Peripheral Nervous System (PNS): General Overview

Nerves

Bundles of Axons in the Periphery

Epineurium

Outermost layer of a PNS nerve; surrounded by a connective tissue

Perineurium

Fibroid tissue surrounding bundles of axons (Fascicles)

Endoneurium

Innermost layer of PNS nerve; individual axons lined with loose connective tissue

Blood Vessels

Nerves in the peripheral nervous system also contain...

Ganglia

Peripheral neuron cell body group; enlargement of nerve root (includes axon fibers)

Dorsal Root Ganglion (DRG)

Most common sensory ganglion; skin to CNS; unipolar and surrounded by satellite cells

Cranial Nerve Ganglion

Sensory ganglion associated with the cranial nerves

True!

True or False

The Trigeminal Nerve can be considered a cranial nerve ganglion.

DRG & Cranial nerve ganglion are part of the SENSORY/SOMATIC division of PNS

Are the Dorsal Root Ganglion (DRG) and Cranial Nerve Ganglion part of the Sensory/Somatic or Autonomic division of PNS?

1. Sympathetic Chain
2. Parasympathetic Chain

What are the two ganglia of the Autonomic System (PNS)?

Sympathetic Chain (ANS)

Located close to the spinal cord; multipolar with dendrites radiating out around the cell body where synapses from the spinal cord neurons are made

1. Paravertebral ganglia
2. Prevertebral (collateral) ganglia

What are the two parts of sympathetic chain ganglia?

Paravertebral ganglia

This part of the sympathetic chain is located on either side of the vertebral column.

Forms sympathetic chain

Prevertebral (collateral) ganglia

This part of the sympathetic chain is technically OUTSIDE of chain and attaches to the organ

Parasympathetic (Terminal) Chain

This Autonomic ganglia lies near or within the viscera of peripheral organs they innervate

LATERAL Horn

Autonomic ganglia receive input from the ??? horn of the thoracic and upper lumbar spinal cord

Preganglionic Fibers

Neurons that conduct signals from the CNS axons to a ganglion. Short and myelinated

Postganglionic Fibers

axons connecting the ganglion cells with the peripheral effectors on target (organs). Long and unmyelinated

short

What is the length of the Preganglionic Sympathetic fibers? Short or Long?

Long

What is the length of the Preganglionic Parasympathetic fibers? Short or Long?

Short

What is the length of the Postganglionic Parasympathetic fibers? Short or Long?

Long

What is the length of the Postganglionic Sympathetic fibers? Short or Long?

ACh (Acetylcholine)

Preganglionic fibers release ??? neurotransmitters to both Sympathetic and Parasympathetic

Nicotinic Receptors

All Pre-ganglionic fibers releasing ACh (acetylcholine) are targeting ??? receptors on Post-ganglionic neurons

Muscarinic Receptors (G Protein Coupled)

Postganglionic fibers release ACh to target neurons in PARAsympathetic ??? receptors

Adrenergic Receptors

Postganglionic fibers release Norepinephrine (NE) to target neurons in SYMPathetic ??? receptors

ACh

Preganglionic Parasympathetic fibers are the longest and release ?? to Nicotinic receptors on post-ganglionic parasympathetic fibers.

ACh

Preganglionic Sympathetic fibers are short and release ?? to Nicotinic receptors on post-ganglionic sympathetic fibers.

Muscarinic

Postganglionic Parasympathetic fibers are short and release ACh to ??? receptors

Norepinephrine (NE)

Postganglionic Sympathetic fibers are long and release ??? to Adrenergic receptors

Cranial Nerves (CN)

The 12 nerves attached to brain; provide sensory and motor function of head and neck

3 - Sensory nerves

How many sensory CN synapse in the brain nucleus?

5 - Motor nerves

How many motor CN strictly connect to skeletal muscles?

4 - Mixed nerves

How many mixed CN are a combination of sensory and motor function?

Ipsilaterally

Do cranial nerves transmit sensory information from the head and neck to brain IPSILATERALLY or CONTRALATERALLY?

Spinal Nerves

Nerves connected to the spinal cord; transmit stimuli between CNS and body

31 Pairs
-Cervical 6
-Thoracic 12
-Lumbar 5
-Sacral 5
-Coccygeal 1

How many pairs of spinal nerves are there?

Dorsal

Sensory enters the ??? nerve root; enlargement of spinal nerve

Ventral

Motor emerges as the ??? root, both motor and autonomic.

Spinal nerve plexus

Reorganization of nerve fibers from different spinal nerves

Cervical Plexus

This plexus connects head, neck, and shoulders

Brachial Plexus

This plexus connects chest, shoulders, upper arms, forearms, and hands

Lumbar Plexus

This plexus connects back, abdomen, groin, thighs, knees, and calves

Sacral Plexus

This plexus connects pelvis, buttocks, genitals, thighs, calves, and feet

Afferent Axons from Periphery

Efferent Axons from Target Organs/Tissues

The Spinal Nerve Plexus contain afferent axons from ??? mixed with ??? axons to target organs/tissues