Ganglion (nervous system)
A ganglion ( plural ganglia ) is an accumulation of nerve cell bodies in the peripheral nervous system . Ganglia are also known as nerve nodes because they are noticeable as nodular thickenings during dissection. Ganglia are a stage in the evolution of nervous systems that appear for the first time in coelenterates and can be found in all further developed complex animals. In annelids and arthropods , the rope ladder nervous system consists of differentiated larger ganglia that developed into the brain in the course of evolution.
Classification of the ganglia
Ganglia can be further subdivided according to the type of nerve cells (neurons) that form the ganglion.
Sensitive ganglia contain the nerve cell bodies ( soma ) of sensitive neurons. All spinal cord nerves have sensitive ganglia in the form of the spinal ganglia . They contain pseudounipolar nerve cells and are surrounded by a connective tissue capsule, from which the trabeculae pull into the interior and form a support structure, the stroma . The cranial nerves III and VII to X have such ganglia, the VIII. Cranial nerve but has, unlike the others, bipolar ganglion cells .
Autonomous (vegetative) ganglia are found in the autonomic nervous system . They also have a connective tissue capsule, with the exception of the ganglia in the wall of the intestine ( intramural ganglia ). Autonomous ganglia contain multipolar nerve cells . In contrast to the sensitive ganglia, the autonomic ganglia switch to a second nerve cell via synapses .
List of mammalian ganglia
The following ganglia occur in the mammalian organism:
- Celiac ganglion , the abdominal ganglion
- Medium cervical ganglion , middle cervical ganglion
- Ganglion cervicale superius (in animals: ganglion cervicale craniale ), upper cervical ganglion
- Ciliary ganglion , ciliary ganglion
- Ganglion Gasseri ( Ganglion trigeminale; Ganglion semilunare ), a ganglion of the fifth cranial nerve , the nervus trigeminus
- Geniculate ganglion in the temporal bone
- Inferior ganglion ( distal ganglion ), lower ganglion
- Ganglion mesentericum superius (in animals: ganglion mesentericum craniale ) in the upper (in animals: anterior) abdominal cavity
- Ganglion mesentericum inferius (in animals: ganglion mesentericum caudale ) in the lower (in animals: posterior) abdominal cavity
- Ganglion oticum at the base of the skull
- Ganglion paravertebral , ganglion
- Preevertebral ganglion
- Submandibular ganglion in the mandibular region
- Pterygopalatine ganglion , alar palatal ganglion
- Spinal ganglion , dorsal ganglion or posterior root ganglion
- Ganglion spiral ( Ganglion Corti ) in a cavity in the center of the spiral coils
- Superior ganglion ( proximal ganglion ), upper ganglion
- Ganglion stellatum ( ganglion cervicothoracicum ) on the side of the first thoracic vertebra
- Vestibular ganglion ( Ganglion Gasteri ) at the bottom of the internal auditory canal
Ganglia of arthropods and lower animals
Particularly noticeable ganglia occur at the front end of the rope ladder nervous system of arthropods and annelids . According to their position above and below the pharynx, they are called the upper and lower pharynx ganglia .
autonomic ( sympathetic and parasympathetic ) ganglia. These are substances with one or two positively charged groups on a nitrogen atom . They either bind competitively to the nicotine receptor and thus suppress the binding of acetylcholine or noncompetitively to the unspecific cation channel of the nicotine receptor.
Differentiation from basal ganglia
Despite their suffix, basal ganglia cannot be assigned to the ganglia because they are located below the cerebral cortex and thus in the central nervous system (CNS) . To distinguish it, nerve cell body accumulations in the CNS are referred to as kernels (nuclei) , the Latin name Nuclei basales is more unambiguous here than the German equivalent.
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