Skeletal System

In this exercise you will become familiar with the skeletal system of the fetal pig. Because the fetal pig had not reached its full gestation, many of the bones have not fully developed, but are instead still cartilaginous. Still, we can look at this structures to gain a better understanding of the axial and appendicular skeletons, along with the joints.

Procedure

1. To begin, lay your underpad down and place your dissecting tray on top of it. Lay out your dissecting tools. Be sure you have all of your safety equipment on before beginning the experiment.

2. Once prepared, gently open the bag your pig is in. Note: DO NOT destroy this bag or empty out the preserving solution within the bag, you will need it for the whole semester.

3. Lay your pig into the dissecting tray, dorsal side facing up. Slide the strings over the dissection tray to hold the pig in place.

4. Look at Figure 21 displaying the skeletal system of a grown pig. Notice the similarities and differences between that of your human skeleton and that of the pig.

6. Due to the rigidity of your pig, it typically will not stay in this position on its own so you will need to hold it while you examine the skeletal system.

7. Begin by examining, through the skin, the axial skeleton as shown in Figure 21. Feel the bones of the skull, then continue down the vertebral column feeling the vertebrae along the way. Notice that the tail of the pig is composed of caudal vertebrae. Note your observations in Table 34.

8. Slide the strings off of the dissection tray and gently turn your pig ventral side up. Slide the strings back under the dissection tray after the pig is correctly positioned.

9. Feel the thoracic cage of the pig. Though you will not cut into the pig today, feel the similarities that occur between the fetal pig and the human skeleton model. Note your observations in Table 34.

10. Turn your attention to the appendicular skeleton. The pig’s four appendages correlate to the human arms and legs. Use Figure 21 as a guide to try and feel the different bones of the arms and legs (humerus, femur, tibia, etc.). Note your observations in Table 34.

11. In Figure 21, look at the pelvic girdle of the pig. This structure appears noticeably different than that of a human. However, the innominate bones of the pig are created by the ilium, ischium and pubis.

12. Focus your attention on the joints of the pig. The pig should be fairly rigid due to the preservation fluids. However, you should still attempt to produce the movements created by synovial joints on the pig (e.g., flexion, rotation, etc.). Notice the joints at which these movements are possible. Do they correlate to human movement? Note your observations in Table 34.

13. Take a photograph of your pig in the dissection tray for the upload document. Make sure that your name is written on a piece of paper that is clearly visible in the background of the photograph.

14. You are now finished with the external observations of the skeletal system. Remember that as you dissect into your pig, you will be able to touch and feel the bones of the skeletal system. As the dissection progresses, always take note of the bones present within the fetal pig.

15. To finish, locate the bag the pig came in. Gently place the pig back into the bag and tightly secure the bag with a rubber band, or place in the zip-seal bag provided in the dissection box.

16. Place the pig back into the cool environment you had previously stored it in. Remember, the best place to keep the pig is in a cool, dark place.

17. After your pig has been put away, clean off your dissecting tray and dissection tools with soap and water. There should not be any biological scraps because you did not cut into the pig. However, biological scraps should not be thrown into the garbage.

18. Clean the area in which you worked with soap and water as well. As long as the underpad has not been damaged, keep it for future experiments.