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26/12/2012 CLASS COURSE ......

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  1. 1. Dereje B. (Dr)
  2. 2.  “Splanchnon” means internal organ/viscera Splanchnolgy is the study of the visceral organs i.e. digestive, urinary, reproductive and respiratory system in its restricted sense. But broadly it includes all the vascular & endocrine system. Viscera are soft organs of the body with or without a cavity are always surrounded by and, if hollow, lined by special layers Most of the viscera have layers (tunics) as follows: Serous, muscular and mucous
  3. 3. The animal body has two main cavities (spaces) Dorsal body cavity  contains the brain (cranial cavity in the skull= cranium) and spinal cord (spinal cavity = spinal canal) Ventral body cavity  is much larger than the dorsal one  contains most of the soft organs (viscera) of the body Is subdivided by the diaphragm into the thoracic cavity cranially and the abdominopelvic cavity caudally
  4. 4.  The major cavities of the body are the - smaller, cranial thoracic cavity - larger caudal abdominal cavity, and - caudal pelvic cavity They contain visceral organs and serous membrane cavities. The organs in the thoracic and abdominal cavity and the walls of these cavities are covered by thin moist transparent serous membrane. The serous membrane lining the wall is designated parietal while that covering the viscera is called visceral. A connecting (intermediate) serous membrane runs between parietal and visceral components
  5. 5. is the 2nd in size of the 3 body cavitiesDorsal wall or roof is formed by The thoracic vertebrae and the ligaments and muscles connected with themThe lateral wall is formed by ribs and intercostals musclesThe ventral wall (floor) is formed by the sternum, cartilages of the sternal ribs and the muscles in connection with these structuresThe caudal wall is formed by the diaphragm (very oblique & strongly convex structure)
  6. 6.  is an important passage way for organs & vessels passing between the neck and the thoracic cavity is relatively small and of narrow oval form is bounded dorsally by the 1st thoracic vertebra, laterally by the 1st pair of ribs and ventrally by manubrium of sternum. Thoracic inlet is occupied by the longus colli m., esophagus, trachea, vessels (supplying head, neck, fore limb & lateral thoracic wall), LN, and nerves. Major structures in thoracic cavity include heart, lungs, esophagus, and major blood vessels
  7. 7.  is a longitudinal septum which extends from the dorsal wall to the ventral and caudal wall. it divides the cavity into two chambers and the two lungs are located with in these two chambers. It is a sagittally placed partition i.e. right pleural cavity is larger than the left. thoracic organs other than the lungs are located in the mediastinal space. the part in which the heart & pericardium are situated is called the middle mediastinal space and the parts cranial and caudal to this are termed, the cranial and caudal mediastinal space respectively.
  8. 8.  The largest cavity and it is separated from the thoracic cavity by the diaphragm and caudally it is continued by the pelvic cavity The line of demarcation between the abdominal and pelvic cavities is terminal line or brim of the pelvis. Formed by the - base of the sacrum dorsally - arcuate line (ileopectinal line) found on the wing of the ilium laterally - cranial border of the pubic bone ventrally Dorsal wall or roof is formed by - lumbar vertebrae and associated muscles and lumbar extension of the diaphragm
  9. 9.  Lateral side is formed by -abdominal muscles (oblique and transverse) -abdominal fascia -cranial part of the ilium and the iliac muscle -cartilages of the asternal ribs and part of the caudal ribs found below the attachment of the diaphragm Ventral side is formed by -rectus abdominis -aponeurosis of the oblique and transverse muscles -abdominal fascia and the xiphoid cartilage Cranial side is formed by -diaphragm
  10. 10. aortic hiatus that pass the aorta oesophagial hiatus, and the foramen venae cavae that transmit the esophagus and caudal vena vava respectively Segments of the abdominal cavity1. Cranial abdominal segment Extends from the diaphragm to a transverse plane at the most caudal point on the costal arc. Organs in the cranial portion of this segment are difficult to examine by external palpation
  11. 11. 2. Middle abdominal segment Extends from the plane through the caudal most point on the costal arc to the most cranial point on the tuber coxae. Consists of the flank and the umbilical region on the ventral mid line. In the dorsal part of the flank is the paralumbar fossa3. Caudal segment Begins from the caudal most point on the tuber coxae and extends to the pelvic inlet. This region consists of a median pubic region, the area in front of the pubic bones; and the inguinal region, which extends laterally to the fold of the flank and thigh
