THE HEAD AND NECK. 235 
X. THE HEAD AND NECK. 
This dissection includes the various structures of the region, with the excep- 
tion of the cervical and occipital musculature and the central nervous system, 
which are treated in the succeeding parts, and the special musculature of the ear, 
which has been omitted. 
To begin the dissection, the skin, which has already been 
divided to the mandibular symphysis and partly reflected, should 
be separated from the underlying platysma along‘the side of the 
head, and reflected until the surface is clear to a point near the 
dorsal median line of the skull. The insertion of the platysma on 
the cheek, and that of its special portion, the depressor conchae 
posterior, on the base of the ear, should be noted. A second band 
of muscle, similar in its relation to the platsyma, arises from the 
lateral border of the mandible, immediately in front of the masseter 
muscle, and is inserted into the base of the ear. This is the de- 
pressor conchae (parotideoauricularis) anterior. 
In removing the skin of the upper and lower eyelids, two mus- 
cles, the orbicularis oculi and the depressor palpebrae infer- 
ioris, may be observed. The former is a somewhat circular band 
of fibres enclosing both eyelids, the fibres lying directly on the skin, 
and being concentrated at the anterior and posterior angles. The 
latter is a very slender muscle arising from the zygomatic arch 
and inserted into the skin of the lower eyelid. The corresponding 
levator palpebrae superioris arises from the orbital wall, and is here 
concealed by the projecting supraorbital process. 
1. On the lateral surface of the head the following structures 
may be made out without further dissection: 
(a) The masseter muscle. Origin: The zygomatic arch; 
tendinous from its anterior angle. Insertion: Lateral sur- 
face of the angle of the mandible. 
(b) The parotid gland (gl. parotis), a diffuse, white or brownish 
gland lying immediately behind the angle of the mandible. 
Its duct (d. parotideus) crosses the masseter and perforating 
the mucous membrane of the cheek opens into the oral 
cavity. 
(c) The chief part of the seventh cranial or facial nerve (n. 
facialis) appears in the anterior portion of the parotid gland, 
