Chapter 6 The Anterior and Posterior Abdominal Walls

Question 1

Which level can you find the transpyloric plane?

Answer 1

Level L1

Question 2

What two structures does the transpyloric structure pass between?

Answer 2

Lower end of the sternum and the umbilicus

Question 3

Which level does the umbilicus lie at?

Answer 3

Between L3/4

Question 4

Which structures does the transtubercular plane pass through and at which level?

Answer 4

Passes through the iliac tubercles at level L5

Question 5

What are the 9 regions of the stomach?

Answer 5

Left & Right hypochondrium
Left & Right lumbar region
Left & Right iliac region
Epigastrium, umbilicus, hypogastric region

Question 6

Which two structures does the mid-inguinal point lie between?

Answer 6

Halfway between the superior iliac spine and the pubic symphysis

Question 7

What is the pubic symphysis and what type of joint is it?

Answer 7

This joins the two pubic bones in the midline anteriorly by secondary cartilaginous joint

Question 8

Where is the pubic crest and pubic tubercle relative to pubic symphysis?

Answer 8

Pubic crest is lateral to the pubic symphysis on the superior pubic ramus. This pubic crest ends in a pubic tubercle 1 - 2 inches from the symphysis.

Question 9

Where does the rectus abdominus run from?

Answer 9

Costal cartilage margins just above the xiphoid process down to the pubic symphysis and pubic crest. There are two muscles lying on each side of the midline.

Question 10

Where do the 3 transverse tendinous portions lie?

Answer 10

Umbilical line, line of xiphisternum, and between the two.

Question 11

What movement is the rectus abdominus responsible for?

Answer 11

Flexing the trunk e.g. getting out of bed.

Question 12

Where are the erector spine muscles located?

Answer 12

Between the spinous and transverse processes lateral to the midline of the back.

Question 13

Where is the origins of the external oblique muscles?

Answer 13

It originates from the lateral aspects of the lower ribs. Posteriorly, it has a free margin lateral to the erector spinae muscles.

Question 14

Describe the attachments of the external oblique aponeurosis

Answer 14

External oblique aponeurosis forms part of the rectus abdominus sheath. Inferiorly, it is attached to the anterior superior iliac spine laterally and the pubic tubercle medially. There is a free lower border in which aponeurosis curls upwards and inwards on itself to form the inguinal ligament.

Question 15

What structures pass through the space between the inguinal ligament and the rim of the bony pelvis?

Answer 15

Femoral nerve, femoral vessels, iliopsoas muscles

Question 16

Where does the internal oblique arise from laterally?

Answer 16

Laterally, it arises from the intercostal margin.

Question 17

Where does the internal oblique arise posteriorly?

Answer 17

Posteriorly it arises from the thoracolumbar fascia

Question 18

What is the thoracolumbar fascia?

Answer 18

This fascia encapsulates the erector spinae muscles between the spinous and transverse processes of lumbar vertebrae.

Question 19

Where do interior muscles arise inferiorly?

Answer 19

Inferiorly, internal oblique muscles arise from the iliac crest and the outer 2/3 of the inguinal ligament.

Question 20

How does the internal oblique pass the spermatic cord?

Answer 20

It arches over the spermatic cord then back down into the bony crest of the pubis, where they become aponeurotic with the deeper fibres of transversus abdominis aponeurosis.

Question 21

What is the angle created by the meeting point of two ilium bones below the pubic symphysis?

Answer 21

Subpubic angle

Question 22

Which direction do the external oblique muscles move?

Answer 22

Downwards and forwards

Question 23

What is the conjoint tendon? Where is it attached to?

Answer 23

The fusion of transverse abdominus and internal oblique aponeurosis that attaches pubic crest.

Question 24

Describe the origins of the transverse abdominus

Answer 24

Posteriorly it arises from the thoracolumbar fascia.
Superiorly it arises from the inner margins of the lower ribs
Inferiorly it arises from the iliac crest and the lateral part of the inguinal ligament.

