5 6 PRACTICAL ANATOMY. 



The second layer surrounds the hyoid depressors and their vessels and 

 nerves. 



The third layer surrounds the larynx, trachea, thyroid, oesophagus, common 

 carotid artery, internal jugular vein, and vagus nerve. 



The fourth layer covers the rectus capitis anticus major and minor muscles 

 and the longus colli. 



8. What becomes of t lie first and second layers below? 

 They are attached to the clavicle and sternum. 



9. Give the origin and insertion of tlic temporal muscle. 



This muscle arises from the complete temporal ridge, from the temporal 

 aponeurosis, from the temporal fossa, and is inserted into the coronoid process 

 of the mandible. 



I o. Analyze the coronoid process. 



This has an outer and an inner surface, an anterior and a posterior border, a 

 base, and an apex. 



11. Of what does the complete temporal ridge consist ? 



It consists of frontal, parietal, and temporal portions. The ridge has a 

 superior part for the attachment of the temporal fascia ; an inferior part for origin 

 of the muscle. 



1 2. What do you find in grooves on the deep surface of the muscle next the bone ? 

 The deep temporal arteries branches of the internal maxillary artery for 



the supply of the muscle. 



1 3. Analyse the zygomatic arch and tell wliat you find under the same. 



The arc us sygomaticiis is made up of the zygomatic processes of the malar 

 and temporal bones. It has a superior border, into which is inserted the tem- 

 poral fascia ; an outer surface, which is subcutaneous ; an inferior border and an 

 inner surface, which are occupied by the origin of the masseter muscle. Under 

 the arch are the coronoid and condylar processes of the mandible ; the sigmoid 

 notch, transmitting the masseteric vessels and nerves ; the external pterygoid 

 muscle ; and a considerable quantity of fatty connective tissue. 



1 4. Describe the masseter muscle. 



This muscle arises ( i ) from the inferior border, anterior two-thirds, and (2) from 

 the inner surface and posterior one-third of the lower border of the zygomatic 

 arch. It is inserted into the external surface of the ramus. It is covered on its 

 outer surface by the masseteric fascia, on which lie the pes anserinus, the parotid 

 gland in part, and Stenson's duct. 



I 5. Describe the stcrno-clcido-mastoid muscle. 



This muscle has two origins a clavicular and a sternal ; and two insertions 

 a mastoid and an occipital. Itextends obliquely across the neck, dividing this 

 region into an anterior and a posterior part. Its nerve-supply is from the spinal 

 accessory and deep branches from the cervical plexus. It lies on the carotid 

 sheath in part of its course, and along its posterior margin emerge the superficial 

 branches of the cervical plexus. (Fig. 22.) 



1 6. Name the superficial branches of the cervical plexus. 



The descending branches are the suprasternal, supraacromial, supra- 

 clavicular; the ascending branches are the great auricular, the small occipital, 

 the lesser occipital, and the superficialis colli. 



Quiz on the Structures in the Second Layer of Deep Cervical Fascia. 



1 . Name the depressor muscles of the hyoid. 



(i) The sterno-hyoid. (2) The omo-hyoid. (3) The sterno-thyroid. (4) The 

 thyro-hyoid. 



2. How are these mitsfles cnsheathed and from what are tliey separated in front 

 and behind ? 



They are ensheathed by a delamination of the second layer of deep cer- 



