In the thoracic region, the ventral rami, in general, have a simple arrangement. With the exception of the first one, a generally intercostal nerve is created by each thoracic ventral ramus, which under the rib of the same section travels laterally from the intervertebral foramen.
The ventral ramus (pl. rami) (Latin for branch) is the anterior division of a spinal nerve. The ventral rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the dorsal rami . Shortly after a spinal nerve exits the intervertebral foramen,...
The dorsal rami primarily supply the deep muscles of the back like the erector spinae and the skin of the back. The ventral rami become divided into ventral and dorsal divisions, in the brachial and lumbosacral plexuses.
The anterior division of the twelfth thoracic nerve is not technically grouped with the other intercostal nerves as it enters the abdominal wall; this nerve is instead referred to as the subcostal nerve. Some techniques utilize the blockage of these nerves for analgesia and also pathology of these nerves giving rise to neuralgia.
The brachial plexus contains ventral rami from spinal nerves C5-T1. This plexus innervates the pectoral girdle and upper limb. The lumbar plexus contains ventral rami from spinal nerves L1-L4. The sacral plexus contains ventral rami from spinal nerves L4-S4.
Ventral rami of the spinal nerves carry sensory and motor fibres for the innervation of the muscles, joints, and skin of the lateral and ventral body walls and the extremities. Both dorsal and ventral rami also contain autonomic fibres.
The brachial plexus (plexus brachialis) is a somatic nerve plexus formed by intercommunications among the ventral rami (roots) of the lower 4 cervical nerves (C5-C8) and the first thoracic nerve (T1).
The anterior division of the first thoracic nerve divides into two branches; one leaves the thorax in front of the neck of the first rib, and enters the brachial plexus; the other, the first intercostal nerve, runs along the first intercostal space and ends on the front of the chest as the first anterior cutaneous ...
What nerves branch out from the thoracic spine?T1 and T2 nerves: These nerves go into the top of your chest and into your arms and hands. ... T3 through T5 nerves: These nerves go into your chest wall. ... T6 through T12 nerves: These nerves affect your abdominal and back muscles.
The phrenic nerves provide motor innervation to the diaphragm and work in conjunction with secondary respiratory muscles (trapezius, pectoralis major, pectoralis minor, sternocleidomastoid, and intercostals) to allow respiration.
The three major nerves of your arm originate from the brachial plexus, the are the median nerve, the ulnar nerve, and the radial nerve. Lumbar plexus: The lumbar plexus originates from lumbar levels one through four and innervates muscles and skin in your hip and thigh.
Of the four major nerve plexuses (cervical, brachial, lumbar, and sacral), only the brachial plexus and sacral plexus can be assessed satisfactorily in the EDX laboratory.
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 five spinal nerve plexuses, except in the thoracic region, as well as other forms of autonomic plexuses, many of which are a part of the enteric nervous system.
The musculocutaneous nerve innervates the three muscles of the anterior compartment of the arm: the coracobrachialis, biceps brachii, and brachialis. It is also responsible for cutaneous innervation of the lateral forearm.
The intercostobrachial nerve (ICBN) is a cutaneous nerve that provides sensation to the lateral chest, medial aspect of the upper arm, and the axilla.
Branches and innervation Along its course in the arm region, the radial nerve provides muscular branches that innervate the triceps brachii, anconeus, and brachioradialis muscles.
In regions other than the thoracic, ventral rami converge with each other to form networks of nerves called nerve plexuses. Within each plexus, fibers from the various ventral rami branch and become redistributed so that each nerve exiting the plexus has fibers from several different spinal nerves.
The ventral rami supply the antero-lateral parts of the trunk and the limbs. They are mainly larger than the dorsal rami . Shortly after a spinal nerve exits the intervertebral foramen, it branches into the dorsal ramus, the ventral ramus, and the ramus communicans.
Ventral ramus. The formation of the spinal nerve from the dorsal and ventral roots. (Ventral ramus labeled at lower left.) Details. Identifiers. Latin. ramus anterior nervi spinalis. TA98. A14.2.00.034.
These rami are called the intercostal nerv es. In regions other than the thoracic, ventral rami converge with each other ...
The sacral plexus contains ventral rami from spinal nerves L4-S4. The lumbar and sacral plexuses innervate the pelvic girdle and lower limbs. Ventral rami, including the sinuvertebral nerve branches, also supply structures anterior to the facet joint, including the vertebral bodies, the discs and their ligaments, ...
