THE SUPERFICIAL CERVICAL REGION. 407 



7. Muscles of the Anterior Vertebral 8. Muscles of the Lateral Vertebral 



Region. Region. 



Rectus eapitis anticus major. Scalenus anticus. 



Rectus eapitis anticus minor. Scalenus medms. 



Rectus lateralis. Scalenus posticus. 



Longus colli. 9. Muscles of the Larynx. 



Included in the description of 

 the Larynx. 



1. Superficial Cervical Region. 

 /Platysma myoides. J Sterno-cleido-mastoid. 



Dissection. A block having been placed at the back of the neck, and the face turned to 

 the side opposite that to be dissected, so as to place the parts upon the stretch, make two trans- 

 verse incisions : one from the chin, along the margin of the lower jaw, to the mastoid process, 

 and the other along the upper border of the clavicle. Connect these by an oblique incision 

 made in the course of the Sterno-mastoid muscle, from the mastoid process to the sternum ; the 

 two flaps of integument having been removed in the direction shown in Fig. 268, the superficial 

 fascia will be exposed. 



The Superficial Cervical Fascia is a thin, aponeurotic lamina which is hardly 

 demonstrable as a separate membrane. Beneath it is found the Platysma myoides 

 muscle. 



The Platysma myoides (Fig. 269) is a broad, thin plane of muscular fibres 

 placed immediately beneath the superficial fascia on each side of the neck. It 

 arises by thin, fibrous bands from the fascia covering the upper part of the Pectoral 

 and Deltoid muscles : its fibres proceed obliquely upward and inward along the 

 side of the neck. The anterior fibres interlace, in front of the jaw. with the fibres 

 of the muscle of the opposite side ; the posterior fibres pass over the lower jaw. a 

 few of them being attached to the bone below the external oblique line, the greater 

 number passing on to be inserted into the skin and subcutaneous tissue of the lower 

 part of the face, many of these fibres blending with the muscles about the angle 

 and lower part of the mouth. Sometimes fibres can be traced to the Zygomatic 

 muscles or to the margin of the Orbicularis palpebrarum. Beneath the Platysma 

 the external jugular vein may be seen descending from the angle of the jaw to the 

 clavicle. 



Surgical Anatomy. It is essential to remember the direction of the fibres of the 

 Platysma in connection with the operation of bleeding from the external jugular vein ; for if the 

 point of the lancet is introduced in the direction of the muscular fibres, the orifice made will be 

 filled up by the contraction of the muscle, and blood will not flow; but if the incision is made 

 across the course of the fibres, they will retract and expose the orifice in the vein, and so allow 

 the flow of blood. 



Relations. By its external surface, with the integument, to which it is united 

 more closely below than above ; by its internal surface, with the Pectoralis 

 major. Deltoid, and Trapezius, and with the clavicle; in the neck, with the 

 external and anterior jugular veins, the deep cervical fascia, the superficial 

 branches of the cervical plexus, the Sterno-mastoid, Sterno-hyoid, Omo-hyoid, 

 and Digastric muscles ; behind the Sterno-mastoid muscle it covers the Scaleni 

 muscles and the nerves of the brachial plexus ; on the face it is in relation 

 with the parotid gland, the facial artery and vein, and the Masseter and Buccinator 

 muscles. 



Action. The Platysma myoides produces a slight wrinkling of the surface of 

 the skin of the neck, in an oblique direction, when the entire muscle is brought 

 into action. Its anterior portion, the thickest part of the muscle, depresses the 

 lower jaw ; it also serves to draw down the lower lip and angle of the mouth on 

 each side, being one of the chief agents in the expression of melancholy. 



The Deep Cervical Fascia (Fig. 275) is a strong, fibrous layer which invests the 

 muscles of the neck and encloses the vessels and nerves. It commences, as an 

 extremely thin layer, at the back part of the neck, where it is attached to the 



