What type of neuron is the most common in the nervous system?
the multipolar
Where are pseudounipolar neurons located?
Only in sensory ganglia
What cranial nerve is associated with bipolar neurons?
CN *
WHat are the main structures we discussed in regards to the central nervous system?
What does the peripheral nervous system consist of?
spinal and cranial nerves
it is located outside the skull and vertebral column
What cranial nerves derive from the cerebral hemisphere?
from the brain stem?
from the spinal cord?
1 and 2 are associated with the cerebral hemisphere
3-10 and 12 are derived derived from the brain stem
11 is derived from the spinal cord, but it enters the cranial cavity before going to it’s target, so it’s referred to as a cranial nerve
How many spinal nerve pairs are there?
How many from each region of the spin?
31 pairs:
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
What does CN1 control?
olfactory
What does CN 2 conrtol?
Optic
WHat does CN 3 control?
oculomotor
CN 4?
trochlear
CN 5?
trigeminal
CN 6?
abducens
CN 7?
facial
CN 8?
vestibulocochlear
CN 9?
glossopharyngeal
CN 10
vagus
CN 11?
Accessory - deltoid and sternocleidomastoid
CN 12?
hypoglossal
How do ganglia and neuclei differ?
A ganglia is a collection of nerve cell bodies located OUTSIDE the CNS
A nucleus is a collection of nerve cell bodies located INSIDE the CNS
WHat are the two general type sof ganglia?
- sensory ganglia: include spinal nerve ganglia (dorsal root ganglia) and cranial nerve ganglia (from CN 5, 7, 8, 9, 10)
- Autonomic/Motor/Visceral Ganglia - includes both sympathetic and parasympathetic ganglia
WHere do spinal sensory nerve fibers (both somatic and ivsceral) have their cell bodies?
In the dorsal root ganglia (sensory ganglia) located outside the CNS
What types of neurons will be found in the dorsal root ganglia?
pseudounipolar neurons with central processes going into the CNS and peripheral processes gonig into the PNS
What is another term for visceral motor ganglia?
autonomic ganglia or motor ganglia
Where are autonomic nerve cell bodies located?
they are located in the motor/visceral/autonomic ganglia found outside the CNS
the spinal autonomic ganglia are in the paravertebral ganglion alongside the vertebral bodies in the sympathetic chain
WHat conneccts the sympathetic chain ganglia to the spinal nerve?
2 communicating rami, or branches
Does the autonomic system consist of 1 neuron or 2 neurons?
2 neurons
the first has a cell body within the CNS, which sends a process out to synapse on a ganglion
the second is a multipolar neuron in the ganglion which sends out a process to its target organs: smooth muscle, cardiac muscle or a gland
WHat are the structures called?
What’s located in the dorsal column or funiculus?
ascending sensory neurons only - they are pseudounipolar neurons with cell bodies in the dorsal root ganglia
What is located in the lateral and anterior columns or faniculi?
ascending sensory neurons and descending motor neurons
What happens to the size and shape of the cord as it moves downard?
it gets smaller and rounder
What happens to the amount of white matter as you move down the spinal cord?
it decreases in amount - it’s because nerves are dropping out and you don’t need as many cell bodies
Where is the amount of grey matter greatest?
in the lower cervical area (you need lots of cells for the arms) and in the lumbosacral L2-S3 areas for the legs
Through what levels is a lateral horn present?
T1-L2
What is located in the sensory (dorsal/posterior) horn?
multipolar neurons that send their asons to multipolar neurons at higher levels in the CNS or in the ventral or anterior horn (interneurons)
WHat does the lateral horn contain?
preganglionic cell bodies (multipolar neurons) of the autonomic nervous system
it’s also known as the intermediolateral cell column
What is contained in the motor (ventral/anterior) horn?
alpha motor neurons (lower motor neurons) that send their asons to innervate extrafusal skeletal muscle fibers/cells
gamma motor neurons that innervate the intrafusal muscle fibers/cells of the neuromuscular spindle
What is the difference between an upper and a lowe rmotor neuron?
an upper motor neuron originates in the CNS and terminate within the CNS
lower motor neurons originate in the CNS and terminate outside the CNS on the organ of innervation - these are the somatic motor neurons
WHat is the difference between the somatic peripheral nervous system and the visceral pripheral nervous system?
somatic neurvous system is innervating the muscles and skin of the body wall. The visceral system goes tot he interior organs - also called the splanchnic system.
Where do somatic nerves come off of?
they are associated with both spinal and cranial nerves
Where does the sympathetic nervous system take origin?
From the spinal cord
it’s a two neuron system, so the pregnaglion neuron will synapse on the paravertebral ganglion and the post ganglionic neuron will terminate on the target organ.
it uses the paravertebral ganglia
Where does the parasympathetic system originate?
where are the parasympathetic ganglia located?
They originate in teh brain stem and from the sacral region of the spinal cord.
This is a two-neuron system again and MOTOR NEURONS ONLY.
the ganglia are located near the organ of innervation.
Are afferent fibers sensory or motor?
sensory
they bring information from the periphery to the CNS
the cell bodies will be in ganglia
what are general somatic afferent fibers (GSA)?
they are sensory nerve fibers that go from the soma to the CNS
WHat are general visceral afferent fibers (GVA)?
they are sensory fibers form the viscera tot he CNS
Is an efferent fiber sensory or motor?
motor
What is a general somatic efferent (GSE) fiber?
a motor fiber that originates int he CNS and terminates on skeletal muscle
What are general visceral efferent (GVE) fibers?
they are motor nerve fibers that come in pairs: 1 that originates int he CNS and terminates in a ganglia and a second that terminates on a visceral organ
Are the rami mixed nerves?
yes - they have both sensory and motor - they’re just branches of the spinal nerve, which is already mixed
What does the dorsal ramus supply? What does the bentral remus give rise to/supply?
THe dorsal ramus supplies the deep muscles of the back and the skin fo the back
The ventral ramus gives rise to the nerve plexi and intercostal nerves that supply the limbs and the remainder of the body wall
In what important way do cranial nerves differ from spinal nerves (besides where they originate)?
each cranial nerve may be purely sensory, purely motor, or mixed, while spinal nerves are all mixed
also, cranial nerves do NOT have dorsal and ventral roots or dorsal and ventral rami
Which 5 cranial nerves are associated with sensory ganglia?
5, 7, 8, 9, and 10
Which three cranial nerves have autonomic or motor ganglia (parasympathetic) in the head?
which one has motor ganglia near the organ of innervation?
3, 7, and 9 have motor ganglia in the head
10 has motor ganglia near or int he organs of innervation
OF the following, which do cranial nerves have?
sensory ganglia
parasympathetic ganglia
sympathetic ganglia
cranial nerves have only sensory and parasympathetic
they do NOT have sympathetic ganglia - those are just with spinal nerves