Anatomy of the Abdominal Wall

Question 1

What are the layers of the abdomen?

Answer 1

Skin
Camper’s fascia
Scarpa’s fascia
External oblique muscle
Internal oblique muscle
Transversalis muscle
Transversalis fascia
Extra parietal fascia
Peritoneum

Question 2

What is the composition of Camper’s fascia?

Answer 2

Superficial fatty layer composed of loose areolar connective tissue between the fat deposits. It provides protection by absorbing impact and for insulation. It derives from the dermatome, a mesoderm derivative. It is supplied by the superior and inferior epigastric arteries. This fascia provides support to prevent vertical hernia extension.

Question 3

What is Scarpa’s fascia?

Answer 3

It is the thinner membranous layer of both dense collagenous connective tissue fascia and loose connective tissue. The parallel orientation of the collagenous fibres allows it to withstand unidirectional force. It is attached to the aponeurosis of the external oblique muscle to the pubic symphysis, crest and tubercle.

Question 4

What is aponeurosis?

Answer 4

An aponeurosis is the connective tissue sheath which connects muscle to bone, provides support and absorbs energy of muscle movement.

Question 5

What is the Linea alba?

Answer 5

Linea alba is the thin band of connective tissue from the xiphoid process to the pubic symphysis and separates the rectus abdominis Linea alba maintains the proximity of the abdominal muscles and when intrabdominal pressure increases, it widens.

Question 6

What is the external oblique aponeurosis?

Answer 6

The external oblique aponeurosis is attached to the pubic crest, pubic symphysis and pubic tubercle. It provides support to absorbs energy of muscle movement. The aponeurosis of the external oblique forms the rectus sheath and the inguinal ligament.

Question 7

What is a tendon?

Answer 7

A tendon is a tough-rope like projection of connective tissue at the end of muscle which connects it to bone.

Question 8

What is a tendon?

Answer 8

A tendon is a tough-rope like projection of connective tissue at the end of muscle which connects it to bone.

Question 9

What is the inguinal ligament?

Answer 9

Inguinal ligament is a muscular band which originates from the anterior-superior iliac spine to the pubic tubercle on either side of the abdomen. It is formed from the inferior edge of the aponeurosis of the external oblique.

Question 10

What is the rectus sheath?

Answer 10

Rectus sheath is the protective fibrous compartment formed by the aponeurosis of the oblique muscles and transversalis muscle. It overlies the rectus abdominus and pyramidalis muscle and maximises compression for support of the viscera.

Question 11

What are the features of the external oblique muscle?

Answer 11

Most superficial abdominal muscle which is lateral and anterior of the abdomen. It rotates the trunk and flexes the trunk downwards to compress the abdomen. It originates from Rib 5-12 and attaches pubic tubercle and iliac crest via the linea alba. At the tip of the 9th costal cartilage, external oblique has aponeurosis of continuous collagen sheet.

Question 12

What are the features of the internal oblique muscle?

Answer 12

Opposite direction to external oblique. It flexes/bends the trunk downwards and creates intrabdominal pressure by depressing the lower ribs for forced expiration or defaecation, micturition and childbirth, Internal oblique originates from the lumbar portion of the thoracolumbar fascia. The internal oblique attaches to rib 10-12, the Linea alba and the pubic tubercle. At the tip of costal cartilage 9, it forms the aponeurosis

Question 13

What is the thoracolumbar fascia?

Answer 13

Thoracolumbar fascia is a diamond shaped area of connective tissue in the lower back which separates the posterior abdominal muscles from the paraspinal muscles.

Question 14

What are the features of the transversus abdominis muscle?

Answer 14

Deepest abdominal muscle around the spine for stability and protection. It originates from the lumbar fascia, the lateral 1/3 of the inguinal ligament and ribs 7-12 . It attaches onto the linea alba, xiphisternum and pubic crest. At costal cartilage 9, transversus abdominis forms the aponeurosis. Forms the conjoint tendon.

Question 15

What is the rectus abdominis?

Answer 15

Rectus abdominis is responsible for flexing the trunk. It originates from the pubic crest and symphysis and attaches to the xiphisternum and costal cartilages 5-9. There are 3 tendinous insertions of the rectus abdominis as a result of the rectus sheath formed from oblique muscle and transversus abdominis aponeurosis.

Question 16

What is the horizontal arcuate line?

Answer 16

The horizontal arcuate line is a demarcation halfway between the umbilicus (bellybutton) and the pubic. This arcuate line is a representation of the posterior portion of the aponeurosis moving anteriorly which allows the inferior gastric artery to supply the abdominal viscera.

Question 17

What is the inguinal canal?

Answer 17

The inguinal canal is a 4-6cm passage from the internal inguinal orifice to the external inguinal orifice. Structures between the abdomen pass through here. It provides a conduit for gonads to descend. For males, this is the testes leaving the lumbar region of the abdominal wall to enter the scrotal sac.

Question 18

What is the inguinal ring?

Answer 18

The inguinal ring surrounds the inguinal orifice inlet and outlet. The superficial inguinal ring lies at the external orifice, formed by fibres of the external oblique. The deep inguinal ring lies at the internal orifice above the inguinal ligament. It is formed from the transversalis fascia.

Question 19

What are the features of the men gonads that passes through the inguinal canal?

Answer 19

spermatic cord, gonadal vessels and lymphatics. The spermatic cord is an extension of the abodminal wall into the testicles which is a collection of vessels, ducts and nerves surrounded by fasica which suspends the testes in the scrotum

Epididymis is the muscular tube in the testes where sperm is stored.
Ductus dans deferens is the band from the epidydymis to the pelvis posterior to the urethra.

Question 20

What are the features of females which pass through the inguinal canal?

Answer 20

In females: the round ligament is a fan-shaped band of connective tissue which connects the uterus to the labia majora and supports the uterus.

Question 21

What are the borders of the inguinal canal?

Answer 21

The roof is the internal oblique, transversus abdominals and transversalis fascia.
The floor is the inguinal ligament and lacunar ligament. Lacunar ligament is also formed by the inferior border of the external oblique aponeurosis.
Anterior wall is the aponeurosis of the external oblique and internal oblique laterally/.
Posterior wall is the transversalis fascia.

Question 22

What is an inguinal hernia?

Answer 22

In the inguinal canal, an inguinal hernia is when a weak portion of the abdominal muscle allows intrabdominal organs or structures to push through and create a lump or swelling. This can be an intestine or the spermatic cord. Inguinal hernias occur before birth, when the lining does not close that creates this weak point.

Question 23

What is the myopectineal orifice?

Answer 23

A weak area in the inguinal canal where inguinal hernias frequently occur

Question 24

What are the paracolic gutter?

Answer 24

The spaces between the abdominal wall and the colon. Infections in here within fluid can collect and spread throughout the abdomen.

Question 25

What is the arcuate line?

Answer 25

The line which demarcates the start of the aponeurosis of the external oblique and the transversus abdominis that passes anteriorly to the rectus sheath.