LECTURE VI. 

 MUSCULAR SYSTEM. 



The peculiar property of muscle tissue is the power of self 

 contraction and self movement. The muscles of the animal body 

 are divided into voluntary and involuntary. 



\'oluntary muscles are under the control of the will through 

 the cerebro-spinal system. 



Involuntary muscles act independently of the will and are 

 under the control of the sympathetic nervous system. 



Voluntary muscles. — ^^What is popularly termed "lean meat" 

 is composed of voluntary muscles. These are classified into sim- 

 ple, digastric, biceps, triceps, penniform, bi-penniform. 



FIG. 13. VOLUNTARY MUSCLE. (J/. //. RJ 



1. Action of Muscle in I'lodiiciiii; Motion. Muscle does its work by short- 

 ening its belly. A, A, Bonis; B, B, tendons; C, belly of muscle; E, articula- 

 tion (joint). 



2. Muscle in Cross Section. Showing "bundle of bundles" arrangement of 

 the Hbers. Dots ropresrnt single fibers. 



3. Diagiam of Sinni)le Muscle. B, B, Tindons; C, belly (lean meat). 



A simple muscle is cliaractcrized by a single belly with not 

 more than one tendon at cither end : a digastric muscle has two 

 bellies connected by a tendon: a biceps muscle has two tendons 

 at one end ; a triceps muscle has three tendons at one end ; penni- 

 form, when the fibers attach to one side of a tendon ; bipcnniform, 



