ANATOMY.

15A

A Gland is a small round or oval body, chiefly composed of aconvolution of one or more arteries of a considerable length, fromwhose sides arise a vast number of excretory ducts. But thoughthe larger secretions are made by visible glands, yet tmconvolvedarteries may al-o have excretory ducts for the same purpose. Inthis wav, probably, secretions are marie from all the membranesthat line cavities, as well as in some other instances. There alsoarise lrom the arteries, which enter into the-composition of agland, lymphatic vessels, whose use seems to be that of taking offthe thinner parts of the blood, in those cases w here a thick fluidis to be secreted. For lymphatics are to be found in the greatestplenty,- in such glands as separate the thickest fluids; as in thetesticles and liver; and it is observable, that where the thickestsecretions are made, the velocity of the blood is the least, as ifnature intended to give those seemingly more tenacious parts moretime to be separated from the blood. The use of glands is toseparate particular humour-; from the mass of blood. They areusually divided into two classes; but it seems more proper todistinguish three kinds of glands, viz. the mucous, conglobate, andconglomerate.

The Mucous Glands, or Follicles, are small cylindricaltubes continued from the end of the arteries. In some parts of thebody, as in the tonsils, for example, several of these follicles may-be seen folded together in one common covering, and openinginto one common sinus. These follicles are the vessels that se-crete and pour out mucus in the mouth, oesophagus, stomach,intestines, and other parts of the body.

The Conglobate Glands are peculiar to the lymphatic sys-tem. Every lymphatic vein passes through a gland of this kindin its wav to the thoracic duct. They are met with in differentparts of the body, particularly in the axiila, groin, and mesentery,and are either solitary, or in distinct clusters.

The Conglomerate Glands are of much greater hulk thanthe conglobate, and seem to be an assemblage of many smallerglands. Of ibis kind are the liver, kidnies, &c. Some of them,as the pancreas, parotids, Ac. have a granulated appearance. Allthese conglomerate glands are plentifully supplied with blood-ves-sels ; but their nerves are in general very minute, and few in number.

The Salivai. Glands may be thus enumerated : Glandula ;parotides, maxillares, sublinguales, molares, buccales, labiates,linguales, amygdala*, glandula: palatina’, uvulares, arytenoidaxc.and glandula thyroidira.

The Parotid Glands are two large, whitish glands, irregularlyoblong and protuberant, situated on each side, between the ex-ternal ear and the posterior or ascending ramus of the lower jaw,and lying 6n some part of the neighbouring masseter muscle. Thesuperior portion of this gland lies before the cartilaginous meatusof the ear, and touches the apophysis zygomatica of the os tem-poris; extending forward and backward under the lobe of the ear,as far as the mastoid apophysis. From the anterior and superiorportion of this gland, a duct runs obliquely forward on the outsideof the masseter; and then perforates the buccinator, opposite tothe intersticebetween the second and third dentes molares.

The Maxillary Glands are smaller and rounder than theparotids ; and are situated each on the inside of the angle of tiielover jaw, near the muscuius pterygoida-us inferior.

The Glandul/e Sublinguales are likewise two in number,of the same kind with the former, only smaller, something oblong,and flatted like a blanched almond. They are situated under theanterior portion of the tongue, one on each side, and send outlaterally several short ducts which open near the gums, at a smalldistance from the fra-num.

The Glandulve Molares are two glands nearly of the samekind with the former, each being situated between the masseterand buccinator.

The Glandul/e Linguales are those of the foramen ci-cumof the basis of the tongue.

The Uv ular Glands are only a continuation of the membraneof the palate, in the form of a small bunch of grapes.

Tlie Amygdala; are two glandular bodies of a reddish colour,lying in the interstices between the two lateral half arches of theseptum palati, one on the right, the other on the left side of thebasis of the tongue. They somew hat resemble an almond shell,in having an uneven surface, and in being full of little holes,through which their secretions are evacuated, whence they have/Obtained the English uayie of almonds.