There are four main plexuses formed by the ventral rami: the cervical plexus contains ventral rami from spinal nerves C1-C4. Branches of the cervical plexus , which include the phrenic nerve, innervate muscles of the neck, the diaphragm, and the skin of the neck and upper chest. The brachial plexus contains ventral rami from spinal nerves C5-T1.
Each of these three structures carries both sensory and motor information. Each spinal nerve carries both sensory and motor information, via efferent and afferent nerve fibers - ultimately via the motor cortex in the frontal lobe and to somatosensory cortex in the parietal lobe - but also through the phenomenon of reflex.
Each thoracic nerve root exits the spinal canal through an intervertebral foramen (formed by two adjacent vertebrae, and its size and shape can slightly shift as the vertebrae move).
Introduction. The thoracic spine has 12 nerve roots (T1 to T12) on each side of the spine that branch from the spinal cord and control motor and sensory signals mostly for the upper back, chest, and abdomen. Each thoracic spinal nerve is named for the vertebra above it. eg the T4 nerve root runs between the T4 vertebra and T5 vertebra.
Spinal nerves are referred to as “mixed nerves.”. The meningeal branches (recurrent meningeal or sinuvertebral nerves) branch from the spinal nerve and re-enter the intervertebral foramen to serve the ligaments, dura, blood vessels, intervertebral discs, facet joints, and periosteum of the vertebrae. Actions of the Thoracic spinal Nerves.
The below are some examples of disfunction of thoracic spinal nerves. Thoracic herniated disc, leading to thoracic radiculopathy, with symptoms of pain, tingling, numbness, and/or weakness radiating along the nerve root.
Each thoracic spinal nerve is named for the vertebra above it. eg the T4 nerve root runs between the T4 vertebra and T5 vertebra.
The intercostal nerves (see R image: Intercostal nerves, the superficial muscles having been removed), are distributed chiefly to the parietes (wall) of the thorax and abdomen, and differ from the anterior divisions of the other spinal nerves, in that each pursues an independent course, i. e., there is no plexus formation.
Each spinal nerve carries both sensory and motor information, via efferent and afferent nerve fibers - ultimately via the motor cortex in the parietal cortex - but also through the phenomenon of reflex. Spinal nerves are referred to as “mixed nerves.”.
The wall of the thorax receives its innervation from intercostal nerves (Fig. 8). These nerves are the ventral rami of segmental nerves leaving the spinal cord at the thoracic vertebral levels. Intercostal nerves are mixed nerves that carry both somatic motor and sensory nerves and autonomics to the skin.
The recurrent laryngeal nerves are the motor to most of the muscles of the larynx. It should be noted that an aneurysm in the arch of the aorta can injure the left recurrent laryngeal nerve and manifest as hoarseness of the voice caused by unilateral paralysis of the laryngeal musculature.
The superior mediastinum contains several important structures, including the branches of the aortic arch, the veins that coalesce to form the superior vena cava, the trachea, the esophagus, the vagus and phrenic nerves, the cardiac plexus of auto-nomic nerves, the thoracic duct, and the thymus (Fig. 10). 7.1.
Intercostal arteries 3-11 (and the subcostal artery) are branches directly from the thoracic descending aorta. The first two intercostal arteries are branches of the supreme intercostal artery, which is a branch of the costocervical trunk from the subclavian artery.
When the walls of the thorax expand, the lungs expand with them because of the negative pressure created in the pleural cavity and the propensity of the visceral pleura to maintain contact with the parietal pleura because of the high surface tension of the liquid between these surfaces (somewhat like two plates of glass sticking together with water in between them). The resultant negative pressure in the lungs forces the subsequent intake of air.
The trachea is a largely cartilaginous tube that runs from the larynx inferiorly through the superior mediastinum and ends by branching into the main bronchi (Fig. 11). It serves as a conduit for air to the lungs. The trachea can be palpated at the root of the neck, superior to the manubrium in the midline. The esophagus is a muscular tube that connects the pharynx with the stomach. The upper part of the esophagus descends behind the trachea, and in contact with it, through the superior mediastinum (Fig. 11). The esophagus continues through the posterior mediastinum behind the heart, pierces the diaphragm at the T10 level, and enters the stomach at the cardia. Both the trachea and esophagus are crossed on the left by the arch of the aorta. The impression of the aorta on the esophagus can usually be seen on a posterior-to-anterior radiograph of the esophagus coated with barium contrast. The trachea and esophagus are crossed on the right side by the azygos vein at the lower border of the superior mediastinum. Both the trachea and esophagus come into contact with the upper lobe of the right lung. The esophagus also contacts the upper lobe of the left lung. The arch of the aorta and its branches shield the trachea from the left lung.
