4 INTRODUCTION 



buttocks [nates], separated by a cleft [crena ani] at the anus. The hip [coxa] 

 connects the pelvis with the lower extremity. 



In the lower extremity, the thigh is joined to the leg by the knee [genu]. The 

 foot includes: heel [calx]; sole [planta]; instep [tarsus]; metatarsus; and five toes 

 [digiti I-V], including the great toe [hallux] and little toe [digitus minimus]. 



The upper extremity is joined to the thorax by the shoulder. The arm is 

 joined to the forearm at the elbow [cubitus]. The hand includes: wrist [carpus]; 



Fig. 2. — Section of the Epidermis of a Finger, from a Human Embryo of 10.2 cm. 



". C5- 



^^^t 



;> ^ 



\Mm'$ 



metacarpus, with palm [vola or palma] and back [dorsum manus]. The five 

 fingers [digiti I-V] include: thumb [pollex], index finger [index]; middle finger 

 [digitus medius]; ring finger [digitus annularis] and little finger [digitus minimus]. 



Organ-systems. — Each of the various parts of the body above outlined is 

 composed of various organs, and the groups of related organs make up organ- 

 systems. 



The various organ-systems are treated as special branches of descriptive 

 anatomy. The study of the bones is called osteology; of the ligaments and joints, 



Fig. 3. — Diagram of a Typical Cell. (Szymonowicz.) 



Nuclear membrane 



Fluid contents 

 of network 



Protoplasmic i, 

 framework 



■Granules 





Cell membrane 



i 



LA. 







^-'^ 



Microsome 



Nuclear fluid- 

 Interfibrillar substance 





'y. -- 



Archoplasm with 

 the centrosome 



-<.'•■ 11 



■-Fibrillar substance 

 ■^^ Microsome 



syndesmology for arthrology); of the vessels, angiology; of the muscles, myology; of 

 the nervous system, neurology; and of the viscera, splanchnology . Further subdivi- 

 sions are also made. The viscera, for example, include the digestive tract, 

 respiratory tract, urogenital tract, etc. 



Tissues and cells. — The body, as above stated, has various parts, each of which may be 

 subdivided into its compoiKuit systems and organs. A further analysis reveals a continued 

 series of structural units of gradually decreasing complexity. Thus each organ is found to con- 

 sist of a number of <i.s.s(/.r;.s (epithelial, connective, muscular or nervous). Finally, each tissue is 

 composed of a group of similar units called cells (figs. 2, ;3) which are the ultimate structural units 



