MUCOS^E. 



469 



1. Structure. The opinion of Haller, that 

 these membranes are ultimately composed of 

 cellular substance, though controverted by 

 Monro and others, is, however, now universally 

 admitted. They are, in fact, like all synovial 

 membranes, essentially composed of cellular 

 substance, entirely destitute of fibre, scantily 

 supplied with vessels, and remarkable for their 

 softness and flexibility. The vaginal bursas 

 are, however, much more delicate than the 

 vesicular. The fatty bundles, mistaken by 

 Havers for glands, are frequently found in their 

 substance. Rosenmuller speaks of distinct 

 synovial follicles as likewise demonstrable, but 

 the existence of any such bodies appears to us 

 more than doubtful. 



2. Contents. Experiments have been made 

 by Monro and others, to shew that the fluid 

 contained in bursae is similar to that contained 

 in synovial membranes. These, however, may 

 now be looked upon as superfluous, inasmuch as 

 this question has merged in the general one, viz , 

 the identity of the two structures. Chemistry, 

 in fact, has proved that their fluid and that of 

 synovial membranes are, if not completely, at 

 least essentially the same. In the subcutaneous 

 bursae it is scanty and thin; in the larger and 

 deeper ones it is said to be somewhat more 

 viscid. 



3. Function. The use of bursae is in all 

 cases the same; they serve to isolate certain 

 parts and facilitate the motions performed by 

 them : hence they are found only in those 

 situations which are the seat of motion. Their 

 fluid, from its oily consistence, must of course 

 tend considerably to diminish the effects of fric- 

 tion. 



4. Development. Bursse are developed at a 

 very early period, and are relatively more 

 pliant and perfect in the child than in the 

 adult, to facilitate, as it would appear, the 

 almost incessant movements natural to that 

 period of life. They become more dense and 

 unyielding in the adult, and in extreme old age 

 are said to become dry and rigid. This, no 

 doubt, is amongst the causes which render the 

 movements of old age slow and laboured. A 

 curious fact connected with this subject is the 

 accidental development of bursae in cases where 

 their presence becomes necessary. When the 

 superficial bursa in front of the patella has 

 been removed by operation, its place is ulti- 

 mately supplied, as Sir Benjamin Brodie has 

 seen, by a newly formed one, similar in every 

 respect to the original sac. In cases of club- 

 foot a large subcutaneous bursa has been found 

 developed upon that portion of the swelling 

 which has been the chief seat of pressure and 

 motion : and in cases of diseased spine, at- 

 tended with considerable angular curvature, a 

 bursa has become developed between the pro- 

 jecting spinous process and the skin. 



PATHOLOGICAL CONDITIONS OF BURS/E MU- 

 cos.. Bursae mucosae, superficial as well as 

 deep, are not unfrequently the seat of inflamma- 

 tion, resulting either from external causes, such 

 as cold or local injury, or from constitutional 

 causes. In the majority of cases inflammation in 

 these structures assumes a chronic form, and its 



ordinary effects are either to increase the quan- 

 tity of the synovial fluid, to determine the 

 effusion of a turbid serum loaded with flakes of 

 lymph, or to end in the formation of matter. 



The general phenomena of bursal inflamma- 

 tion may be studied with most advantage in the 

 large subcutaneous bursa in front of the knee- 

 joint : it is more frequently inflamed than any 

 other in the system. This, however, is not 

 owing to any peculiarity of structure predis- 

 posing it to disease, but merely to the accidental 

 circumstance of its situation, which exposes 

 it more than any other to external injury. In 

 those persons who continue for a long time 

 in the kneeling attitude, in devotional exer- 

 cises for example, and still more remarkably 

 in those whose occupation obliges them not 

 only to support the body but also to move 

 upon the knees (as carpenters, housemaids, 

 and others), inflammation of this bursa is very 

 frequently met with. In many instances it 

 occasions little general or local disturbance, 

 merely causing an increased effusion of the 

 proper synovial secretion, without producing 

 any change whatever in its natural properties. 

 In other cases the fluid is not only increased 

 in quantity, but becomes changed likewise in 

 quality ; it assumes the appearance of a turbid 

 serum, with numerous flakes of lymph floating 

 in it; or where the disease has been of long 

 standing, the fluid is frequently found loaded 

 with a number of loose bodies, almost of the 

 consistence of cartilage, and of a flattened oval 

 form. Sir Benjamin Brodie compares their 

 appearance not inaptly to that of melon-seeds, 

 and he considers them as portions of lymph 

 originally of an irregular shape, but which, by 

 the motions and pressure of the surrounding 

 parts, have had their angles worn off, and 

 assumed by degrees a firm consistence. They 

 have been found likewise in the smaller burso?. 

 Monro has seen upwards of fifty extracted from 

 the small bursa of the flexor pollicis longus 

 tendon, where, by excessively distending the 

 surrounding parts, they had produced severe 

 pain. When the great vaginal bursae of the 

 flexor tendons have become the seat of effusion, 

 a very remarkable appearance may present itself, 

 at once explicable, however, by referring to the 

 anatomy of the part. The fluid can by pressure 

 be forced downwards under the annular liga- 

 ment, and into the palm of the hand, and thence 

 upwards again into the forearm. Some authors 

 have deemed it proper to designate by a par- 

 ticular name this termination of the disease by 

 effusion, and the words thygroma and ganglion 

 have been applied with a good deal of con- 

 fusion by different persons; but it appears to 

 us that there exists no necessity for a specific 

 name to refer to this accidental mode in which 

 inflammation terminates. 



A much more important termination of the 

 disease is that in which, owing to local or con- 

 stitutional causes above alluded to, the inflam- 

 mation, having run a severer course, ends in 

 suppuration. Sir Benjamin Brodie has in this 

 case observed that the matter may take either 

 of two courses : it may come directly to the 

 surface ; or, without pointing forwards, it may 



