General Nervous System Flashcards
What bony cavities protects the central nervous system?
Cranial cavity and vertebral canal
What are the three layers of central nervous system membranes known as?
Meninges
The central nervous system is composed of what?
Encephalon (brain) and spinal cord (medulla spinalis)
What part of the nervous system is protected by bony cavities and meninges?
Central nervous system
The peripheral nervous system is composed of what?
12 pairs of cranial nerves
36 pairs of spinal nerves
Nerves and trunks of the autonomic nerve system
What is the functional division of the CNS?
Somatic nervous system and autonomic nervous system
The somatic nervous system controls what?
Voluntary systems, skeletal muscles
The autonomic nervous system controls what?
Involuntary systems, visceral muscles, smooth and nonstriated muscles, heart, glands
What makes up the somas in CNS?
Grey matter, nucleus cortex
What makes up the somas in PNS?
Ganglion
True or false: there are no nerves in the brain itself.
True
What does the axons in the CNS contain?
White matter
Tract, funiculo, fasciculus, lemniscus, peduncle
Fibers: association, projection, commissural
What do the axons of PNS contain?
Nerves
Root, trunk, branch
The somas and axons make up what in the CNS?
Reticular formation
What is the first (outer) layer of the nerve system during embryonic development? What does it develop into?
Ectoderm
Develops into neural tissue and epidermis
What is the second (middle) layer of the nerve system during embryonic development? What does it develop into?
Mesoderm
Develops into somites that differentiate into skeletal and muscle tissues, blood vessels, dermis, and connective tissues
What is the third (inner) layer of the nerve system during embryonic development? What does it develop into?
Endoderm
Develops into epithelium of the digestive and respiratory systems, organs associated with the digestive system, such as liver and pancreas
The neural plate is formed where during embryonic development?
In the ectoderm, dorsal to the notochord of the mesoderm
The cells in the neural plate form what?
Neural groove
The cells in the borders of the neural groove form what?
Neural crests
The cells of the neural crests will form most of what system, including what structures?
Peripheral nervous system, including Ganglia and spinal nerves
The cells remaining in the neural groove (those that do not form the neural crests) will close and form what?
Neural tube
The neural tube forms what system, including what structures?
Central nervous system, including encephalon and spinal cord
What is the pyramidal decussation of the spinal cord?
Limit between spinal cord and brainstem
Place where the pyramidal fiber (Upper motor neurons) cross over to the opposite side of the spinal cord
What is the medullary cone?
End of the spinal cord
Located between L6 and L7 in dogs, S2 and S3 in cats
The segments that gives origin to the nerves supplying the thoracic and pelvic limbs are called?
Intumescentiae
Why is the spinal cord enlarged at the cervical and lumbar intumescences?
Due to the need for more neurons to send info to muscles
The funiculi are composed of what?
Ascending and descending axon fibers
The body of neurons are called what?
Somas
The ventral root carries what type of signals to the spinal nerve?
Motor / efferent
The dorsal root carries what type of signals to away from spinal nerve and towards CNS?
Sensory / afferent
Afferent neurons are also called what?
Pseudounipolar neurons
In the domestic dog, how many pairs of cervical spine nerves are there?
8 pairs
In the domestic dog, how many pairs of thoracic spine nerves are there?
13 pairs
In the domestic dog, how many pairs of lumbar spinal nerves are there?
7 pairs
In the domestic dog, how many pairs of sacral spinal nerves are there?
3 pairs
In the domestic dog, how many pairs of caudal spinal nerves are there?
5 pairs
What are the vertebra of the cervical region?
C1-C5
What are the vertebra of the cervical intumescence?
C6-T2
What are the vertebra of the thoracolumbar region?
T3-L3
What are the vertebra of the lumbosacral intumescence?
L4-S3
What are the vertebra of the caudal segments?
Cd1-Cd5
Define efferent
Motor impulse to a muscle that will stimulate the contraction of the muscle cells
True or false: a motor neuron will travel in both the ventral and dorsal branches.
True
What type of neuron is confined to the CNS?
Upper motor neuron
What type of neuron has its cell body in the CNS but the axon in the periphery?
Lower motor neuron
Afferent neurons are responsible for what?
Proprioception, tactile and nociception
Tactile and nociception receptors are found where?
Skin, cornea, mucosa, hair/feather follicle, connective tissue
Proprioception receptors are found where?
Tendons, ligaments, muscles, joints
True or false: sensory neurons can travel to both the ventral and dorsal branches.
True
A reflex comprises three parts. What are they?
Sensory input from a peripheral receptor
Central connection in brain or spinal cord
Output from lower motor neuron that connects to muscle via a neuromuscular junction
Are the dorsal and ventral roots unidirectional or bidirectional?
Unidirectional
What happens to a reflex if the upper motor neurons are damaged?
Reflexes will still be present; they may even be increased due to loss of inhibitory UMN influence (can cut UMN and still have function)
What happens to the reflex if the lower motor neurons are damaged?
Damage in LMNs results in reduced/lost reflexes (lose function)
Do motor nerves have some sort of sensory aspect?
Yes, all motor nerves contain proprioception afferent fibers
