## Layers ![[Pasted image 20250114205808.png]] - 7 layers of the abdominal wall: 1. skin 2. subcutaneous fat (Camper's fascia) 3. superficial (Scarpa) fascia 4. subscarpal fat 5. anterior rectus sheath 6. muscle 7. posterior rectus sheath ### Skin - Abdominal skin quality varies based on genetics, age, pregnancies, and weight changes - **striae** may form from attenuated or absent dermis ### Fat - Abdominal fat fall into 2 layers, separated by the superficial fascia - **superficial fat layer**: more dense and durable, with greater blood supplied from the skin - **deeper fat layer**: less dense, with blood supplied from the subdermal plexus and myocutaneous perforators > Distinct vascular supply of the deeper fat layer along with its less dense content makes it an easier target for thinning in [[Abdominoplasty]] without compromising the skin ### Muscles - 4 pair of muscles make up the abdominal wall: 1. rectus abdominis 2. External oblique 3. Internal oblique 4. Transversus abdominis - Above the **arcuate line** (1/2 between the umbilicus and symphysis pubis): - The external oblique and internal oblique aponeurosis form the anterior rectus sheath - The Internal oblique and transversus abdominis aponeurosis form the posterior rectus sheath - Below the arcuate line, both rectus sheath join into only an anterior rectus sheath ## Arterial Supply ![[Pasted image 20250114210840.png]] - Vascular supply to the abdominal wall fall into **3 zones**:^[Huger, W. E. (1979). The anatomic rationale for abdominal lipectomy. _The American Surgeon_, 45(9), 612–617.] 1. Zone I: superficial superior and inferior epigastric systems 1. Between lateral border of the rectus sheath 2. Inferior to the costal margin & superior to the line connecting ASIS 2. Zone II: superficial circumflex iliac and external pudendal vessels 1. Inferior to the line connecting the ASIS 2. Superior to the pubic and inguinal creases 3. Zone III: intercostals, subcostals, and lumbar vessels 1. Lateral to zone I 2. Superior to zone II ## Innervation - Sensation of the abdominal wall derives from **intercostal nerves T7-12** - Lateral cutaneous branches - Perforate the intercostal muscles at the midaxillary line - Then, travel within the subcutaneous plane - Anterior cutaneous branches - Travel between the transversus abdominus and internal oblique muscles to penetrate the posterior rectus sheath lateral to the rectus - Then, enter the rectus and pass to the overlying fascia and skin - Lateral femoral cutaneous nerve (lateral thigh innervation) - emerges close to the ASIS ⇒ **leave a layer for fat over the ASIS to prevent injury** ![[Pasted image 20250114211143.png]] ## Landmarks ### Umbilicus ![[Pasted image 20250114211236.png]] - The umbilicus locates near the midline at the level of the iliac crest - **Vascular supply** of the umbilicus: - Subdermal plexus - Right and left deep inferior epigastric artery - Ligamentum teres - Median umbilical ligament - An **aesthetically pleasing umbilicus** shows:^[Nahai, F. (Ed.). (2005). _The art of aesthetic surgery: principles & techniques_. Quality Medical Pub.] - superior hooding - inferior retraction - round or ellipsoid shape - shallow #anatomy #Plastics #General