  12. 12. Pelvis: is the caudal part of the trunk and encloses the pelvic cavity. It communicates cranially with the abdominal cavity. Boundaries forming the pelvic cavity: Dorsal wall: by sacrum and first few caudal vertebrae Lateral wall: by the iliac caudal to the arcuate line Ventral wall: by the pubis and the ischial bonepelvic inlet- entrance to the pelvic cavity - osseous oval ring (linea terminalis) dorsally the base of the sacrum laterally of the body of the ilium ventrally by the pecten of the pubis
  13. 13. The pelvic outlet is formed -dorsally by the 3rd/4th caudal vertebrae -laterally by the sacrotuberal part of the sacroisciatic ligament and -ventrally by the tubera isciadica and the arc that connects them Except in carnivores, the pelvic outlet is greater than the inlet. The pelvic cavity is covered (lined) by the pelvic fascia and some part (cranial part) of it by the peritoneum. Organs located within this cavity include: rectum and anal canal, variable portions of the bladder, pelvic urethra and accessory genital glands and the caudal part of the female genital tract
  14. 14.  The retroperitoneal part of the pelvic cavity is known as perineum pelvic diaphragm in man (erect position) carries the viscera and prevents prolapse of the anus, or the vagina and uterus. But in quadrupeds, the pelvic organs are supported principally by the bony floor of the pelvis, and hence the diaphragm is not as well developed as in man Nevertheless it functions to contain pelvic viscera during abdominal press, i.e. during defecation, urination, copulation , parturition, labored breathing, and (in draft animals) when pulling heavy loads
  15. 15. lined by serous membrane normally empty (except for microscopic cells and a film of fluid) preclude adhesions among organs A serous membrane consists of a single layer of flattened mesothelial cells applied to the surface of a thin layer of collagenous tissue that attaches to underlying endothoracic/ transversalis fascia. The mesothelium of the serous membrane forms the lining of a closed serous membrane cavity. The serous membrane lining the wall of a serous cavity is designated parietal while that covering viscera is called visceral. Connecting serous membrane runs between parietal and visceral components.
  16. 16. 1. Pleura: covers the lung Pleura-visceral pleura/pulmonary pleura/: immediate membrane covering the lung The visceral pleura is continued by the parietal pleura which is further divided into: costal, diaphragmatic and mediastinal pleura Connecting pleura forms the pulmonary ligament Plural cavity - Is the cavity between the parietal and visceral pleura - There is a serous fluid in it, called pleural fluid - The importance of this fluid is lubrication, which prevent friction between the lung and the thoracic wall and between the two lungs - It is divided in to two chambers separated by the mediastinum forming the left and right pleural sacs, of which the right is larger than the left - Organs within the mediastinum include the heart, esophagus, trachea, aorta and other large vessels. Apart from this vessels (the caudal vena cava) and other nerves located enclosed in a special fold of the pleura called the plica venae cavae
  17. 17. 2. Pericardium: covers the heart (doesn’t cover the Pericardium whole part) - forms the pericardial cavity - The space between the visceral and the parietal pericardium is filled with a serous fluid called pericardial fluid.3. Peritoneum: a thin serous membrane which forms Peritoneum the peritoneal cavity within the abdominal and pelvic cavity, more or less covering the viscera found within these two cavities The visceral and parietal layer are connected by a series of double fold intermediate (connecting) peritoneum:
  18. 18. - Omentum attaches the stomach with the parietal layer - Mesentery attaches the small intestine with the parietallayer - Mesocolon attaches the colon with the parietal layer - Mesorectum attaches the rectum - kidney is retroperitoneal - ureter is largely retroperitoneal and leaves the wall of thepelvic cavity and enters genital fold in male and broadligament in female - Cranial part of the broad ligament which suspends theovary is mesoovarium, the part which envelopes the uterinetube is mesosalpinx, and the part which support the horn andthe body of the uterus is mesometrium
  19. 19.  Vaginal tunics - The cavity of the vaginal process begins at the vaginal ring and extends into the scrotom around the spermatic cord and testis - Connecting vaginal tunic forms: mesorchium and mesoductus deferens