understanding the peritoneal cavity

Question 1

what is the origin of the gut? 4

Answer 1

• gastrula (stage following the blastula)
• endoderm- majority of gut, including most of the epithelium and glands of the digestive tract
• mesoderm- muscular layers- gives rise to the visceral peritoneum
• ectoderm- epithelium at extremities of tract (cranial and caudal)

Question 2

describe the primitive gut? 4

Answer 2

• formed as a result of two folds:
• cranial-caudal (head to tail)
• lateral (side to side)
• at 4 weeks, the cranial and caudal ends are still closed by membranes: bucco-pharyngeal and cloacal

Question 3

describe gut division? 3

Answer 3

• foregut
• midgut
• hindgut

Question 4

what does the foregut consist of? 5

Answer 4

• oesophagus
• stomach
• proximal half duodenum
• liver
• pancreas

Question 5

what does the midgut consist of? 5

Answer 5

• distal half duodenum
• jejunum
• ileum
• cecum
• ascending and 3/4 transverse colon

Question 6

what does the hindgut consist of? 2

Answer 6

• 1/4 transverse, descending and sigmoid colon

- rectum

Question 7

how is the primitive gut held in place?

Answer 7

by mesenteries (a structure of mesodermal origin)

Question 8

what is a mesentery? 4

Answer 8

• formed by a double layer of peritoneum, dorsal or ventral according to its position with respect to the gut tube
• suspends intestines
• pathway for blood, innervation and lymphatics to reach the gut
• ventral mesentery degenerates during development, except for the foregut

Question 9

describe the anomaly of gut rotation? 3

Answer 9

• cause is unclear
• format is duodenum constriction, midgut volvulus leading to ischaemia, necrosis or death
• symptoms include vomiting, pain and abdominal distention

Question 10

describe the dorsal mesentery?

what does it give rise to? 4

Answer 10

• attaches gut organs to posterior abdominal wall
• give rise to:
• gastrosplenic ligament
• linenorenal ligament
• greater omentum
• mesentery of small and large intestine

Question 11

describe the ventral mesentery?

what does it give rise to? 3

Answer 11

at the foregut region only

• give rise to:
• ligaments around liver
• falciform ligament
• lesser omentum

Question 12

what is the lesser omentum? 2

Answer 12

• attaches lesser curvature of the stomach to back of the liver
• has a free edge

Question 13

where is the abdomen? 3

Answer 13

• below the diaphragm
• abdominal cavity is occasionally called abdominopelvic (abdomen proper and greater pelvis)
• greater pelvis is continuous with lesser pelvis

Question 14

where is the inguinal ligament?

Answer 14

• runs between the anterior superior iliac spine and the pubic tubercle

Question 15

what makes up the abdominal wall? 2

Answer 15

• flat abdominal muscles

- lumbar vertebral column

Question 16

what muscles are in the anterior abdomen wall? 4

Answer 16

• external oblique (from outer surface of lower eight ribs to linea alba, iliac crest and public tubercle)
• internal oblique (from lateral 1/3 of inguinal ligament and anterior 2/3 of iliac crest, to linea alba costal margin and crest of pubic bone)
• transverse abdominis (from lateral 1/3 inguinal ligament , interior surface of lower 6 ribs and iliac crest, to the linea alba and crest of the pubic bone)
• rectus abdominis (from pubic symphysis and crest to xiphoid process and 5th-7th costal cartilages)

Question 17

what is the blood supply/ drainage to muscles in the anterior abdomen wall? 2

innervation?

Answer 17

• Arteries: superior and inferior epigastric, intercostal, circumflex iliac
• Veins: thoracoepigastric
• thoracoabdominal nerves (also thoracic and subcostal nerves for rectus abdominis)

Question 18

what are the functions of the muscles in the anterior abdomen wall? 4

Answer 18

• External oblique= work with internal oblique for torsional movement of trunk
• Internal oblique= flew and rotate trunk, compress viscera
• Transversus abdominis= compress and support viscera
• Rectus abdominis= flexes trunk, compress viscera

Question 19

what are the lesser and greater sacs? 4

Answer 19

• formed as a result of organ rotation
• lesser sac if behind stomach
• rest of peritoneal cavity= greater sac
• communicate via the epiploic foramen (of Winslow)

Question 20

what is the inguinal canal? 4

Answer 20

• serves as a passageway for the spermatic cord to reach the scrotum in the male and the round ligament of the uterus to reach the labia majora in the female
• limited by superficial and deep inguinal rings
• for both genders the genital nerves (a branch from the genitofemoral) and other blood and lymphatic vessels also travel thoughout this canal
• the inguinal canal is considerably larger in males than females

Question 21

describe the spermatic cord? 5

Answer 21

• consists of vas deferens, gonadal vessels, nerves, lymphatics and the cremaster muscle
• as the spermatic cord passes through the abdominal wall, it takes a sleeve or covering from each of the 3 layers
• transveralis fascia= contributes the innermost covering of the spermatic cord, the internal spermatic fascia
• internal oblique= contributes the middle covering layer to the cord, the cremasteric fascia
• the external oblique= contributes the outer covering of the cord, the external spermatic fascia

Question 22

what is the abdomen?

Answer 22

a specifically defined region

Question 23

what is does the peritoneum cover?

Answer 23

abdomen and abdominal organs

Question 24

what is the peritoneal cavity divided into?

Answer 24

divided into sacs