Calf, sheep, and goat were all commonly used, and other animals, including pig, deer, donkey, horse, or camel were used on occasion. However, in Europe, from Roman times, the word was used for the best quality of prepared skin, regardless of the animal from which the hide was obtained. The word "vellum" is borrowed from Old French vélin 'calfskin', derived in turn from the Latin word vitulinum 'made from calf'. Quran from the 7th century written on vellum It is used for a variety of purposes including tracing, technical drawings, plans and blueprints. Modern "paper vellum" is made of synthetic plant material, and gets its name from its similar usage and high quality. Scratching the surface with pumice, and treating with lime or chalk to make it suitable for writing or printing ink can create a final look. To create tension, the process goes back and forth between scraping, wetting and drying.
#The vellum skin
The making involves the cleaning, bleaching, stretching on a frame (a "herse"), and scraping of the skin with a crescent-shaped knife (a "lunarium" or " lunellum"). Vellum is generally smooth and durable, but there are great variations in its texture which are affected by the way it is made and the quality of the skin. Thus the term avoids the distinction between vellum and parchment.
It may be very hard to determine the animal species involved (let alone its age) without going to a laboratory depending on the way of making the paper. Modern scholars and experts use the general and potentially-confusing term "membrane" more often. Vellum is prepared for writing and printing on and used for single pages, scrolls, codices, or books. It is distinguished from parchment when it is made from calfskin, rather than that made from other animals, or having a higher quality when it is not. Vellum is prepared animal skin or membrane, typically used as writing material. The space between the two leaves of pia contains the posterior medial choroidal arteries 3.A vellum deed dated 1638, with pendent seal attached
If larger and exterting mass effect it is known as a cavum velum interpositum cyst. When somewhat distended by fluid it forms a small triangular (in axial section) space and is referred to as a cavum velum interpositum. It varies in shape from person to person, sometimes interposed between the internal cerebral veins and splenium, and depending on whether or not there is a cavum vergae (in which case the columns of the fornices are displaced inferiorly, narrowing the velum interpositum). Posteriorly: the narrow base of the triangle abuts the splenium of the corpus callosum 2 Inferiorly: the internal cerebral veins and tela choroidea of the third ventricle Superiorly: the body of the fornix and hippocampal commissure ( psalterium) reaching as far forward as the foramen of Monro In other words, the velum interpositum is like a room in a house and the choroid fissure is merely the threshold of the doorway into the room. Opening the choroidal fissure between the fornix and the thalamus will lead into the velum interpositum. The slit of the choroid fissure is where pia mater and ependyma are in direct contact with each other and evaginate into the lateral ventricles as choroid plexus 1. The concavity of the C shaped slit is contained by the thalamus (upper and posterior surfaces) and the tail of the caudate nucleus. The convexity of the C shape is contained by the body and crus (pillar) of the fornix, the fimbria and the hippocampus. It is important to understand that the choroidal fissure is merely a C-shaped slit in the medial wall of the cerebral hemisphere extending from the interventricular foramen of Monroe, to around the thalamus and cerebral peduncle as far as the uncus of the temporal lobe. The velum interpositum is often said to be the medial part of the choroidal fissure, but this is incorrect. The velum interpositum is formed by an invagination of pia mater forming a triangular membrane the apex of which points anteriorly.
The velum interpositum is a small membrane containing a potential space just above and anterior to the pineal gland which can become enlarged to form a cavum veli interpositi.
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