#Frog dissection guide answers skin#

#Frog dissection guide answers skin#

Formed by the union of brachial from the fore limb and musculocutaneous from the skin and muscles of the back. It is the middle one and receives internal jugular from the head region and subscapular from the shoulder. The anteriormost vein formed by the union of lingual from the tongue and faciomandibular coming from the facial region and lower jaw. To expose the femoral and sciatic veins coming from the hind limbs, split the disc formed by the fusion of two halves of the pelvic girdle into two, with a sharp scalpel. Expose the veins received by the median postcaval, and the veins of the hepatic portal and renal portal systems. Trace a precaval and the veins it receives. The branches joining to form the precavals are identical. Locate the two precavals anteriorly and the postcaval vein which is posterior.

The narrow posterior end of the heart is now directed anteriorly. Remove the pericardium and carefully turn the heart upwards. All the veins together and the heart constitute venous system (Fig. Vessels bringing back blood to heart are veins. It continues forward and divides into two truncus arteriosus. The left atrium receives pulmonary veins.Ī highly muscular thick walled conical structure posterior to the atria.Ī very short but stout, whitish vessel, arises from the right side of the base of the ventricle. The right one is larger in which the sinus venosus opens. Two thin walled chambers in front of the ventricle. 16.3).Ī large, dorsally placed, thin walled, triangular sac. It is a reddish, muscular structure and consists of five parts (Fig. Remove the semitransparent pericardium and the heart is exposed. Open the viscera following the procedure described previously. It is the major organ, both in the venous and arterial systems.ĭissection. The heart is partly venous and partly arterial. The heart, veins, arteries and capillaries constitute the circulatory system. It lies between the stomach and the duodenum. The common bile duct opens into the duodenum.Ī large, cream white, irregular gland surrounding the common bile duct. The small, spherical gall bladder is median in position. The left lobe is larger than the right one and sub-lobed. It is bounded by two toothless jaws.Ī large, reddish-brown, bilobed gland connected by a short, narrow, median portion.

Display the organs properly by fixing them with pins.Ī large, semicircular opening at the anterior end of the head. The whole of the alimentary canal is exposed (Fig.16.2). Cut the mesentery, as required, to uncoil the intestine. Remove the pericardium with heart and adjacent tissues to expose the oesophagus. The organs of the viscera are fully exposed.

Push the cut ends of the pectoral girdle outwards taking care that blood vessels are not damaged, and fix them with pins. Turn the flaps of the abdominal wall and pin them down. Proceed backwards up to the posterior limit of the coelom. Continue the longitudinal incision up to the anterior limit of the coelome cutting the pectoral girdle. Separate it carefully from the abdominal wall. Lift the cut end of the abdominal wall with a pair of forceps and find out the anterior abdominal vein attached to the dorsal surface of the wall. Proceed for a short distance both anteriorly and posteriorly. Give an incision on the abdominal wall at about its middle at a distance of about 6 mm either on the right or the left side of the mid-ventral line. Separate the skin from underlying muscles of the ventral surface and the limbs. With lateral incisions cut the skin of the limbs along the length. Pushing the blunt arm of a pair of scissors through the cut, give an incision in the skin along the mid-ventral line extending anteriorly up to the lower jaw, and posteriorly to the end of the trunk.