Front Matter

428 Canine Sports Medicine and Rehabilitation

The head initiates all purposeful movement,
not only by determining the proposed activity
through mentation, but also by determining
the position that the body occupies in space
through the vestibular apparatus within the
skull. “Where the head goes, the body must fol­
low” is a common phrase among rehabilitation
therapists. It is understood that head position
and movement initiates the next body move­
ment and allows for appropriate body mechan­
ics. Visual and olfactory input as well as reflex
modification are important but are not critical
for the vestibular system to perform its duties
although they may be critical for developing
training routines. A better understanding of
how the neural feedback loops initiate, main­
tain, and protect propulsion and in this case,
related spinal structures, is critical to attain
peak performance.

The thoracic limbs

The thoracic limbs play a major role in main­
taining the head’s normal positions in space.
The most cranial thoracic vertebrae with their
large dorsal spines form the anchor that allows
the head to be suspended at some distance from
the body (Figure  17.4). These cranial thoracic
vertebrae are supported directly by the thoracic
limbs. The weight of this entire unit is supported
by the thoracic limbs and it is often noted that
this represents 60% of the body‐weight of the

animal. Considering the tremendous variation

in conformation that exists from breed to breed

and from individual to individual this would

have to be a very rough estimate.

The thoracic limb has no bony or ligamen­

tous attachment to the spine. The extrinsic tho­

racic limb muscular apparatus attaches the

thoracic limb to the thoracic body wall allow­

ing for freedom of movement that permits

extreme changes in direction while protecting

the spinal column’s rigidity throughout the

area of the rib cage.

The pelvic limbs

The pelvic limbs are responsible for carrying the

weight of the caudal portion of the body. The

pelvic limbs interact with the body in a com­

pletely different manner from the thoracic limbs

(Figure  17.5). The coxofemoral joint transmits

forces to the caudal spine through the sacroiliac

joint. Although the box‐like structure formed by

the pelvis has less flexibility than the muscular

attachment of the thoracic limb to the body wall,

there is significant rotational advantage afforded

by the range of motion of the ball and socket

joints. This also allows the pelvic limbs to move

far forward under the body, producing signifi­

cant forward propulsion. When turning, a great

deal of the actual body movement has been

committed by the trajectory of the head, and the

actions of the forelimbs and thoracic cavity. The

Figure 17.4 Lateral view of the cervical and rostral thoracic vertebrae demonstrating the functional anatomy described
in the text.