he ligaments of the patella.
6, The cartilage of the tibia 12, The cartilage of the femur. * * * *,
The synovial membrane.]

114. CARTILAGE is a smooth, solid, elastic substance, of a pearly
whiteness, softer than bone. It forms upon the articular surfaces of
the bones a thin incrustation, not more than the sixteenth of an inch
in thickness. Upon convex surfaces it is the thickest in the centre,
and thin toward the circumference; while upon concave surfaces, an
opposite arrangement is presented.

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112. Describe the phalanges. 113-118. _Give the anatomy of the
joints._ 113. What is said of the joints? Of what are the joints
composed? What is illustrated by fig. 21? By fig. 22? 114. Define
cartilage.

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115. The SYNOVIAL MEMBRANE is a thin, membranous layer, which covers
the cartilages, and is thence bent back, or reflected upon the inner
surfaces of the ligaments which surround and enter into the
composition of the joints. This membrane forms a closed sac, like the
membrane that lines an egg-shell.

[Illustration: Fig. 23. The anterior ligaments of the knee-joint. 1, The
tendon of the muscle that extends the leg. 2, The patella. 3, The
anterior ligament of the patella, near its insertion. 4, 4, The synovial
membrane. 5, The internal lateral ligament. 6, The long external lateral
ligament. 7, The anterior and superior ligament that unites the fibula to
the tibia.]

[Illustration: Fig. 24. 2, 3, The ligaments that extend from the clavicle
(1) to the scapula (4.) The ligaments 5, 6, extend from the scapula to
the first bone of the arm.]

116. Beside the synovial membrane, there are numerous smaller sacs,
called _bur'sae mu-co'sae_. These are often associated with the
articulation. In structure, they are analogous to synovial membranes,
and secrete a similar fluid.

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115. Describe the synovial membrane. 116. Describe the bursae mucosae.
What is represented by fig. 23? By fig. 24?

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117. The LIGAMENTS are composed of numerous straight fibres, collected
together, and arranged into short bands of various breadths, or so
interwoven as to form a broad layer, which completely surrounds the
articular extremities of the bones, and constitutes a capsular
ligament. These connecting bands are white, glistening, and inelastic.
Most of the ligaments are found exterior to the synovial membrane.

118. The bones, car