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

ABDOMINAL CAVITY
(Ox, Sheep & Goat, Horse)

Ox

• The abdominal cavity is the largest of the body cavities
• It is separated from the thoracic cavity by the diaphragm and continuous behind with the pelvic cavity; the line of demarcation being the terminal line or pelvic inlet
• The cavity is ovoid in form and is compressed laterally
• Its long axis extends obliquely from the centre of pelvic inlet to the sternal part of diaphragm
• Its greatest dorso ventral diameter is at the level of the first lumbar and the greatest transverse diameter near the pelvis.
• It presents a roof, floor, two lateral walls and cranial wall.
• The lumbar vertebrae, lumbar part of diaphragm and sub-lumbar muscles forms the roof
• The oblique and transverse abdominal muscles, tunica abdominalis, part of ilia, iliacus muscles, cartilages of asternal ribs and parts of caudal ribs below the line of attachment of diaphragm form the lateral walls
• The two recti abdominis, aponeuroses of oblique and transverse abdominis muscles, tunica abdominalis and xiphoid cartilage form the floor
•  The diaphragm forms the cranial wall

Note

The costal attachment of diaphragm is almost vertical from the ventral end of the 8th rib to the dorsal end of the 13th rib (and the last 4 ribs enter more largely into the formation of the abdomen than in horse).The flank is more extensive than in horse.The transverse diameter between the last ribs is greater than in horse.The abdomen in the ox is more capacious than that of the horse

• A layer of fascia lines the muscular walls and the subserous tissue unites the fascia and the peritoneum, the latter is loaded with fat except over diaphragm and sends laminae into various peritoneal folds. The abdomen is lined by the serous membrane-the peritoneum
• The walls of abdominal cavity are pierced by five openings, three of the diaphragm and two of the inguinal canals. In the fetus, there are in addition, the umbilical openings
  • Foramen vena cava-for the passage of caudal venacava
  • Hiatus oesophagi-for the passage of esophagus and dorsal and ventral branches of vagus nerve
  • Hiatus aorticus-for the passage of abdominal aorta
  • Femoral ring-it is placed on either side of the pelvic brim and transmits femoral vessels
  • Inguinal ring-for the passage of spermatic cord in males and external pudic vessels and nerves in the female
  • Umbilical opening-it is placed only in the fetus for the passage of two umbilical arteries, two umbilical veins and urachus

Contents

• Greater part of digestive and urinary organs, part of the internal genital organs, blood vessels, nerves, lymphatic glands, ductless glands and certain fetal remnants
• For description of the location of these organs, the abdominal cavity is divided into 9 regions by four imaginary planes

• Two of these are sagittal and two are in transverse plane. Of the two, one transverse plane pass through the last thoracic vertebra and the other through the 5th lumbar vertebrae
• The transverse planes divide the abdomen into three zones, one behind the other - Epigastric, Mesogastric and Hypogastric
• These are again subdivided in to nine regions by sagittal planes, which pass through the centre of the inguinal ligament

Left parachondriac	Xiphoid	Right parachondriac
Left lumbar	Umbilical	Right lumbar
Left iliac	Prepubic	Right iliac

• Other regional terms used for descriptive purposes are sublumbar, diaphragmatic and inguinal
• The inguinal regions lie in front of the inguinal ligament. Flank is that part of lateral wall which is formed only of soft structures
• The triangular depression in the upper part of the flank (bounded dorsally by the lateral border of the longissmus, ventrally by the upper border of obliquus abdominis internus and in front by the last rib) is termed the paralumbar fossa

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Sheep and Goat

• It is as in ox

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Horse

• Abdomen is less capacious due to
  • the lumbar transverse process being one fourth shorter than in ox (flank less extensive)
  • the transverse diameter between the last ribs being lesser than in ox
  • the costal attachment of the diaphragm being a gentle curve and not steep as in ox
• Flanks are not hollow and the floor of the abdomen is more tucked up

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