SKIN AND SUBCUTANEOUS TISSUE
- The skin is composed of epidermis and dermis.
- It is traversed by lines of cleavage called Langer’s lines. First described by Langer in 1861, these lines represent parallel rows of collagen bundles present in the dermal tissue. When these lines are transected the skin edges are pulled apart.
- Skin incisions following these lines generally heal with a thinner scar.
- The Langer’s lines on the abdomen run in a transverse fashion (Fig.1).
(Fig.1) Langer’s lines of the abdomen.
A, Transverse section of the anterior abdominal wall above the arcuate line. The posterior leaf of the aponeurosis of the internal oblique muscle and the aponeurosis of the transversus abdominis muscle unite to form the posterior wall of the rectus sheath. B, A transverse section through the anterior abdominal wall. Below the arcuate line, the posterior wall of the rectus sheath is formed only by the transversalis fascia. 1, External oblique; 2, internal oblique; 3, transversus abdominis; 4, rectus abdominis; 5A, posterior rectus sheath; 5B, transversales fascia; 6, linea alba; 7, perperitioneal fat; 8, peritoneum
- Camper’s fascia: Superficial fatty layer that can be several centimeters thick in an obese patient
- Scarpa’s fascia
a.A membranous layer lying beneath Camper’s fascia
b.Continuous with Colle’s fascia of the perineum and joins the deep fascia lata of the anterior thigh 2 cm inferior to the inguinal ligament
- Rectus fascia
a. The rectus fascia is a tough band of connective tissue that is com’ posed of the aponeuroses of the external oblique, internal oblique, and transversus abdominis muscles and their point of insertion at the midline in the avascular linea alba.
b. Superior to the arcuate line, a landmark found in the midline at the level of the anterior superior iliac spine, the aponeuroses form an anterior and posterior sheath to the rectus abdominis muscles.
- The anterior rectus sheath consists of the aponeuroses of the external oblique and the split aponeurosis of the internal oblique.
- The posterior rectus sheath consists of the remaining portion of the internal oblique coupled with the aponeurosis of the transversus abdominis muscle.
c. Inferior to the arcuate line, the posterior rectus sheath disappears.
d. The transversus abdominus and the entire internal oblique aponeurosis is found anterior to the rectus abdominus muscle.
e. Therefore, below the arcuate line, the anterior rectus sheath con- sists of the aponeuroses of the external and the entire internal oblique and transversus abdominus.
f. In this region the anterior abdominal wall is weaker and there is an increased incidence of incisional hernias.
g. Tendinous insertions between the rectus abdominus muscles and the anterior rectus sheath exist in several horizontal bands along the course of the muscle.
- 4. Transversalis fascia: a membranous layer that lies deep to the rectus muscles and superficial to the peritoneum.