Question 25

Describe how the transverse abdominus and the internal oblique muscle form the conjoint tendon.

Answer 25

Both transverse abdominus and internal oblique muscles arch over the spermatic cord and fuse together in aponeurosis as they approach the pubic crest. This is called the conjoint tendon.

Question 26

What is the transversalis fascia and what occurs between this and the peritoneal cavity?

Answer 26

Transversalis fascia is a fibrous membrane that lines the deep surface of the abdominal wall muscles. Between this and the peritoneal cavity, there is extraperitoneal fat.

Question 27

Explain what occurs in the transversalis fascia when it reaches the kidneys.

Answer 27

Transversalis fascia runs across the posterior abdominal wall until it reaches and splits around the kidneys, forming renal fascia.

Question 28

What is perirenal fat?

Answer 28

This the fat that occurs between the capsule of the kidneys and the renal fascia.

Question 29

Where do the psoas fascia and the fascia iliaca stem from?

Answer 29

These two fascia surrounding the iliacus and psoas muscles on the posterior abdominal wall stem from tranversalis fascia.

Question 30

How does aponeurosis form the rectus sheath?

Answer 30

External oblique aponeurosis passes in front of the rectus abdominis muscle. Transverse abdominal aponeurosis passes behind the rectus abdominis muscle. Internal oblique splits. These aponeurotic fibres meet at the midline fibrous band called the linea alba. They also meet on the lateral border of the rectus sheath called the linea semilunaris.

Question 31

What is the acruate line? Where does it occur?

Answer 31

Seen from behind the muscle, this line marks the point in which all aponeurotic sheets of the anterior abdominal musculature and rectus abdominis moves in front of the muscle. It occurs midway between the umbilicus and the pubic symphysis.

Question 32

Which nerves supply the anterior abdominal wall?

Answer 32

T7 - L1

Question 33

Where is the neurovascular layer?

Answer 33

Between the internal oblique and the transverse abdominus.

Question 34

How do the lowermost nerves gain entry to the neurovascular layer?

Answer 34

They first appear on the posterior surface of the abdominal wall muscles. They then pass around the abdominal wall, across the linea semilunaris and enter the rectus sheath to become cutaneous.

Question 35

In which different direction do the nerves move along in the anterior abdominal wall?

Answer 35

Upper nerves run up and towards the midline along the costal cartilages. Lower nerves run down towards the umbilicus or the pubic symphysis. L1 does not reach the midline.

Question 36

Which nerve innervates the pubic symphysis?

Answer 36

T12

Question 37

What are the two terminating branches of the internal thoracic arteries?

Answer 37

Superior epigastric artery and the musculophrenic artery

Question 38

Describe direction of the superior epigastric artery

Answer 38

This is a terminal branch of the internal thoracic artery and enters the rectus sheath close to the xiphoid cartilage.

Question 39

Describe direction of the inferior epigastric artery

Answer 39

This is a branch of the external ilac artery. It first passes medially from external iliac artery and hooks under the ductus deferens, before turning upwards and entering the rectus sheath below the arcuate line.

Question 40

Where do the inferior and superior epigastric arteries anastomose?

Answer 40

Within the rectus sheath

Question 41

Describe the blood supply to the anterior and lateral abdominal wall

Answer 41

The anterior and lateral abdominal wall is supplied by branches from the anastomosis of superior and inferior epigastric arteries, branches from the lower intercostal arteries and from the lumbar branches of the abdominal aorta.

Question 42

Discuss venous drainage above the umbilicus

Answer 42

Veins drain into the internal thoracic veins, then into the subclavian veins and then to superior vena cava.

Question 43

Discuss venous drainage below the umbilicus

Answer 43

Superficial veins drain to the femoral veins and then to the inferior vena cava.

Question 44

What may a caput Medusae around the umbilicus indicate?

Answer 44

Portal venous obstruction in the abdomen, causing distension of epigastric veins since they offer an alternative route back to superior vena cava.

