What Are the Intercostal Nerves?

One of the spinal nerves. Formed by the anterior branch of the thoracic nerve. Located in the intercostal space, 11 on each side. The intercostal nerve travels through the intercostal internal muscles, and on the side of the chest and abdomen wall, the lateral cutaneous branch is issued. The perforator is shallow and is distributed on the skin of the chest and abdomen sidewall.

One of the spinal nerves. Formed by the anterior branch of the thoracic nerve. Located in the intercostal space, 11 on each side. The intercostal nerve travels through the intercostal internal muscles, and on the side of the chest and abdomen wall, the lateral cutaneous branch is issued. The perforator is shallow and is distributed on the skin of the chest and abdomen sidewall.

Chinese name

Intercostal nerve

Make up

Thoracic nerve

Three distributions

Segmental distribution

Related diseases

1. Intercostal neuritis 2. Intercostal neuralgia

Intercostal nerve overview

The main trunk continues to move forward, with the upper 6 intercostal nerves reaching the lateral edge of the sternum, and the lower 6 costal nerves slanting downward and inward, traveling between the internal abdominal obliques and transverse abdominal muscles and entering the rectus abdominis sheath, near the white line The anterior wall through the rectus sheath is shallow. These superficial branches are called anterior cutaneous branches and are distributed on the skin of the anterior wall of the thorax and abdomen. The cutaneous branches of the fourth, fifth, and sixth intercostal nerves are distributed in the breast. The muscle branches of the intercostal nerve dominate the intercostal internal and external muscles, transverse pectoralis, upper and lower posterior serratus, internal and external obliques, transverse abdominal muscles and rectus abdominis.

Intercostal neuroanatomical features

1.The walking and distribution of intercostal nerves

After the inferior intercostal nerve issues a lateral cutaneous branch near the mid-axillary line, the main trunk accompanies the posterior intercostal artery and continues between the internal oblique and transverse abdominal muscles, moving inward and downward. The intercostal nerve trunk is highly variable at this level. It is common that the trunk travels in a single branch in parallel to the outer edge of the rectus abdominis muscle; it can also be seen that the trunk emits 2 to 3 branches obliquely inward and down to the rectus abdominis muscle. Outer edge. In addition, it can be seen that some nerve trunks or branches join adjacent intercostal nerves to form the combined trunk and reach the outer edge of the rectus abdominis.

The segmental intercostal nerve and the semilunar line were inclined at an angle of 45 ° ± 5 ° and penetrated the rectus abdominis sheath at the junction of the rectus abdominis muscle into the rectus abdominis area. The intersections of the T9 and T10 nerves with the meniscus are located at (5.6 ± 1.8) cm and (1.2 ± 0.9) cm above the umbilicus, and the intersections of the T11 and T12 nerves with the meniscus are located at (1.7 ± 1.4) cm and (5.6) below the umbilicus, respectively. ± 1.6) cm. Most nerves penetrate the rectus abdominis after walking 1 to 4 cm behind the rectus abdominis, and their penetration points are located in the 1/3 area outside the rectus abdominis. Each of the main nerves or their branches crosses the sub-abdominal blood vessels in front of or behind the blood vessels, and sometimes different nerve branches of the same main body cross the sub-abdominal blood vessels in front of and behind the blood vessels. The intersections of the T9 nerve and the inferior abdominal wall artery are located at (2.6 ± 1.4) cm above the umbilical cord, and the intersections of the T10, T11, and T12 nerves and the inferior abdominal wall artery are located at (1.3 ± 0.7) cm, (5.0 ± 1.5) cm, ( 7.8 ± 1.5) cm.

2.The movement and distribution of intercostal neuromotor branches (muscle branches)

After the intercostal nerve penetrates the rectus abdominis through the rectus abdominis, it first sends out 1 or 2 recurrent branches, which dominate the rectus abdominis at the outside of the penetration point; and the trunk continues to travel obliquely inward and downward, or gradually from the trunk The upper and lower branches, or directly branched branches, walk in the rectus abdominis at the median point of penetration. Between adjacent segment nerves, it can be observed that the motor nerve branches coincide with each other in the rectus abdominis muscle to form a communication branch. In the same region of the rectus abdominis muscle, the motor branches issued by the adjacent segment nerves are commonly dominated. Most of the intramuscular motor nerve branches are accompanied by small blood vessels.

3.The walking and distribution of intercostal sensory nerve branches (cutaneous perforating branches)

We define the perforator branch that penetrates the anterior sheath into the subcutaneous tissue as the "pure" sensory branch (in fact, it contains some autonomic nerve fiber components). The sensory nerve branch is separated from the intercostal nerve trunk in two ways: (1) Before the nerve trunk penetrates into the rectus abdominis, it is directly branched from the trunk and penetrated through the rectus abdominis in the form of a "pure" sensory branch. After reaching the superficial anterior sheath or walking directly on the superficial surface of the rectus abdominis, the anterior sheath was then passed out. (2) It is branched from the mixed nerve branch running in the rectus abdominis muscle. The intramuscular nerve branch divides the motor branch and sends out the sensory branch to penetrate the anterior sheath. The sensory nerve branch is closely related to the perforating branch of the abdominal wall. The two form a vascular nerve bundle to penetrate the anterior sheath and enter the subcutaneous tissue. In the rectus abdominis muscle, the running relationship between the sensory nerve branch and the perforating branch of the abdominal wall: one form is that they are accompanied by each other in the muscle, and the anterior sheath is passed through the rectus abdominis muscle; the other form is the nerve perforation. The branches and vascular perforating branches are not accompanied, but pass through the rectus abdominis from different directions to the superficial surface of the muscles, and then form a vascular nerve bundle to exit the anterior sheath. Vascular nerve bundles are roughly divided into the inner and outer rows in the anterior sheath. The sensory nerve branches are defined as the inner and outer branches.