278 



THE TISSUES. 



Fig. 176. 



part of the corium of the skin, and of serous and mucous mem- 

 branes ; and of the vascular membranes, so called, as the pia mater 

 and the plexus choroides. 



2. It also forms the white, dense tunics of many soft organs ; as 

 the perineurium, the sclerotica and cornea, the fibrous coat of the 

 spleen and kidneys, and the fibrous tunic of the testis, ovaries, 

 penis, and clitoris. 



In all the preceding structures the yellow fibrous tissue is found 

 in combination with the white. The arrangement of the latter, in 

 all except the true membranes, will be disposed of here. 



1. Structure of tendons and ligaments. These consist of parallel 

 bundles of white fibrous tissue, united by loose areolar tissue into 

 large cords. Between these the vessels ramify, and a relatively 



very small number of elastic fibres, or 

 of networks formed of them. Fig. 

 261 shows a transverse section of a 

 tendon. The latter and the ligaments 

 have no nerves or lymphatics. The 

 vessels of a tendon of an ostrich are 

 shown by Fig. 176. The manner of 

 union between tendon and muscle, and 

 further particulars in regard to the 

 tendons, will be explained in the chap- 

 ter on "Striated Muscular Tissue." 



2. Aponeuroses are composed of fas- 

 ciculi of white fibrous tissue, so inter- 

 woven as to form a membraniform ex- 

 pansion of varying thickness. If very thin, no vessels are sent 

 among the fasciculi, but only to the areolar sheath in contact with 

 each surface. If thick, the vessels penetrate between the fasciculi 

 in an irregular manner. Aponeuroses are found at the origins of 

 muscles, as the tendons constitute their insertion. They also exist 

 distinctly from muscles, as in the case of the deep fascia of the 

 extremities (femoral and brachial aponeurosis, &c.). 



3. Fibro-cartilages have the same structure as tendons and liga- 

 ments, except that cartilage-cells are scattered among the bundles 

 of white fibrous tissue, and that they contain no finer elastic fibres. 

 Fig. 202 represents a section of fibro-cartilage. They exist as spe- 

 cial organs (interarticular fibro-cartilages and the cotyloid liga- 



a. Vessels of the tendon of an ostrich. 

 6, c. Vessels of muscle and tendon, unit- 

 ingatd. (Queckett.) 





