The human nervous system. Sky blue is PNS; yellow is CNS.
The formation of the spinal nerve from the posterior and anterior roots
3D Medical Animation still shot of Lumbosacral Plexus
Spinal nerve
Typical spinal nerve location
Scheme showing structure of a typical spinal nerve
1. Somatic efferent.
2. Somatic afferent.
3,4,5. Sympathetic efferent.
6,7. Autonomic afferent.
Cervical nerves
Lumbar plexus and branches
Plan of sacral and pudendal plexuses
Areas of distribution of the cutaneous branches of the posterior divisions of the spinal nerves. The areas of the medial branches are in black, those of the lateral in red
A portion of the spinal cord, showing its right lateral surface. The dura is opened and arranged to show the nerve roots.
Distribution of the cutaneous nerves. Ventral aspect.
Distribution of the cutaneous nerves. Dorsal aspect.
The spinal cord with dura cut open, showing the exits of the spinal nerves.
The spinal cord showing how the anterior and posterior roots join in the spinal nerves.
A longer view of the spinal cord.
Projections of the spinal cord into the nerves (red motor, blue sensory).
Projections of the spinal cord into the nerves (red motor, blue sensory).
Schematic diagram of cervical plexus.
Cerebrum. Inferior view. Deep dissection.
Cerebrum. Inferior view. Deep dissection.
Spinal nerves. Spinal cord and vertebral canal. Deep dissection.

The spinal nerves are part of the peripheral nervous system.

- Spinal nerve

For the rest of the body, spinal nerves are responsible for somatosensory information.

- Peripheral nervous system
The human nervous system. Sky blue is PNS; yellow is CNS.

3 related topics

Alpha

The spinal cord (in yellow) connects the brain to nerves throughout the body.

Spinal cord

Long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column.

Long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column.

The spinal cord (in yellow) connects the brain to nerves throughout the body.
Part of human spinal cord. 1 – central canal; 2 – posterior median sulcus; 3 – gray matter; 4 – white matter; 5 – dorsal root + dorsal root ganglion; 6 – ventral root; 7 – fascicles; 8 – anterior spinal artery; 9 – arachnoid mater; 10 – dura mater
Diagram of the spinal cord showing segments
A model of segments of the human spine and spinal cord, nerve roots can be seen extending laterally from the (not visible) spinal cord.
Spinal cord seen in a midsection of a five-week-old embryo
Spinal cord seen in a midsection of a 3 month old fetus
Spinal cord tracts.
Spinal Cord Sectional Anatomy. Animation in the reference.
Diagrams of the spinal cord.
Cross-section through the spinal cord at the mid-thoracic level.
Cross-sections of the spinal cord at varying levels.
Cervical vertebra
A portion of the spinal cord, showing its right lateral surface. The dura is opened and arranged to show the nerve roots.
The spinal cord with dura cut open, showing the exits of the spinal nerves.
The spinal cord showing how the anterior and posterior roots join in the spinal nerves.
The spinal cord showing how the anterior and posterior roots join in the spinal nerves.
A longer view of the spinal cord.
Projections of the spinal cord into the nerves (red motor, blue sensory).
Projections of the spinal cord into the nerves (red motor, blue sensory).
Cross-section of rabbit spinal cord.
Cross section of adult rat spinal cord stained using Cajal method.
An overview of the spinal cord.
Sagittal section of pig vertebrae showing a section of the spinal cord.
The base of the brain and the top of the spinal cord
Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view.
Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view.
Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view.
Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view.
Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view.
Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view.
Spinal cord. Spinal membranes and nerve roots.Deep dissection. Posterior view.
Cerebrum.Inferior view.Deep dissection
Cerebrum.Inferior view.Deep dissection
Spinal cord. Brachial plexus. Cerebrum.Inferior view.Deep dissection.
Spinal cord. Brachial plexus. Cerebrum.Inferior view.Deep dissection.
Spinal cord
Medulla spinalis of 8-week-old human embryo

The spinal cord is the main pathway for information connecting the brain and peripheral nervous system.

The nerve roots then merge into bilaterally symmetrical pairs of spinal nerves.

Autonomic nervous system innervation.

Autonomic nervous system

Autonomic nervous system innervation.
Autonomic nervous system, showing splanchnic nerves in middle, and the vagus nerve as "X" in blue. The heart and organs below in list to right are regarded as viscera.
Function of the autonomic nervous system
A flow diagram showing the process of stimulation of adrenal medulla that makes it release adrenaline, that further acts on adrenoreceptors, indirectly mediating or mimicking sympathetic activity.

The autonomic nervous system (ANS), formerly referred to as the vegetative nervous system, is a division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of internal organs.

In or near the wall of an organ innervated by the Vagus (Cranial nerve X) or Sacral nerves (S2, S3, S4)

Schematic diagram showing the central nervous system in yellow, peripheral in orange

Central nervous system

Part of the nervous system consisting primarily of the brain and spinal cord.

Part of the nervous system consisting primarily of the brain and spinal cord.

Schematic diagram showing the central nervous system in yellow, peripheral in orange
Dissection of a human brain with labels showing the clear division between white and gray matter.
Diagram of the columns and of the course of the fibers in the spinal cord. Sensory synapses occur in the dorsal spinal cord (above in this image), and motor nerves leave through the ventral (as well as lateral) horns of the spinal cord as seen below in the image.
Different ways in which the CNS can be activated without engaging the cortex, and making us aware of the actions. The above example shows the process in which the pupil dilates during dim light, activating neurons in the spinal cord. The second example shows the constriction of the pupil as a result of the activation of the Eddinger-Westphal nucleus (a cerebral ganglion).
A map over the different structures of the nervous systems in the body, showing the CNS, PNS, autonomic nervous system, and enteric nervous system.
Schematic image showing the locations of a few tracts of the spinal cord.
Reflexes may also occur without engaging more than one neuron of the CNS as in the below example of a short reflex.
Diagram depicting the main subdivisions of the embryonic vertebrate brain, later forming forebrain, midbrain and hindbrain.
Development of the neural tube

Microscopically, there are differences between the neurons and tissue of the CNS and the peripheral nervous system (PNS).

From and to the spinal cord are projections of the peripheral nervous system in the form of spinal nerves (sometimes segmental nerves ).