THE AURICULAR REGION 365 



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, Chough variable; interval, which is 

 occupied by the aponeurosis. 



The epicranial aponeurosis (yalea aponeurotica) 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 por- 

 tions; and on each side it gives origin to the Attollens and Attrahens aurem muscles 

 of the pinna. This aponeurosis is closely connected to the integument by the 

 firm, dense, fibrofatty layer which forms the superficial fascia; it is connected 

 with the pericranium by loose cellular tissue, which allows of a considerable 

 degree of movement of the integument. It is continuous with the temporal 

 fascia below the temporal ridge, and it is in reality the representative of the 

 deep fascia. 



Nerves. The frontal portion of the Occipitofrontalis is supplied by the temporal branches 

 of 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 alter- 

 nately 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. 



Applied Anatomy. The skull is covered by the scalp (Fig. 288). This consists, from without 

 inward, of five layers: (1) Skin; (2) subcutaneous fat; (3) the Occipitofrontalis muscle and apo- 

 neurosis; (4) a layer of connective tissue beneath the Occipitofrontalis aponeurosis (subaponeu- 

 rotic tissue) ; (5) the pericranium. The subcutaneous tissue is composed of bands of fibrous 

 tissue enclosing spaces filled with fat. The fibrous character of this tissue greatly limits discolor- 

 ation and swelling when inflammation occurs. The edges of a wound which does not involve the 

 aponeurosis or muscle do not retract, hence the wound does not gape. The bloodvessels run prac- 

 tically in the skin, and as they lie in very dense tissue and are adherent to it, wounds bleed profusely, 

 the arteries being unable freely to contract and retract. It is very difficult or impossible to pick 

 up with forceps a vessel in the skin of the scalp, and bleeding must be arrested by suture liga- 

 tures or by the stitches which close the wound. Sebaceous glands in the skin of the scalp may 

 develop into sebaceous cysts (wens). If a wound involves the muscle or aponeurosis, it gapes 

 widely, the greatest amount of gaping being observed in transverse wounds. The space between 

 the aponeurosis and the pericranium is called by Treves the dangerous area of the scalp. It con- 

 tains a layer of connective tissue, and suppuration in this tissue spreads widely. An abscess in 

 the dangerous area should be opened above the superior curved line of the occipital bone, above 

 the eyebrow or above the zygoma. In a wound or contusion superficial to the aponeurosis but 

 little blood can be effused in the tissue because its fibrous structure prevents it, and abscesses do 

 not tend to spread widely. Between the aponeurosis and the pericranium a great amount of 

 blood can be effused. An effusion of blood beneath the pericranium is called a cephalhematoma. 

 Such a condition may occur from pressure during birth. An extravasation beneath the peri- 

 cranium is limited to the surface of one bone. The pericranium is tightly attached to the sutures, 

 but adheres lightly to the surface of the bone, and abscess beneath the pericranium is restricted 

 to the surface of one bone. 



2. The Auricular Region (Fig. 289). 



Attrahens aurem. Attollens aurem. 



Retrahens aurem. 



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 



