Intercostal nerve
Ventral rami of the 12 intercostal nerves
Thoracic
T1
The smaller part of the T-1 participates as an intercostal but the larger part of the ventral
ramus of T-1 participates in the brachial plexus
This small branch does not usually have a lateral branch
They contribute preganglionic sympathetic fibers to the sympathetic chain through white
rami communicates
They receive postganglionic fibers from the sympathetic chain ganglia through gray rami
communicates
Thoracic intercostals are T 1-6
Initially lie between pleura and internal intercostal ligament
Thenbetween the external and internal as far as the side of chest
They enter a separation between two lamina of the internal oblique
Then go deep to the costal cartilage and can be found between the internal intercostal and
the transverse thoracis muscle
Lateral branches arise at the axillary line and pierce the externao oblique and serratus
anterior and divide into anterior and posterior branches
The lateral cutaneous branch of T-2 is the interchostal brachial nerve
The thoracic intercostal nerves terminate as the anterior cutaneous branch at the side of
the sternum they have short media and long laterals
Thoraco-abdominal intercostal nerves T 7-11
At the anterior ends of the costal cartilages these intercostals pass between the internal
intercostal muscle and the transversus abdominis muscle
They suipplyt eh internal obliques ante external obliques and the transversus abdominis
In their course they supply the internal intercostal external inercoatal the posterior
inferior serratus muscles and end in
End as anterior cutaneous braches
The lateral cutaneous braches in the axillary line and divide into anterio and posterior
branches and the anterior branch supplies as far as the lateral border of the rectus
Jthe anterior cutaneous branch comes up at the midline and has short medial and longer
lateral branches that go to the lateral border of the rectus
Subcostal nerve large ventral ramus of the t-12 nerve
Crosses the venr=tral surface of the quadratus lumborum under the transversalis fascia
penetrates the transversus abdominis muscle
Communicates twith the ilio-huypogastric
The lateral branch of the subcostal does not have an anterior or posterior branch but goes
over the iliac crest several centimeters behind the ASIS
Woodburne page 365 to innervate the skin as far down as the greater trochanter