4 
anastomoses with its fellow of the opposite side, with branches of the crico-thyroid artery 
and with the terminal branches of the inferior thyroid artery. 
(c) The sterno-mastoid branch (ramus sterno-cleidomastoideus) passes downwards and 
backwards along the upper border of the anterior belly of the omo-hyoid muscle and across 
the common carotid artery to the under surface of the sterno-mastoid muscle. It anasto- 
moses, in the sterno-mastoid, with branches of the occipital and suprascapular arteries. 
(2) In the muscular triangle (d) a crico-thyroid branch (ramus crico-thyroideus) runs 
forwards, either over or under the sterno-thyroid, and crosses the crico-thyroid muscle to 
anastomose in front of the crico-thyroid membrane with its fellow of the opposite side, and, 
by branches which perforate the crico-thyroid membrane, with laryngeal branches of the 
superior and inferior thyroid arteries. It supplies the adjacent muscles and membrane. 
(ec) The terminal branches are anterior and posterior respectively. 
The anterior terminal branch (ramus anterior), often much larger than the crico- 
thyroid artery, descends along the anterior border of the lateral lobe of the thyroid body, 
and, extending on to the upper border of the thyroid isthmus, anastomoses with its fellow 
of the opposite side. The posterior branch (ramus posterior) descends along the posterior 
border of the lateral lobe, and both terminal branches supply the thyroid body (rami 
glandulares). They anastomose with each other and with branches from the inferior 
thyroid artery. 
760 THE VASCULAR SYSTEM. 
(2) Lingual Artery.—The lingual artery (a. lingualis, Figs. 554 and,556) springs 
from the front of the external carotid, opposite the tip of the ereat cornu of the 
hyoid bone, and terminates, as the ranine artery, beneath the tip of the tongue, 
where it anastomoses with its fellow of the opposite side. 
Course.—From its commencement, and whilst in the carotid triangle, the first 
part of the artery forms a loop with the convexity upwards. A second. part passes 
forwards, immediately above the great cornu of the hyoid bone, to the anterior 
border of the hyo-glossus muscle, where it gives off a sublingual branch. A third 
part passes obliquely forwards and upwards under cover of the anterior border of 
the hyo-glossus, and a fourth part runs directly forwards on the under surface of 
the tongue to the tip. The third and fourth parts are frequently described together 
as the ranine artery (a. profunda lingure). 
Relations.—The first part of the lingual artery is crossed superficially by the hypo- 
glossal nerve, but beyond this it is only covered by skin, fascia, and the platysma ; it rests 
internally against the middle constrictor of the pharynx. In the rest of its course the 
artery is for the most part more deeply placed. The second part, remaining in contact 
internally with the middle constrictor, passes beneath the hyo-glossus muscle, by which it 
is separated from the hypoglossal nerve, the ranine vein, and the lower part of the sub- 
maxillary gland. The third part ascends almost vertically, parallel with and under the 
anterior fibres of the hyo-glossus, which is here covered by ‘the mylo-hyoid, and between it 
and the genio-hyo- glossus. The fourth part runs forwards between the inferior lingualis 
and the genio-hyo-glossus muscles, and is only covered on its lower surface by the mucous 
membrane of the tongue. Thus the lingual artery at its termination, near the frenum 
linguee, is again comparatively superficial. 
Branches. —(a) The supra-hyoid (ramus hyoideus), a small branch which arises in 
the carotid triangle and runs along the upper border of the great cornu of the hyoid bone. 
It anastomoses with its fellow of the opposite side and with the infrahyoid branch of the 
superior thyroid artery. 
(6) The dorsalis lingue (ramus dorsalis linguze) is a branch of moderate size which 
arises from the second part of the artery. It ascends on the genio-hyo-glossus to the 
dorsum of the tongue, where it branches and anastomoses with its fellow of the opposite 
side round the foramen cecum. It supplies the posterior part of the tongue as far back 
as the epiglottis, and sends branches backwards to the tonsil which anastomose with the 
tonsillar branches of the ascending palatine branch of the facial and with the ascending 
pharyngeal artery. 
(c) A sublingual branch (a. sublingualis) arises at the lower part of the anterior border 
of the hyo-glossus muscle and runs forwards and upwards, between the mylo-hyoid and 
the genio-hyo-glossus, to the sublingual gland, which it supplies ; it also supplies the mylo- 
hyoid, the genio-hyo-glossus, and the genio-hyoid muscles, and it anastomoses with its 
fellow of the opposite side, with the continuation of the lingual by a branch which it 
sends along the frenum linguze, and through the mylo-hyoid muscle with the submental 
branch of the facial. 
