Question

2. How might the movements produced by the rabbit be different than in human muscles? 3. How are the pectoralis major and biceps brachii muscle fibers arranged in the rabbit? 4. Which of the two muscles examined in this exercise would produce the most force?

Answer 1

Rabbit belong to the family leporidae. In total there are 13 wild rabbit species among which seven are the cottontailed. The major difference between smaller animals and human is the body and the muscle size. The increase in the muscle size either during the individual or during the evolution of the species with different body size poses a number of structural and functional problems. Muscle length increases as the body size increase.

Pectorial major is a wide band of muscle located in the ventral pectoral region. It pulls humerus towards the chest in the caudal direction . The muscles in the pectoral appendages are referred to as triceps brachii, biceps brachii. Triceps brachii is the dorsal side that connects to the scapula which extends the forearm/elbow.

Biceps brachii is the large cranial muscle on the ventral side. It flexes the arm at the elbow and rotated the hand laterally. During limb lengthening, muscles are thought to increase the number of sarcomeres. However, this adaptation may differ among muscles with diverse architecture. Muscle contraction is generated by sarcomeres, the minimum functional units of muscle. The two major myofilaments are actin and myosin filaments which has the consistent length in the striated muscle. As the contraction force in the sacromere due to the overlap of actin and myosin filament, the length of the sacromere is an important determinent of muscle force generation. This is how mucle force is generated.