Gross Anatomy Lecture 4 Nervous system

What are The structural divisions of The nervous system?

Central and peripheral

What are The funcional divisiones of The nervous system

Sensory (afferent) and motor (efferent)

Based on target organs, what too kinds of innervations are there?

somatic and visceral innervation

What is grey matter?

The cell bodies that are unmyelinated

What is White matter?

Myelinated axons and devarite processes • does not house cell bodies

What is The Ganglion?

Bump an dorsal root that houses The cell bodies outside of The central nervous system

What does efferent mean?

(Ewww, get AWAY from me ) goes from CNS away towards The body - are motor neurons

What are afferent neurons?

( Ahhh!! It'S coming at me) - Goes from body towards /at The CNS. Sensory neurons

What do general/sensory nerve fibers do?

Also known as general somatic afferent. Pain, temperature, touch pressure from the skin/ muscles

What do somatic motor (general somatic efferent ) fibers do?

Motor signals to skeletal muscles

What do visceral sensory (general visceral afferent GVA ) do?

Reflex pain from organs, glands, and blood vessels

What do visceral motor (General visceral efferent GVE ) do?

Motor signals to smooth muscles, such as the gut

#1

Bipolar

#2

Pseudo-unipolar

#3

Multipolar

Where do spinal nerves C1 -c7 emerge from?

Above each respective intervertebral foreman

Where do spinal cords c8 - rest of the spinal nerves among from

Below each respective intervertebral foramen

How many cervical vertebrae and spinal nerveS are there?

7 cervical vertebrae and 8 cervical nerves

How many thoracic vertebrae and spinal nerves are there?

Twelve thoracic vertebrae and 12 thoracic nerves

How many lumbar vertebrae and spinal nerves are there?

5 lumbar vertebrae and 5 lumber spinal nerves

How many sacral vertebrae and spinal nerves are there?

5 fused sacral vertebrae and 5 sacral nerve

How many coccygeal vertebrae and spinal nerves?

(About 4) fused coccygeal vertebrae and one coccygeal spinal nerve

A strip of skin innovated of a single spinal nerve level (sensory) is called

Dermatome

A group of muscles and action, innovated by a single spinal nerve (motor) is called

A myotome

Multiple levels of spinal nerves mix to form a

Peripheral nerve and/or plexus (like brachial plexus)

#1

Ventral root

#2

Spinal nerve

#3

Ventral primary ramus

#4

Dorsal primary ramus

#5

Dorsal root ganglion ( DRG))

#6

Dorsal root

#1

Spinal nerve

#2

Ventral primary ramus

#3

Dorsal primary ramus

#4

Myotome

#5

Dermatome

What kind of signal is found in the dorsal primary ramus?

Mixed! Sensory and motor - motor are for intrinsic back muscles • sensory are for skin of back and zygapophyseal joints

What kind of signal are for the ventral primary ramus?

Mixed! Sensory and motor

Motor to all other skeletal muscle / sensory to rest of skin to form plexuses

Where are the cell bodies of afferent neurons located?

Outside of the spinal cord l dorsal root ganglion)

Where are the cell bodies of the efferent neurons?

In the ventral horn of the spinal cord

Which dermatome is responsible for the nipple area?

T4

Which dermatome is responsible for the umbilicus?

T10

What are spinal reflexes?

Involuntary responses after stimulation of certain receptors

Which spinal nerves are responsible for the biceps reflex?

C5 - c6

Which spinal nerve is responsible for the thee (patellar) reflex?

L3- L4

Which spinal nerves are responsible for the triceps reflex?

C6 - c7

Which spinal nerves are responsible for the calcaneal Achilles reflex?

s1

What is the autonomic nervous system?

Involuntary motor innervation to smooth muscle cells and visceral layers / pathway for sensory information

Sympathetic autonomic nervous system includes

Thoraco-lumbar region / fight or flight

Parasympathetic autonomic nervous system includes

Cranial-sacral area / rest and digest (feed and breed)

For the central nervous system, where are presynaptic cell bodies located?

They are always In the CNS (the spinal cord)

For the peripheral nervous system, where are the cell bodies located?

Post-synaptic neuron cell bodies are always in a ganglion in the PNS

What does the exact location of the CNS and PNS cell bodies and pathways depend on?

