VERTICAL LONGITUDINAL SECTION (AFTER OWEN) OF A 

 HUMAN MOLAR TOOTH 



The lower part is embedded in a socket in the jaw and surrounded 

 by the gum the derma of the dense mucous membrane of the mouth. 

 Two roots or "fangs" are shown, surrounded by a thin layer of bone 

 called "cement" (c). Through the basal openings shown there enter 

 blood-vessels and nerves. In the centre of the tooth is the vascular 

 pulp-cavity (v), from which fine processes extend into the ivory o- 

 dentine (d). Over the crown there is the enamel (e), the hardest 

 tissue in the body. 



A.(Ktloxed) B.(Conh-act,d) 



Vave of Contraction \fave ofRtloxoHon 



\.\ar muscl* 

 coot 



Coat with luhr-icating gland* Longitudinal muscle 



eoaf 



Reproduced by permission from Keith's " The Engines of the Human Body" ( Williams 

 & Margate). 



A PORTION OF THE (ESOPHAGUS OR GULLET LAID OPEN TO SHOW 

 A BOLUS OF FOOD PASSING DOWN 



It will be seen that the muscular wall of the gullet relaxes in front of the bolus of 

 food and contracts behind it. 



A, a small fragment of the outer muscular coat magnified to show the individual 

 spindle-shaped muscle fibres of which it is composed in a relaxed state. B, the 

 same muscle fibres or spindles, greatly enlarged, showing the contracted state. 



