Hi I'm Cristina Prall.
In this video I'll show you some basic skinning techniques that will be helpful in lab.
The goal of skinning is to remove the superficial most layer of skin in order to see what lies
deep to it.
One of the most intimidating aspects of dissecting for beginners can be estimating just how deep
to make that first incision.
Although the cutaneous and subcutaneous layers of tissue will be removed throughout the dissection-
important structures such as cutaneous nerves and superficial veins do exist within these
layers.
So if you are trying to maintain any superficial layers you will want to only remove the skin.
So when we are ready to skin we will take the tip of the scalpel blade and make a very
shallow incision like so to insure that we don't go too deep.
And then we will immediately check our work to see how deep we went and distinguish the
clear difference between the skin and the subcutaneous tissue.
As seen here.
So when we are thinking about skinning its important to remember that there are two layers
of skin.
The first and most superficial is the epidermis which acts as a barrier to infection and also
regulates trans-epidermal water loss.
The second layer which is tightly adhered to the epidermis is the dermis and it cushions
the skin from stress and strain.
So when we say the skin, it is a term that combines both the epidermis and dermis as
one unit.
You cannot distinguish the difference between the two layers of skin in lab with the naked
eye.
Deep to the dermis you will find the subcutaneous tissue also known as the hypodermis which
functions in fat storage.
So in order to preserve any superficial vessels or cutaneous nerves we are going to leave
the hypodermis behind as we only remove the epidermis and dermis.
To do that we are going to use the forceps to pick up the skin and angle our blade parallel
to the skin in order to use a blade to separate the skin from the subcutaneous tissue.
A good indicator that you are only removing the skin is that you look on the deep side
of the dermis and you can see some dermal pitting which is the dermal papillae projecting
up into the epidermis giving the appearance of little pits.
And then you can simply continue skinning until you have removed the appropriate amount
of skin for your dissection.
If you do not wish to preserve any superficial structures in the subcutaneous tissue then
you can go ahead and remove the subcutaneous tissue.
However we are still going to make a very superficial incision with the tip of our scalpel
blade just to see where we are at.
We can see we have our layer of epidermis and dermis here but we can kind of keep incising
and checking to see how deep we are going little by little until we start to see some
muscular fibers which I can see here.
I am going to make the incision a little bit wider so I can grab the full thickness of
the skin including all three of the layers and then again I will angle my blade parallel
to that of the skin and run my blade along the plain of the muscular fascia which we
are going to stay just superficial to.
As you might notice in the donor the subcutaneous tissue can sometimes take on the same color
as muscle tissue which can make things confusing.
Just remember to analyze the texture and look for muscle fibers to distinguish between fat
and muscle tissue.
You may have a little bit of subcutaneous tissue left behind on top of the muscle but
thats okay you can come back again later and clean that up.
And you will just continue removing the skin until you have removed the amount you are
looking for.
If you find that the skin you are working with is getting to be a large flap, a helpful
tip is to incise a loophole in the skin to fit your finger through and pull back and
this makes the skin taught for the dissector and just helps the skinning process to go
a little bit more smoothly as you are working.
Like so.
It is helpful to keep in mind that the inferior-lateral back, abdomen, arm and thigh will have a significantly
thicker layer of subcutaneous tissue than other areas of the body such as the dorsum
of the hand or scalp.
So keep this in mind when your estimating just how deep to make that first incision.
Remember that the depth of skinning will depend on the goal of each dissection and the structures
you are trying to identify.
And as a reminder- scalpels should primarily be used for skinning purposes only.
In our next video I'll show you how to retract and reflect muscles as well as how to clean
neurovasculature.