Spinal ganglia: anatomy, characteristics and function

Spinal ganglia: anatomy

Spinal ganglia are a group of nodules located in the dorsal or posterior roots of the spinal nerves, where the bodies of the afferent or sensory pathway neurons of the peripheral nervous system are housed .

In this article we will explain what spinal ganglia are and their relationship to each part of the peripheral nervous system.

The Peripheral Nervous System

The peripheral nervous system (PNS) includes the spinal nerves, the cranial nerves and their associated ganglia (groups of nerve cells outside the central nervous system [CNS]). The nerves contain nerve fibers that conduct information to (afferent) or from (efferent) the CNS .

Generally, efferent fibers are involved in motor functions, such as muscle contraction or gland secretion; and afferent fibers transmit sensory stimuli from the skin, mucous membranes, and deep structures.

The main task of the SNP is to connect the various stimuli that our body receives (external, internal and proprioceptive or relating to information about the position of one’s muscles) with the central nervous system; and the latter, in turn, to connect with the organs and body systems that it has to regulate and manage.

The SNP is composed of 12 pairs of cranial nerves, which exit the skull through various openings, and 32 pairs of spinal nerves, each identified by its relationship to the vertebra or spinal canal from which it exits .

Spinal nerves

The spinal nerves extend from the spinal cord, through the vertebral muscles, to different areas of the body.

Each of the 31 pairs of spinal nerves has a ventral and a dorsal root ; each root is made up of 1 to 8 tiny raicilli or bundles of nerve fibres. In the dorsal root of a typical spinal nerve, near the junction with the ventral root, is a ganglion of the dorsal or spinal root, a bulge containing bodies of nerve cells.

The dorsal (or posterior) roots are mainly sensory. Each dorsal nerve root (except, in general, C1) contains afferent (sensory or receptor) fibers of the nerve cells in its ganglion. Dorsal roots contain fibers that come from deep, cutaneous structures.

Nerve fibres can be classified according to their anatomical and physiological basis into: efferent somatic fibres, which innervate skeletal muscles; and afferent somatic fibres, which transmit sensory information from the skin, joints and muscles to the central nervous system.

The cell bodies of afferent fibers are made up of unipolar cells (characterized by a single protruding extension of the soma) in the spinal nodes, which are interposed in the course of the dorsal roots (dorsal root ganglia).

The peripheral branches of these ganglion cells are distributed over the somatic structures; and the central branches transmit sensory impulses through the dorsal roots to the dorsal cord of the grey matter and the ascending tracts of the spinal cord.

Spinal ganglia

Nerve ganglia are groups of cells that constitute small nodules located outside the central nervous system that function as relays or intermediate connections between different neurological structures of the body.

Spinal ganglia are a group of nodules located in the dorsal or posterior roots of the spinal nerves, where the bodies of the afferent or sensory pathway neurons of the peripheral nervous system are housed .

In this article we will explain what spinal ganglia are and their relationship to each part of the peripheral nervous system.

The Peripheral Nervous System

The peripheral nervous system (PNS) includes the spinal nerves, the cranial nerves and their associated ganglia (groups of nerve cells outside the central nervous system [CNS]).
The nerves contain nerve fibers that conduct information to (afferent) or from (efferent) the CNS .

Generally, efferent fibers are involved in motor functions, such as muscle contraction or gland secretion; and afferent fibers transmit sensory stimuli from the skin, mucous membranes, and deep structures.

The main task of the SNP is to connect the various stimuli that our body receives (external, internal and proprioceptive or relating to information about the position of one’s muscles) with the central nervous system; and the latter, in turn, to connect with the organs and body systems that it has to regulate and manage.

The SNP is composed of 12 pairs of cranial nerves, which exit the skull through various openings, and 32 pairs of spinal nerves, each identified by its relationship to the vertebra or spinal canal from which it exits .

Spinal nerves

The spinal nerves extend from the spinal cord, through the vertebral muscles, to different areas of the body.

Each of the 31 pairs of spinal nerves has a ventral and a dorsal root ; each root is made up of 1 to 8 tiny raicilli or bundles of nerve fibres. In the dorsal root of a typical spinal nerve, near the junction with the ventral root, is a ganglion of the dorsal or spinal root, a bulge containing bodies of nerve cells.

The dorsal (or posterior) roots are mainly sensory.
Each dorsal nerve root (except, in general, C1) contains afferent (sensory or receptor) fibers of the nerve cells in its ganglion. Dorsal roots contain fibers that come from deep, cutaneous structures.

Nerve fibres can be classified according to their anatomical and physiological basis into: efferent somatic fibres, which innervate skeletal muscles; and afferent somatic fibres, which transmit sensory information from the skin, joints and muscles to the central nervous system.

The cell bodies of afferent fibers are made up of unipolar cells (characterized by a single protruding extension of the soma) in the spinal nodes, which are interposed in the course of the dorsal roots (dorsal root ganglia).

This type of inflammation can induce blood cells (such as macrophages) to release substances that trigger classical inflammation (such as histamine), so that both types of inflammation would be potentiated in a reciprocal way. And in fact, the release of chemical mediators of inflammation could also increase or directly trigger pain.

Bibliographic references:

  • Carpenter, M., Sutin, J., Mascitti, T. and Lorenzo, I. (1990). Human neuroanatomy. Buenos Aires: El Ateneo.
  • Navarro, X. (2002) Physiology of the autonomic nervous system. Neurology Journal, 35(6): 553-562.

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