Page 122 - Anatomy and Physiology of Farm Animals, 8th Edition

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domestic animals include ginglymus, plane, Joints of the Axial Skeleton
trochoid, spheroid, and condylar. An addi-
VetBooks.ir tional types of joint, primarily described in The joints of the skull are chiefly sutures,

the dog, is the saddle joint.
Hinge (ginglymus) joints move only in with adjacent bones united by fibrous tissue.
In old age these typically ossify, becoming
their sagittal plane. The movements in this synostoses. In addition to the sutures asso-
type of joint are flexion, extension, and, in ciated with the braincase, the skull also
some joints, hyperextension. The fetlock is features the symphysis of the mandible, the
a good example of a ginglymus joint. synchondrosis at the junction of the sphe-
Plane joints have only a slight gliding noid bone and occipital bone at the base of
movement between relatively flat apposed the skull, and the temporomandibular joint.
surfaces. These surfaces are called facets. The temporomandibular joint between
The joints between adjacent carpal bones the mandible and the temporal bone of the
of the same row are examples of plane skull consists of an articular surface on the
joints. skull and one on the mandible, with a plate
A pivot (trochoid) joint is one in which of cartilage (articular disk or meniscus)
rotary movement occurs around one axis. between. The temporomandibular joint
The atlanto‐axial joint is the best example acts as a ginglymus joint when the mouth
of a pivot joint. opens and closes and as a plane joint when
Spheroid (ball and socket) joints the jaw moves from side to side and for-
permit movement in nearly any direction. ward and back, as in grinding food. This
A spherical head on one bone fits into a combination of movements with the shape
cup‐shaped depression in the other. of the articular surfaces means the tempo-
Flexion, extension, adduction, abduction, romandibular joint may be described as a
rotation, and circumduction are all possible condylar joint.
in spheroid joints. The coxofemoral (hip) The atlanto‐occipital joint between the
joint is the best example of a spheroid joint, occipital bone of the skull and first cervical
although the hip in most farm animals is vertebra (the atlas) is strictly a ginglymus
reduced in its ability to move outside of joint. Two condyles on the occipital bone
flexion and extension by virtue of the soft fit into corresponding depressions in the
tissue components of the joint. atlas. The only movements possible are
In a condylar (condyloid) joint, convex flexion and extension in the sagittal plane,
articular condyles articulate with some- as in nodding the head “yes.”
what concave articular surfaces. The tem- Rotation of the head occurs between the
poromandibular and femorotibial (stifle) atlas and axis, at the atlantoaxial joint.
joints are examples. Some authorities call The dens, a toothlike projection from the
this sort of joint an ellipsoid joint, which cranial extremity of the axis, projects into
describes the articular surfaces that are the vertebral foramen of the atlas, where
expanded more in one direction than it is held by a group of strong ligaments
another. The distinction between condylar that permit considerable rotary movement.
and ellipsoid joints is very small, and this The atlantoaxial joint is the best example
sort of joint, beyond the examples given of a pivot joint, in which one segment
above, is not a common one in farm rotates around the long axis of another.
animals. The symphyseal (fibrocartilaginous) joints
The saddle joint has surfaces that resem- between adjacent vertebrae throughout
ble an English saddle. It permits all types of the rest of the vertebral column exhibit
movement except rotation. The carpomet- relatively little motion. The bodies of adja-
acarpal joint of the human thumb is the cent vertebrae are united by a heavy disk
best example, but the interphalangeal of fibrocartilage, the intervertebral disk
joints of the dog are sometimes classified (IVD), that is flexible enough to permit
as saddle joints. some bending in any direction, even twisting.