TBL 15: Anterolateral Abdominal Wall

Question 1

What does the abdominopelvic cavity extend from and what does it consist?

Answer 1

Abdominopelvic cavity extends between thoracic and pelvic diaphragms and it contains digestive organs. The cavity can ascend superiorly to the 4th intercostal space.

Question 2

What abdominal organs are protected by the thoracic cage?

Answer 2

-liver stomach and spleen are protected by the thoracic cage

Question 3

Transection of the median plane and the transumbilical plane create what four quadrants:

Answer 3

-right upper quadrant, left upper quadrant, right lower quadrant, left lower quadrant

Question 4

What regions make up the anterior abdominal wall?

Answer 4

-epigastric, umbilical, and pubic regions makes up the anterior abdominal wall; visceral pain from the abdominal organs is referred to the anterior abdominal wall

Question 5

What is the musculotendinous sheet and what is it derived from?

Answer 5

-musculotendinous sheet is the fused aponeurosis of the external oblique, internal oblique, and transverse abdomens muscles forming the anterior aspect of the sheet; it is derived from mesenchymal cells derived myoblasts and fibroblasts of parietal mesoderm

Question 6

What is prune belly syndrome?

Answer 6

Prune belly syndrome is partial or complete absence of abdominal musculature; abdominal wall is so thin that organs are visible and easily palpated ; associated with malformation of urinary tract or bladder including urethral obstruction; defects cause accumulation of fluid that distends the abdomen → atrophy of abdominal muscles

Question 7

Describe the external oblique muscles.

Answer 7

External oblique muscles: superficial layer of muscle and it runs inferomedially from the lateral surface of the 5th-12th ribs to iliac crest

Question 8

Describe the internal oblique muscles

Answer 8

Internal oblique muscles is the intermediate muscle layer and fibers run superomedially from the iliac crest to the inferior borders of the 10th - 12th ribs

Question 9

What forms the two-bellied oblique muscle and what is its function?

Answer 9

-two-bellied oblique muscles: formed by the external oblique muscle and the contralateral internal oblique and share a common central aponeuroses -function flexion and rotation for torsional movement of trunk; when bringing the right shoulder towards the left hip

Question 10

Describe the transverse abdominis muscle

Answer 10

• Innermost muscle layer • Fibers run transverse and orientation is circumferential • From internal surfaces of the 7th-12th ribs to the linea alba • It is ideal for compressing abdominal contents → increasing intraabdominal pressure

Question 11

Describe the formation of the rectus sheath

Answer 11

-Rectus sheath is formed through the fused aponeuroses of external oblique, internal oblique, and transverse abdomens; it encloses paired rectus abdomens muscles ; -linea alba is formed from the midline fusion of the bilateral rectus sheaths and separate the rectus abdominis muscles

Question 12

Describe the surgical relevance of linea alba

Answer 12

o Linea alba → used surgically for rapid midline incisions that is relatively bloodless and avoids major nerves

Question 13

Describe the rectus abdominis muscle and what is its function?

Answer 13

• Extends vertically from pubic symphysis to the 5th to 7th costal cartilages • Muscle flexes the vertebral column, especially the lumbar regions

Question 14

Why does lack of anterolateral wall muscle tone contribute to visceroptosis (sinking of the abdominal viscera below their normal position) and excessive lordosis?

Answer 14

• Abdominal muscles protect and support the viscera effectively when they are well-toned • can get excessive lordosis of the lumbar region when the anterior abdominal muscles are underdeveloped or become atrophic due to old age or insufficient exercise because there’s insufficient tonus to resist the increased weight of protuberant abdomen on anterior pelvis; pushes the pelvis anteriorly

Question 15

Why do palpation-induced spasms of anterolateral wall muscles provide a clinical sign of acute abdomen?

Answer 15

There is intense guarding or involuntary spasms of the muscles during palpation of an inflamed organ; the involuntary muscular spasms protects the viscera from pressure which is painful when abdominal infection is present

Question 16

Why can transverse incisions of the rectus abdominis be made without permanent damage to the muscle?

