Anatomy of the anterior abdominal wall

Question 1

What are the different layers of the anterior abdominal wall?

Answer 1

1) Skin

2) Superficial fascia

3) Muscle (laterally there is 3, however medially there is one “rectus abdominus”)

4) Transversalis fascia

5) Extraperitoneal connective tissue

6) Peritoneum

• If we cut open the peritoneum we will be in the greater sac

Question 2

What are the two components/layers found in the superficial fascia?

Answer 2

1) Superficial fatty layer (camper’s fascia)

2) Deep membranous layer (Scarpa’s fascia)

Question 3

What is langer’s lines/cleavage lines?

Answer 3

• They are abdominal skin lines that runs parallel with the neurovascular structures, and split the muscles in the direction of their fibers
• These lines are important for surgeons as incisions are made by them

Question 4

What is the water shed line?

Answer 4

It is the same as the transumbilical plane, where the venous blood and lymphatic fluid drains upwards above the plane or below the plane of the umbilicus

• Lymphatic drainage above the water-shed line is the axillary lymph nodes, while the superficial inguinal lymph nodes drains below the water-shed line

Question 5

What happens to the superficial fascia at the anterior superior iliac spine?

Answer 5

• The superficial fascia splits into two (fatty layer, and a membranous layer)

1) Superficial fatty layer (campers fascia)

• The superficial fatty layer (camper’s fascia) below the superior iliac spine is the site of liposuction and it is continuous with the superficial fascia of the thorax and thighs
• In obesity excess fat accumulates here
• Continuous into the scrotum as dartos fascia (responsible for the wrinkling of the scrotum)

2) Deep membranous layer (Scarpa’s fascia)

• Below the superior iliac spine the deep membranous layer will pass over the inguinal ligament blending with the fascia of the thigh (fascia lata) forming holden’s line
• It is continuous with the fascia of the perineum (Colles fascia)

Question 6

What is holden’s line?

Answer 6

It is the line formed by the joining of the deep membranous layer with the deep fascia of the thigh

Question 7

If a urethra is ruptured and the fluid accumulates deep to the fascia can it escape to the thigh?

Answer 7

NO

Question 8

To which fascias is the deep membranous layer (Scarpa’s fascia) connected?

Answer 8

1) Fascia lata of the thigh

2) Colles fascia of the perineum

Question 9

What are the muscles of the anterior abdominal wall?

Answer 9

1) External oblique

2) Internal oblique

3) Transversus abdominis

• The first three muscles become aponeurotic between the midclavicular line and the midline, and the aponeurosis interweave to form the sheath around the rectus abdominis muscle

4) Rectus abdominis

5) Pyramidalis

6) Cremaster

Question 10

what is meant by the rectus sheath?

Answer 10

It contains the rectus abdominis and the pyramidalis if present, formed by the anterior and posterior covering of the transversus muscle and the forward covering of the external oblique and backward covering by the internal oblique

Question 11

What is the origin of the external oblique muscles?

Answer 11

The outer and lower border of the lower 8 ribs (5-12)

Question 12

What is the insertion of the external oblique muscles?

Answer 12

1) Anterior half of the outer lip of the iliac crest, It gets attached to the ASIS till the pubic tubercle forming the inguinal ligament

2) The posterior margin is free, compared to the other two flat abdominal muscles which are attached to the thoracolumbar fascia

3) Anteriorly the aponeurosis decussates at linea alba and becomes continuous with the aponeurosis of the contralateral external oblique

Question 13

What is the linea alba?

Answer 13

• A groove in the midline
• It is made of a strong fibrous raphe (collagen fiber)
• Decussating and interweaving of the aponeuroses of the 3 flat abdominal muscles
• It extends from the xiphoid process till the pubic symphysis
• It contains the umbilical ring (which has a low blood supply)

Question 14

Why is a median incision through the linea alba a common surgical approach?

Answer 14

1) It consists of connective tissue only

2) It does not contain important nerves or blood vessels

• However due to the low blood supply healing will take more time

Question 15

What is the inguinal ligament (Poupart’s ligament)?

Answer 15

• It is the thickened lower border of the external oblique aponeurosis
• It extends between the pubic tubercle and the anterior superior iliac spine
• Its lateral part is oblique while its medial part is horizontal
• It serves as a retinaculum for the femoral nerve, artery and vein

Question 16

What is the lacunar ligament?

