Development of the Peripheral Nervous System Flashcards
Neurulation begins when
3rd week
Peripheral nervous system consists of
Cranial and spinal nerves
Ganglia
Enteric plexus
Sensory receptors
Gray matter
Location of cell bodies of neurons
Dorsal/posterior horn- sensory
Lateral horn- autonomics/visceromotor
Ventral/anterior horn- motor
White matter
Location of axons
Dorsal funiculus- sensory
Lateral funiculus- sensory and motor
Anterior funiculus- primarily motor
Neural tube is caudal or cephalad to fourth pair of somites
Caudal
Zones of the spinal cord
Ventricular zone- closest to neural canal
Intermediate zone
Marginal zone- around the edge of spinal cord furthest from canal
Neuroepithelium/neuroectoderm gives rise to what types of cells
Apolor neuroblast- axons/dendrites
Glioblast- astrocytes/oligodendrocytes
Ependyma- epithelium of choroid plexus
Position of spinal cord in third month in utero, at birth, and as an adult
3rd month in utero- End of sacrum
Birth- L2/3
Adult- L1/2
High BMP levels and spinal cord formation
High BMP levels activate PAX3/7- for sensory neuron differentiation at alar plate
High SHH levels and spinal cord formation
High SHH levels activate NKX2.2/6.1- ventral neuron formation at basal plate
Where are levels of SHH/BMP high/low
Dorsal- high BMP low SHH
Ventral- high SHH low BMP
What forms the peripheral nervous system
Neural crest and ectodermal placode
What cells develop from the neural tube
Motor neurons
Pre-ganglionic autonomic neurons
What cells develop from neural crest
Neurons of dorsal root ganglia Sensory ganglia of cranial nerves Schwann cells Sympathetic ganglia/post-ganglion cells Parasympathetic ganglia/post-ganglion cells
Dorsal ramus of segmental spinal nerve function
Motor to dorsal muscles
Sensory to dorsal integument
Ventral ramus of segmental spinal nerve function
Motor to limbs, lateral and ventral body wall
Sensory to integument of same regions
Ramus communicantes of segmental spinal nerve function
Motor and sensory to viscera
General visceral efferent function
Autonomics to smooth and cardiac muscle and glands
Special visceral efferent function
Muscles derived from pharyngeal arches
General somatic afferent function
Sensory in skin, joint capsule, tendon, muscle (ectoderm)
General visceral afferent function
Sensory of visceral structures (endoderm)
Special somatic afferent function
Hearing, balance and sight
Special visceral afferent function
Taste/smell: chemical senses
Efferent somatic vs visceral
Somatic- motor fibers ending on skeletal muscle
Visceral- motor fibers ending on autonomic ganglion cells, which in turn control smooth muscle/cardiac muscle and glands
Afferent sensory somatic vs visceral
Somatic- sensory fibers from integument
Visceral- sensory fibers from viscera
What structure is responsible for formation of pre-ganglion cells
Neuroectoderm
Pre vs post ganglionic myelination in sympathetic nervous system
Pre-ganglionic sympathetic nerves are myelinated while post ganglionic are not
What neurotransmitter is/are used for sympathetic preganglionic and postganglionic motor neurons
Preganglionic use Acetylcholine
Postganglionic use NE
Where is the sympathetic nervous system located in the spinal cord
Thoraco-lumbar region
Where is the parasympathetic nervous system located in the spinal cord
Cranial-sacral region
How many cranial ganglia are there
4
What neurotransmitters are used in parasympathetic pre/post ganglion nerves
Both use acetylcholine Maybe?
What cells are responsible for myelination in CNS and PNS and when does it occur
CNS- oligodendrocytes- form during late fetal period or 6th month through puberty?
PNS- schwann cells
Motor roots myelinated before sensory roots
4th month
What gives rise to microglial cells
Mesenchymal cells
