Remove skin and subcutaneous tissue from the anterior abdominal wall
Find these structures:
Superficial epigastric vein
1.) Incise the skin (not the subcutaneous layer) mid-sagittally from the xiphoid process of the sternum to the pubic symphysis. Cut around the umbilicus in order to maintain this landmark.
Photo 1. Procedural: planning abdominal wall skin incisions
Photo 2. Procedural: laterally reflecting the skin
Photo 3. Procedural: skin reflected, subcutaneous layer intact
Photo 4. Procedural: inferior-most skin strip reflection
Note: The superficial epigastric vein is a tributary of the femoral vein. With portal hypertension, the superficial epigastric vv. may become distended and anastomose with patent paraumbilical vv. This phenomenon is known as caput medusae.
Photo 5. Superficial epigastric vein
Note: As you remove the subcutaneous tissue, appreciate any cutaneous neurovasculature that pierces the fascia and subcutaneous tissue.
Photo 6. Procedural: incision line
Photo 7. Procedural: incising the subcutaneous tissue
Photo 8. Procedural: subcutaneous tissue removed
Find these structures:
External oblique muscle
Inguinal ligament
Superficial inguinal ring
Medial crus
Lateral crus
Round ligament of uterus or spermatic cord
Anterior labial or anterior scrotal branches of the ilio-inguinal nerve
Rectus sheath
Linea alba
Note: The external oblique muscles are the most superficial of the anterolateral abdominal muscles. The muscle fibers are oriented inferomedially (think “hands in your ipsilateral pockets”).
Photo 9. External oblique muscles
Note: The inguinal ligament extends from the anterior superior iliac spine (ASIS) of the ilium to the pubic tubercle of the pubis. It forms the inferior portion of the inguinal canal.
Photo 10. Inguinal ligament
Note: The superficial inguinal ring is the medial aperture of the inguinal canal that transmits either the round ligament of the uterus, or spermatic cord. The margins of the superficial inguinal ring are called the medial crus (attaching to the pubic crest) and the lateral crus (attaching to the pubic tubercle).
Photo 11. Procedural: Blunt dissection
Photo 12. Superficial inguinal ring, medial & lateral crura
Note: The round ligament of uterus is a remnant of the female gubernaculum, connecting the labium majus and the uterus. The round ligament appears as a tubular collection of adipose tissue.
Note: The spermatic cord will be dissected in more detail in a later lab. It contains the cremaster muscle, cremasteric artery, testicular artery, ductus deferens, artery of ductus deferens, pampiniform venous plexus, genital branch of the genitofemoral nerve, sympathetic nerve fibers, and lymphatic vessels.
Photo 13. Round ligament and anterior labial branch of ilio-inguinal nerve
Photo 14. Spermatic cord and anterior scrotal branch of ilio-inguinal nerve
Note: The rectus sheath is the aponeuroses of the three lateral abdominal muscles (external oblique, internal oblique, and transversus abdominis), and encloses the rectus abdominis muscle. The linea alba spans between the xiphoid process and the pubic symphysis, and is a medial attachment point of the three abdominal oblique muscles.
Photo 15. Rectus sheath, linea alba, external oblique muscle
Find these structures:
Internal oblique muscle
Iliohypogastric nerve (L1)
Ilio-inguinal nerve (L1)
12.) Beginning at the anterior superior iliac spine (ASIS), cut the external oblique muscle to its superior-most costal attachments (approximately at rib 5). Take care to preserve the nerves deep to this muscle.
Photo 16. Procedural: external oblique incision lines
Photo 17. Procedural: two finger breadths from ASIS
Note: The internal oblique muscle fibers are oriented superomedially (think “hands in your contralateral pockets”).
Photo 18. Internal oblique muscle
Note: The iliohypogastric nerve is superior to the ilio-inguinal nerve. Both nerves run parallel to the inguinal ligament. These nerves share a common source (L1), and typically present as two separate nerves superficial to the internal oblique m. However, the common source may pierce the internal oblique m.
Note: The iliohypogastric and ilio-inguinal nerves serve as a means of distinguishing between the muscle fibers (if orientation is confusing) of the external and internal oblique muscles.