Parasympathetic vs sympathetic systems

Sympathetic nerves originate in which regions?pre-synaptic neuron origin

Thoracic lumbar; the lateral horns of the Thoraco -lumbar spinal levels T1-L2

In which region do the parasympathetic nerves originate? Pre-synaptic neuron origin

Para means either side, so originations are on either side of the sympathetic regions → cranial and sacral ( cranial nerves 3, 6,9, and 10 and also the sacral spinal area)

Nuclei of cranial nerves but the lateral horns of the sacral nerves

Where is the location of the synapse?

Synapse is at the location of the cell body of neuron 2, which is always in PNS

Where is the sympathetic synapse?

In the para vertebral ganglion or the prevertebral ganglion

Where is the parasympathetic synapse?

In a ganglia at or near the target organ!

Are there any parasympathetic fibers heading to limbs or body wall?

No! Because the parasympathetic division of the autonomic nervous system almost exclusively focused on visceral organs

What are the routes of (parasympathetic) cranial nerves 3,7, and 9

The pre- synaptic neuron follows the cranial nerve branches synapses at one of 4 named ganglia in the head and the post-synaptic neuron goes to its respective head and neck organ

What are the parasympathetic routes of cranial nerve 10?

Pre-synaptic neuron travels through the plexuses synapses at or near the target organ and the post-synaptic neuron goes to the thorax and abdominal organs

What are the parasympathetic routes of cranial nerve 10?

Pre-synaptic neuron travels through the plexuses synapses at or near the target organ and the post-synaptic neuron goes to the thorax and abdominal organs

What are the routes of the parasympathetic sacral nerves?

Presynaptic neuron travels through the pelvic splanchnics synapses at or near the target organ and the postsynaptic neuron goes to the pelvic organs

What is another word for paravertebral ganglia?

Sympathetic chain

#1

Gray ramus communicans

#2

White ramus communicans

What is the route of sympathetic nerve fibers?

Pre-synaptic neuron starts at the lateral horn of spinal cord areas T1 -L2, synapses at a pre-or para- vertebral ganglia, and the postsynaptic neuron leads to the target organ

Where do all sympathetic motor fibers start?

In the lateral horn

After originating in the lateral horn, where do sympathetic motor fibers leave the spinal cord?

Sympathetic motor fibers leave Te spinal cord Va the ventral (anterior) root

After leaving the spinal cord via the ventral root, how do the sympathetic nerve fibers enter the sympathetic chain?

Sympathetic nerve fibers enter the sympathetic chain ( paravertebral ganglia ) by a white rami communicans

Once in the sympathetic chain, nerve fibers may go up or down the chain and will either…

Synapse in the chain or leave the sympathetic chain without synapsing via thoraco abdominal splanchnic to synapse in the prevertebral ganglia

If the postsynaptic neuron synapses in the chain but doesn't exit via grey rami communicans, where else would it exit?

The cardio-pulmonary splanchnic nerve (to heart /lungs ) or they follow blood vessels to the head

If motor fibers leave the sympathetic chain without synapsing they will synapse in the prevertebral ganglia, then the post synaptic neurons will…

Post-synaptic neurons will follow blood vessels to get to the abdominal and pelvic organs

Are viscera sensitive to pain?

Viscera are relatively insensitive to pain, but irritation of an organ can cause the sensation of localized pain

Visceral pain does not correspond to the region of skin overlying the organ itself; instead it presents in the..

Visceral pain presents in the dermatomes corresponding to the spinal cord segments supplying the sympathetic innovation

Example of visceral pain in reference to dermatomos

• Left arm pain (TI) = heart attacks

• Appendix pain = imbilicous region

the dorsal root of a spinal nerve contains…

sensory fibers only

where are the cell bodies of the preganglionic sympathetic motor nerves found?

in the lateral horns of the thoraco-lumbar region (T1-L2)

each spinal nerve exits the vertebral column through the …

intervertebral foramen (if two adjacent vertebrae are present)

just “notch” if looking at a single vertebrae for reference

which of the following is true regarding the presynaptic fibers of the parasympathetic nervous system?

they originate from cranial nerves III, VII, IX, and X

which of the following structures ONLY houses motor fibers?

Ventral root