detail in another lecture.
Innervation of the thoracic wall, there are
several nerves that will help provide for
innervation to the wall. These would include
the intercostal nerves, the subcostal nerves,
long thoracic nerves and the medial and lateral
This slide is showing the same illustration,
but it shifts our attention to the intercostal
nerves. There are 11 pairs of intercostal
nerves traveling within the intercostal spaces.
The nerves accompany the intercostal arteries
and nerves within those spaces. And here,
we have a couple of examples of intercostal
nerves. These are anterior rami of spinal
And as you proceed along the lateral margin
of an intercostal space, you will see that
we have this lateral branch that’s issuing
from the intercostal nerve and this lateral
branch can help supply the lateral portion
of the skin associated with the thoracic wall.
And then the intercostal nerve will continue
within its intercostal space and assume an
anterior course and then end on along the
lateral border of your sternum and provide
for some other cutaneous branches that will
pop through the intercostal space. And certainly,
as they travel within the intercostal spaces,
these nerves are also going to provide for
muscular innervation of the intrinsic muscles
that we mentioned earlier.
Now, we can put everything together with respect
to the nerves, to the arteries and to the
veins that travel within the intercostal spaces.
So, here, we’re looking at our intercostal
neurovasculature. And there is a relationship
that exists between these three structures
as they travel in the intercostal space.
If we take a look right here, here is a rib.
Here is the inferior margin of the rib. This
groove area that we see here is that costal
groove. And then we see our intercostal structures
traveling within or inferior to that groove
and there is this consistent relationship
of having the intercostal vein being the more
superior of the three. Intercostal artery
being the middle one of the three. And you
can see your intercostal nerve being the inferior most
structure of the three.
And the mnemonic to remember this relationship
is VAN for the intercostal vein is most superior,
artery is the middle and then your intercostal
nerve would be the most inferior of these
Understanding this relationship is extremely
important in performing a procedure referred
to as a thoracentesis. In a thoracentesis,
a needle would have to be advanced through
the intercostal space into the pleural cavity
to remove excessive fluid. When you advance
the needle into the intercostal space, you
want to make sure that you avoid the intercostal
structures that are located more superiorly,
so you’ll advance your needle over the superior
margin of the rib below, for example.
Another nerve that innervates the thoracic
wall is your long thoracic nerve. That is
seen in through here. The long thoracic nerve
has a superficial course which is a bit unusual
for nerves. Most nerves that innervate muscles
will assume a deep course and be protected
by the more superficial muscle mass. But,
this one is superficial. It lies just underneath
the skin and the fascia. So, a laceration
along the lateral side of the thoracic wall
that does go through the skin and the subcutaneous
fascia could injure this particular nerve.
And as we mentioned earlier, when we were
talking about the fact it innervates the serratus
anterior, injury to this nerve could result
in paralysis of the serratus anterior muscle.
And a common sign here, in that case, would
be the fact the the scapula would wing out,
particularly if you had the patient push against
The pectoral nerves, the medial and lateral
pectoral nerves, are going to innervate your
pectoral muscles. The medial pectoral nerve
will issue from the medial cord of the brachial
plexus whereas the lateral pectoral nerve
issues from the lateral cord of the brachial
plexus. The medial pectoral nerve is running
deep to the pectoralis minor, so we kind of
just see it and its branching pattern. It
will pierce the pectoralis minor and innervate
the minor and then once it gets pierced through
the minor, it will then pierce into the major
to assist in innervating that muscle as well.
The lateral pectoral nerve, which we see coming
in through here, sends branches into the pectoralis
major. So, the major is also innervated by
the lateral pectoral nerve.
That now brings us to the important take-home
messages from this presentation.
First, the ribs, sternum and thoracic vertebrae
constitute the osteology of the thoracic wall.
The 12 pairs of ribs define 11 intercostal
spaces that house intercostal vessels and
nerves. And remember your VAN relationship.
Ribs are classified on the basis of points
of articulation as well as being true or false.
The sternal angle is a landmark for the identification
of the second rib.
Thoracic vertebrae possess facets for articulation
with the head and, in most cases, the tubercle
of the rib.
Movements of the thoracic wall are designed
to alter thoracic volume as required for ventilation
or respiratory movements.
Muscles of the thoracic wall can be categorized
as extrinsic and intrinsic on the basis of
Innervation and vasculature of the thoracic
wall is segmental and non-segmental.
The acronym VAN, as mentioned a moment ago,
again, describes the relationship of neurovascular
structures in the intercostal spaces.
Thank you for joining me on this journey of
“The Thoracic Wall”.