RETINACULUM 



the morbid condition caused by an effusion of liquid 

 between the retina and the choroid. R., De- 

 tachment of, disconnection from the choroid. R., 

 Epilepsy of, a symptom of migraine or of epilepsy, 

 characterized by transient loss of sight. R., Fovea 

 centralis of. See Fovea. R., Leopard or Tiger, 



1259 



RETINITIS 



i, i. Layer of 

 rods and cones, 

 a. Rods. 3 

 Cones. 4, 4- 

 Membrana limi- 

 tans externa, s, 

 5. Outer and in- 

 ner granular 

 layers. 6. Outer 

 granular layer. 

 7. Inter-granular 

 c . Inner 

 granular layer. 

 9. Layer of gray 

 matter. 10. Gran- 

 ular portion of 

 this layer. 11. 

 Cellular portion. 

 Fibrous 

 layer. :3. Mem- 

 brana limitans 

 interna. 14, 14. 

 Radiating fibers 

 inserted into this 

 membrane. 



E 



Vertical Section of the Retina. 



the appearance of the retina in chronic retinitis pig- 

 enlosa. R.. Limbus luteus of. See Macula 

 'en. R., Membrana limitans of. See Mem- 

 ana limitans. R.. Pulsation of. See Pulsation. 

 R.. Shot-silk Appearance of. See Reflex, Watered- 

 silk. R., Sustentacular Fibers of. See Fibers 

 "tiler. 

 Retinaculum {ret - in - ak'- u - lum) \retinere, to hold 

 back: //., Retinacula']. 1. A term applied to such 

 bands or membranes as hold back an organ or part, as 

 the Retinaculum of the ileo-cecal valve. 2. An instru- 

 ment at one time used in operations for hernia. 3. In 

 biology: 1(7) That viscid, discoid portion of the rostellum 

 of an orchid which holds the pollen masses in place and 

 is removed with them by a visiting insect ; it is also 

 called proscolla, and viscid disc ; (/>) the hardened, 

 uncinate funiculus of the seeds of many of the Acantha- 

 the little plate or scale which in certain in- 

 sects restrains the protrusion of the sting. Retinae - 

 ula of Barry, tense filaments running from the 

 thickened portion of the cellular membrane lining the 

 Graafian follicle to other parts of the membrane. R. 

 costae ultimatae. Same as Lumbocostal Ligament, 

 o. v. Retinacula cutis, fibrous bands connecting the 

 corium with the underlying fascia. R. ligamenti 

 arcuati. the short external lateral ligaments of the 

 knee-joint, q. v. Retinacula morgagni, or Retinac- 

 ula of the Ileo-cecal Valve, the membranous ridge 

 formed by the coming together of the valve-segments 

 at each end of the opening between the cecum and the 



ileum. Retinacula ossis brachii, fibrous bands in- 

 serted into the neck of the humerus and having their 

 origin in the capsule of the humero-scapular articula- 

 tion. R. patellae externum, the lateral, patellar 

 ligaments. R. patellae internum, the ligamentum 

 patellae mediale. Retinacula patellae, laterale et 

 mediale. See Lateral Patellar Ligaments. R. 

 peroneorum inferius, a fibrous band running over 

 the peroneal tendons as they pass through the grooves 

 on the outer side of the calcaneum. R. peroneorum 

 superius, R. tendinum peroneorum. See Liga- 

 ment, Extreme Angular {of Ankle). Retinacula val- 

 vulae. See Retinacula morgagni. R. of Weit- 

 bricht, bands of ligamentous tissue situated on the 

 neck of the trochanter of the femur. 



Retinal {ret'-in-al) \retinalis ; rete, a network]. Per- 

 taining to the retina. R. Apoplexy, hemorrhage into 

 the retina. R. Horizon, a term used by Helmholtz 

 to describe the horizontal plane passing through the 

 transverse axis of the eyeball. R. Image, the image 

 of external objects as reflected on the retina. R. 

 Ischemia, anemia of the retina. R. Melanin. See 

 Fuscin. R. Purple. Same as Rhodopsin. 



Retinerved {re'-tin-ervd) [rete, net; nervus, nerve]. 

 In biology, reticulate ; netted- veined. 



Retinitis (ret-in-i'-tis) [retina, retina ; trie, inflamma- 

 tion]. Inflammation of the retina, classed, according 

 to its etiology, into albuminuric, diabetic, leukemic, 

 pigmentary (R. pigmentosa), syphilitic, etc., most of 

 which are characterized by distinctive ophthalmoscopic 

 appearances. R. albuminurica, the form due to 

 nephritis, usually chronic. Numerous white spots 

 may be seen scattered over the fundus, some having 

 an irregular outline, while others are stellated. 

 There are also spots of hemorrhagic extravasation. 

 R., Central Punctate, a form seen most in the 

 aged. A great number of striae or white spots are 

 visible in the fundus. R., Central Relapsing, a 

 form of syphilitic retinitis in which there is a gray 

 or yellow area in the macular region, or numerous 

 small yellowish-white spots and pigment-dots. It is 

 a rare form, and is inclined to relapse. R. cere- 

 bralis, retinitis due to intracranial inflammation. 

 R., Choroido-, a form of syphilitic retinitis with 

 cellular infiltration, exudation, atrophy, and prolifera- 

 tion of the pigment-epithelium in the choroid, be- 

 tween the choroid and retina, and in the retinal layers. 

 R. circumpapillaris, a form in which there is 

 proliferation of the outer layers of the retina around 

 the disc. R., Diabetic, the form of retinitis occur- 

 ring in diabetes. R., Diffuse. See R. serosa. R., 

 Diffuse Parenchymatous, the parenchymatous 

 form affecting the limitans, the externa, the in- 

 terna, and the adventitia. R. exsudativa, retinitis 

 with parenchymatous exudation. R., Glycosuric. 

 Same as R., Diabetic, q. v. R. gravidarum, a form 

 occurring in pregnant women and which is similar to 

 retinitis albuminurica, and is of grave prognostic im- 

 port. R. haemorrhagica, a form in which there 

 is swelling of the papilla and opaque infiltration of 

 the surrounding retina ; there are distended, dark, and 

 tortuous veins, and the arteries are small ; there are 

 hemorrhages, linear or irregular and round in appear- 

 ance. R. hepatica, a rare form which sometimes 

 occurs in cases of parenchymatous hepatitis. R. 

 leukaemica, a form characterized by pallor of the 

 retinal vessels and optic disc, the boundary of the 

 latter being indistinct. Hemorrhages appear at vari 

 ous points of the membrane, while numerous white 

 patches and round bodies are visible about the disc in 

 the retina. It is a result of systemic anemia. R. 

 macularis. Same as R., Central Relapsing, q. v. 





