Front Matter

430 Canine Sports Medicine and Rehabilitation

the side that widens as the spine routinely and
regularly changes from one angle to another
through all gaits. Faster gaits will also involve
greater changes in dorsoventral movements as
the pelvis is alternately tilted to gain more dis­
tance with each stride. This spinal flexibility is
dramatically demonstrated in the canter, trot,
and gallop gaits.
An interspinous ligament stabilizes the dor­
sal spines of the vertebrae. The articular sur­
faces, which are extensions of the dorsal lamina
of each vertebra, form joints with the vertebrae,
both cranial and caudal. The cranial articular
surface is ventral to the caudal articular surface
of the vertebra cranial to it (Figure 17.7). All of
these intervertebral articulations allow for a
significant but limited motion that permits the
spine to bend in all planes. The sacral vertebrae
are fused and have the least flexibility in any
plane. The thoracic wall and the rib attach­
ments limit the amount of mobility of the tho­
racic vertebrae (Figure 17.8).
The chest wall, which consists of the inter­
connecting vertebrae, ribs, and associated soft
tissue, forms a stable element and serves to

anchor the more flexible and mobile cervical

and lumbar regions of the spine. The increased

mobility at the cervicothoracic, thoracolumbar,

and lumbosacral junctions in comparison to

other spinal segments is quite significant. The

forces produced at these junctures are most

likely responsible for a higher degree of degen­

eration at these sites.

The atlanto‐occipital and atlanto‐axial joints

are unique and allow for tremendous freedom

of movement of the skull. This is critical so that

the special senses are able to harness informa­

tion from the widest possible area. Head mobil­

ity is extremely important, too, as the mouth is

the dog’s main means of defense. The occipital

condyles are extremely large and allow for con­

siderable dorsoventral range of motion of the

head. The odontoid process bound to the floor

of the atlas and the joints formed by the articu­

lar surface of the atlas and axis permit consider­

able rotation of the head in relation to the neck

(Figure 17.3).

The muscles that act upon the spine are too

extensive and numerous to enumerate in this

book. These are classified as intrinsic muscles

Figure 17.7 Several lumbar vertebrae showing how they articulate and the appearance of the joint surfaces when
disarticulated.

Figure 17.8 Lateral radiograph of the thoracic spine showing the ribs and chest wall that give it its rigidity.