Branchial sac

“ They give rise to forms with a very different organization to that of the parent. They are compared by Gegenbaur to a spoon, the bowl of which is formed by the branchial sack, and the handle by the stalk attaching the bud to the stolon. The oral opening into the branchial sack is directed upwards: an atrial opening is remarkably enough not present. The branchial sack is perforated by numerous openings. It leads into an alimentary tract which opens directly to the exterior by an anus opposite the mouth. ”

“ The structure of the dorsal spines is similar. There are no secretory glands imbedded in the membranes of the sacs and the fluid must be secreted by their mucous membrane. The sacs are without an external muscular layer and situated immediately below the thick, loose skin which envelops the spines at their extremity. The ejection of the poison into a living animal, therefore, can only be effected as in Synanceia, by the pressure to which the sac is subjected the moment the spine enters another body. ”

“ In anatomy the term is used to denote a cover or envelope partly or wholly surrounding a structure. Every diarthrodial joint possesses a fibrous or ligamentous capsule, lined with synovial membrane, attached to the adjacent ends of the articulating bones. The term is particularly applied to the sac which encloses the crystalline lens of the eye; to Glisson’s capsule, a thin areolar coat of fibrous tissue lying inside the tunica serosa of the liver ”

“ If the sac contains bowel and omentum, it is safer to open it over the omentum than over the bowel. When a small opening is made, an escape of the contained fluid takes place, and then the sac should be slit up as far as its neck by a probe-pointed bistoury, guided by the finger, introduced to protect the bowel, whenever the opening is sufficiently large. The forefinger must now be cautiously insinuated into the neck of the sac, the nail being directed to the bowel, the pulp to the crescentic margin of Gimbernat's ligament, and any constriction very cautiously divided. ”

“ Some are rounded sacs, species of bladders; such are those upon the supra-spinatus, the psoas, iliacus, obturator internus, &c. All these membranes are remarkable for this, that they never cover the tendon entirely, but only on one side; that they never form internal folds and that they are never surrounded by fibrous sheaths. 2d. The others, belonging especially to the flexors, and to the different tendons which traverse the sole of the foot, form at first a kind of cylindrical sac which lines the canal half fibrous, half cartilaginous in which the tendon slips ”

“ This organization is cellular, as is proved by dissection, inflation and especially maceration. The sac which the ganglions form is evidently only a production of the cellular organ; now it is known that this sac exhales and contains a fluid similar to the synovia. Wherever the synovial membrane is free, it is attached externally to this organ and is confounded with it in so direct a manner, that by raising successively its different layers they are seen to be gradually condensed and finally united together to form it. So that in the serous membranes no fibre is visible. ”

“ All the organs of the abdominal cavity are outside the sac. In the course of their development these organs have encroached on the peritoneal sac. Each has grown against the outer wall of the sac to a greater or less extent and has forced a part of this wall ahead of it into the cavity. In some cases the encroachment has gone so far that the organ in question lies apparently within the peritoneal cavity, suspended from the wall of the sac by a fold of that wall. ”

“ The sac was exposed and carefully dissected free from its surrounding tissues, and upon examination was found to be continuous with the covering of the testacle (giving the appearance of a congenital hernia) . The sac was next opened and found to contain small intestines and a Meckel's diverticulum. Following this the intestines were replaced in the abdominal cavity. Digital examination through the internal ring showed the bladder to be adherent to the peritoneum at the margin and toward the median line. The sac was tied close to the internal ring, cut free. ”

“ They are best developed in those birds which fly most. There are four pairs of cells and one single cell from which all other expansions and extensions are made. These sacs are as follows: a single anterior thoracic, and, in pairs, cervical, anterior diaphragmatic, posterior diaphragmatic, and abdominal.
The Anterior Thoracic Air-sac.—The anterior thoracic air-sac is located above the clavicles and the interclavicular space, in the cavity of the thorax. It is related superiorly with the trachea and the esophagus; laterally with the lungs and the cervical air-sacs ”

“ If the rupture is large, a single linear, or a T-shaped incision, exposing the base of the tumour, will be sufficient to allow the requisite dilatation of the opening to be made. It is not at all necessary in every case to open the sac of the peritoneum. If required, it must be done with great caution, as the sac is generally very thin. In cases where the hernia is chiefly omental, the sac should be opened, lest a knuckle of bowel be inclosed and strangulated in the omentum. ”

“ The sac is completely closed, so that no communication exists between the serous cavity and the parts in its neighborhood. The various serous membranes are the pleura which envelops the lungs; the pericardium which surrounds the heart; the peritoneum which invests the viscera of the abdomen, and the arachnoid in the spinal canal and cranial cavity. In health the serous membranes secrete only sufficient fluid to lubricate and keep soft and smooth the opposing surfaces. ”

“ Every serous membrane represents a sac without an opening, spread upon the respective organs that it embraces, and which are sometimes very numerous, as in the case of the peritoneum, sometimes single, as in the case of the pericardium, covering these organs so that they are not contained in its cavity, and so that if it was possible to dissect them from their surface, we should have this cavity whole. ”

“ When all of the spinal nerves are cut, the scalpel is introduced in the spinal canal upward, as near to the foramen magnum as possible, and the cord and dura are cut transversely. The cord should be held by the dura; direct pressure with forceps or fingers upon the soft substance of the cord should never be made. If the forceps cannot be used to hold the dura with advantage, then the cord enclosed in the dural sac may be gently but firmly held in the palm of the left hand and lifted and drawn downward towards the sacrum with the greatest care. ”

