572 



DISSECTION OF THE NECK. 



SECTION VI. 



DISSECTION OF THE NECK. 



Boundaries 

 of the side 

 of the neck. 



Division 

 into two 

 triangles 

 by sterno- 

 mastoid. 



Hollows. 



Objects in 

 middle line 

 of neck : 



hyoid bone, 



thyroid 

 cartilage, 



thyro-hyoid 

 interval, 



cricoid 

 cartilage, 



crico- 



thyroid 



interval, 



and supra- 

 sternal 

 depression. 



Dissection 

 of the 

 platysma. 



Position. For the dissection of this part, the neck is supported 

 on a block of a moderate height, the chin drawn up so as to put 

 the parts on the stretch and the shoulder depressed as much as the 

 work that is being done on the axilla will allow, and the face 

 should be turned to the opposite side. 



Surface Marking. The side of the neck has a somewhat irregularly 

 quadrilateral outline, and is limited in the following way : Below 

 is the prominence of the clavicle ; and above is the base of the 

 lower jaw with the skull. In front, the boundary is the middle 

 line of the neck between the chin and sternum ; and behind, a line 

 from the occiput to the acroinial end of the clavicle. The part 

 thus included is divided into two triangular spaces (anterior and 

 posterior) by the diagonal prominence of the sterno-mastoid muscle 

 (fig. 209). And in consequence of the position of that muscle the 

 base of the anterior triangle is at the jaw, and the apex at the 

 sternum ; while the base of the posterior one is at the clavicle, and 

 the apex at the head. 



The surface in front of the sterno-mastoid is depressed at the 

 upper part of the neck, near the position of the carotid vessels ; 

 and behind the muscle, just above the clavicle, is another hollow, 

 the supraclavicular fossa, which indicates the position of the 

 subclavian artery. 



Along the front of the neck the following parts can be recognised 

 through the skin : About two inches and a half from the chin, in 

 the retiring angle formed by the outline of the front of the neck, 

 the body of the hyoid bone may be felt, with its large cornu 

 extending backwards on each side. Below this is the prominence of 

 the thyroid cartilage, called pomum Adami, which is more marked 

 in the male sex ; and between the cartilage and the hyoid bone is a 

 slight interval, corresponding with the thyro-hyoid membrane. 



Below the thyroid is the narrow prominent ring of the cricoid 

 cartilage ; and between the two the finger may distinguish another 

 interval, which is opposite the crico-thyroid membrane. 



Immediately above the sternum, and bounded on each side by the 

 prominent sterno-mastoid muscle, is a narrow depression supra- 

 sternal fossa, the depth of which is much increased in emaciated 

 persons, and in it the tube of the trachea can be recognised. In 

 some bodies, especially in women, the swelling of the thyroid gland 

 may be felt by the side of the air-tube. 



Direction. As it is necessary for the liberation of the upper limb 

 to have an early dissection of the posterior part of the neck, the student 

 should lay bare now only the part behind the sterno-mastoid muscle. 



Dissection. To raise the skin from the posterior triangle of the 

 neck, make an incision along the sterno-mastoid muscle from the 

 tip of the mastoid process to the clavicle one inch external to its 



