224 FASCIA AND MUSCLES OF THE HORSE 



Relations. — The muscle is crossed outwardly by the lingual artery. 

 Blood-supply. — Lingual artery. 

 Nerve-supply. — Glosso-pharyngeal nerve. 



6. Hyoideus Transversus. — This is a thin, unpaired muscle, which extends 

 transversely between the two small cornua of the hyoid bone. 



Attachments. — The small cornua close to the junction with the great cornua. 

 Action. — When relaxed, its upper surface is concave; when it contracts, it 

 elevates the root of the tongue. 



Structure. — Fleshy, composed of parallel transverse bundles. 

 Blood-supply. — Lingual artery. 

 Nerve-supply. — Glosso-pharyngeal nerve. 



7. Stemo-thyro-hyoideus, and 



8. Omo-hyoideus. — These are described with the muscles on the ventral 

 surface of the neck. 



The Fascia and Muscles of the Neck 



It is convenient to divide the muscles of the neck into ventral and lateral 

 groups, the two lateral groups being separated from each other by the ligamentum 

 nuchae. 



THE FASCI.E OF THE NECK 



The superficial fascia is in part two-layered, and contains the cervical portion 

 of the panniculus. The fasciae of the right and left sides are attached along the 

 dorsal line of the neck to the ligamentum nuchse, while along the ventral line they 

 meet in a fibrous raphe. A deep layer is detached which passes underneath the 

 panniculus, bridges over the jugular furrow, and crosses over the deep face of the 

 mastoido-humeralis and omo-hyoideus to join the superficial layer. It again sepa- 

 rates to pass under the cervical trapezius, and become attached to the ligamentum 

 nuchse. Along the ventral line a septum is detached which separates the sterno- 

 cephalici. Two other layers in front of the shoulder inclose the prescapular lymph- 

 glands. 



The deep fascia also forms two layers. The superficial layer is attached to 

 the wing of the atlas and the lower edge of the trachelo-mastoideus and scalenus. 

 Passing downward, it incloses the trachea, and, together with the deep layer, 

 furnishes sheaths for the vagus and sympathetic nerves and the carotid artery. 

 Passing upward it detaches septa between the extensor muscles of the spine. An- 

 teriorly it covers the thyroid gland, the guttural pouch, the adjacent vessels and 

 nerves and the larynx, and is attached to the mastoid process of the temporal bone 

 and the thyroid cornu of the hyoid bone. Posteriorly, it is attached to the first 

 rib and the cariniform cartilage of the sternum. The deep layer (prevertebral 

 fascia) covers the ventral surface of the longus colli, and incloses the trachea and 

 oesophagus. Anteriorly, it forms, with the corresponding layer of the opposite 

 side, a septum between the guttural pouches; posteriorly, it becomes continuous 

 with the endothoracic fascia. A fascia propria forms a tubular sheath around the 

 trachea, inclosing also the recurrent nerves. 



VENTRAL MUSCLES 



This group consists of eleven pairs of muscles which lie almost entirely 

 ventral to the vertel^rie. 



1. Panniculus carnosus. — The cervical panniculus (platysma myoides of 

 man) has a fleshy origin on the cariniform cartilage (manul^rium) of the sternum. 



