A&P Neuroanatomy and Neurophysiology

Sensory neurons for control of skin, muscles, and joints

Sympathetic, parasympathetic, and enteric subdivisions that are responsible for involuntary innervation of various organ systems.

brain and spinal cord

cranial and spinal nerves and receptors

• afferent- bring sensory input to the brain
• efferent- descending, takes input away from brain, innervates muscles.

basic functional cell of the CNS

• cell body aka perikaryon
• dendrites
• a single axon- carries impulses away

• Single axons emerge from cell body at the axon hillock.
• They may branch to form collateral nerves at the point distal to neuron cell body.
• Axon diameter range from 0.2- 20 micrometers
• Most in brain are a few mm long
• In spinal cord can be up to a meter long.

produce conduction in toward cell body, and then conduction away from the cell body by way of the axon

Unipolar- found only in lower invertebrates

Bipolar- found in the retina, ear, and olfactory mucosa

Pseudounipolar- have one cytoplasmic process that exits the cell and divides into two branches, one serving as dendrite and other serving as axon.

-present in the dorsal root ganglia and cranial ganglion cells, enabling sensory impulses to travel from the dendrite directly to the axon without passing through the cell body.

Multipolar neurons- have multiple dendritic processes but only one axon and constitute the majority of the CNS neurons

neuron cell bodies in the CNS

composed of mylinated axons

regions of concentrated cell bodies within the peripheral nervous system form cranial, spinal, and autonomic ganglia