| Nerve plexus | |
|---|---|
 Superimposed image of the spinal plexuses on a human back. | |
| Identifiers | |
| TA2 | 6172 |
| FMA | 5901 |
| Anatomical terms of neuroanatomy | |
Anerve plexus is aplexus (branching network) of intersectingnerves.[1] A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels. There are fivespinal nerve plexuses, except in the thoracic region, as well as other forms ofautonomic plexuses, many of which are a part of theenteric nervous system. The nerves that arise from the plexuses have both sensory and motor functions. These functions include muscle contraction, the maintenance of body coordination and control, and the reaction to sensations such as heat, cold, pain, and pressure. There are several plexuses in the body, including:
The following table shows the nerves that arise from each spinal plexus as well as the spinal level each plexus arises from.
Spinal plexus | Spinal level | Nerves (superior to inferior) |
C1 – C5 | ||
C5 – T1 | ||
L1 – L4 | ||
L4, L5, S1 – S4 | ||
S4, S5, Co | helps contribute to pudendal |
Thecervical plexus is formed by the ventral rami of the upper four cervical nerves and the upper part of fifth cervical ventral ramus. The network of rami is located deep to the sternocleidomastoid within the neck. The cervical plexus innervates muscles of the neck and areas of skin on the head, neck and chest. The deep branches innervate muscles, while the superficial branches supply areas of skin. A long branch (primarily of fibers of C4 and with contributions of fibers from C3 and C5;nervus phrenicus) innervates muscles of thediaphragm. The cervical plexus also communicates with thecranial nervesvagus nerve andhypoglossal nerve.
Thebrachial plexus is formed by the ventral rami of C5-C8-T1 spinal nerves, and lower and upper halves of C4 and T2 spinal nerves. The plexus extends toward the armpit. The ventral rami of C5 and C6 form upper trunk, the ventral ramus of C7 forms the middle trunk, and the ventral rami of C8 and T1 join to form the lower trunk of the brachial plexus. Under the clavicle, the trunks reorganize to form cords(fasciculi) around theaxillary artery(arteria axillaris). The lateral cord(fasciculus lateralis) is formed by the upper and middle trunk, all three trunks join to form the posterior cord(fasciculus posterior), the lower trunk continues to the medial trunk(fasciculus medialis). Thenerves (containingmotor andsensory fibers) to theshoulder and to theupper limb emerge from the brachial plexus.
Since thelumbar plexus andsacral plexus are interconnected, they are sometimes referred to as thelumbosacral plexus. Theintercostal nerves that give rami to the chest and to the upper parts of the abdominal wallefferentmotor innervation and to thepleura andperitoneumafferentsensory innervation are the only ones that do not originate from a plexus.The ventral rami of L1–L5 spinal nerves with a contribution of T12 form lumbar plexus. This plexus lies within thepsoas major muscle. Nervi of the plexus serve the skin and the muscles of the lowerabdominal wall, thethigh andexternal genitals. The largest nerve of the plexus is thefemoral nerve. It supplies anterior muscles of the thigh and a part of skin distal to theinguinal ligament.
Ventral rami of L4–S3 with parts of L4 and S4 spinal nerves form thesacral plexus. It is located on the posterior wall ofpelvic cavity (pelvis minor). Nervi of the plexus innervate theperineal region,buttocks and thelower limb. The largest nerve of the human body, thesciatic nerve, is the main branch that gives rami to themotor innervation of themuscles of thethigh, theleg, and thefoot. Common peroneal nerve and its branches innervate some parts of the skin of the foot, the peroneal muscles of the leg, and the dorsal muscles of the foot.
Coccygeal plexus originates from the ventral rami of spinal nerves S4, S5, and Co. It is interconnected with the lower part ofsacral plexus. The only nerve of the plexus is thecoccygeal nerve, that serves sensory innervation of the skin in thecoccygeal region.
Autonomic plexuses can contain both sympathetic and parasympathetic neurons.
Thecardiac plexus is located near the aortic arch and the carina of the trachea.
Thepulmonary plexus supplies innervation to the bronchial tree.
The celiac, orsolar plexus, is located around the celiac trunk and contains the celiac ganglia. The solar plexus is the largest autonomic plexus and provides innervation to multiple abdominal and pelvic organs.
Thesuperior mesenteric plexus includes the superior mesenteric ganglia and is located around the superior mesenteric artery. Theinferior mesenteric plexus includes the inferior mesenteric ganglia and is located around the inferior mesenteric artery. Together, these plexuses innervate the intestines.
Some other plexuses include thesuperior andinferior hypogastric plexus,renal plexus,hepatic plexus,splenic plexus,gastric plexus,pancreatic plexus, andtesticular plexus /ovarian plexus.
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