PNS I Filip Barinka PNS divisions Somatic nervous

PNS I Filip Barinka

PNS - divisions • Somatic nervous system • Autonomous nervous system - Sympathetic - Parasympathetic • (Enteric nervous system)

Peripheral nerves • Spinal nerves • Cranial nerves

Fibers in peripheral nerve • Efferent - Somatic motor fibers - Autonomous (motor) fibers • Afferent - Somatic sensitivity fibers - Viscerosensitivity fibers

Picture from „Netter: Atlas of Neuroscience“

Schematic view of the spinal nerve!!! For simplicity, meningeal branch is not marked

Some important concepts • Area radicularis sensitiva – part of the body, from which the sensory information is led by one dorsal root of spinal nerve (or one cranial nerve) • Consists of DERMATOM (skin area) and internal organs and muscles area, innervated by the same dorsal root.

Dermatom • Dermatoms form longitudinal strips on the surface of the body.

Some important concepts • Area radicularis motorica (Myotom) – muscles innervated motorically by one ventral root of spinal nerve (or one cranial nerve). (But one muscle can by also innervated by more than one ventral roots of spinal nerves. ) Area radicularis = area radicularis sensitiva + area radicularis motorica

Some important concepts • Area nervina – part of the body innervated by one peripheral nerve. Some nerves form nervous plexus and here, as a peripheral nerve we mean the nerve distally to the plexus from which it arises.

Spinal nerve Spinal cord segment Dorsal branch (ramus posterior) Ventral branch (r. anterior) Nerve plexus „Peripheral nerve“ Nerve plexus is allways formed only by ventral branches of spinal nerves!

Nerve plexuses are formed by ventral branches of: 1. nerves C 1 -C 4 Plexus cervicalis 2. nerves C 5(C 4)-Th 1 Plexus brachialis 3. nerves Th 12 -L 4 Plexus lumbalis 4. nerves L 4 -S 5(Co) Plexus sacralis Picture from Petrovický a spol. : Systematická, topografická a klinická anatomie

Difference between dermatom ( or generally area radicularis sensitiva) and area nervina (sensitiva) Dermatom 1 Dermatom 2 Area nervina (sensitiva) (Bodies of pseudounipolar neurons aren´t drawn in this scheme. )

Autonomous nervous system • Has two portions- sympathetic and parasympathetic nervous system. Both of them are efferent (motor, or more accurately visceromotor) and they innervate glands and smooth muscles of internal organs and vessels.

Autonomous nervous system • Both of them consist of two neurons – the first one is located in CNS, its axon runs to the periphery and forms synapse with the second neuron, which is located in the autonomous (sympathetic or parasympathetic) ganglion.

Variants of sympathetic pathways. b. ) a. ) c. ) d. )

Some additional details • Dorsal root leads somatosensory,

Some additional details • Dorsal root leads somatosensory, but also viscerosensory information.