VAN 221: Veterinary Splanchnology and Applied Anatomy (1+1)

PELVIC CAVITY
(Ox, Sheep, Goat, Horse)

Ox

• The pelvis is the smallest of the three body cavities
• It is continuous in front with the abdominal cavity, the line of demarcation being the terminal line or the pelvic inlet
• The sacrum and the first 3 coccygeal vertebrae form the roof. The pubis and ischium furnish the floor
• The lateral walls are formed by parts of the ilium and the sacro-sciatic ligaments
• The outlet is bounded above by the 3rd coccygeal below by the ischial arch and laterally by the caudal border of the sacrosciatic ligaments. Perineal fascia, anus, its muscles, roots of penis in the male and vulva in the female close the outlet
• This cavity contains rectum, parts of internal genital and urinary organs, vessels and nerves, muscles and some fetal remnants
• The pelvic peritoneum is continuous with that of the abdomen
• It lines the cavity for a variable distance backward and is then reflected on the viscera and from one organ to another
• Thus there is an cranial peritoneal and a caudal retroperitoneal part of the cavity
• In the male the peritoneum is arranged as follows,
  •  The peritoneum is reflected from the sacrum to the rectum, forming mesorectum. Between the sacrum and rectum there is a pouch called sacro rectal pouch, which is continuous laterally with the rectogenital pouch
  • In male, a transverse fold of peritoneum extends between the inferior face of the rectum and the dorsal surface of the bladder. This is the genital fold, which contains the vas deferens and seminal vesicles
  • The ventral layer of this fold is reflected on to the dorsal surface of the bladder. Thus there is a pouch formed between the rectum and the bladder
  • Thus a pouch is formed between the rectum and the bladder the recto vesical pouch that is partially subdivided by the genital fold into recto-genital and vesico-genital cavities
  • From the bladder, the peritoneum is reflected to the lateral walls of pelvic cavity, forming the lateral umbilical fold or middle ventral ligament of the bladder
  • The lateral ligaments contain the so-called round ligament of the bladder, the partially occluded umbilical artery, of the fetus
  • In the female, by the presence of uterus, the genital fold is enlarged to enclose the uterus and a small part of the vagina
  • It forms two extensive folds the broad ligaments of the uterus, which attach the organ to .the sides of pelvic cavity and upper part of the flanks below the level of tuber coxae
  • It thus divides the recto-vesical pouch completely into dorsal and ventral compartments -the recto-genital and vesico-genital pouches
  • In the fetus and the newborn these three folds extend to the umbilicus in conformity with the abdominal position of the bladder
  • When the bladder becomes pelvic in position, the lateral ligaments conform to the change and end at the vertex of bladder. The median fold may still be traceable to the umbilicus

Sheep and Goat

• As in ox

Horse

• Pelvic cavity is relatively short and broad
• The inlet is less oblique and its transverse diameter is greater than in ox
• The peritoneum extends as far back as caudal end of sacrum only and so the retro peritoneal part is more than in ox