FASCIAE OF THE HEAD AND NECK. 247 



sheaths to all the muscles and tendons. It is thick upon the outer 

 and least protected side of the limb, and thinner upon its inner side. 

 It is firmly connected to the bones and to the prominent points of 

 each region, as to the pelvis, knee, and ankle, in the lower, and to 

 the clavicle, scapula, elbow, and wrist in the upper extremity. It 

 assists the muscles in their action, by keeping up a tonic pressure 

 on their surface ; aids materially in the circulation of the fluids in 

 opposition to the laws of gravity ; and in the palm of the hand and 

 sole of the foot is a powerful protection to the structures which enter 

 into the formation of these regions. In some situations its tension 

 is regulated by muscular action, as by the tensor vaginas femoris 

 and gluteus maximus in the thigh, by the biceps in the leg, and by 

 the biceps and palmaris longus in the arm ; in other situations it 

 affords an extensive surface for the origin of the fibres of muscles. 



The fasciae may be arranged like the other textures of the body 

 into 1. Those of the head and neck. 2. Those of the trunk. 3. 

 Those of the upper extremity. 4. Those of the lower extremity. 



FASCIA OF THE HEAD AND NECK. 



The temporal fascia is a strong tendino-fibrous membrane which 

 covers in the temporal muscle at each side of the head, and gives 

 origin by its internal surface to the superior muscular fibres. It is 

 attached to the whole extent of the temporal ridge above, and to 

 the zygomatic arch below ; in the latter situation it is thick and 

 divided into two layers, the external being connected to the upper 

 border of the arch, and the internal to its inner surface. A small 

 quantity of fat is usually found between these two layers, together 

 with the orbital branch of the temporal artery. 



The superficial cervical fascia contains between its layers the 

 platysma myoides muscle. 



The deep cervical fascia is a strong cellule-fibrous layer which 

 invests the muscles of the neck, and retains and supports the vessels 

 and nerves. It commences posteriorly at the ligamentum nuchse, 

 and passes forwards at each side beneath the trapezius muscle to 

 the posterior border of the sterno-mastoid ; here it divides into two 

 layers which embrace that muscle and unite upon its anterior border 

 to be prolonged onwards to the middle line of the neck, where it 

 becomes continuous with the fascia of the opposite side. Besides 

 thus constituting a sheath for the sterno-mastoid, it also forms sheaths 

 for the other muscles of the neck over which it passes. If the super- 

 ficial layer of the sheath of the sterno-mastoid be traced upwards, 

 it will be found to pass over the parotid gland and masseter muscle, 

 and to be inserted into the zygomatic arch; and if it be traced 

 downwards, it will be seen to pass in front of the clavicle and be- 

 come lost upon the pectoralis major muscle. If the deep layer of 

 the sheath be examined superiorly, it will be found attached to the 

 styloid process, from which it is reflected to the angle of the lower 



