144 THE SURGICAL ANATOMY OF THE HORSE 



The efferent vessels from the prepectoral glands of the right side 

 help to form the accessory lymphatic duct (sometimes called the great 

 lymphatic vein), whilst those from the left side empty themselves into 

 the thoracic duct. 



The Submaxillary Glands. — These are placed in the submaxillary 

 space, in the grooves which are bounded externally by the inferior 

 belly of the digastricus muscle and internally by the mylo-hyoid and 

 subscapulo-hyoideus muscles. 



A careful examination of the position, size, and relations of these 

 glands is of extreme clinical importance, since their efferent vessels 

 drain the lymph from the nasal cavities, the nostrils, the tongue, lips 

 and cheeks ; and enlargement of these glands is one of the first 

 symptoms of infection of these important areas. 



The Pharyngeal Glands. — These run across the side of the pharynx, 

 below the guttural pouches. They frequently extend as far back- 

 wards as the thyroid bodies, and are deeply seated to the parotid 

 glands. 



The afferent vessels of the submaxillary group empty themselves 

 into the pharyngeal glands. In fact all the lymph of the head passes 

 through these latter glands, including that derived from a small gland 

 embedded in the substance of the parotid. Four or five large afferent 

 vessels are given off from these glands on either side, and these vessels 

 follow the course of the carotid arteries. These lymphatic vessels 

 present several small glands in their course, forming what is known 

 as the " carotid chain " of glands. The vessels ultimately empty 

 themselves into the prepectoral glands. 



Diseases of the Lymphatic Glands 

 The pharyngeal lymphatic glands are frequently diseased. Enlarge- 

 ment and abscess formation in them is of common occurrence during 

 the course ot strangles, and may follow as a sequel any infection of 



