352 THE HORSE. 
Llood-vessels— White fibrous tissue contains few blood-vessels. They 
usually follow the course of the fasciculi; in ligaments they run in a 
longitudinal direction, sending off communicating branches across the 
fasciculi, and eventually forming an open network. ‘The periosteum is 
much more vascular, but the vessels do not strictly belong to the mem- 
brane, as the ramifications found in it are chiefly intended for supplying 
blood to the bone which it covers. 
Nerves.—Small tendons contain no nerves, and large ones only small 
filaments. In the periosteum, nerves are abundant; they exist there 
chiefly for supplying the bones with sensibility. The pain caused in rheu- 
matism, which is an intensely painful disease, is a proof of the sensibility 
of white fibrous tissue. 
FIBRO-CARTILAGE. 
THIS SUBSTANCE, intermediate in structure and uses between cartilage 
and fibrous tissue, is composed of a network of white glistening fibres col- 
lected into fasciculi of various sizes, and containing within its meshes cells 
and a sub-fibrous tissue resembling that of true cartilage. Fibro-cartilage 
admits of arrangement in four groups :— 
1. INTERARTICULAR FIBRO-CARTILAGE is placed between the moving 
surfaces of bones. It serves to connect them together, to facilitate their 
gliding motion, and to act as a cushion, thus preserving the articular sur- 
faces from attrition, and the bones from the effects of sudden concussion. 
It is usually placed where much motion is enjoyed, as in the lower jaw 
and knee, in the form of round oval plates growing thinner in the centre. 
Marginal cartilages such as that around the cotyloid cavity are of the 
same kind. 
2. STRATIFORM FIBRO-CARTILAGES form a thin coating to the bony grooves 
over which tendons play. 
3. INTEROSSEOUS FIBRO-CARTILAGE occurs between the vertebra, at the 
ischio-pubic symphysis, &c. 
4, FREE FIBRO-CARTILAGES are met with in the tarsal cartilages of the 
eyelids, &c. 
SYNOVIAL MEMBRANES. 
THE SYNOVIAL MEMBRANE is a thin layer, which invests the articular 
cartilages of opposite bones, and is continued from one to the other by 
being reflected beneath the ligaments which connect them. It resembles 
the serous membrane in being a shut sac or bladder, and a synovial cap- 
sule may be compared to a small bladder, containing only as much fluid 
as will adhere to its interior, placed between the opposite ends of two 
bones forming a joint. The secretion formed by it, synovia (ov, together, 
wor, an egg), is alkaline, and contains albumen, which is coagulable by 
boiling. Heale has ascertained, by the aid of the microscope, that this 
membrane is actually reflected over the articular cartilage, a point which 
has been long disputed. Besides the joinws, the synovial membranes also 
form smaller sacs which lubricate the tendons as they pass over the ends 
of the bones, and which are called bursce mucose. The epithelium lining 
these membranes is of the kind called tesselated ; it is developed in the 
same manner with that of other free surfaces, being continually repro- 
duced as it is worn away. Synovial membranes, in many situations, are 
closely and completely invested externally by fibrous layers—the fibrous 
capsules, as they are termed. These fibrous coats are met with especially 
in situations where the articulation is either wholly unprotected or 
