(seq. 129)

60 Lect 5

because such Cavities in the Fibres could not be
found; & it would upon Contraction greatly increase the
Bulk of the Muscle, which is not the Case. We should rather
attribute the Power of Motion to the Elasticity ^Irritability of the fibres.
There are in the Muscles, Interstices to receive Arteries, Veins
& Nerves. These Arteries carry Blood to nourish the Muscles
& ^{as well as} to give it it's red Appearance. A Tendon is an Appendage to
a Muscle ^{Some suppose it a direct continuation of the muscular fibres others not.}, & is a shining white, smooth, hard, Compact elastic
Chord. Most Muscles have Tendons at each End, some only at
one & some at neither. The great Advantage of Tendons is ev-
ident. They being more compact require less Room, & being
smooth & hard not so liable to be abraded by the Bones. Some
Tendons seem to be only a Continuation of the muscular fibres
others receive the muscular Fibres obliquely, as the feathers
are inserted into the Side of a Quill. If it should be asked, why
Muscles or Bones, would not do without Tendons. I answer, the
former by Reason of it's Bulk, the latter by it's want of Flexion.
Some Tendons are long & some short, as most convenient.
The Tendons are vascular & contain a serous fluid, which fa-
cilitates Motion. Each Muscle is enveloped by a smooth Memb-
rane to make the Secretion easy. The Tendons often expand
over the Ends of Muscles, forming a kind of Membrane called