In
neuroanatomy, a plexus (from the Latin term for "braid") is a branching network of vessels or
nerves. The vessels may be
blood vessels
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...
(veins, capillaries) or
lymphatic vessels. The nerves are typically
axons
An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, th ...
outside the central nervous system.
The standard plural form in English is plexuses.
Alternatively, the Latin plural plexūs may be used.
Types
Nerve plexuses
The four primary
nerve plexuses are the
cervical plexus
The cervical plexus is a plexus of the anterior rami of the first four cervical spinal nerves which arise from C1 to C4 cervical segment in the neck. They are located laterally to the transverse processes between prevertebral muscles from the medi ...
,
brachial plexus,
lumbar plexus, and the
sacral plexus.
Cardiac plexus
Celiac plexus
Renal plexus
Venous plexus
Choroid plexus
The
choroid plexus is a part of the
central nervous system in the
brain and consists of capillaries,
brain ventricles, and
ependymal cells.
Invertebrates
The plexus is the characteristic form of nervous system in the
coelenterates and persists with modifications in the
flatworm
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegment ...
s. The nerves of the
radially symmetric
Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, take the face of a human being which has a pla ...
echinoderms also take this form, where a plexus underlies the
ectoderm
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from t ...
of these animals and deeper in the body other nerve cells form plexuses of limited extent.
References
Nervous system
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