This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
The upper part of the abdomen is drained by small branches emptying into the superior epigastric, the intercostal, and laterally into the axillary veins. Below, there are the superficial epigastric and superficial circumflex iliac veins. In cases of obstruction to the flow of blood in the large deep veins the superficial veins become visible; thus a branch often becomes visible on the side running from the axillary vein to the superficial epigastric or femoral vein, - it is called by Braune (" Das Venensystem des menschlichen Korpers,". 1884, Joessel and Waldeyer, Topog. chirurg. Anat., pp. 22, 147) the vena tho-racica epigastrica longa tegumentosa (Fig. 392). Other small veins around the umbilicus become very much enlarged, and, branching in various directions around the umbilicus, have given rise to the term caput Medusas.
Kelly (" Operative Gynecology," p. 48) describes two small veins running from the symphysis up to the umbilicus in the subcutaneous tissue on each side of the linea alba, and calls them celiotomy veins.
The superior epigastric, deep epigastric, and circumflex iliac arteries are accompanied by veins. There is also a vein in the round ligament of the liver emptying into the portal vein, called by Schiff, and later by Sappey, the vena parumbilicalis (Memoires de l'acad. demed.", 1859). In some cases two small veins can be seen on the interior of the abdominal wall, running up to the umbilicus from the symphysis on each side of the median line, and two coming down to the umbilicus on each side of the median line.
The superficial parts above the umbilicus are drained by lymphatics which empty into the axillary nodes; the vessels below the umbilicus empty into the oblique set of nodes in the groin. The lymphatics of the deep surface of the abdominal wall above the umbilicus drain into the mediastinal nodes, while those below drain into the pelvic lymphatics along the iliac arteries.
The front and sides of the abdomen are supplied by the anterior and lateral cutaneous branches of the sixth, seventh, eighth, ninth, tenth, and eleventh intercostal nerves, the twelfth thoracic or subcostal, and the iliohypogastric and ilioinguinal branches of the first lumbar. The sides of the abdomen are supplied by the lateral cutaneous branches which supply the skin as far forward as the rectus muscle. The recti muscles and skin overlying them are supplied by the anterior branches. These pass forward between the internal oblique and transversalis muscles to enter the sheath of the rectus, and. after supplying the muscle, pierce the anterior layer and are distributed to the integument above. The sixth and seventh supply the infrasternal region, the eighth about half way down to the umbilicus, the ninth just above the umbilicus, the tenth the region of the umbilicus, and the eleventh just below, - being about opposite the fold of Douglas, while the twelfth supplies the region above the pubes.
Fig. 392. - Obstruction of the right iliac vein from phlebitis. The vena thoracica epigastrica longa is seen running from the groin up to the axilla.
The iliohypogastric emerges through the external oblique about 2 or 3 cm. above the external ring, while the ilio-inguinal emerges through the external ring and supplies the parts adjacent. From this distribution it is evident why disease posteriorly, such as caries of the spine or pleurisy, will cause pain to be complained of in the corresponding distribution anteriorly. Incisions through, or along the outer edge of the rectus, will divide the nerves supplying it, and cause paralysis of the muscle. Incisions made across the lateral muscles of the abdomen cannot be efficiently repaired by sewing the cut muscles together, because this-does not restore the function of the nerves which have been divided.