Spinal Cord Flashcards
Where do the CNS and PNS derive from?
CNS- process of neurulation
PNS- neural crest cells also from neurulation
Functional division of the nervous system
Somatic
autonomic
What does the somatic nervous system do?
The sensory system receives pain, temp, touch, position to conscious level.
Motor system innervates skeletal only causing voluntary and reflexive movement.
What does the autonomic NS do?
consist of visceral efferent and afferent fibers which are organized into sympathetic and parasympathetic groups.
What are the differences between sympathetic and parasympathetic?
1) location of presynaptic cell bodies.
2) the nerves that conduct presynaptic fibers from CNS
explain the role of efferent and afferent divisions of the NS.
- efferent conducts the signals to gernerate movement and leave the anterior horn.
- afferent conducts signals based on sensations and enter the posterior horn.
What are the types of somatic fibers and functions?
- general somatic afferent: send sensation from body to CNS. extero and proprioceptive.
- general somatic efferent:send impulse to skeletal muscle.
What are the Visceral fibers?
- afferent: pain or reflex signal from hollow organ or blood vessels.
- efferent: postsynaptic and presynaptic fibers send signal to smooth muscle and glandular tissue.
What are the meninge layers of spinal cord?
Dura mater: the outermost covering. Covers the post/ant nerve roots.
Pia mater:innermost layer, covering spinal root nerves and blood vessels. Forms the filum terminale. Contain denticulate ligaments to suspend spinal cord.
Arachnoid mater: middler layer which maintains the CSF. connect to pia mater via arachnoid trabeculae.
What are the major components of a spinal nerve?
- ventral nerve root: efferent fibers pass ant. horn of grey matter to peripherally located effector organs.
- dorsal nerve root: afferent fibers in dorsal root ganglion extending peripherally and centrally to the posterior horn of grey matter.
What are the two structural divisions of the nervous system?
Central nervous system( consisting of brain and spinal cord.)
Peripheral nervous system (consisting of parts outside CNS)
What are multipolar neurons?
-motor neurons with 2+ dendrites and 1 axon in a collateral branch. Most common in CNS/PNS
A pseudounipolar sensory neuron
- double process to conduct impulse from receptor to cell body, and then from cell body to CNS.
- part of PNS; cell body located in sensory neurons.
Neuroglia (glial cells)
- non excitable
- CNS: oligodendroglia, astrocytes,ependymal, microglia
- PNS: satellite cell, autonomic ganglia, schwann cell.
Differentiation of spinal cord levels
- prosencephalon: telencephalon, diencephalon
- mesencephalon: midbrain
- rhombencephalon: myelencephalon, metencephalon
Somatic Fibers
-transmit sensation from body to CNS, extero/proprioceptive.
Visceral Fibers
- sensory:pain or visceral reflex sensations from blood vessels, organs
- motor: impulse to smooth muscle and glandular tissues.
What are the different horns in the spinal cord?
- lateral: visceral innervations.
- dorsal: sensory
- Ventral: motor
Anterior Rami
Branches that are located AFTER the root ganglion.
-generally thicker and contain sensory and motor
Posterior Rami
Smaller region, mostly with the back (epaxial)
-contain sensory and motor. Located after root ganglion.
Dermatomes
-areas on the skin that can be tracked back to a spinal nerve root.
Myotome and its features
-large area of muscles that can be traced back to nerve root. have large overlap with dermatomes.
Monosynaptic Reflex
- 1 synapse occurs, no interneurons are used.
ex. patellar reflex
Polysynaptic Reflex
- 2 or more synapses with one occurring with interneuron in the lateral horn.
- longer response due to more synapse signals.
- ex. withdrawal reflex.
Golgi Tendon reflex
prevents excessive skeletal muscle tensing.
nerve ending located in tendons. Allow muscle to relax, and prevents hyperactivity.