The intercostal nerves pass out of the intervertebral foramina and run inferior to the rib. As they reach the costal angle, the nerves pass between the innermost and the internal intercostal muscles. The motor innervation to all the intercostal muscles comes from the intercostal nerves.
Each spinal nerve almost instantaneously splits into a large ventral ramus as well as smaller dorsal ramus.
The ventral and dorsal rami consist of both sensory and motor fibers contrary to the spinal roots. As they continue into the spinal nerves, this occurs due to mixing of fibers from dorsal and ventral roots.
The ventral rami become divided into ventral and dorsal divisions, in the brachial and lumbosacral plexuses.
Compared to the dorsal ones, the ventral rami innervate much larger parts of the body; this explains why the ventral rami consist of more nerve fibers and are much thicker compared to the dorsal ones. Some of the ventral rami combine in order to create plexuses.
On both sides of the vertebral column the cervical, lumbar and sacral ventral rami create five entitled plexuses:
31 pairs of spinal nerves are found in the human body. All spinal nerves originate through a ventral root and a dorsal root. Note that in the human anatomy, anterior and posterior are correspondingly equivalent of ventral and dorsal.
The sacral plexus produces nerves that innervate the pelvic floor and perineum and is created from the S3 to S5 ventral rami.
Spinal nerve. Figure 13.9 Anatomy of a Ganglion. The dorsal root ganglion contains the somas of unipolar sensory neurons conducting signals to the spinal cord. To the left of it is the ventral root of the spinal nerve, which conducts motor signals away from the spinal cord. (The ventral root is not part of the ganglion.)
The dorsal and ventral roots merge, penetrate the dural sac, enter the intervertebral foramen, and there form the spinal nerve proper.
Proximal Branches. Each spinal nerve has two points of attachment to the spinal cord (fig. 13.11). Dorsally, a branch of the spinal nerve called the dorsal root divides into six to eight nerve rootlets that enter the spinal cord (fig. 13.12).
There are 31 pairs of spinal nerves: 8 cervical (C1-C8), 12 thoracic (T1-T12), 5 lumbar (L1-L5), 5 sacral (S1-S5), and 1 coccygeal (Co) (fig. 13.10). The first cervical nerve emerges between the skull and atlas, and the others emerge through intervertebral foramina, including the anterior and posterior foramina of the sacrum.
General Anatomy of Nerves and Ganglia. The spinal cord communicates with the rest of the body by way of the spinal nerves. Before we discuss those specific nerves, however, it is necessary to be familiar with the structure of nerves and ganglia in general.
Many nerves often described as motor are actually mixed because they carry sensory signals of proprioception from the muscle back to the CNS. If a nerve resembles a thread, a ganglion19 resembles a knot in the thread. A ganglion is a cluster of cell.
In most nerves, the nerve fibers are gathered in bundles called fascicles , each wrapped in a sheath called the perineurium. The per-ineurium is composed of one to six layers of overlapping, squamous, epithelium-like cells. Several fascicles are then. Saladin: Anatomy & I 13.
The phrenic nerve is the only nerve innervating the diaphragm. brachial plexus. -The brachial plexus is the most complicated of the four because it innervates the complex musculature found in the upper limb (particularly the forelimb muscles).
winging of scapula. -The long thoracic nerve branches off the roots of C5-C7 and travels inferiorly to innervate the serratus anterior muscle. The serratus anterior rotates the scapula so that its inferior angle moves laterally and upward.
nerve plexuses. - Nerves emanating from regions of the spinal cord that control the muscles of the neck, upper limbs, and lower limbs combine to form complex nerve plexuses. -This is a developmental phenomenon resulting from the fusion of small skeletal muscles into larger muscles of compound origins as the limbs formed.
rami communicantes. -In the thoracic region, the ventral rami of the spinal nerves split off another ramus carrying autonomic nerve fibers. These are called the rami communicantes, and their fibers enter the sympathetic trunk located on both sides of the vertebral column. sympathetic trunk. -The sympathetic trunk is comprised ...
shuffling gait. -If the tibial nerve is damaged, the calf muscles cannot plantar flex the foot resulting in a shuffling gait. dermatome. -The area of the skin innervated by a single pair of spinal nerves is called a dermatome. -Every spinal nerve except C1 innervates dermatomes.