Question 45

Where do the psoas muscles arise from?

Answer 45

Either side of the lumbar vertebral column from the intervetebral discs and adjacent parts of bony vertebral bodies.

Question 46

Where do the psoas muscles lead to?

Answer 46

They pass inferiorly and laterally under the inguinal ligament to enter the thigh and leave the pelvis.

Question 47

Where does the iliacus muscle arise and terminate?

Answer 47

This arises from the inner aspect of the iliac blade. It meets the psoas muscle downwards to form combined iliopsoas muscle. (There is a groove at the junction). It enters under the lateral portion of the inguinal ligament to form tendon that inserts into the lesser trochanter of the femur.

Question 48

What movement are psoas and iliacus muscles responsible for?

Answer 48

Flexion of the thigh

Question 49

Where do psoas and iliacus muscles get their nerve supply from?

Answer 49

Segments L2 and L3

Question 50

Where do quadratus lumborum muscles arise and terminate from?

Answer 50

Quadratus lumborum arise from the lower aspect of the 12th rib and from the tips of the transverse processes of the lumbar vertebrae. It passes downwards and inserts on to the posterior aspect of the iliac crest.

Question 51

What movement is the quadratus lumborum responsible for?

Answer 51

Lateral flexor of the vertebral column in the lumbar region.

Question 52

Which nerves supply the qudratus lumborum?

Answer 52

L1-L4

Question 53

What are the lateral, medial, and median arcuate ligaments?

Answer 53

These are fibrous arches that are part of the posterior inferior margin of the diaphgam. They span across the quadratus lumborum, psoas, and right and left crus respectively.

Question 54

Which level does the left crus originate?

Answer 54

L1, L2

Question 55

Which level does the right crus originate?

Answer 55

L1, L2, L3

Question 56

What is the lumbar plexus?

Answer 56

A mixing of nerves found within the substance of the psoas muscle from ventral rami of L1-L4.

Question 57

What is the subcostal nerve? How does enter the neurovascular plane?

Answer 57

This is the most superior nerve to run across the posterior wall of the abdomen that arises behind the diaphragm just below the 12th rib (T12). It passes beneath the lateral arcuate ligament on the anterior surface of the quadratus lumborum, behind the kidney. Then it passes laterally and runs off quadratus lumborum to pierce transversus abdominis muscle into the neurvascular plane. It travels around this to enter the rectus sheath.

Question 58

Where does the subcostal nerve become cutaneous?

Answer 58

It becomes cutaneous just above the pubic symphysis.

Question 59

Which nerve branches off the first lumbar ventral ramus?

Answer 59

The iliohypogastric nerve comes of the first lumbar ventral ramus, and gives off a collateral branch called the ilioingunal nerve.

Question 60

Where does the iliohypogastric nerve pass into the neurovascular plane?

Answer 60

The iliohypogastric nerve passes out of the psoas muscle and onto the anterior surface of the quadratus lumborum. It passes downwards and laterally to run off along the iliac crest, where it pierces the transversus abdominus and continues on the neurovascular plane.

Question 61

Which tissues do the iliohypogastric nerve supply?

Answer 61

It does not supply the rectus abdominis. In the anterior wall it pierces the internal oblique muscle and external oblique aponeurosis to supply the skin just superior to the pubic symphysis.

Question 62

Where does the ilioinguinal nerve pass into the neurovascular plane?

Answer 62

Like the subcostal and the iliohypogastric nerve, it passes behind the kidney below the iliohypogastric nerve. As it runs further laterally, it passes onto the iliacus muscle and does not pierce the transversus abdominus until it reaches the anterior superior iliac spine.

Question 63

Which tissues do the ilioinguinal nerve supply?

Answer 63

Supplies the lower fibres of the transversus abdominis and internal oblique muscle fibres. It then pierces internal oblique muscle to lie between this and external oblique. It enters the inguinal canal and then leaves it at the superficial ring, piercing external spermatic fascia to become cutaneous. It is sensory to the root of the penis, anterior aspect of the scrotum and the adjacent part of the thigh.

