    
|
 Helping San Diego, California and beyond since 1997 |
|
|
Helping San Diego, California and beyond since 1997 |
Click here and add this page to your favorites!
|
Encyclopedia Britannica - Main :: SAR-SCY |
|
|
SCALP (0. Dutch schelpe, a shell) , in anatomy, the whole covering of the top of the head from the skin to the bone. Five layers are recognized in the scalp, and these, from without inward, are: (1) skin, (2) superficial fascia, (3) aponeurosis or epicranium, (4) lymph space, (5) periosteum or pericranium. The skin of the scalp is thick and remarkable for the large number of hair follicles contained in it. The superficial fascia consists of dense bundles of fibrous tissue which pass from the skin to the third layer or aponeurosis and bind the two structures together so closely that when one of them is moved the other must needs be moved too. The fibrous bundles are separated by pellets of fat, and it is in this second layer that the vessels and nerves of the scalp are found. Here, as elsewhere, the vessels are arteries, veins and lymphatics, and the arteries are specially remarkable, firstly, for their tortuosity, which is an adaptation to so movable a part; secondly, for their anastomosing across the middle line with their fellows of the opposite side, an arrangement which is not usual in the body
tissue already spoken of, so that bleeding is more free in the scalp than it is from arteries of the same size elsewhere in the body
The veins do not follow the twists of the arteries but run a straight course; for this reason there is often a considerable distance between an artery and its companion vein. Accompanying the veins are the larger lymphatic vessels, though there are no lymphatic glands actually in the scalp. From the forehead region the lymphatics accompany the facial vein down the side of the face and usually reach their first gland in the submaxillary region, so that in the case of a poisoned wound of the forehead sympathetic swelling or suppuration would take place below the jaw. From the region of the temple the lymphatics drain into a small gland lying just in front of the ear, while those from the region behind the ear drain into some glands lying close to the mastoid process. In the occipital region a small gland (or glands) is found at the edge of the scalp close to the point at which the occipital artery reaches it, that is to say about a third of the distance from the external occipital protuberance to the tip of the mastoid process (see SKULL). The nerve supply of the scalp in its anterior part is from the fifth cranial or trigeminal nerve (see NERVES, CRANIAL); in the forehead region the supratrochlear and supraorbital branches come out of the orbit from the first or ophthalmic division of the fifth, while farther back, in the anterior part of the temporal region, the temporal branch of the second or maxillary division of the same nerve is found. Farther back still, in front of the ear, is the area of the auriculo-temporal nerve, a branch of the third or mandibular division of the fifth cranial.Behind the ear the scalp is supplied with sensation by two branches of the cervical plexus of nerves, the great auricular and the small occipital (see NERVES, SPINAL), while behind these, and reaching as far as the mid line posteriorly, the great occipital, derived from the posterior primary division of the second cervical nerve, is distributed. Sometimes the posterior primary division of the third cervical nerve reaches the scalp still nearer the middle line behind. The third layer of the scalp or epicranium is formed by the two fleshy bellies of the occipito-frontalis muscle and the flattened tendon or aponeurosis between them. Of these two bellies the anterior (frontalis) is the larger, and, when it acts, throws the skin of the forehead into those transverse puckers which are characteristic of a puzzled frame
movement
The fifth and deepest layer of the scalp is the pericranium or the external periosteum of the skull bones. This, until the sutures of the skull close in middle life, is continuous with the dura mater which forms the internal periosteum, and for this reason any subpericranial effusion is localized to the area of the skull bone over which it happens to lie. Moreover, any suppurative process may extend through the sutures to the meninges of the brain. (F. G. P.) Surgery of the Scalp.In connexion with the treatment of surgical and other wounds of the scalp, it used to be thought that it was dangerous to treat them by suturing, because of the risk
As the result of septic infection by an accidental wound, abscess is likely to form beneath the scalp, and if it is left to increase in size unchecked it may detach a large area of the scalp. As soon, there-fore, as it is thought that matter is forming beneath the scalp, an incision should be made down to the bone, and provision taken for insuring free drainage. Naevi of the scalp are best treated by electrolysis or by removal by dissection. If they are supplied by large blood-vessels, each artery should be under-pinned or tied before the removal by dissection is undertaken. Sebaceous cysts of the scalp should be removed by incision under the ether-spray whilst they are still small, the whole of the cyst- wall
malignant disease. (E. O.")End of Article: SCALP (0. Dutch schelpe, a shell) If you wish, you can link directly to this article.
<a href="http://jcsm.org/StudyCenter/Encyclopedia/SAR_SCY/SCALP_0_Dutch_schelpe_a_shell_.html"> SCALP (0. Dutch schelpe, a shell) </a> |
|
|
(Previous) SCALIGER |
(Next) SCALPING |
Jesus Christ Saves Ministries, P.O. Box 70696, Pasadena, CA 91117JCSM is a 501(c)(3), non-profit organization. Copyright © 1997-present. |
Free & Cheap Cell
Phones |
Cheap Long Distance
Phone Service Carriers |
Talk America Local Phone Service
|
Ztel & MCI - Unlimited Long Distance
Compare
Cell Phone Plans & Companies |
International Calling Cards & Prepaid Phone Cards |
Voice Over IP Broadband Internet Phone
Service | Wireless
Phone Plans & Cheap Cell Phones
|
_____________________________________________________________________________