Answer 16

It is an extension of the inguinal ligament, on its deep medial aspect, it is slightly convex as the fascia lata of the thigh is attached to it pulling it downwards

Question 17

What is the superficial inguinal ring?

Answer 17

• It is a small opening in the external oblique aponeurosis, antero-medially, this will allow some structures to pass by but the fibers of the external oblique muscle will attach to it
• Basically a triangular deficiency in the external oblique aponeurosis
• It serves as an opening for the passage of testes in males and round ligaments in females

Question 18

What forms the superficial inguinal ring?

Answer 18

1) Apex: Points laterally

2) Base: Pubic crest

3) Borders: Lateral and medial crura of the aponeurosis of the external oblique muscles

Question 19

What are all of the ligaments that are formed by the external oblique muscle?

Answer 19

1) Inguinal ligament

2) Lacunar ligament (some fibers of the inguinal ligaments that are attached to the pectinal line)

3) Pectineal ligament (continuation of the inguinal/lacunar ligament along the pectineal line)

4) Reflection of the inguinal ligament (fibers in the floor/between the lateral and medial crus of the superficial inguinal ring, these fibers passes upwards and medially from the lateral crus to under cover of the medial crus)

Question 20

What is the origin of the internal oblique muscle?

Answer 20

1) Thoracolumbar fascia

2) The intermediate lip of the iliac crest

3) Lateral 2/3rd of the inguinal ligament

Question 21

What are the site of internal oblique muscle insertion?

Answer 21

• The fibers runs upwards and medially

1) Inserted to the lower 3/4 ribs, costal cartilage and the remaining end into the aponeurosis

Question 22

What is the origin of the transversus abdominis muscle?

Answer 22

1) Lower 6 ribs and costal cartilage (7-12)

2) Thoracolumbar fascia

3) Inner lip of iliac crest

4) Lateral 1/3rd of the inguinal ligament

Question 23

What is the insertion of the transverse muscle?

Answer 23

• The inguinal fibers will form the roof of the inguinal canal then it becomes aponeurotic and inserts into

1) Pubic crest

2) Medial part of pectin pubis/pectineal line

• The remaining part is aponeurotic

Question 24

Iliac crest is the origin of which abdominal muscles?

Answer 24

1) Outer lip gives attachment to external oblique

2) Intermediate lip gives attachment to internal oblique

3) Inner lip gives attachment to Transversus abdominis

Question 25

What is the function of the external oblique muscles?

Answer 25

It helps in the forward flexion

Question 26

What are the blood vessels that anastomoses in the rectus sheath?

Answer 26

1) Superior epigastric (a branch of the internal thoracic artery)

2) Inferior epigastric

Question 27

What is the conjoint tendon formed of?

Answer 27

It is formed by the joining of the aponeurosis of the inferior arching fibers of the internal oblique and transverse abdominis, arising from the inguinal ligament

• It gets attached to the pubic crest and the pectineal line

Question 28

What is the inguinal canal?

Answer 28

• It is a inter-muscular canal between the deep to the superficial ring (passage between the deep and superficial inguinal openings)
• It is about 4cm in length
• It is superomedial to the inguinal ligament

Question 29

What forms the posterior wall of the superficial inguinal ring?

Answer 29

The reflected part of the inguinal ligament

Question 30

Why does the inguinal canal oblique?

Answer 30

• In order for it to act like a valve when there is an intra-abdominal pressure
• Otherwise if it wasn’t oblique and we had a intra-abdominal pressure then whatever inside will pop off

Question 31

Where is the inguinal canal located?

Answer 31

We have to look at the mid-point of the inguinal ligament, where we will also see a femoral nerve

Question 32

Does the transverse abdominal muscle pass in front of the deep inguinal ring?

Answer 32

No

Question 33

What is the interfoveolar ligament?

Answer 33

It is a thickening of the fascia transversalis (it is found at the medial side of the internal ring and anterior to the inferior epigastric vessels)

• it’s nothing but a part of the transversalis fascia. It’s also partially attached to the transverse abdominis muscle; when it contracts it goes more horizontal so it pulls the opening more laterally
• The transverse abdominis muscle is attached to the superior crus of the deep inguinal ring, in order for it to pull the ring laterally and increase the obliquity of the exit
• When u reduce the hernia they play around those ligaments to tighten it up.

Question 34

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