Note: The ilio-inguinal nerve will ultimately lie within the inguinal canal.
Photo 19. Iliohypogastric and ilio-inguinal nerves
Find these structures:
Transversus abdominis m.
Intercostal nn. brs. (T7-T11)
Subcostal n. br. (T12)
Photo 20. Procedural: internal oblique muscle incisions
Photo 21. Internal oblique reflected
Note: The transversus abdominis muscle fibers run transversely, except for the inferior fibers which run in a similar direction as the internal oblique muscle fibers.
Note: The nerves present in this view are the distal anterior and lateral branches of the intercostal nerves (ventral rami). These nerves are often referred to as thoraco-abdominal nerves.
Photo 22. Intercostal nn. brs. and subcostal n. br.
Find these structures:
Rectus abdominis m.
Superior epigastric a. & v.
Inferior epigastric a. & v.
Transversalis fascia
Arcuate line
Inguinal triangle
18.) Open the rectus sheath on one side with a vertical incision lateral to the linea alba. Reflect laterally.
Photo 23. Procedural: incising the rectus sheath
Photo 24. Rectus sheath reflected
Note: The superior and inferior epigastric a. and v. may be adhered to the deep part of the rectus abdominis m. and will need to be carefully extracted through blunt dissection.
Photo 25. Procedural: reflecting rectus abdominis m.
Note: The superior epigastric a. is the continuation of the internal thoracic a. The superior epigastric v. drains into the subclavian v.
Note: The inferior epigastric a. is a branch of the external iliac a. The inferior epigastric v. drains into the external iliac v.
Photo 26. Superior and inferior epigastric neurovasculature
Note: The transversalis fascia is deep fascia that covers the inner surface of the transversus abdominis m., and extends medially to the anterior abdominal wall. The lateral abdominal wall is composed of seven layers. From superficial to deep, these layers are skin, subcutaneous tissue, external oblique muscle, internal oblique muscle, transversus abdominis muscle, transversalis fascia, and parietal peritoneum.
Photo 27. Transversalis fascia and arcuate line
Photo 28: Layers of the abdominal wall
Note: The boundaries for the inguinal triangle are inferior epigastric vessels (superolaterally), lateral border of rectus abdominis (medial), and inguinal ligament (inferiorly).
Note: Direct inguinal hernias enter the inguinal canal through the ‘weak fascia’ (e.g. transversalis fascia) in the inferomedial portion of the inguinal triangle.
Photo 29: Inguinal triangle
Find these structures:
Median umbilical fold
Medial umbilical folds
Lateral umbilical (epigastric) folds
Deep inguinal ring
Inguinal canal
23.) Locate the cut edge (three lateral abdominal muscles) of the inferolateral abdominal wall. Cut through the transversalis fascia and parietal peritoneum along the same line, if not already completed. Separate all layers from the costal margin, and reflect the entire anterior abdominal wall inferiorly.
Photo 30: Procedural: inferiorly reflecting the abdominal wall
Note: The median umbilical fold is located in the midline (extending from umbilicus to the apex of the urinary bladder) and is created by the median umbilical ligament (a remnant of the urachus).
Note: The medial umbilical folds are located lateral to the median umbilical fold. The fossae in between are the supravesicular fossae.The medial umbilical folds are created by the medial umbilical ligaments (obliterated umbilical aa.).
Note: The lateral umbilical folds are located lateral to the medial umbilical folds. The fossae in between are the medial inguinal fossae. Direct inguinal hernias are associated with these fossae. The fossae lateral to the lateral umbilical folds are the lateral inguinal fossae, and these are associated with indirect inguinal hernias. The lateral umbilical folds are created by the inferior epigastric vessels.
Photo 31: Umbilical folds
Note: The deep inguinal ring is the internal aperture of the inguinal canal through which the round ligament of the uterus or spermatic cord enters the inguinal canal. The ring is an invagination of the transversalis fascia. Indirect inguinal hernias enter the inguinal canal through the deep inguinal ring.
Photo 32: Deep inguinal ring
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