Page 119 - Anatomy and Physiology of Farm Animals, 8th Edition

104 / Anatomy and Physiology of Farm Animals

This fibrous layer may be thickened in role in complex joint movements. Menisci
are truly intracapsular in that they are not
certain areas to form the extracapsular
VetBooks.ir (or periarticular) ligaments that connect covered by synovial membrane. Prominent
menisci are found in the stifle and the
adjacent bones and help stabilize the joint.
Ligaments are connective tissue bands temporomandibular joint.
that extend from bone to bone. (Folds of
serous membrane as seen in the thoracic, Other Synovial Structures
abdominal, and pelvic cavities are also
called ligaments and are described with Synovial membrane is also an important
the appropriate organs in other chapters.) feature of two other structures, discussed
Tendons are connective tissue bands that more completely in Chapter 7. A bursa is a
connect muscle to bone. They are described small, fluid‐filled sac lined with synovial
in Chapter 7. Both ligaments and tendons membrane. Bursae act as cushions and are
are composed primarily of dense, regularly generally found where tendons cross over a
arranged bundles of collagen. bony prominence.
Intracapsular (intra‐articular) liga- Tendons may also be protected from
ments are found within joints and are cov- bony prominences by a synovial (tendon)
ered by the synovial membrane (Fig. 6‐2). sheath, a synovial membrane‐lined tube
The cruciate ligaments of the stifle are that wraps around the tendon’s circum-
intracapsular ligaments. ference (Fig. 6‐3). Synovial sheaths are
Extracapsular (periarticular) ligaments particularly noteworthy in the distal limbs,
are external to the joint and constitute band‐ where long tendons pass over joints.
like thickenings of the fibrous capsule. These Inflammation of a synovial sheath and its
include collateral, dorsal, palmar, plantar, tendon, or tenosynovitis, may follow
and annular ligaments. Collateral ligaments trauma or penetrating injury and can result
lie on the medial and lateral aspects of a in a very obvious and painful distension of
joint. Dorsal and palmar (or plantar) liga- the sheath. Tendons and synovial sheaths
ments lie in front of and behind the joint. are discussed more completely in Chapter 7.
Annular ligaments surround the joint, and
their fibers generally circle the joint to
strengthen and protect the capsule. Movements of Joints
Menisci (fibrocartilage disks) are inter-
posed between surfaces of some joints, Joints may also be described on the basis of
where they contribute to the congruency of the sort of movement they facilitate. Of the
the articular cartilages and probably play a various types of joints, only synovial joints

Tendon sheath
t

Mesotendon

b

Figure 6-3. Tendon sheath. The tendon (t) is closely invested by a synovial membrane (blue line) which
reflects off the tendon at the mesotendon and encircles the tendon as part of the tendon sheath. The small
space between tendon and sheath contains synovial fluid. Connective tissue of the sheath may blend with
the periosteum of adjacent bones (b) to anchor the tendon, as shown here. Blood vessels, nerves, and
lymphatic vessels reach the tendon through the mesotendon.