“ Each of these appendages possesses its own mixed nerve, glossopharyngeal or vagus, its own cartilage, its own set of visceral muscles, its own sense-organs, just as do the respiratory appendages of Limulus.
The branchial unit in the vertebrate is not the gill-pouch, but the branchial bar or appendage between the pouches. Embryology shows how each such appendage grows inwards, how a cœlomic cavity is formed in it, similarly to the ingrowing of the branchial appendage in scorpions. ”

“ A series of sacs lined with an epithelium, the proliferation of which gives rise to the ova or spermatozoa, alternate between the caeca of the intestine. When mature, each sac pushes out a process to the exterior, and this forms the genital duct. The line of the genital openings is usually dorsal to the lateral nerve. The whole sac, with its epithelial wall and its contained genital cells, arises ultimately from some of the parenchymatous cells of the body. ”

“ By the hypodermic method of treating mucous sacs some escharotic is employed with the object of causing the absorption of the sacculated mucosa. The object to be accomplished ought to determine the proper strength of any escharotic used. Whatever will absorb the mucous membrane involved in the sac in the slowest and mildest manner is the best remedy or the best way to employ any of the tissue absorbers you might select. ”

“ When the operation has been performed thus far with perfect skill and success, the most opposite measures are required according to the actual state of the organs contained in the sac. If they are agglutinated together—if portions of them are in a state of mortification, to return them into the cavity of the abdomen in that condition would in general be certain death. Preternatural adhesion must be removed ”

“ And in a little recess in the sac there is, occupying its floor, its front wall, and part of its outer wall, a patch of hair-cells covered by a gelatinous material with numerous small crystalline otoliths. The only other point that calls for notice is that the membranous sac does not fit closely in the bony cavity in which it lies, while the diameter of the membranous semicircular canals is considerably less than that of their bony tunnels, except at the ampullæ, or swellings, where they fit pretty closely. ”

“ When a hernia occurs under either of these circumstances, it will be found deprived of a sac.
All the blood vessels and nerves of the abdomen lie external to the peritonaeum. Those vessels which traverse the abdomen on their way to the external organs course outside the peritonaeum; and at the places where they enter the abdominal parietes, the membrane is reflected from them. This disposition of the peritonaeum in respect to the spermatic and iliac vessels is exhibited in Plate 32. ”

“ They all assume the ordinary cell character, with outer and inner sac,—the inner sac forming on the side, like the Purkinjean vesicle itself; but it does not retain this position, for, as soon as its wall is formed and it becomes a distinct body, it floats away from the side and takes its place in the centre. Next there arise within it a number of little bodies crystalline in form, and which actually are wax or oil crystals. They increase with great rapidity, the inner sac or mesoblast becoming sometimes so crowded with them, that its shape is affected by the protrusion of their angles. ”

“ Cases are on record of perforation of the sac with a knife,35 and through the oesophagus by means of a sword swallowed by a juggler.36 Sometimes the perforations communicate with organs that contain gas, as the stomach or intestine or the oesophagus. Graves has recorded a case in connection with abscess of the liver. When the pericardial sac is intact, the distending gas may arise from decomposing fluid in the pericardium: it is supposed that it may even be secreted by the blood of the coronary vessels. Pure air, such as we breathe, is never developed in the sac. ”

“ These filaments becoming conjoined present themselves as a membranous and gelatinous tunic or empty sac. Even as the plexus choroides is extended through the ventricles of the brain, is this oblong sac produced through the whole of either horn and the intervening cavity of the uterus, insinuating itself between the wrinkles of the flabby internal tunic, and sending delicate fibres among the aforementioned rounded protuberances, being nearly in the same manner as the pin mater dips between the convolutions of the brain. ”

“ These capsules form a kind of cylindrical sac open at the two extremities, attached by the circumference of its openings, around the superior and inferior articular surfaces, intermixing at its insertion with the periosteum. They are so much the more loose, as the motions of the articulations are the more extended; that of the humerus, for example, allows a much greater separation of the osseous articular surfaces, than that of the femur ”

“ As the space which the femoral arch spans external to the vessels is fully occupied by the psoas and iliacus muscles, and, moreover, as the abdominal fibrous membrane and its prolongation, the femoral sheath, closely embrace the vessels on their outer anterior and posterior sides, whilst on their inner side the membrane and sheath are removed at a considerable interval from the vessels, it is through this interval (the canal) that the hernia may more readily pass. The peritonaeum, 2, and crural septum, 13, form at this place the only barrier against the protrusion of the bowel into the canal. ”

“ The glands enclose no cavity, and there is no duct, so that whatever poisonous fluid their cells secrete is probably set free by the rupture of the cells and discharged into the grooves, along which it passes to the point of the spine, somewhat after the fashion of a hypodermic syringe. The origin of the gland-cells from an in-pushing of the epidermis is indicated by the continuity of the two structures near the point of the spine. Both in structure and in their relation to poison-glands each of the spines of the {177}dorsal fin is almost precisely similar to the opercular spine. ”

“ Lining the interior of the capsule, and all other parts of the joint cavity except where the articular cartilage is present, is the synovial membrane (fig. 4, dotted line) ; this is a layer of endothelial cells which secrete the synovial fluid to lubricate the interior of the joint by means of a small percentage of mucin, albumin and fatty matter which it contains.
A compound diarthrodial joint is one in which the joint cavity is divided partly or wholly into two by a meniscus or interarticular fibro-cartilage (fig. 5, Fc) . ”