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

1. Dereje B. (Dr)

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. 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.  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. is the 2nd in size of the 3 body cavities
Dorsal wall or roof is formed by
 The thoracic vertebrae and the ligaments and
muscles connected with them
The lateral wall is formed by ribs and intercostals
muscles
The ventral wall (floor) is formed by the sternum,
cartilages of the sternal ribs and the muscles
in connection with these structures
The caudal wall is formed by the diaphragm (very
oblique & strongly convex structure)

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

8.  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.

9.  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

10.  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

12. 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 cavity
1. 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

13. 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
fossa
3. 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

14. 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 bone
pelvic 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

15. 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

16.  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

17. 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.

18. 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

19. 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:

20. - Omentum attaches the stomach with the parietal layer
- Mesentery attaches the small intestine with the parietal
layer
- Mesocolon attaches the colon with the parietal layer
- Mesorectum attaches the rectum
- kidney is retroperitoneal
- ureter is largely retroperitoneal and leaves the wall of the
pelvic cavity and enters genital fold in male and broad
ligament in female
- Cranial part of the broad ligament which suspends the
ovary is mesoovarium, the part which envelopes the uterine
tube is mesosalpinx, and the part which support the horn and
the body of the uterus is mesometrium

21.  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