LABORATORY EXERCISE 54

CAT DISSECTION: MUSCULATURE

Instructional Suggestions

1. You may want to provide the students with preserved cats that have been preskinned. Such cats are available from various biological supply companies. The use of preskinned cats will save about an hour of class time and avoid the unpleasantness that some students associate with the skinning procedure.

2. You may want to reduce the amount of time spent in dissecting the cat muscles by having the students dissect only selected areas of the cat. For example, you might have them complete Procedure D (muscles of the thorax), Procedure E (muscles of the abdominal wall), Procedure F (muscles of the shoulder and back), and Procedure H (muscles of the hip and hind limb), omitting the other sections.

Laboratory Report Answers

PART A

1. Sternocleidomastoid 3. Sternohyoid, mylohyoid

2. Masseter

PART B

1. Pectoantebrachialis 3. External oblique

Xiphihumeralis Internal oblique

2. Pectoralis major Transversus abdominis

Pectoralis minor Rectus abdominis

PART C

1. Clavotrapezius 3. Supraspinatus

Acromiotrapezius 4. Infraspinatus

Spinotrapezius 5. Infraspinatus

2. Clavodeltoid (clavobrachialis) Teres major

Acromiodeltoid

Spinodeltoid

PART D

1. Biceps brachii 2. Epitrochlearis

Brachialis 3. Triceps brachii

PART E (FIG. 54.24)

1. Pectoralis major 9. Infraspinatus

2. Biceps brachii 10. Teres major

3. External oblique 11. Triceps brachii

4. Rectus abdominis 12. Latissimus dorsi

5. Sartorius 13. Gluteus medius

6. Rectus femoris 14. Gluteus maximus

7. Vastus medialis 15. Biceps femoris

8. Tibialis anterior 16. Gastrocnemius

LABORATORY EXERCISE 55

CAT DISSECTION: CARDIOVASCULAR SYSTEM

Laboratory Report Answers

PART A

1. The parietal pericardium forms a relatively thick, tough sac that encloses the heart. It is attached to the large blood vessels at the base of the heart and to the diaphragm.

2. The walls of the atria are much thinner than those of the ventricles. The wall of the left ventricle is much thicker than that of

the right ventricle.

3. Wall thickness is related to the force of its contraction and the amount of pressure it imparts to the blood inside a heart

chamber. The left ventricle has the thickest wall, contracts with the greatest force, and creates the greatest amount of blood

pressure in the heart chambers. The left ventricle is the pump for the systemic circuit.

4. In the human, the right common carotid artery branches from the brachiocephalic artery, whereas the left common carotid artery comes directly from the aortic arch. In the cat, both common carotid arteries branch from the brachiocephalic artery.

5. In the human, the aorta divides to form the two common iliac arteries, which in turn give rise to external and internal iliac arteries. In the cat, the aorta divides to form the external iliac arteries, and the internal iliac arteries branch from the aorta independently.

PART B

1. In the human, the brachiocephalic vein is formed by the union of the internal jugular and the subclavian vein on each side. In the cat, the brachiocephalic vein is formed by the union of the external jugular and the subclavian vein on each side.

2 In the human, the internal jugular vein is somewhat larger than the external jugular vein. In the cat, the external jugular vein is larger.

3 Answers will vary as there are more than twelve correct answers. Most of the veins in the cats are also found in humans.

LABORATORY EXERCISE 56

CAT DISSECTION: DIGESTIVE SYSTEM

Laboratory Report Answers

PART A

1. The major salivary glands (parotid, submandibular, and sublingual) in the human and the cat occupy similar locations.

2. The adult cat has 6 incisors, 2 canines, 8 premolars, and 2 molars in the upper jaw; the lower jaw teeth are similar, except 4 premolars are present. The adult human has 4 incisors, 2 canines, 4 premolars, and 6 molars in the upper and lower jaw.

3. The cat’s canine teeth are adapted for stabbing and holding prey whereas its rear molars are adapted for cutting meat.

4. The uvula is missing in the cat.

5. The transverse ridges help to hold food.

6. Many of the papillae on the cat’s tongue have spiny projections that help the cat to clean its fur. These are lacking on the human tongue.

PART B

1. The peritoneum is the membrane that lines the abdominal cavity and covers the abdominal organs. Double-layered folds in this membrane form the mesentery that supports the abdominal organs.

2. The inner lining of the stomach is folded to form many ridges called gastric folds (rugae).

3. The cat’s liver has five lobes; the human liver has four.

4. The cat’s pancreas is relatively smaller than that of the human and it is double-lobed. One lobe lies along the duodenum, and the other extends behind the stomach toward the spleen.

5. The appendix is missing in the cat.

LABORATORY EXERCISE 57

CAT DISSECTION: RESPIRATORY SYSTEM

Laboratory Report Answers

1. The auditory tube allows air to pass between the cavity of the middle ear and the outside environment. As a result, air pressure normally remains equal on both sides of the eardrum.

2. The glottis is the opening of the superior (anterior in cats) end of the larynx. The epiglottis is a flap-like structure that shunts food and liquid away from the glottis during swallowing.

3. The tracheal rings are incomplete as they are in the human.

4. The structure of the primary bronchi and the trachea are similar.

5. The cat has three main lobes in each lung (anterior, middle, and posterior). The posterior lobe on the right side has an accessory lobe associated with it, making a total of four lobes on the right lung. The human has three lobes in the right lung and two in the left.

6. The diaphragm is attached to the rim of the thorax and to a central tendon.

7. The heart, esophagus, trachea, and thymus gland are found in the mediastinum. These are the same major structures found in the human mediastinum.