distribution of intercostal nerves in musculis rectus abdominis

this study was conducted on 48 specimens of rectus abdominis muscles for recognition and definition of passage and ramification of lower intercostal nerves. the main results of this study are as follows: 1- the seventh and eight intercostal nerves penetrated to posterior layer of the rectus sheath while other intercostal nerves perforated to dorsal layer of internal oblique abdominis aponeurosis. 2- distance between lateral border of the rectus abdominis muscle till penetrate point for all nerves were 18±1 mm, but the subcostal nerve was 16±1 mm. 3- each intercostal nerve was ramified in thickness of muscle and formed many branches that maximum of this was middle longitudinal region and minimum of that was lateral longitudinal region. in addition we did not observe the nerve anastomosis between intercostal nerves. 4- the lower primary branch of the intercostal nerve after piercing of anterior layer of the rectus sheath was named anterior cutaneous branch and terminated to abdominal skin. 5- all of intercostal nerves at first was placed right angle to muscle fibers but immediately decrease its and was placed parallel to muscle fibers. 6- the entrance, passage and ramification of intercostal nerves in both male and female cadavers were similar.