Dynamics of breathing 9
a wide section of the body. The uppermost part reaches the space between the third and
fourth ribs, and its lowest fibers attach to the front of the third and second lumbar verte-
brae; nipple to navel is one way to describe it.
Muscular attachments of the Diaphragm
Muscles attach at origin and insertion points. The determination of origin or insertion is
dependent on two factors: structure and function.
- Structurally, the end of the muscle closest to the core of the body—the proximal
end—is usually referred to as the origin. The distal end, the one that attaches more
peripherally, is usually referred to as the insertion. - Functionally, the end of the muscle that is more stable on contraction is referred to
as the origin, and the more mobile end the insertion.
Although this seems to make sense—proximal structures are generally more stable
than distal ones—this is only true some of the time, as is explored further in chapter 4.
For example, a reversal of functional origins and insertions occurs when you have a mobile
core and stable extremities while moving the body through space.
The muscle that moves space through the
body—the diaphragm—possesses an unmis-
takably three-dimensional form and function,
which makes its origin and insertion anything
but cut and dried. To avoid confusion as we
begin to examine the attachments of its mus-
cular fibers, we simply refer to the diaphragm’s
lower attachments and upper attachments.
lower attachments
The lower edges of the diaphragm’s fibers attach
at four distinct regions. Traditional texts list only
three regions: sternal, costal, and lumbar (see
figure 1.10).
1.Sternal—The back of the xiphoid process
at the bottom of the sternum
2.Costal—The inner costal cartilage surfaces
of ribs 6 through 10
3.Arcuate—The arcuate ligament^4 that runs
from rib 10’s cartilage to the lumbar spine,
attaching along the way to the floating ribs
(11 and 12) and the transverse process and
body of L1- Lumbar—The crura (Latin for legs) at the
front of the lumbar spine, L3 on right and
L2 on left E5267/Kaminoff/fig1.11/417559/alw/pulled-r2
Sternal
CostalArcuate
Lumbar(^4) Traditional texts label each arc of the arcuate ligament individually. It is much clearer to think of it as a single, long ligament
that attaches to the tips of the bony surfaces mentioned. In dissection, when the arcuate ligament is deprived of these
attachments, it clearly stretches out into a single, straight ligament.
Figure 1.10 Attachments of the
diaphragm muscle.