Graduated Cylinder

GRADUATED CYLINDER (from Latin mensura-measure, measurement), a vessel for measuring liquids, of conical or cylindrical shape with marked graduations. A special type of graduated cylinder represents medicine cups or drinking glasses with graduations showing (approximately) the contents of a teaspoon, dessert spoon, or tablespoon (5, 7¹/₂ and 15 cm³). Measurements with graduated cylinders are often imprecise due to their wide cross-section; deviations when measuring small amounts of liquid can reach up to ±40% (J. Gronberg).-Graduated cylinders are sometimes used to measure water by volume when preparing aqueous medicinal forms in the pharmacy. The graduated cylinder is also used for taking medicine orally. MENINGEAE ARTERIAE, VENAE. Aa. meningeae - arteries supplying the dura mater. The most powerful of them, a. meningea media, arises from a. maxillaris int. in the "second segment" (i.e., along the course between m. pterygoideus ext. and m. temporalis) and, immediately directing itself inward (along the inner surface of m. pteryg. ext.) and upward, reaches for. spinosum, through which it penetrates into the cranial cavity. Here it closely adjoins on one side the outer surface of durae matris, and on the other - the inner surface of the bone, leaving on it a trace in the form of sulcus meningeus. In the region of pterion and the lower angle of the parietal bone, this groove in 50% of cases passes into a bony canal, and thus the artery for some distance (1/₂-1 cm) is enclosed in bone. At a distance of 3-5 cm from for. spinosum a. meningea med. divides into branches: ram. anterior and ram. posterior. The anterior branch, more developed and constant in its course, curves upward with its convexity directed forward; the posterior branch goes backward and upward, in the direction toward sutura lambdoidea. Both branches anastomose abundantly with each other and with other arteries of dura, as well as with aa. frontalis, temporalis superficialis, occipitalis, lacrimalis, pharyngea ascendens and stylo-auricularis. For. spinosum is usually located behind for. ovale and thus the artery passes behind and at some distance from the third branch of the trigeminal nerve; however, in 1% of cases for. spinosum is located in front of for. ovale, resp. n. mandibularis, which must be kept in mind during operations on Gasser's ganglion.-Branches of a. mening. mediae: 1) ramus meningeus accessorius; arises before the artery enters the cranial cavity; it goes to mm. pteryg. and the Eustachian tube; more often this branch arises from a. maxillaris int.; 2) ramus petrosus superfic. and 3) a. tympanica superior. The first goes to hiatus canalis facialis, anastomosing there with a. stylo-mastoidea (from a. auricul. post.), the second penetrates into the tympanic cavity. A. meningea ant. arises from the anterior ethmoidal artery (a. ethmoidalis ant.) from a. ophthalmica (where the latter penetrates through for. ethmoid. ant.) and through the cribriform plate it goes forward.-A. meningea post. arises from a. pharyngea ascendens; it reaches the base of the skull together with a. carotis int., located outside of it, and penetrates into the cranial cavity through for. jugulare.-From the occipital artery (a. occipitalis) arises a. meningea post. externa, s. ramus mastoideus a. occipitalis, which penetrates into the cranial cavity through for. mastoideum and supplies the dura mater in the region of the posterior cranial fossa. Finally, from the vertebral artery arises a branch (ram. mening. a. vertebralis), which also supplies dura mater of the posterior cranial fossa and penetrates here through for. occipit. magn.-Variations mainly concern a. meningea media and show great diversity. Among them should be noted a. meningea parva (a branch of a. mening. mediae), which penetrates into the cranial cavity through a special opening located near for. spinosum; supplying dura mater, it gives branches to the soft coverings, penetrating through the suture and frontal fontanelle or for. mastoideum, anastomosing in the latter case with ram. post. a. tempor. superfic. and with branches of the occipital artery. Sometimes from the trunk of a. mening. med. arise a. tempor. post. prof. and a. pterygoidea, or from its anterior branch - an anastomosis or even the main trunk of a. ophthalmicae, which in these cases passes through fiss. orbitalis sup. The projection of the main trunk of a. mening. med. onto the external coverings is determined, according to Kronlein, by the intersection of the anterior vertical line with the lower horizontal line (see Eranio-cerebral topography); the anterior and posterior branches - by the intersection of the anterior and posterior vertical lines with the upper horizontal line. According to Vogt, the projection of the anterior branch is determined by the intersection of lines located at a distance of one transverse finger behind the frontal process of the zygomatic bone and two transverse fingers above the zygomatic arch. Injury to a. mening. mediae is one of the most common causes of intracranial hematoma formation. In this case, hemorrhages can accumulate: 1) only between the bone and dura (epidural hematoma), if only the artery is damaged, while the bone and dura are intact; 2) between the bone and the dura mater and under dura mater, if the latter is damaged while the bone remained intact; 3) between the periosteum and the bone and between the bone and the dura mater, if the bone is damaged while the skin coverings are not damaged (so-called two-layer hematomas). According to Kronlein, two main groups of hematomas are distinguished: haematoma diffusum and haematoma circumscriptum. The latter by localization are divided into: 1) haematoma anterius, s. fronto-temporale, 2) haematoma medium temporo-parietale and 3) haematoma posterius, s. parieto-occipitale. The second, resulting from injury to the trunk of a. mening. med., occurs in 75%, the anterior - in 10% and the posterior - in 15%. Injury to the artery in adults usually occurs when the skull is injured by some instrument, and it can occur either at the place where the artery enters the cranial cavity (for. spinosum) or in the region of the lower-anterior angle of the parietal bone, where sulcus meningeus turns into a canal, and when this canal is damaged, even with the apparent integrity of the skull box, the artery lying in the canal ruptures. In newborns, damage to the integrity of the artery can be the result of changes in the ratio of diameters of the head, exceeding the limits of elasticity, when the fetal head passes through the pelvic ring. The frequency of this cause is determined by the figures of the Zurich clinic of Wyder: out of 14,659 newborns, 1,277 died in the first eleven days, and of these 29 from epidural hematomas (2%).-Operative assistance consists of trepanation, ligation of the injured artery and removal of clots. In the absence of brain injury, the operation gives 70-80% recoveries. Ligation of the artery is performed when there is damage to the bone through the existing defect, expandable as needed; fragments are removed, clots are scooped out; when the bone is intact, a trepanation hole is made according to the principle of final or temporary resection at the site of the artery's projection. If the trunk of the artery is enclosed in a bony canal and thus application of a ligature is impossible, bleeding is stopped by driving pins, Krause hooks, paste or muscle tamponade into the canal. Meningeae venae - veins of the dura mater - are embedded in dura; on a section they gape and have no valves; they accompany (usually in double number) the corresponding arteries. The largest are vv. mening. mediae, and the anterior of them in almost half of cases is so significantly expressed that it bears the name sinus spheno-parietalis, s. alae parvae Brescheti. This vein lies near the artery only in the middle part, but above and below it is removed from it; it communicates with the longitudinal sinus, with a network of veins in the region of for. ovale and with plexus pterygoideus (through for. spinosum). In general, all veins communicate with each other, with neighboring sinuses and mainly with the superior sagittal.-Of pathological processes, thrombosis of v. mening. is most often observed (in meningitis, brain abscesses, etc.), often extending into the superior sagittal sinus.