10 yoga anatomy
Upper attachments
All the muscular fibers of the diaphragm rise upward in the body from their lower attach-
ments. They eventually arrive at the flattened, horizontal top of the muscle, the central
tendon, into which they blend. In essence, the diaphragm connects to itself—its own center,
which is fibrous noncontractile tissue. The central tendon’s vertical movements within the
body are limited by its strong connection to the heart’s fibrous pericardium, to which it is
inextricably linked.
Traditional texts refer to the lower attachments as the muscle’s origin, and the central
tendon as the insertion. The following text offers our reevaluation of that assumption.
Challenging traditional labeling of origin and insertion
As we will see later in this chapter, there is much confusion among breathing teachers about
the action of the diaphragm. Why is there so much confusion, and where did it begin? A
major factor may be that the structural origin and insertion of the diaphragm have histori-
cally been mislabeled in anatomy texts. This has resulted in a functional confusion about
which end of the muscle is stable and which is mobile when the diaphragm’s fibers contract.
assumptions about Structure In terms of structure, traditional anatomy texts present
the origin of the diaphragm as its lower attachments, and the central tendon is labeled as
its insertion. Upon closer scrutiny, this categorization breaks down.
Let’s see how true this is for the location of your diaphragm’s lower attachments (see
figure 1.10 on page 9). If you place your fingertips at the base of your sternum, you can
usually touch the tip of your xiphoid process. You can then sweep your fingers around the
edges of your costal cartilage, and from there around your back to the region of the float-
ing ribs, and then to the top of your lumbar spine.
At every point of contact you just traced on your body, your fingertips were as little
as 1/4 inch (0.6 cm) and no more than one 1 inch (2.5 cm) away from the sternal, costal,
arcuate, or lumbar attachments of your diaphragm. Your fingers were on the surface of
your body, not near its core, and neither were the attachments you just traced.
Now, let’s see if you can trace your diaphragm’s upper attachments. Can you get your
fingertips close to your central tendon? Not really, because it is at the core of the body. In
fact, your heart is anchored to it. Describing this structure as central is apt, which is why
using a term that is usually reserved for distal structures (insertion) is all the more confusing.
lower fibers The lower muscular fibers of the diaphragm attach to flexible cartilage
and ligament. The bottom of the xiphoid process is mostly cartilage. The costal cartilage
is springy and flexible and has many joints that attach it to the ribs, which are among
the more than 100 joints that make up the rib cage articulations. The arcuate ligament
is a long, ropy band that attaches to the tips of the floating ribs. The front surface of the
lumbar spine is covered with the anterior longitudinal ligament, which is anchored to the
anterior surfaces of the cartilaginous intervertebral discs as well as the anterior surfaces of
the lumbar vertebrae.
Assuming that the rib cage is allowed to move freely, we can make a strong case that
these lower attachments of the diaphragm have considerable potential for movement. Even
the crura have this potential in situations involving lumbar motion and the action of the
psoas muscles, which share common attachments in the upper lumbar region.
Upper fibers The center of the diaphragm and the heart have never been apart. The
tissue that will become the central tendon actually originates outside of the thoracic cavity
in our embryonic development. At this early stage, it is called the transverse septum, and
it lies adjacent to the primordial heart tissue. With the inward folding of the embryo’s
structure in the fourth week in utero, the heart and transverse septum move together into