|
FIBRES may be medullated or non-medullated, but, whichever they
are, they consist of the See also: long See also:process or axon of a See also:nerve See also:cell; in a
non-medullated nerve this process is either naked or enclosed in a
delicate membrane called the See also:primitive sheath or neurilemma, but in
a medullated nerve the process or See also:axis See also:cylinder is encased by a See also:- WHITE
- WHITE, ANDREW DICKSON (1832– )
- WHITE, GILBERT (1720–1793)
- WHITE, HENRY KIRKE (1785-1806)
- WHITE, HUGH LAWSON (1773-1840)
- WHITE, JOSEPH BLANCO (1775-1841)
- WHITE, RICHARD GRANT (1822-1885)
- WHITE, ROBERT (1645-1704)
- WHITE, SIR GEORGE STUART (1835– )
- WHITE, SIR THOMAS (1492-1567)
- WHITE, SIR WILLIAM ARTHUR (1824--1891)
- WHITE, SIR WILLIAM HENRY (1845– )
- WHITE, THOMAS (1628-1698)
- WHITE, THOMAS (c. 1550-1624)
white
fatty substance called myelin, and so the See also:term " myelinated " is
often used instead of " medullated " for these nerves (see fig. 1).
Axis Outside this white sheath the neurilemma is
cylinder See also:present in most nerves, but is lost when they are massed to See also:form the white See also:matter of the central See also:nervous See also:system and in the optic nerve.
Myelin At See also:regular intervals the myelin is interrupted by some substance which stains deeply with See also:silver nitrate, and these breaks are known as nodes of Ranvier. They do not, however, affect the axis cylinder. In a large nerve, such as the median, the nerve fibres are collected into small
Primitive bundles called funiculi, enclosed in a connective
sheath See also:tissue sheath, the perineurium, and separated from it by a See also:lymph space. From this sheath delicate processes penetrate among the fibres, and these are known as the endoneurium. The funiculi are collected into bundles called fascicuti, and the whole nerve consists of a variable number of fasciculi surrounded by a dense fibrous sheath, the epineurium. The various bundles do not remain distinct, but break up and re-arrange themselves, so that following them up with the scalpel is a difficult and tedious See also:work. The nerve fibres, however, never join one another and are often several feet in length.
End of Article: FIBRES
Additional information and Comments
There are no comments yet for this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.
Links to articles and home page are always encouraged.
|
del.icio.us it!