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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.
2.) Prepare to remove three bilateral sets of skin strips:
2.) Prepare to remove three bilateral sets of skin strips:
a.) Superior skin strip: two incisions extending to the midaxillary line
a.) Superior skin strip: two incisions extending to the midaxillary line
i.) Superior along the costal margin (already completed)
i.) Superior along the costal margin (already completed)
ii.) Superior to the umbilicus in a transverse plane.
ii.) Superior to the umbilicus in a transverse plane.
b.) Intermediate skin strip: transverse incision spanning laterally past the iliac crest.
b.) Intermediate skin strip: transverse incision spanning laterally past the iliac crest.
c.) Inferior skin strip: incision beginning medially about two finger breadths inferolateral to the labia majora or scrotum and extending laterally to the iliac crest in the midaxillary line.
c.) Inferior skin strip: incision beginning medially about two finger breadths inferolateral to the labia majora or scrotum and extending laterally to the iliac crest in the midaxillary line.
Photo 1. Procedural: planning abdominal wall skin incisions
3.) Remove skin of the superior and intermediate skin strips from medial to lateral.
3.) Remove skin of the superior and intermediate skin strips from medial to lateral.
Photo 2. Procedural: laterally reflecting the skin
Photo 3. Procedural: skin reflected, subcutaneous layer intact
4.) Beginning laterally, remove the inferior-most skin strip. Reflect skin to approximately two finger breadths superolaterally from the labia majora or penis. Remove the skin flap carefully with scissors to avoid potentially cutting through the round ligament of the uterus or spermatic cord.
4.) Beginning laterally, remove the inferior-most skin strip. Reflect skin to approximately two finger breadths superolaterally from the labia majora or penis. Remove the skin flap carefully with scissors to avoid potentially cutting through the round ligament of the uterus or spermatic cord.
Photo 4. Procedural: inferior-most skin strip reflection
5.) With blunt dissection, locate the superficial epigastric vein. This vein may be visible through the subcutaneous tissue. If not, bluntly dissect superior to the inguinal ligament region.
5.) With blunt dissection, locate the superficial epigastric vein. This vein may be visible through the subcutaneous tissue. If not, bluntly dissect superior to the inguinal ligament region.
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
6.) Starting from the superior-most incision and moving inferiorly, elevate the subcutaneous tissue from the deep fascia down to the level approximately 3 fingerbreadths superior to the pubic symphysis. Using scissors, incise the subcutaneous tissue at this level, and remove completely.
6.) Starting from the superior-most incision and moving inferiorly, elevate the subcutaneous tissue from the deep fascia down to the level approximately 3 fingerbreadths superior to the pubic symphysis. Using scissors, incise the subcutaneous tissue at this level, and remove completely.
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
Clean and examine the external oblique muscles, and examine the external features of the inguinal canal
Clean and examine the external oblique muscles, and examine the external features of the inguinal canal
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
7.) Clear the muscular fascia from the external oblique muscles.
7.) Clear the muscular fascia from the external oblique muscles.
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
8.) Carefully clean the external oblique aponeuroses to the inguinal ligaments (if not done previously), which are the inferior-most margins of the aponeuroses of the external oblique muscles.
8.) Carefully clean the external oblique aponeuroses to the inguinal ligaments (if not done previously), which are the inferior-most margins of the aponeuroses of the 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
9.) Locate specializations of the aponeurosis of the external oblique muscle: superficial inguinal ring, and medial and lateral crura of the superficial inguinal ring. This will require careful blunt dissection in order to not damage the neurovasculature in this region.
9.) Locate specializations of the aponeurosis of the external oblique muscle: superficial inguinal ring, and medial and lateral crura of the superficial inguinal ring. This will require careful blunt dissection in order to not damage the neurovasculature in this region.
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
10.) Clean and identify the round ligament of uterus or spermatic cord as it exits the superficial inguinal ring. In this area, locate the small anterior labial or anterior scrotal branches of the ilio-inguinal nerve.
10.) Clean and identify the round ligament of uterus or spermatic cord as it exits the superficial inguinal ring. In this area, locate the small anterior labial or anterior scrotal branches of the ilio-inguinal nerve.
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
11.) Locate the rectus sheath medial to the external oblique muscles. In the midline, identify the linea alba.
11.) Locate the rectus sheath medial to the external oblique muscles. In the midline, identify the linea alba.
