Peritoneal Cavity

Question 1

Introduction

Answer 1

Gastrula - the stage following the blastula. The embryo develops 3 layers: Ecto, meso and endoderm

Question 2

Endoderm
Mesoderm
Ectoderm

Answer 2

Endoderm: Majority of gut, including epithelium and glands of digestive tract
Mesoderm: Muscular layers
Ectoderm: Epithelium at extremities of tract (cranial and caudal)

Question 3

Primitive gut

Answer 3

Formed by the result of 2 folds, cranial-caudal and lateral
At 4 weeks, the two ends are still closed by membranes: Bucco-pharyngeal and cloacal
Held in position by mesenteries (a structure of mesodermal origin)

Question 4

Gut division and fate [4]

Answer 4

Foregut: Oesophagus, Stomach, Proximal half Duodenum, Liver and pancreas

Midgut: Distal half duodenum, jejunum, ileum, cecum, Asc + 3/4 Transverse colon

Hindgut: 1/4 Transverse & Descending & Sigmoid Colon & Rectum

Question 5

Mesentery

Answer 5

Formed by double layer of peritoneum

Mesentery – dorsal or ventral according to its relative position with respect to gut tube

Suspends gut organs & pathway for blood, innervation, lymphathics to reach the gut

Ventral mesentery degenerates during development, except for foregut

Question 6

Dorsal mesentery

Answer 6

Attaches gut organs to posterior abdominal wall

Gives rise to: Gastrosplenic ligament, lienorenal ligament, greater omentum and mesentery of small & large intestine

Question 7

Ventral mesentery

Answer 7

At foregut region only and gives rise to: Ligaments around the liver, falciform ligament and lesser omentum

Lesser omentum attaches lesser curvature stomach to the back of liver and has a free edge

Question 8

Abdomen

Answer 8

Trunk below diaphragm
Abdominal cavity occasionally called Abdominopelvic (Abdomen proper + greater pelvis)

Greater pelvis is continuous with lesser pelvis

Question 9

Abdominal wall (external)

Answer 9

Flat abdominal muscles

Lumbar vertebral column

Question 10

Muscles Anterior Abdominal wall
External oblique
Internal oblique

Answer 10

External oblique: From outer surfacer of lower 8 ribs to linea alba (iliac crest and pubic tubercle)

Internal oblique: From lateral 1/3 inguinal ligament and anterior 2/3 of iliac crest to linea alba (2/3 costal margin and crest of pubic bone)

Question 11

Muscles Anterior Abdominal wall
Transverse abdominis
Rectus abdominis

Answer 11

Transverse abdominis from lat 1/3 inguinal ligament, int surface of lower 6 ribs and iliac crest to linea alba

Rectus abdominis: FRom pubic

Question 12

Foregut

Answer 12

Foregut: Oesophagus, stomach, proximal half duodenum, liver and pancreas

Question 13

Midgut

Answer 13

Midgut: Distal half duodenm, jejunum, ileum, cecum, ascending & 3/4 transverse colon

Question 14

Hindgut

Answer 14

Hindgut: 1/4 transverse + descending sigmoid colon and rectum

Question 15

Oesophagus, stomach, proximal half duodenum, liver and pancreas

Answer 15

Foregut

Question 16

Distal half duodenm, jejunum, ileum, cecum, ascending & 3/4 transverse colon

Answer 16

Midgut

Question 17

1/4 transverse + descending sigmoid colon and rectum

Answer 17

Hindgut

Question 18

Muscles Anterior Abdominal wall

• Blood supply/drainage
• Innervation

Answer 18

Muscles Anterior Abdominal wall
Blood supply/drainage
• Arteries: Superior and inferior epigastric, intercostal and circumflex iliac
• Veins: Thoracoepigastric (between lateral thoracic and superior epigastric)
Innervation: Thoracoabdominal nerves (also thoracic and subcostal nerves for rectus abdominis)

Question 19

Muscles Anterior Abdominal wall Function

Answer 19

• External Oblique: Work with internal oblique for torsional movement of trunk
  
  • Internal Oblique: Flex and rotate trunk, compress viscera
  • Transverse Abdominis: Compress and support viscera
  • Rectus Abdominis: Flexes trunk and compress viscera

Question 20

Lesser and greater sacs

Answer 20

Formed as a result of organ rotation
Lesser sac behind stomach
Rest of peritoneal cavity - greater sac
Communicate via the epiploic foramen (of Winslow)

Question 21

The inguinal canal serves as a passageway for

Answer 21

spermatic cord to reach the scrotum in the male

- the round ligament of the uterus to reach the labia majora in the female

Question 22

Inguinal canal - gender

Answer 22

For both genders the genital nerve (a branch from the genitofemoral) and other blood and lymphatic vessels also travel through this canal

The inguinal canal is considerably larger in males, compared with females

Question 23

Inguinal canal

Answer 23

As the spermatic cord passes through the abdominal wall it takes a sleeve or covering from each of the 3 layers:

- transversalis 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 24

spermatic cord consists of

Answer 24

vas deferens, gonadal vessels, nerves, lymphatics and the cremaster muscle.