THE STOMACH

The Stomach is the principal organ of digestion. It is the most dilated part of the alimentary canal, and is situated between the termination of the oosophagus and the commencement. of the small intestine. Its form is somewhat pyriform with the large end (fundus) directed upward and the small end bent to the right. It is situated in the left hypochondriac and epigastric regions, and is placed, in part, immediately behind the anterior wall of the abdomen and beneath the Diaphragm. Viewing the stomach from in front it appears that the right margin of the oosopha­gus is continued downward as the upper two-thirds of the lesser curvature of the stomach, the remaining third of this border bending sharply backward and to the right, to complete the smaller curvature .

  

Surfaces.With regard to the so-called anterior and posterior surfaces        of the stomach, it must be borne in mind that these names are not       strictly correct, as the anterior surface has a certain amount of        inclination upward and the posterior downward.

THE ABDOMEN

The Abdomen is the largest cavity in the body. It is of an oval form, the extremities of the oval being directed upward and downward: the upper one being formed by the under surface of the Diaphragm, the lower by the upper concave surface of the Levatores ani. In order to facilitate description, it is artificially divided into two parts: an upper and larger part, the abdomen proper; and a lower and smaller part, the pelvis. These two cavities are not separated from each other, but the limit between them is marked by the brim of the true pelvis. The space is wider above than below, and measures more in the vertical than in the transverse diameter. The abdomen proper differs from the other great cavities of the body in being bounded for the most part by muscles and fascire, so that it can vary in capacity and shape according to the condition of the viscera which it contains; but, in addition to this, the abdomen varies in form and extent with age and sex. In the adult male, with moderate distention of the viscera, it is oval or barrel-shaped, but at the same time flattened from before backward. In the adult female, with a fully developed pelvis, it is conical with the apex above, and in young children it

THE ORGANS OF DIGESTION

The muscles of the soft palate are five on each side: the Levator palati, Tensor palati, Azygos uvulm, Palato-glossus, and Palato-pharyngeus . The following is the relative position of these structures in a dissection of the soft palate from the posterior or nasal to the anterior 01' oral surface: Immediately beneath the nasal mucous membrane is a thin stratum of muscular fibres, the posterior fasciculus of the Palato-pharyngeus muscle, joining with its fellow of the opposite side in the middle line. Beneath this is the Azygos uvulm, consist­ing of two rounded fleshy fasciculi, placed side by side in the median line of the soft palate. Next comes the aponeurosis of the Levator palati, joining with the muscle of the opposite side in the middle line. Fourthly, the anterior fasciculus of the Palato-pharyngells, thicker than the posterior, and separating the Levator palati from the next muscle, the Tensor palati. This muscle terminates in a tendon which, after winding round the hamular process, expands into a broad aponeurosis in the soft palate, anterior to the other muscles which have been enumerated. Finally, we have a thin muscular stratum, the Palato-glossus muscle, placed in front of the aponeurosis of the Tensor palati, and separated from the oral mucous membrane by adenoid tissue. The Tonsils (amygdalce) are two prominent bodies situated one on each side of the fauces, between the anterior and posterior pillars of the soft palate. They are of a rounded form, and vary considerably in size in different individuals. A recess, the fossa supra-tonsillaris, may be seen, directed upward and backward above the tonsil. His regards this as the remains of the lower part of the second visceral cleft. It is covered by a fold of mucous membrane termed the plica triangularis. Externally the tonsil is in relation with the inner surface of the Superior constrictor, to the outer side of which is the Internal pterygoid muscle. The internal carotid artery lies behind and to the outer side of the tonsil, and nearly an inch  distant from it. It corresponds to the angle of the lower jaw. Its inner surface presents from twelve to fifteen orifices, leading into small recesses, from which numerous follicles branch out into the substance of the gland. These follicles are lined by a continuation of the mucous membrane of the pharynx, covered with epithelium; around each follicle is a layer of closed cap­sules imbedded in the submucous tissue. These capsules are analogous to those of Peyer's glands, consisting of adenoid tissue. No openings from the capsules into the follicles can be recognized. They contain a thick grayish secretion. Sur­rounding each follicle is a close plexus of lymphatic vessels. From these plexuses the lymphatic vessels pass to the deep cervical giands in the upper part of the neck, which frequently become enlarged in affections of these organs.

THE EYES

                         

 

These two Iaminee are connected by an intermediate stratum; which is      destitute of pigment-cells and consists of fine elastic fibres. On the inner surface of the lamina chorio-capillaris is a very thin, structureless, or, according to Kolliker, faintly fibrous membrane, called the lamina basalis or membrane of Bruch; it is closely connected with the stroma of the choroid, and separates it from the pigmentary laver of the retina . • Tapetum.-This name is applied to the iridescent appearance which is seen in the outer and posterior part of the choroid of many animals. The ciliary body should now be examined. It may be exposed, either by detaching the iris from its connection with the Ciliary muscle, or by making a transverse section of the globe, and examining it from behind. The ciliary body comprises the orbiculus ciliaris, the ciliary processes, and the Ciliary muscle. The orbiculus ciliaris is a zone of about one-sixth of an inch in width, directly continuous with the anterior part of the choroid; it presents numerous ridges arranged in a radial manner. The ciliary processes are formed by the plaiting and folding inward of the various layers of the choroid-i. e., the choroid proper and the lamina basalis-at its anterior margin, and are received between corresponding foldings of the suspensory ligament of the lens, thus establishing a connection between the choroid and inner tunic of the eye. They are arranged in a circle, and form a sort of plaited frill behind the iris, round the margin of the lens. They vary between sixty and eighty in number, lie side by side, and may be divided into large and small j , the latter, consisting of about one-third of the .entire number, are situated in the spaces