300 THE MUSCLES AND FASCIA. 



muscular, and ascend in a parallel direction to terminate in a tendinous aponeu- 

 rosis. The frontal portion (sometimes called the frontalis muscle) is thin, of a 

 quadrilateral form, and intimately adherent to the superficial fascia. It is broader, 

 its fibres are longer, and their structure paler than the occipital portion. Its internal 

 fibres are continuous with those of the Pyramidalis nasi. Its middle fibres become 

 blended with the Corrugator supercilii and Orbicularis palpebrarum ; and the 

 outer fibres are also blended Avith the latter muscle over the external angular pro- 

 cess. According to Theile, the innermost fibres are attached to the nasal bones, 

 the outer to the external angular -process of the frontal bone. From these 

 attachments the fibres are directed upward, and join the aponeurosis below the 

 coronal suture. The inner margins of the frontal portions of the two muscles are 

 joined together for some distance above the root of the nose ; but between the 

 occipital portions there is a considerable, though variable, interval, which is occupied 

 by the aponeurosis. 



The aponeurosis covers the upper part of the vertex of the skull, being 

 continuous across the middle line with the aponeurosis of the opposite muscle. 

 Behind, it is attached, in the interval between the occipital origins, to the occipital 

 protuberance and highest curved lines of the occipital bone ; in front, it forms a 

 short and narrow prolongation between the frontal portions ; and on each side it 

 has connected with it the Attollens and Attrahens auriculam muscles; in this 

 situation it loses its aponeurotic character, and is continued over the temporal 

 fascia to the zygoma as a layer of laminated areolar tissue. This aponeurosis 

 is closely connected to the integument by the firm, dense, fibro-fatty layer 

 which forms the superficial fascia ; it is connected with the pericranium by 

 loose cellular tissue, Avhich allows of a considerable degree of movement of the 

 integument. 



Nerves. The frontal portion of the Occipito-frontalis is supplied by the 

 facial nerve ; its occipital portion by the posterior auricular branch of the facial. 



Actions. The frontal portion of the muscle raises the eyebrows and the skin 

 over the root of the nose, and at the same time draws the scalp forward, throwing 

 the integument of the forehead into transverse wrinkles. The posterior portion 

 draws the scalp backward. By bringing alternately into action the frontal and 

 occipital portions the entire scalp may be moved forward and backward. In the 

 ordinary action of the muscles, the eyebrows are elevated, and at the same time 

 the aponeurosis is fixed by the posterior portion, thus giving to the face the 

 expression of surprise : if the action is more exaggerated, the eyebrows are still 

 further raised, and the skin of the forehead thrown into transverse wrinkles, as in 

 the expression of fright or horror. 



2. Auricular Region (Fig. 195). 



Attrahens auriculam. Attollens auriculam. 



Retrahehs auriculam. 



These three small muscles are placed immediately beneath the skin around 

 the external ear. In man, in whom the external ear is almost immovable, they 

 are rudimentary. They are the analogues of large and important muscles in 

 some of the mammalia. 



Dissection. This requires considerable care, and should be performed in the following 

 manner : To expose the Attollens auriculam, draw the pinna, or broad part of the ear, downward, 

 when a tense band will be felt beneath the skin, passing from the side of the head to the 

 upper part of the concha; by dividing the skin over this band in a direction from below 

 upward, and then reflecting it on each side, the muscle is exposed. To bring into view the 

 Attrahens auriculam, draw the helix backward by means of a hook, when the muscle will be 

 made tense, and may be exposed in a similar manner to the preceding. To expose the Ketra- 

 hens auriculam, draw the pinna forward, when the muscle, being made tense, may be felt beneath 

 the skin at its insertion into the back part of the concha, and may be exposed in the same 

 manner as the other muscles. 



The Attrahens auriculam (Auricularis anterior), the smallest of the three, is 

 thin, fan-shaped, and its fibres pale and indistinct; they arise from the lateral 



