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the body is the cloaca. The skin, loosely attached to the 

 underlying muscles, is smooth, moist, and pigmented. 



Mention the Structures of the Roof and Floor of the Mouth 

 (Buccal Cavity). 



ON THE ROOF. The maxillary teeth on the upper jaw 

 (premaxilla and maxilla). The vomerine teeth, on the 

 vomers in the front part of the roof. The internal nares, 

 two openings in front of the vomers and towards their 

 outer sides. The prominent eyeballs, between the sides 

 and central part of the skull. Posteriorly, the two 

 openings of the Eustachian tubes above the angles of the 

 mouth. 



ON THE FLOOR. The lower jaw (without teeth) bordering 

 the fleshy floor, which has a supporting thin cartilaginous 

 hyoid plate. The tongue, which is attached in front (to 

 front part of floor) and loose behind. Posteriorly, the 

 glottis, the slit-like opening of the tubular larynx (trachea) 

 leading from the lungs. 



Which Structures are exposed when the Skin is reflected 

 or removed from the Ventral Surface of the Trunk 

 and Head? 



Subcutaneous lymph sacs, numerous cutaneous blood- 

 vessels, especially the musculo-cutaneous vein which joins 

 the brachial to form the subclavian at the shoulder, also 

 the following muscles of the ventral body wall and 

 head : 



Two large longitudinal recti abdomini muscles (each 

 divided transversely into bellies) extending forwards to 

 the sternum ; the dark line between them indicates the 

 anterior abdominal vein immediately above. The pectoral 

 muscles, arising on each side, like outspread fans, from the 

 surface of the recti abdomini and from the sternum along 

 its whole length. The mylohyoid, a muscle sheet extending 

 across from side to side of the lower jaw. By dividing the 

 mylohyoid along the middle line and reflecting the flaps, 

 the narrow longitudinal geniohyoid muscles (between the 

 chin and the hyoid) are exposed, and on each is seen the 

 hypoglossal nerve (spinal nerve II.) passing forward to the 

 tongue. 



