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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.
brachial plexus see brachial plexus.
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.
celiac plexus solar plexus.
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.
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.
solar plexus see solar plexus.
tympanic plexus a network of nerve fibers supplying the mucous lining of the tympanum, mastoid air cells, and pharyngotympanic tube.
the network of nerves formed by the ventral primary divisions of the first four cervical nerves. Each nerve, except the first, divides into the superior branch and the inferior branch, and both branches unite to form three loops. The plexus is located opposite the cranial aspect of the first four cervical vertebrae. It communicates with certain cranial nerves and numerous muscular and cutaneous branches.
cer·vi·cal plex·us(sĕr'vi-kăl pleks'ŭs)
Formed by loops joining the adjacent ventral primary rami of the first four cervical nerves and receiving gray communicating rami from the superior cervical ganglion; it lies deep to the sternocleidomastoid muscle, and sends out numerous cutaneous, muscular, and communicating rami.
pertaining to the neck or to the cervix.
ankylosis of the intervertebral joints. See also hypervitaminosis A.
segmental aplasia of the genital tract may be manifested by the absence or deformity of the cervix. Infertility is absolute. Diagnosis in large animals can be performed by rectal palpation; small animals may require surgical exploration.
caused by severe laceration at parturition; a rare cause of dystocia.
one of the vertebral curves of the body.
satisfactory method of euthanasia for laboratory mice, immature rats and poultry. Must be performed by an experienced person in order to achieve rapid and humane death.
suturing of the cervix through the vaginal floor to the prepubic tendon. Used in the treatment of vaginal prolapse in cows.
damage to the cervix during parturition in the mare may cause its deformity and render it incapable of effectively closing off the uterus from the vagina. Infection of the uterus and infertility result.
incomplete cervical dilation
incomplete dilation of the cervix during parturition in adult cows, less commonly in heifers, may necessitate obstetrical, even cesarean, assistance; thought to be hormonal. See also ringwomb in ewes.
cervical instability, cervical malformation, cervical malarticulation
see canine wobbler syndrome.
cervical line lesions
of the tooth neck characterized by progressive, subgingival, osteoclastic resorption. These occur commonly in cats. See odontoclastic resorption.
infection with abscessation of cervical lymph nodes in guinea pigs; usually caused by Streptococcus zooepidemicus.
suitable for use only in cows. The fetus is pulled up into the cervix and light traction maintained while a well-lubricated hand is pushed gently between the cervix and the fetus. This is done repeatedly and continued if there is no evidence of trauma. The cervix may dilate sufficiently to allow normal delivery of the calf.
from the cervix. Its presence in liberal amounts is used as an indication of estrus.
inability to lift the head, usually accompanied by paralysis of all four limbs.
see cervical plexus.
a supernumerary rib arising from a cervical vertebra.
cervical spinal cord lesion
includes fracture-dislocation, cervical vertebral abscess, compression due to exostosis, spinal myelitis and myelacia, congenital lesions including spinal canal stenosis.
cervical spondylolisthesis, spondylopathy
see canine wobbler syndrome.
see cervical ankylosis (above).
cervical static stenosis
one of the two syndromes listed under cervical vertebral stenotic myelopathy; characterized by compression of the cord at C5 to C7 in large male horses 1-4 years of age; the position of the neck is immaterial; the resulting syndrome is characterized by an insidious onset of ataxia. See also enzootic equine incoordination.
cervical stenotic myelopathy
focal myelopathy caused by compression of the spinal cord by excessive flexion of the neck in patients, especially dogs, in which there is a pre-existing narrowing of one of the two vertebral foramina in one or more vertebrae, especially cervical vertebrae. See also degenerative myeloencephalopathy.
swab of the os cervix for bacterial and virological examination for pathogens likely to affect fertility adversely. Used in fertility examination of cases of prolonged infertility in ruminants. See also uterine swab.
clinical signs caused by a lesion of the spinal cord between C1 and C5. They include tetraparesis to tetraplegia or hemiparesis to hemiplegia, hyperreflexia, hypertonia, depressed postural responses and sometimes cervical pain.
most common are lacerations during parturition; resulting adhesions and fibrosis may cause subsequent dystocia.
the skeleton of the neck, in most mammals comprising seven vertebrae, in birds up to 25.
cervical vertebra fracture
in horses occurs as a result of head-on collisions at speed; causes recumbency and inability to move limbs voluntarily, but there is full consciousness and patient can eat and drink if assisted.
cervical vertebral malformation malarticulation syndrome
see wobbler syndrome
cervical vertebral stenotic myelopathy
one of the causes of incoordination in young horses. See also enzootic equine incoordination.
pl. plexus, plexuses [L.] a network or tangle, chiefly of veins or nerves.
see brachial 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.
nerve plexuses surrounding the common, external and internal carotid arteries.
a plexus of autonomic fibers and sympathetic nerve ganglia which surround the origin of the celiac artery, and supply the abdominal viscera.
a plexus of autonomic nerve fibers and sympathetic ganglia around the origin of the celiac and cranial mesenteric arteries; called also solar plexus.
a network of nerve fibers formed by the first four cervical nerves and supplying the structures in the region of the neck.
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.
a nerve plexus formed by the ventral branches of the coccygeal and last sacral nerves.
a venous plexus within the coronet of the hoof.
superficial, middle and deep, inter-communicating plexuses of blood vessels are identified as supplying blood to haired skin.
a nerve plexus near the gallbladder.
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.
the collection of parasympathetic and sympathetic nerves to the gonads.
plexus of veins draining the hoof region in the horse.
see lumbar plexus.
see lumbosacral plexus.
parasympathetic and sympathetic nerve supply to the abdominal organs.
see auerbach plexus.
a plexus composed of intermingled nerve fibers.
1. a plexus of veins from the testis and the epididymis, constituting part of the spermatic cord.
2. a plexus of ovarian veins in the broad ligament of the uterus.
the venous plexus within the broad ligament providing venous drainage to the uterus and vagina.
see plexus papilloma.
the array of autonomic nerves which supply the lungs.
autonomic nerve supply to the kidney.
a plexus arising from the ventral branches of the last few lumbar and first few sacral spinal nerves.
see celiacomesenteric plexus (above).
a network of nerve fibers supplying the mucous lining of the tympanum and auditory tube.