Hello anatomy colleagues this is Dr Alsup and in this learning objective
we are going to focus on muscle compartments sometimes referred to as fascial compartments.
So our goals here are to understand what makes up a muscle compartment so it's more than just muscle,
and then spend a bit of time considering the role fascia plays in musculoskeletal anatomy.
A muscle or fascial compartment is composed of a few things. First
it is composed of a group of muscles that are enveloped in deep fascia, so just kind
of looking at a group of muscles here that is surrounded by or enveloped within deep fascia.
And specifically deep fa-, so recall that fascia is a generic term for grossly visible connective
tissue, and specifically deep fascia is located deep to the superficial fascia.
So this kind of adipose filled layer or subcutaneous layer under the skin.
These muscle compartments that are surrounded by this deep fascia contain groupings of muscles that
share a similar neurovascular supply as well as share similar actions. And in certain areas there
are going to be particularly thick portions of deep fascia and these are referred to as intermuscular
septa. So these are deep fascia as well they're just thicker portions of the deep fascia
that's served to truly compartmentalize as well as occasionally serve as a muscle attachment
site. You don't really see intermuscular septa or at least prominent ones other than in the limbs,
so it's really where you have these considerable areas of thickening when we're talking about the
appendages. Muscle compartments serve several functions, which we will discuss, but I want to
note it's also helpful for students of anatomy as it really helps to reduce the cognitive load that
comes with learning of all these muscles and all these bones and all these actions and all these
nerves. So instead of learning the nerve supply and actions for each individual muscle instead
you can learn that for a grouping of muscles, so you can learn the nerves that supply these
four muscles within this muscle compartment, and the similar action that occurs with these muscles.
So a bit more about deep fascia. As I mentioned this is grossly visible connective tissue but
importantly in this area it tends to be continuous with a few things. Deeper connective
tissue coverings of the muscle such as that paramecium and the epimysium
in addition to being connected to periosteum that surrounds the bone. The deep fascia that surrounds
the compartments, so you'd have deep fascia surrounding the compartments of the muscle,
will also limit the outward expansion of the bellies of the contracting muscle, so they're
unyielding to a certain extent the deep fascia. And this helps with the directionality of the
venous flow as blood is pushed or directed as the veins of the muscles and the compartments
are compressed when there's contraction so it won't allow for the contraction to spread too
far out it will keep it within the compartment which will compress appropriately the veins. And so
these valves within the veins allow the blood to flow in the correct direction, so towards the heart,
and prevent backflow. So the deep fascia the contracting muscles and those veins with valves
work together as a type of muscular venous pump to return deoxygenated blood to the heart. And this is
particularly important in the lower limbs where blood is moving against the gravitational pull.
So there are a lot of functional benefits to these compartments but there can be issues
that arise because the fascial boundaries that limit the compartments are largely inelastic so
not much give there. Which as we mentioned can be a good thing in helping direct venous blood flow
but in conditions that lead to an increase in the volume of those compartmental contents
such as muscle swelling local infection or hemorrhages, that can lead to a significant
increase in intercompartmental pressure. And if this pressure if this increased, pressure is not
relieved, this can lead to compressive occlusion of vasculature within the compartment as well as
potential damage to the nerves and muscles due to that decreased blood flow to those regions.
And this is referred to as compartment syndrome. This can occur in any muscle or fascial
compartment but it is most common in the anterior compartment of the leg, so this region right here.
All right excellent we have reached the summary slide and this is our introduction to
the muscle fascial compartments. And we will start in the next learning objective
starting to actually name these muscle compartments and locate these muscle compartments.
Thank you for your time and attention here and I hope you have a great rest of your day.