Question 64

Which levels do the genitofemoral nerves arise?

Answer 64

L1-L2

Question 65

Where does the genitofemoral nerves pass?

Answer 65

Runs out of the psoas muscle on its anterior surface, and continues to run down anterior surface laterally to the external iliac artery as it travels towards the inguinal ligaments.

Question 66

What does the genitofemoral nerve divide into?

Answer 66

At the inguinal ligament, the genitofemoral nerve divides into the genital branch and the femoral branch. The genital branch passes into the deep inguinal ring to supply the cremaster muscle. The femoral branch passes under inguinal ligament on front of femoral artery and pierces the fascia of the thigh to supply skin on front of thigh below the inguinal ligament.

Question 67

Which levels does the lateral femoral cutaneous nerve of the thigh?

Answer 67

L2 and L3

Question 68

Where does the lateral femoral cutaneous nerve pass?

Answer 68

This passes out of the psoas and directly onto the iliacus muscle. At the anterior superior iliac spine it passes out into the tigh beneath the inguinal ligament to supply the skin of the lateral aspect of the thigh.

Question 69

What nerves arise from the segmental origin of L2-L4?

Answer 69

Femoral nerves arise from dorsal divisions of the ventral rami and obturator nerves from the anterior divisions of the ventral rami.

Question 70

Where do the femoral nerves run?

Answer 70

Between the grooves of the iliacus and psoas muscles, passing into the thigh under the inguinal ligament.

Question 71

Where do the obturator nerves run?

Answer 71

It appears at the medial border of the psoas muscle at the level of the sacroiliac joint and runs along the lateral wall of the pelvis, lateral to the internal iliac artery and vein and ureter. It leaves the pelvis through the obturator foramen just beneath the superior pubic ramus.

Question 72

What is the pectineal line?

Answer 72

The ridge on the superior ramus of the pubic bone. The pectineal line forms part of the pelvic brim.

Question 73

Where does the inguinal ligament run from?

Answer 73

The anterior superior iliac spine and the pubic tubercle.

Question 74

What is the triangular lacunar ligament?

Answer 74

This connects the inguinal ligament to the pectineal ligament near the point where they both insert on the pubic tubercle. It has a free lateral margin (crescent shaped) and is the medial boundary of the femoral canal beneath the inguinal ligament. This lies horizontally and supports the spermatic cord as it passes into the scrotum.

Question 75

Describe the descent of the testis

Answer 75

Gonads first develop high in the abdominal cavity in ragion of suprarenal glands. They migrate down through the inguinal canal and into the scrotum as the gubernaculum shortens.

Question 76

What is a hydrocole?

Answer 76

When the tunica vaginalis is filled with fluid after an injury and disease.

Question 77

How is the tunica vaginalis formed?

Answer 77

As the testis is pulled down by the gubernaculum, A pouch of peritoneum called the vaginal process is pulled down into the scrotum. This elongates and narrows in the middle portion. A balloon of peritoneum eventually buds off at the distal end in the scrotum and the elongated neck usually degenerates. This becomes the tunica vaginalis, which a double layered serous lined sac located on the anterior surface of the testis.

Question 78

Describe the 3 fascial sleeves of the spermatic cord

Answer 78

The internal spermatic fascia is an extension of the transversalis fascia. As the cord penetrates the anterior abdominal wall, it meets the the internal oblique muscle which forms the cremaster muscle and fascia. It continues to extend to the external oblique aponeurosis, which forms the external spermatic fascia. It does not pull the transverse abdominus muscle because it passes below the lowermost muscle fibres.

Question 79

What structures do the cord contain?

Answer 79

The cord contains the vas defrens (duct) and 3 arteries: one from vas deferens from vesical artery to the bladder, one from inferior epigastric artery to the cremaster muscle, one from aorta to the testicals. It also contains the pampiniform plexus.