Nervous System General Concepts Flashcards
Central Nervous system
-encephalon
-spinal cord (medulla spinalis)
Peripheral nervous system
-cranial nerves (12)
-spinal nerves (36)
- nerves and trunk of autonomic nerve system (ANS)
Nervous system functional divisions
Somatic nervous system
Autonomic nervous system
Somatic nervous system
Voluntary
squeletic muscles
Autonomic nervous system
Involuntary or visceral
Smooth muscle
Heart
Glands
Central nervous system neuron
Somas = grey matter, nucleus cortex
Axons = white matter, tract funículo, fasciculus lemniscus peduncle
- fibers - association projection and
commissural
Somas and axons = reticular formation
Peripheral nervous system neurons
Somas = ganglion (group of somas) may or may not be synapsed
Axons= nerve root trunk branch
Ectoderm
Neural tissue and epidermis
Mesoderm
Develops into somites that turns into skeletal and muscle tissues and blood vessels and connective tissue
Endoderm
Digestive system
Neural plate
Formed in the ectoderm dorsal to the notochord of the mesoderm
Notochord
Stimulates neural plate formation
Neural groove
Formed from the neural plate
Neural crests
Formed from neural groove
What forms the peripheral nervous system
Neural crests
What forms the central nervous system
Neural tube which is formed from the neural groove which includes the neural canal in the middle
Neural tube
Contains cerebral spinal fluid
Gray matter vs axon
Gray matter stays central by canal where axons stay peripheral
Neural tube forms
The vesicles of the brain
Mesencephalon
Midbrain
Rombencephalon
Hindbrain
Prosencephalon
Forebrain
Spinal cord in domestic dog
8 pairs = cervical spinal nerves
13 pairs = thoracic spinal nerves
7 pairs = lumbar spinal nerves
3 pairs = sacral spinal nerves
5 pairs = caudal spinal nerves
Pyramidal decussation
Cranial end between spinal cord and brain stem
Cranial limit
Medullary cone
Caudal limit
No spinal cord in tail but there is nerves
Stops at L6-L7
Medullary cone stops at (cats and dogs)
Dogs = L6 and L7
Cats = S2 and S3
Intumescentae
Segment that gives origin to the nerves supplying the thoracic and pelvic limbs
Cervical intumescence
C6-T2
Thoracic limbs innervation
Main place where connection of nerves to and from thoracic limb
Lumbar intumescence
L4-S3
Pelvic limbs and pelvic viscera innervation
Main hub for nerves to and from pelvic
White substance axons
-dorsal finiculus
- lateral funiculus
-ventral funiculus
Funicululi (found in CNS)
Composed of ascending and descending axon fiber
Many are grouped with bundles of common origin designation and function (basically the white substance or axons)
Gray substance of neural somas
Dorsal horn
Lateral horn = (thoracic and lumbar segments) motor neurons
Ventral horn = autonomic nervous system
Functional regions on spinal cord
-cervical = C1-5 (neck)
-cervical intumescence C6-T2 (thoracic limb)
- thoracolumbar T3-L3 (trunk)
- lumbosacral intumescence L4-S3 (pelvic limbs and pelvic viscera)
-Caudal segments Cd1-5 (tail)
Spinal nerves top portion of gray matter vs bottom
Top portion of gray matter = sensory or afferent (from body to CNS)
-DORSAL HORN
Bottom portion of gray matter = efferent toward a muscle or gland
-VENTRAL HORN
What goes to dorsal horn
Dorsal root
Spinal ganglion
What goes to ventral horn
Ventral root
Pseudounipolar neurons (afferent or efferent)
Afferent
Communicating branch
Communicate with sympathetic trunk
Small but important
GSE
General = similar pathways for skeletal muscles in the body
somatic = body as general
efferent =motor impulse to a muscle that will stimulate the contraction of the muscle cells
Controls striated and skeletal muscles
General somatic efferent how many neurons
One neuron
Root vs branch
Root goes directly to horn
Branch is a segment from the root (branches of root)
Upper motor neurons
Confined to the central nervous system
Brain and spinal cord
PART OF GSE
Lower motor neuron
Cell body in the CNS but the axon is in the periphery
PART OF GSE
GSA
General = similar pathways
Somatic= body
Afferent = transmits sensory impulse toward the CNS
Two sensory impulses to afferent
Tactile and nociception =receptors in skin cornea muscles hair/feather follicle connective tissue
- pain receptor
Proprioception = receptors in tendons ligament muscles and joints
- sense of self movement force and body position
Pathway to dorsal horn
From dorsal branch to spinal ganglion to sensory neuron in dorsal root to dorsal horn
Pathway to ventral horn
Ventral branch to motor neuron of spinal nerve to motor neuron of ventral root to ventral horn
Reflexes
3 parts
Sensory input = peripheral receptor -afferent neuron
Central connection = brain or spinal cord interneuron
Output = lower peripheral motor neuron connects muscle via neuromuscular junction
Myotatic reflex arc.
Gravity stretches the extensor muscle stimulating its contraction via reflex arc.
Flexor muscle is inhibited by collateral fiber and an inhibiting interneuron
Damages to LMN
Results in reduced or loss of reflexes
Damages to UMN (upper motor neurons)
Reflexes will still be present may even be increased due to loss of inhibitory UMN influence
Upper Motor Neuron
Central nervous system (brain and spinal cord)
Central motor neuron
Lower motor neuron
Has cell body in central nervous system but axon in pheriphery
Periphery motor neuron
