REGIONAL ANATOMY. 



THE NECK. 



THE neck is the constricted, cylindrical segment ex- 

 tending between the head and trunk ; it varies in form 

 in the sexes, and at different ages ; in the young adult 

 male it is laterally compressed, and presents, in the 

 median line anteriorly, the projecting larynx; at the 

 sides are the prominent, oblique, rounded elevations, 

 which mark the sterno-mastoid muscles ; posteriorly, the 

 neck is flattened. In the young adult female the neck 

 is nearly cylindrical, but slightly broader at its base. 

 In infancy it presents numerous transverse or circular 

 grooves and folds, due to the accumulation of fat in the 

 subcutaneous structures. At old age the skin is wrin- 

 kled and presents two prominent folds, which pass from 

 the sides of the chin downward and backward ; they 

 correspond to the anterior edges of the platysma muscles. 

 Up to an advanced period the skin of the neck is loosely 

 attached to the subcutaneous structures; in operations 

 in this region it is necessary to fix or steady it by 

 pressure or traction, to preserve the relations of the in- 

 cisions to the deeper structures. 



The superficial fascia is separable into two layers, 

 between which pass the fibres of the platysma myoides 

 muscle, which arises over the clavicle and passes obliquely 

 upward, to be inserted on the fascia of the lower part of 

 the face. Some of its fibres blend with the fibres of the 

 orbicularis oris. The deep leaflet of the superficial fascia 

 is very thin and membranous. The deep fascia a thin, 

 fibrous, investing structure is exceedingly complex in 

 (440) 



