468 Animal Biology 



have a rather rapid rate of action, and fatigue, rather quickly. Many 

 unnamed, unstriated (smooth), mononucleated, muscle cells compose 

 the muscles of the internal organs (viscera), such as the esophagus, 

 stomach, intestines. These visceral muscles are not under the control of 



K 



mm 



#' 



TrapezlixS 



Deltoid 



■ i-^Tferea minor 



Teres mdjor 

 Fascia over ^ 

 infraspinatus 



Rhomboideus 

 major 



LatiasLmus dorsl 



■Triceps 



> 'ii/ 



Irt — External obVuJue muscle Of abdonnen 



— * Lun 



imbodorsal fascia 



,S" 



'Gluteus medius 



-Gluteus maLxlmus 



^V^M 



i 



/^.l^llll»:.^ 



Fig. 233. — Human muscles (back view). (From Francis: Fundamentals of Anat- 

 omy, The C. V. Mosby Co.) 



the will (involuntary), have a rather slow, rhythmic rate of action, and 

 do not fatigue easily. Numerous, indistinctly striated, mononucleated, 

 cardiac muscle cells compose the walls of the heart and arteries. Cardiac 