The Glandula Thyroid/ea is a large reddish mass, coveringthe anterior convex side of file larynx. It seems to be made upof two oblong glandular portions united by their inferior extremi-ties, below the cricoid cartilage, in such a manner as to have semeresemblance to a crescent, with the cornua turned upward. Thesecond lateral portions lie on the musculi thyroidal, and the mid-dle or inferior portion on the crico-thyroida-i.

The Thymus is a conglobulate gland , the use of which is notperfectly ascertained, its excretory duct not having yet been dis-covered. It is of an oblong figure, and is larger in the fa-tus andin young children than in adults, being sometimes neariy el facedin very old subjects. It is placed in the upper part of the thorax,between the two lamina; of the mediastinum ; but at first is not al-together contained within the cavity o. lire chest, being found toborder upon the upper extremity of the sternum.

There are many glands, called Bronchial, at the root of thelungs, where the large blood-vessels enter. Tlu-y generally areof a blackish colour in the human subject, and have been sus-pected to secrete the mucus which is spit up from the trachea; butiateranatomists having frequently distinctly filled them with mer-cury, by injecting the lymphatic vessels of the lungs, think itevident that they are not mucous, but lymphatic glands.

The Absorbents of the Heart, which have been knownonly by the latest anatomists, come from its superficial and deepparts. 'I liese afterwards form principal trunks which accompanythe coronary arteries and veins, and like them the largest belongto the left ventricle. From the side of the right coronary artery,an absorbent passes over the arch of the aorta, to a gland com-monly found behind the origin of the carotid arteries. Thelymphatic, accompanying the left coronary artery, is funned oftwo principal branches; one of which runs up in the groove be-tween tlie ventricles, and on the superior surface of the heart;the other runs in a corresponding groove on the under side of theheart; and having reached the space between the auricles andventricles, turns round to join tlu; former branch near the originof its corresponding artery. Frequently, there are a considerablenumber on its sides, and upon the lumbar vertebra;.

There are also lymphatic glands over the trunks of blood-vesSelsof the spleen, liver, kidnies, and renal capsulx, which belongto the lymphatic vessels of these organs. In the thorax, a lew-glands are found on the fore-part of the pericardium, and uppersurface of tlie diaphragm, belonging to the liver or diaphragm.Others are situated between the lamina; of the anterior portion ofthe mediastinum. Lymphatic glands are sometimes observed bythe sides of tlie thoracic duct, particularly about the middle of thethorax; which belong principally to the Vessels of the lungs.

'Flu-re are likewise many bronclflal lymphatic glands, near theroot of the lungs: these glands are placed upon the lymphatic ves-sels, where they quit the lungs. But no lymphatic glands haveyet been observed in tlie substance of tlie lungs; and the tubercles,which some suspect to be obstructed lymphatic glands, seem tohave a different origin. There are likewise some glands seen onthe lymphatic vessels, which lie near the subclavian veins at the>er part of the thorax, and which belong to tlie lungs,lesides these, there are some lymphatic glands U|um the aorta,near the oesophagus ; and there are also others occasionally metwith in the intercostal spaces. There are generally two or threecontiguous to the thoracic duct, at the lower part of the neckand upper part of the thorax, near tlie termination of that duct,in the angle between the left jugular and the left subclavian vein;and a few are found over tlie internal mammary vessels w here theabsorbents of the liver pass up within the thorax.

V. NEUROLOGY ;

Or, Doctrine of the Nerves.

. The Nerves are soft, white, and fibrous c hords, nearly of acylindrical shape, arising from the brain, or medulla spinalis, andterminating in the organs of sense, vessels, viscera, muscles,bones, Ac.

The Brain, which is the origin of the nerves is a soft andsomew hat white substance , situated in the cavity of the skull, andcorresponding in form to that cavity. It is divided into three par-ticular portions; the cerebrum, or brain properly so called, tliecerebellum, and medulla oblongata, and the medulla spinalisbeing a continuation of the medulla oblongata.

Tlie Integuments of tlie brain are two membranes, calleddura mater and pia mater. The first is very strong, and lies con-tiguous