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
Reflect the external oblique muscles, and identify the internal oblique muscles and L1 spinal nerve branches
Reflect the external oblique muscles, and identify the internal oblique muscles and L1 spinal nerve branches
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.
13.) Reflecting the external oblique muscle medially, relieve the muscle from its remaining superior attachments to the ribs and inferior attachments to the iliac crest. Only reflect the muscle inferiorly to the level of two finger breadths inferior to the ASIS to avoid damaging the integrity of the inguinal canal.
13.) Reflecting the external oblique muscle medially, relieve the muscle from its remaining superior attachments to the ribs and inferior attachments to the iliac crest. Only reflect the muscle inferiorly to the level of two finger breadths inferior to the ASIS to avoid damaging the integrity of the inguinal canal.
Photo 16. Procedural: external oblique incision lines
Photo 17. Procedural: two finger breadths from ASIS
14.) Identify and clean the internal oblique muscle.
14.) Identify and clean the internal oblique muscle.
Note: The internal oblique muscle fibers are oriented superomedially (think “hands in your contralateral pockets”).
Photo 18. Internal oblique muscle
15.) Identify the iliohypogastric and ilio-inguinal nerves lying superficial to the internal oblique muscle.
15.) Identify the iliohypogastric and ilio-inguinal nerves lying superficial to the 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
Reflect the internal oblique muscles, and identify the transversus abdominis muscles and intercostal nerves
Reflect the internal oblique muscles, and identify the transversus abdominis muscles and intercostal nerves
Find these structures:
Transversus abdominis m.
Intercostal nn. brs. (T7-T11)
Subcostal n. br. (T12)
16.) Cut the internal oblique muscle vertically in the mid-axillary plane extending from the iliac crest to its attachments on the ribs. Make two transverse incisions: medially through the most superior attachment to the ribs, and medially from the anterior superior iliac spine to the lateral aspect of the rectus sheath. Reflect the muscle medially, taking care to preserve the deep nerves.
16.) Cut the internal oblique muscle vertically in the mid-axillary plane extending from the iliac crest to its attachments on the ribs. Make two transverse incisions: medially through the most superior attachment to the ribs, and medially from the anterior superior iliac spine to the lateral aspect of the rectus sheath. Reflect the muscle medially, taking care to preserve the deep nerves.
Photo 20. Procedural: internal oblique muscle incisions
Photo 21. Internal oblique reflected
17.) Clean the transversus abdominis m., and identify the intercostal nn. brs. (T7-T11) and subcostal n. br. (T12) superficial to the muscle.
17.) Clean the transversus abdominis m., and identify the intercostal nn. brs. (T7-T11) and subcostal n. br. (T12) superficial to the muscle.
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.
Open the rectus sheath, and examine the rectus abdominis muscles
Open the rectus sheath, and examine the rectus abdominis muscles
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
19.) On one side, relieve the rectus abdominis m. from its superior attachment above the costal margin. Reflect the entire muscle inferiorly, taking care to preserve the deep vasculature.
19.) On one side, relieve the rectus abdominis m. from its superior attachment above the costal margin. Reflect the entire muscle inferiorly, taking care to preserve the deep vasculature.
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.
20.) Locate and clean the superior and inferior epigastric vasculature. Take note of their anastomosis.
20.) Locate and clean the superior and inferior epigastric vasculature. Take note of their anastomosis.
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
21.) Locate the posterior wall of the rectus sheath. Follow the sheath inferiorly until it disappears and only the thin transversalis fascia is present. This transition is marked by the arcuate line.
21.) Locate the posterior wall of the rectus sheath. Follow the sheath inferiorly until it disappears and only the thin transversalis fascia is present. This transition is marked by the arcuate line.
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
22.) Identify the inguinal triangle. This triangle is more evident after the anterior abdominal wall is reflected.
22.) Identify the inguinal triangle. This triangle is more evident after the anterior abdominal wall is reflected.
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
Examine the deep surface of the anterior abdominal wall
Examine the deep surface of the anterior abdominal wall
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
24.) On the deep surface, identify the three types of peritoneal folds: median umbilical fold, medial umbilical folds, and lateral umbilical (epigastric) folds.
24.) On the deep surface, identify the three types of peritoneal folds: median umbilical fold, medial umbilical folds, and lateral umbilical (epigastric) folds.
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
25.) Lateral to the lateral umbilical folds (inferior epigastric vasculature), locate the deep inguinal rings.
25.) Lateral to the lateral umbilical folds (inferior epigastric vasculature), locate the deep inguinal rings.
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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