724 LYMPHATIC SYSTEM OF THE OX AND SHEEP 
part of the nasal cavity, the maxillary and palatine sinuses, and the larynx; and the 
rectus capitis ventralis major. The efferent vessels, four to eight in number, con- 
cur in forming the tracheal lymph duct. 
A small parapharyngeal 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-nastoideus tendon, and partly under 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 em.) in length. One or more small lymph nodes may 
occur near the large constant one, and small hemolymph 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 lymph 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 em.) 
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 (Leg. hyoidew) 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 (ea. 1-1.5 em.) 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 lymph vessels from the mandible which issue from the 
mandibular foramen. The efferent vessels go to the atlantal gland. 
The anterior cervical lymph glands (Leg. 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. 1-2.5 em.). 
The middle cervical lymph glands (Legg. cervicales medi) 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 em.). 
There are usually hemolymph glands near them. 
The posterior cervical lymph glands (Legg. 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 em.) 
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. Hzemolymph 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 esophagus, 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. 
