454 THE MUSCLES 



Insertion. — (1) The superficial muscular stratum which covers the side and 

 adjacent part of the under surface of the tongue; (2) it is partly continuous with 

 the deep transverse lingualis muscle. 



Structure. — Arising in a thin muscular sheet, its fibres form as they pass out- 

 wards a small cylindrical bundle which, lying in front of the tonsil and against 

 the w^all of the pharynx, constitutes the anterior pillar of the fauces. This bundle 

 runs downwards and forwards till it reaches the side of the tongue at the junction 

 of its middle and posterior thirds. Here some of the fibres pass forwards and 

 downwards to join the superficial stratum formed by the stylo-glossus and hyo- 

 glossus. The rest pass inwards towards the midtlle line, being continued into the 

 deep transverse lingualis muscle. This part of the two muscles, together Avith 

 the associated portion of the lingualis transversus, forms a sphincter muscle round 

 the front part of the faucial opening. 



Nerve-supply. — Filaments from the pharyngeal plexus. 



Action. — (1) To draw dowaiwards the sides of the soft palate; (2) to draw 

 upwards and backwards the sides of the tongue. The combination of these two 

 actions closes the front part of the faucial opening, as in the second part of 

 swallowing, when the back of the tongue comes into contact with the soft palate, 

 and prevents the return of the food which is being grasped by the constrictors. It 

 should be remembered, however, that the elevation of the tongue is chiefly due to 

 the muscles Avhich raise the hyoid bone. 



Relations. — Superficially, it is covered by the mucous membrane of the soft 

 palate and the side of the tongue; deeply, it is in contact with the aponeurosis of 

 the soft palate, the superior constrictor of the pharynx, and the hyo-glossus; 

 behind it lies the tonsil. 



For ^luscles of the Palate see page 944. For Muscles of the Pharynx see 

 pages 950-952. 



THE DEEP MUSCLES OF THE FRONT OF THE NECK 



The deep muscles of the front of the neck consist of an inner and an outer 

 group, separated from one another by the line of the anterior tubercles of the 

 cervical vertebrae. Both groups are covered in front b}' the prevertebral fascia. 



Outer Geoup 



The outer group is formed by the three scaleni, which pass from the first two 

 ribs upwards and inwards to the transverse processes. 



1. SCALENUS ANTICUS 



The scalenus anticus — named from its shape (scalenus = of unequal sides, 

 being a term a]>pli('d to certain triangles in geometry) and its relation to its fellows 

 — is a thick triangular sheet. 



Origin. — The scalene tubercle near the inner liorder of the upper surface of the 

 first rib. 



Insertion. — Tlie anterior tul)ercles of the third, fourth, fifth, and sixth cervical 

 vertebne. 



Structure. — Arising by a short, somewhat flattened tendon, which is continued 

 upwards for a short distance upon the front and outer surface of the muscle, the 

 fleshy fibres diverge as they pass upwards and slightly backwards and inwards to 

 be inserted by four short tendons into the transverse processes. 



Nerve-supply. — From the anterior jirimarv branches of the fourth, fifth, and 

 sixth cervical nerves close to their points of emergence. 



Action. — (1) The rib being fixed, it will help to flex the neck botli forwards 



