sympathetic cell bodies in the lateral horn

- White ramus communicons

Cardiopulmonary splanchnic nerves

All para vertebral ganglia that are from the superior cervical ganglion to T5 are attached to what nerve?

Brain stem

Where are the preganglionic parasympathetic cell bodies found

Vagus nerve X

In parasympathetic pathways, how do the preganglionic parasympathetic axons travel to the body

middle cervical ganglion (C5-C6)

The vagus nerve and the sympathetic chain travel together for a short period of time in pathways , where do they separate in the parasympathetic nerve pathway

in the wall of the organ

In parasympathetic nerve pathways, where are the postganglionic cell bodies found

Pain

The damage of the visceral structure, poorly localized

Non-pain

Sensations such as fullness, bloating, and cramping

Sympathetic

Which pathway does pain follow

Parasympathetic

Which pathway does non-pain follow

Dorsal ramus

1

Dorsal root ganglion

2

Dorsal root

3

Dorsal horn

4

White matter

5

Lateral horn

6

Grey matter

7

Grey ramus communicons

8

Ventral horn

9

Ventral root

10

Paravertebral ganglion

11

White ramus communicons

12

Ventral ramus

13

Sensory

Is this an example of a sensory of motor neuron

Sensory

What neuron is on the dorsal aspect

Motor

What neuron is on the ventral aspect

Epaxial muscles

What are the dorsal nerves innervating (general)

Hypaxial muscles

What are the ventral nerves innervating (general)

False

T/F - this could be a nerve pathway of a motor neuron to the intrinsic back muscles

somatic motor innervation

What type of innervation is this

Somatic sensory innervation

What type of innervation is this

A

Would this be a somatic sensory signal from the skin on the:

A - back

B - paw

C - tail

D - Belly

Pre-ganglionic

Is this a pre-ganglionic or post-ganglionic sympathetic pathway

True

T/F - this could be an example of a nerve pathway that is a sympathetic pathway to the body wall

Cranial to the diaphragm

Is this a sympathetic pathway cranial or caudal to the diaphragm

Cardiopulmonary splanchnic nerve

If this is a sympathetic pathway to cranial to the diaphragm, what is the nerve indicated by the black arrow

Caudal to the diaphragm

Is this a sympathetic pathway cranial or caudal to the diaphragm

No

In a sympathetic pathways Caudal to the diaphragm, does the synapse occur in the paravertebral ganglion

prevertebral ganglia

In this pathway, where is synapse occuring

Effector organ

In this pathway, where does the impulse travel after synapse in the prevertebral ganglion.