Answer 16

• made through the anterior layer of rectus sheath and rectus abdominis → it provides good access and causes the least possible damage to the rectus abdominis nerve supply • a new transverse band forms when muscle segments are rejoined • transverse incisions are not made through tendinous intersections because cutaneous nerves and branches of epigastric vessels pierce the fibrous regions of the muscle

Question 17

Describe the layers of the anterior abdominal wall.

Answer 17

skin –> camper fascia –>scarpa fascia –> external oblique–>internal oblique–>transverse abdominis –>transversalis fascia –> extraperitoneal fat –> parietal peritoneum

camper fascia: superficial fatty layer of subcutaneous tissue; has superficial lymphatic vessels

scarpa fascia: deep membranous layer of subcutaneous tissue

transversalis fascia: endoabdominal fascia that lines the internal surface of musculotendinous sheet and lines the internal surface of the transverse abdominis muscle

Question 18

Why is the endoabdominal fascia of special importance to abdominal surgery?

Answer 18

Endoabdominal fascia: important in abdominal surgery and can provide a plane to be opened and surgeon can approach the structures on anterior part of the abdominal wall such as the kidney or bodies of lumbar vertebrae without entering the peritoneal sac which contains the abdominal viscera

Question 19

Describe the somatic motor innervation of the anterolateral abdominal wall?

Answer 19

• intercostal nerves (T5-T11)
• subcostal nerve (T12)
• Iliohypogastric nerve (L1)
• Ilioinguinal nerve (L1)

Question 20

What is the somatic sensory innervation of the anterolateral abdominal wall?

Answer 20

• epigastric region: supplied by the peripheral fibers from DRG at T5-T9
• Umbilical Region: T10-T11
• Hypogastric region: T12-L1

Question 21

What happens to the lymph above/below the transumbilical plane?

Answer 21

Lymph above the transumbilical plane–> go to axillary lymph nodes
Lymph below the transumbilical plane –> go to superficial inguinal lymph nodes

Question 22

There are longitudinal folds of the parietal peritoneum, below the umbilicus on the internal surface of the anterior abdominal wall and they are:

Answer 22

1. Median umbilical fold: extends from the apex of the urinary bladder to umbilicus; covers the median umbilical ligament: remnant of the urachus (joins the apex of fetal bladder to umbilicus)
2. Medial umbilical fold: covers the medial umbilical ligaments: formed by occluded parts of umbilical arteries
3. Lateral umbilical fold: covers the inferior epigastric vessels and if cut will bleed

Question 23

Describe the falciform ligament.

Answer 23

Falciform ligament: reflection of parietal peritoneum off the superoanterior abdominal wall that extends to the liver; It encloses the round ligament of the liver and para-umbilical veins

Round ligament of the liver: fibrous remnant of umbilical vein which passed from umbilicus to the liver prenatally

-falciform ligament separates the right and left lobes of the liver

Question 24

Describe the inguinal ligament.

Question 25

Describe the inguinal canal.

Answer 25

inguinal canal: superior and parallel to the medial half of the inguinal ligament

superficial inguinal ring: superolateral to the pubic tubercle

deep inguinal ring: superior to the midpoint of the inguinal ligament and lateral to the inferior epigastric artery

anterior wall: external oblique aponeurosis

posterior wall: conjoint tendon: merged aponeuroses of internal oblique and transverse abdominis muscle

Question 26

What is the main occupant of the inguinal canal in males and females?

Answer 26

Males: main occupant of the inguinal canal is the spermatic cord; the testis and attached spermatic cord traverse the deep inguinal ring to enter the inguinal canal and exit the canal via the superficial ring

Females: main occupant of the inguinal canal is the round ligament of the uterus

Question 27

What is an inguinal hernia and how is it detected?

