plexus
[plek´sus] (pl. plex´us, plexuses) (L.) a network or tangle, chiefly of veins or nerves; see also
rete. adj.,
adj plex´al.
plexus basila´ris a venous plexus of the dura mater located over the basilar part of the occipital bone and the posterior part of the body of the sphenoid bone, extending from the cavernous sinus to the foramen magnum.
cardiac plexus the plexus around the base of the heart, chiefly in the epicardium, formed by cardiac branches from the vagus nerves and the sympathetic trunks and ganglia, and made up of sympathetic, parasympathetic, and visceral afferent fibers that innervate the heart.
carotid p's nerve plexuses surrounding the common, external, and internal carotid arteries.
cervical plexus a nerve plexus formed by the ventral branches of the first four cervical spinal nerves and supplying the structures in the region of the neck. One important branch is the phrenic nerve, which supplies the diaphragm.
choroid plexus infoldings of blood vessels of the pia mater covered by a thin coat of ependymal cells that form tufted projections into the third, fourth, and lateral ventricles of the brain; they secrete the cerebrospinal fluid.
coccygeal plexus a nerve plexus formed by the ventral branches of the coccygeal and fifth sacral nerve and by a communication from the fourth sacral nerve, giving off the anococcygeal nerves.
cystic plexus a nerve plexus near the gallbladder.
dental plexus either of two plexuses (inferior and superior) of nerve fibers, one from the inferior alveolar nerve, situated around the roots of the lower teeth, and the other from the superior alveolar nerve, situated around the roots of the upper teeth.
lumbar plexus one formed by the ventral branches of the second to fifth lumbar nerves in the psoas major muscle (the branches of the first lumbar nerve often are included).
lumbosacral plexus the lumbar and sacral plexuses considered together, because of their continuous nature.
lymphatic plexus an interconnecting network of lymph vessels that provides drainage of lymph in a one-way flow. An example is the lymphocapillary vessels, collecting vessels, and trunks.
myenteric plexus a nerve plexus situated in the muscular layers of the intestines.
nerve plexus a plexus composed of intermingled nerve fibers.
pampiniform plexus 1. in the male, a plexus of veins from the testis and the epididymis, constituting part of the spermatic cord.
2. in the female, a plexus of ovarian veins draining the ovary.
sacral plexus a plexus arising from the ventral branches of the last two lumbar and first four sacral spinal nerves.
tympanic plexus a network of nerve fibers supplying the mucous lining of the tympanum, mastoid air cells, and pharyngotympanic tube.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.