ORIGIN: Spinal cord segment T7.

COURSE/DISTRIBUTION: This nerve takes origin from spinal cord segment T7 and leaves the vertebral canal by passing through the intervertebral foramen between T7 and T8 vertebrae. It immediately divides into two rami- dorsal and ventral rami.

Dorsal ramus:

It immediately turns backwards, close to T7 costotransverse joint and divides into medial and lateral branches.

bulletThe medial branch immediately passes between the joint and the superior costotransverse ligament with the corresponding intertransversarii. It runs between the semispinalis thoracis and multifidus. Its cutaneous branches now enter the skin at the side of T7 vertebra to supply the medial part of posterior aspect of T7 dermatome.
bulletThe lateral branch runs laterally and occupies the interval between the superior costotransverse ligament and the intertranversarii. It then turns on the medial aspect of the T7 levator costae. It runs between the longissimus thoracis and iliocostalis thoracis. Its muscular branches supply these muscles; pierces the latissimus dorsi, and supplies it before it then pierces the skin of the remaining lateral part of the T7 dermatome to supply it with cutaneous branches.

Ventral ramus:

bullet Continues as the seventh intercostal nerve, which runs in the costal groove of the 7th rib under the 7th posterior intercostal artery. The 7th superior anterior intercostal artery later replaces this artery in the same groove. It later enters the anterior abdominal wall to supply the external oblique and internal oblique muscles of abdomen and the transversus abdominis. It lies behind the rectus abdominis in the rectus sheath to supply that muscle.


bulletCutaneous branches
bulletMuscular branches
bulletDorsal ramus
bulletVentral ramus
  1. Continues as 7th intercostal nerve.




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