638 BLOOD-VASCULAR SYSTEM OF THE HORSE 
In some cases the thyroid and laryngeal arteries arise from the carotid separately or by a 
short common stem. A laryngeal branch is often detached from the carotid in front of the thyro- 
laryngeal and enters the larynx with the anterior laryngeal nerve. The pharyngeal branch fre- 
quently comes directly from the carotid. 
Fie. 558.—Derrp Dissection oF Neck or Horspr, 
a, a, Ends of sterno-cephalicus; 6, anterior part of omo-hyoideus; c, sterno-thyro-hyoideus; d, trachea; e, eesopha- 
gus; /, cariniform cartilage; g, rectus cap. ventralis major; A, stump of longissimus atlantis; 7, intertransversales; k, 
multifidus; J, m, scalenus; n, serratus cervicis; 0, 0, stumps of splenius; p, longissimus cervicis; g, complexus (most of 
which is removed); r, rhomboideus; s, trapezius; ¢, spinalis et semispinalis; u, lamellar part of lig. nuchw; v, brachio- 
cephalicus; w, anterior deep pectoral; x, supraspinatus; y, anterior superficial pectoral; z, tuber scapule; 1, /, articular 
processes of cervical vertebre; 2, 2, transverse processes of same; 3, atlas; 3’, axis; 4, 4, jugular vein (remainder re- 
moved); 5, common carotid artery, from which a piece is removed to show the accompanying nerves and the esophagus; 
6, vago-sympathetic trunk; 7, 7, tracheal and muscular branches of carotid artery; 8, recurrent nerve; 10, left tracheal 
lymph-duct; 1/, 12, ascending and descending branches of inferior cervical artery (13); 14, cephalic vein; 15-20, ven- 
tral branches of second to seventh cervical nerves; 21, roots of phrenic nerve; 22, pectoral nerves; 22’, nerve to ser- 
ratus ventralis; 23, musculo-cutaneous nerve; 24, median nerve; 25, ulnar nerve; 26, radial nerve; 27, axillary nerve; 
28, dorsal branches of cervical nerves; 28’, accessory nerve (cut); 29, deep cervical artery; 30, muscular branch of ver- 
tebral artery; 31, posterior branch of occipital artery; 32, vertebral artery; 33, muscular branches of occipital artery; 
34, obliquus capitis post.; 35, obl. cap. ant.; 36, twig from dorsal branch of third cervical nerve. (After Ellenberger- 
Baum, Top. Anat. des Pferdes.) 
5. The posterior thyroid artery (A. thyreoidea caudalis) is a small and incon- 
stant vessel which arises from the carotid at a variable distance behind the anterior 
thyroid or from the latter or the parotid artery. It sends branches into the pos- 
terior part of the thyroid gland, and detaches small tracheal and muscular twigs. 
In some cases it is distributed chiefly or entirely to the adjacent muscles. 
