Diseccion

Laura Cano
Mrs. Germain
Anatomy Period 3
19 December 2012
Disection Notes
Dissection Instruments:
Scalpel: Use for your initial incisions and for the removal of skin. Scissors: Use for further cutting of tissue.
Probe: Use for tracing tubes or passageways and for separating tissue. Forceps: Use for pulling apart, separating,lifting, and removing tissues. Teasing needle: Use for lifting and pushing aside tissue.
THE ORAL CAVITY
1A. Open the jaws as wide as you can without cutting, and identify the oral cavity. The tongue is on its ventral surface, and the hard palate forms its dorsal surface. The hard palate separates the oral cavity from the nasal cavities.
1B. Make the firstincisions on your fetal pig from the corner of the mouth to the bottom of the ear on both sides of the head .Use scissors to cut through the tissue and bone including the jawbone to the base of the tongue. Do NOT cut through the tissues at the back of the throat.
1C. Spread the jaws so the oral cavity is completely exposed .Examine the tongue.
Oral Cavity
1D. Thesoft palate, located at the posterior border of the hard palate, contains no bone. In humans, an extension of the soft palate, the uvula, hangs down into the throat.
1E. Locate the upper and lower gums and the few teeth that may have erupted. Those that have erupted will probably be the third pair of incisors and canines. Cut into the gums of your pig to locate the molar teeth.Remove them and observe their characteristics.
1F. The posterior region of the oral cavity is known as the pharynx. Both food and air pass through this area. The cavity is defined ventrally by the base of the tongue and dorsally by the rear border of the soft palate.
1G. Locate the epiglottis, a small flap of tissue located at the base of the tongue. The epiglottis protectsthe opening to the trachea by diverting food or liquid directly to the esophagus. The opening is the glottis. The first portion of the trachea is the larynx. A second opening, which leads to the esophagus, lies posterior to the glottis. The esophagus is the muscular tube that leads from the mouth to the stomach.
1H. Locate the opening to the nasal passageway on the roof of the mouthto the rear of the soft palate. This is called the nasopharyngeal opening.
THE NECK REGION
For the second incision, turn your pig ventral side up and remove a large segment of skin that runs posteriorly from the middle of the lower jaw to the chest and laterally to the sides of the throat .Use care when cutting the skin.
2A. The first tissues that will bevisible when the skin is removed will be thin fibers that run anterior-posterior .These fibers are muscles. They must be removed to expose the thymus glands which run down both sides of the throat in the neck region and into the chest cavity. The glandular tissue is very different in appearance from the muscle fibers, and it appears cheesy in consistency. The thymus glands are not part of thedigestive system. They function in the young mammal to process lymphocytes, a kind of white blood cell that serve as one of the animal's defenses against infectious disease.
2B. You will have to go a bit deeper to see a second smaller gland, the thyroid gland, located ventral to the trachea. It is usually dark reddish-brown in color which makes it rather easy to identify.
2C.Using a probe, separate the superficial muscles and glands from one another without cutting them. Probe down into the deeper layers of the neck. Medially, beneath several strips of muscle, you will find the hard-walled larynx and trachea, parts of the respiratory passageways .Dorsal to the trachea, probe for the esophagus. One way to be certain that you have located the esophagus is to open the...