Anatomy Of Somatic NS Flashcards
What are the anatomical divisions of the CNS
Brain
Spinal chord
Optic nerve in eye
What are the anatomical divisions of the PNS
Everything else but the CNS.
Function of the PNS
Connects CNS to target organs
Connects sensory to CNS
Function of the CNS
to PROCESS information received through sensory systems and other parts of the body and to activate appropriate actions to the external/internal stimuli.
Two functional parts of the NS
Somatic (voluntary)
Autonomic (involuntary)
3 divisions of the autonomic NS
Sympathetic
Parasympathetic
Enteric (gut)
What does the PNS include
31 spinal nerve pairs
12 cranial nerve pairs
Ganglia (autonomic/ sensory)
nerve plexuses
Enteric NS (gastrointestinal tract)
What is ganglia
Cluster of neuronal cell bodies
What are two components of NS
Neurones
Glial cells (90%)
Function of neurone
Responsible for conducting impulses
Microanatomy of neurone
Cell body
Dendrites
Axon
Synapses
Main types of neurones
Multipolar- motor neurones
Bipolar- relay and special sense (retina/ olfactory)
Pseudo/unipolar- sensory (cell body branches off)
4 types of glial cells
Astrocytes
Oligodendrocytes
Microglia
Ependymal
About Astrocytes
Star shaped
Provide metabolic and structural support
Most abundant type
Contribute to the blood brain barrier
Cancer due to Astrocytes
Gliomas
Astrocytes have the ability to regenerate
About microglia
Immune function- phagocytosis
Maintain brain homeostasis
Disease due to dysregulation of microglia
Neurological disease
Autoimmune disease- Alzheimer’s
About Ependymal cells
Simple ciliated epithelial cells lining the ventricles
Regulate the movement of cerebrospinal fluid synthesis
CFS?
Cerebrospinal fluid synthesis
Provides nutrients
Protection- buoyancy fluid layer
Oligodendrocytes?
Create myelin sheaths around neurones in CNS
Provide metabolic support and electrical insulation
Maintain axon integrity
Schwann cells?
Create myelin sheaths around neurones in PNS
Metabolic support and electrical insulation.
Difference between Oligodendrocytes and Schwann cells?
Oligo can myleinate multiple axons (one cell body but multiple glial units)
Oligo in CNS but Schwann in PNS
Unmyelinated neurones?
Axons still surrounded my Schwann cell but not totally encapsulated
Afferent division?
Sensory info
Ascending tract
Dorsal horn (top)
Sensory neuron cell bodies in dorsal root ganglion
Efferent division?
Motor info
Descending tract
Ventral horn (bottom)
Motor neuron cell bodies in Cranial nerve nuclei in brain stem
What do intercostal nerves innervated:
Segmentally supply motor innervation to intercostal muscles
Sensory innervation to underlying parietal pleura and overlying skin (anterolateral T1-T12 dermatomes)
Where intercostal nerves arise from
Ventral ramus as travels between internal and innermost intercostal muscles
From thoracic spinal nerves from T1 to T11
Situated between adjacent ribs
What is a dermatome
Area of skin innervated by a single spinal cord level
Segmental organisation
Overlap between some dermatomes
How to test dermatomes
Certain points on dermatomes with no overlap
Test sensory innervation by palpating