The sciatic nerve is actually two nerves, the tibial and common fibular (AKA common peroneal) which are wrapped together into a common sheath by connective tissue. sciatic nerve.
sacral nerves. -5 pairs of sacral. coccygeal nerves. -1 pair of coccygeal nerves (Co1) roots. -each spinal nerve connects to the spinal cord through dorsal and ventral roots with each root forming from a number of rootlets that attach along the length of the particular spinal cord segment. -The roots are carrying either sensory (dorsal root) ...
As the nerves leave the paravertebral space, they enter the intercostal space below the respective rib of each, lying between the innermost intercostal muscle and the pleura. Lateral to the paravertebral muscles, the prominent angles of the ribs are palpable as the primary landmark for intercostal nerve block. At the angle of the rib, the nerve lies between the innermost intercostal muscle and the inner intercostal muscle. At this distance, the thickness of the rib is about 8 mm, and the costal groove is widest. 10 Here the nerve is positioned below the intercostal vein and artery, under or below the rib ( Fig. 75-1 ). A cadaver study found that the intercostal nerve remained in a classic subcostal position only 17% of the time. 11 It was shown to be in a midcostal location most frequently (73%), and it was supracostal in some cadavers (10%). Just beyond the midaxillary line, the lateral cutaneous branch of the nerve arises, providing sensory innervation anteriorly and posteriorly to much of the thorax and abdomen 12 ( Fig. 75-2 ).
Thoracic nerve root lesions account for less than 2% of all radiculopathies and are most commonly caused by diabetes and thoracic disk herniation ( Dumitru and Zwarts, 2002 ). The EDX study is somewhat limited except for the T1 root, in which case the median CMAP and medial antebrachial cutaneous sensory response can aid in diagnosis. For all other thoracic segments, the NEE consists mainly of thoracic paraspinal and abdominal wall muscles. Intercostal muscles may be studied as well, but are often avoided given the risk of pneumothorax ( Tavee and Levin, 2011 ). In patients with diabetic thoracic radiculopathy, needle examination may reveal fibrillation potentials in the affected thoracic segments. When abnormalities are seen, the lesion can at best be localized to upper, middle, and lower thoracic segments rather than specific root levels, due to the significant overlap in paraspinal and abdominal wall innervation.
A common posterior parasagittal fluoroscopically guided approach may be made toward the thoracic nerve root, dorsal root ganglia, sympathetic ganglia, and, in the lower thoracic region, splanchnic nerves . The patient is placed prone on the fluoroscopy table, and the skin of the back is prepared in the standard fashion.
Lateral to the paravertebral muscles, the prominent angles of the ribs are palpable as the primary landmark for intercostal nerve block. At the angle of the rib, the nerve lies between the innermost intercostal muscle and the inner intercostal muscle.
The thoracic nerve root, dorsal root ganglia, sympathetic ganglia, and splanchnic structures may be reached by a novel posterior parasagittal approach using curved electrodes . This approach provides access to the thoracic paravertebral sympathetic structures at any level from T2 through T12, decreases the risk of inadvertent pneumothorax, and allows access to the midthoracic levels, which were previously difficult to approach safely using a traditional posterolateral approach. The use of blunt-tipped electrodes greatly improves the safety of thoracic posterior parasagittal techniques, especially when applied toward lesions of the thoracic sympathetic and splanchnic structures. This “posterior parasagittal curved-needle approach” developed by one of the authors (W.Y.) has been used in more than 500 individual thoracic segmental procedures, with no pneumothorax to date.
The thoracic nerves also have their own set of dorsal root ganglia. They are primarily found foraminal between their respective thoracic vertebrae, where the cephalad vertebra is the one that gives its number to the spinal nerve that arises beneath it (i.e., the T1 dorsal root ganglion is noted to be in the foramen created by the T1 and T2 vertebrae). There is very little literature that talks about studies of the anatomy, positioning, and variance of thoracic dorsal root ganglia (Bergman, Thompson, & Afifi, 1998 ). However, it should be known the clinical significance of these ganglia arise in topics such as herpes zoster neuralgia or neuropathic pain postthoracic procedure.
The first two nerves supply fibers to the upper limb in addition to their thoracic branches, the next four are limited in their distribution to the parietal pleura of the thorax, and the lower five supply the parietal pleura of the thorax and abdomen. The seventh intercostal nerve terminates at the xyphoid process.