724 LYMPHATIC SYSTEM OF THE OX AND SHEEP 



part of the nasal cavity, the maxillary and palatine sinuses, and the larynx; a. id the 

 rectus capitis ventralis major. The efferent vessels, four to eight in number, con- 

 cur jp forming the tracheal Ijrmph duct. 



A small parapharjmgeal lymph gland is usually present on the lateral wall of 

 the pharynx, under cover of the mandibular salivary gland or at its posterior border. 

 It is ventral to the carotid artery and the atlantal gland. Its afferent and efferent 

 vessels are similar to those of the atlantal gland. 



The atlantal lymph gland is situated ventral to the wing of the atlas, on the 

 cleido-mastoideus tendon, and partly umder cover of the mandibular salivary gland. 

 It is related ventrally to the carotid artery. It is usually discoid and an inch and a 

 half to two inches (ca. 4-5 cm.) in length. One or more small lymph nodes may 

 occur near the large constant one, and small hsemolymph glands are commonly 

 present here. The afferent vessels come from the tongue, the salivary glands, the 

 gums in part; the cervical part of the thymus; most of the hyoid and cervical 

 muscles. It also receives vessels from the parotid, mandibular, and suprapharyn- 

 geal Ijnmph glands. The efferent vessels, three to six in number, concur in forming 

 the tracheal lymph duct. 



The pterygoid lymph gland (Lg. pterygoidea), which is present in the majority 

 of cases, is situated on the dorsal part of the lateral face of the pterygoid muscle, 

 close to the maxillary tuberosity. It is usually about half an inch (ca. 1-1.5 cm.) 

 in length and width, but may be much smaller and escape observation. Its affer- 

 ent vessels come from the hard palate and adjacent part of the gums. The efferent 

 vessels, to or three in number, go to the mandibular lymph gland. 



The hyoid lymph glands (Lgg. hyoidese) occur in about 20 per cent, of cases. The anterior 

 hyoid gland (Lg. hyoidea oralis) lies on the thyroid cornu of the hyoid bone, at the insertion of the 

 stylohyoideus muscle. It is about half an inch (ca. 1-1.5 cm.) long. It receives afferent vessels 

 from the tongue. The efferent vessels, two or three in number, go to the atlantal gland, and may 

 go in part to the suprapharyngeal gland. The posterior hyoid gland (Lg. hyoidea aboralis) lies 

 on the dorsal end of the great cornu of the hyoid bone or in the angle between the bone and the 

 occipito-hyoideus muscle. It receives Ij'mph vessels from the mandible which issue from the 

 mandibular foramen. The efferent vessels go to the atlantal gland. 



The anterior cervical lymph glands (Lgg. cervicales craniales) are situated on 

 the anterior part of the trachea, along the course of the carotid artery. They are 

 variable in number and size. Four or five may be present. They vary in length 

 from about half an inch to two inches (ca. 1-5&5 cm.). 



The middle cervical Ijrmph glands (Lgg. cervicales media;) lie on each side of 

 the trachea, in the middle third of the neck. They vary in position, number, and 

 size. The series may extend to the anterior group, or may reach back almost to 

 the posterior group. The number appears to vary from one to seven on either side. 

 Their length ranges from about one-fourth inch to an inch or more (ca. 0.5-3 cm.). 

 There are usually hsemolymph glands near them. 



The posterior cervical lymph glands (Lgg. cervicales caudales) are situated 

 near the thoracic inlet. One of them lies dorsal to the manubrium sterni and the 

 cervical muscles attached to it. It is usually about half an inch (ca. 1-1.5 cm.) 

 long. Three or four others usually occur on either side. Of these, one is ventral 

 to the brachial vein at the first rib, one or two lie on the brachial vessels here, and 

 others are dorsal and ventral to the jugular vein. Haemoljrmph glands usually are 

 present in the fat about this group. 



The cervical lymph glands receive afferent vessels from the ventral muscles of 

 the neck, the oesophagus, the larynx, the trachea, the thyroid gland, and the cervical 

 part of the thymus. The anterior cervical glands receive efferent vessels of the 

 atlantal gland. The efferent vessels go in general to the tracheal lymph ducts, but 

 efferents from some of the posterior group may go to the terminal part of the thora- 

 cic duct or to the common jugular vein. 