Answer 27

Inguinal hernia: protrusion of parietal peritoneum and viscera such as small intestine, through normal or abnormal opening from the cavity to which they belong

Indirect inguinal hernia: due to failure of closure of processus vaginalis; it occurs lateral to the inferior epigastric artery; travels through the deep and superficial inguinal ring into the scrotum; detected by mass in the deep inguinal ring and impulse at superficial inguinal ring

Direct inguinal hernia: occurs due to weakness of anterior abdominal wall in inguinal triangle; it is medial to the inferior epigastric artery and protrude through superficial inguinal ring; detected by forceful impulse due to cough or strain felt over the inguinal triangle

Question 28

Where does an undescended testis commonly lie and what is its clinical risk? How can an undescended testis be distinguished from an inguinal hernia in infants?

Answer 28

Cryptorchidism: undescended testis; usually lies in the inguinal canal; there is a greater risk for developing malignancy because it is not palpable and not detected until cancer has progressed

Question 29

What is processus vaginalis?

Answer 29

Processus vaginalis: a pouch of peritoneum that is carried into the scrotum by the descent of the testicle and which in the scrotum forms the tunica vaginalis; processus vaginalis pushes the muscular and fascial layers of the anterolateral wall ahead of it into the inguinal canal

Processes vaginalis has stalk, which collapses around the spermatic cord; and saccular part: forms the tunica vaginalis and closely adheres to testes and epididymis

Question 30

What is tunica vaginalis surrounded by?

Answer 30

Tunica vaginalis is surrounded by internal spermatic fascia –> cremaster fascia and muscle –> external spermatic fascia

Internal spermatic fascia: formed by trasversalis fascia

Cremaster muscle: formed by the internal oblique muscle and aponeuroses

External spermatic fascia: formed by aponeuroses of external oblique muscles

Question 31

How is a persistent processus vaginalis related to a hydrocele of the testis and how does a hydrocele of the spermatic cord differ from a hydrocele of the testis?

Answer 31

Presence of excess fluid in a persistent processus vaginalis; may be associated with indirect inguinal hernia

The fluid is from secretion of abnormal amount of serous fluid from visceral layer of tunica vaginalis

Size of hydrocele: depend on how much of processus vaginalis persists

Hydrocele of testis: confined to the scrotum and distends the tunica vaginalis

Hydrocele of spermatic cord: confined to the spermatic cord and distends persistent part of the stalk of the processus vaginalis

Question 32

Describe the cremasteric reflex

Answer 32

Cremaster muscle: innervated by the genital branch of the genitofemoral nerve: provides somatic motor fibers to the cremaster muscle

Superomedial thigh: ilioinguinal nerve provides somatic sensory fibers to the skin of the superomedial thigh

Cremaster reflex: due to genital branch of genital femoral nerve and ilioinguinal nerve

Cremasteric reflex tested by;

Light stroking of the skin on the medial aspect of the superior part of the thigh; ilioinguinal nerve supplies this area of the skin
Causes rapid elevation of the testis: cremasteric reflex
Cremasteric reflex: extremely active in children

Question 33

Describe what is present in the spermatic cord.

Answer 33

Spermatic cord: contains ductus deferens, testicular artery, pampiniform venous plexus

Pampiniform venous plexus: cools blood in the testicular artery to maintain the testis a few degrees below body temperature thereby insuring normal spermatozoa production

Pampiniform venous plexus: converges superiorly as the testicular vein

Histology of vas deferens:

Mucosa surrounded by circular bundles of smooth muscle

Sympathetic-mediated contraction of muscle propels spermatozoa along the ductus deferens during ejaculation

Question 34

What is a hematocele of the testis?

Question 35

Why is torsion of the spermatic cord a surgical emergency?

Question 36

Why does a palpable varicocele seem to disappear when the patient lies down?

Question 37

Describe the round ligament of the uterus.

Question 38

How is the round ligament related to metastasis of uterine cancer?

Answer 38

There are some lymphatic vessels that follow the course of the round ligament in the inguinal canal so metastatic uterine cancer cells especially from tumors adjacent to proximal attachment of round ligament can spread from uterus –> labium majus –> superficial inguinal lymph nodes

Superficial inguinal lymph nodes: receive lymph from skin of the perineum including labia