00:01
In this lecture, we're going to look
at the axilla and brachial plexus.
00:05
So, let's start by looking at the axilla, an important
space in the superior aspect of the upper limb.
00:14
So, before we look at the axilla, let's just remind ourselves
of some important bony structures around this region.
00:21
So, highlighted on the screen in
green, we have the humerus.
00:25
We then, have the scapula more posteriorly.
Here, we have the clavicle at the superior aspect.
00:31
And then, we have some of the ribs,
ribs one through to five,
you could see highlighted on the lateral aspect
of this upper part of the thoracic wall.
00:41
And the axilla really is a space.
It's a fat-filled space
that contains a number of important blood
vessels and nerves and lymphatic structures
which we'll look at in a few moments time,
look past between the neck and the upper limb.
00:58
It's a space therefore that has a number
of boundaries. It has an apex and a base.
01:03
It then, has four walls which are the medial wall,
the lateral wall, the posterior, and the anterior wall.
01:12
And these boundaries form that axilla, this
important space at the superior aspect of the upper limb.
01:21
So, let's just remind ourselves of this structure
in a little bit more detail with some muscles now included.
01:27
So, here, we can see looking down
onto the superior aspects,
we can see we have the apex of the axilla
highlighted here and we could see,
we have the boundaries being the first rib medially.
And then, anteriorly, we have the clavicle.
01:43
And then, here, we have the superior border
of the scapula on the posterior aspect.
01:49
It contains a number of important structures
that are passing from the neck into this axilla.
01:54
Highlighted in blue, we have the subclavian vein.
Then, we have the subclavian artery.
01:59
And we have an incredibly important network
of nerves. This is called the brachial plexus.
02:06
So, these structures are passing from
the neck region into the upper limb
or as the venous structure indicates, passing
from the upper limb into the neck region.
02:16
And they do this by passing through
that space which is the axilla.
02:20
They run very closely as you can see
on the diagram here to the first rib.
02:24
And therefore, any damage to the first
rib, perhaps, by a fracture
or something, can actually damage
some of these vessels.
02:31
Importantly, it can damage the subclavian artery
which runs very close to this structure.
02:38
Here, we can see some of the bony makeup now
of the axilla. So, anteriorly, we have pectoralis major.
02:44
We also have that small muscle underneath
the clavicle, subclavius and we also have pectoralis minor.
02:51
These muscles passing from the chest wall, across
to the upper limb, forming the anterior boundary.
02:57
We also have that sheet of fascia,
the clavipectoral fascia
that is running all the way across
the anterior aspect of the axilla.
03:06
Medially, we have a couple of bone -
a couple of muscular structures.
03:09
We have the various muscles that make up
the thoracic wall, including the ribs.
03:15
So, we have the intercostal muscles
and we also have serratus anterior,
that important muscle on the lateral
aspects of the chest wall.
03:24
Laterally, we have the intertubercular
sulcus of the humerus.
03:28
We'll come back to this when we look at
the muscles in the arm
as that's an important pathway for various
tendons and that forms part of the lateral wall.
03:37
Posteriorly, we then have an important muscle which is
subscapularis that lies on the anterior surface
of the scapula. So, here, we have subscapularis muscle.
Also on the posterior wall,
we have triceps brachii and we
have teres major muscles.
03:52
Some important muscular structures
that form the posterior wall.
03:56
Most inferiorly of this group, we have
latissimus dorsi as well.
04:01
The floor of the axilla, if we could now see
with the anterior wall put back in place,
the floor of it really is the skin
of the armpit region.
04:10
And you can grab this aspect if you were to pinch the skin
flap that's connecting your chest wall to your arm.
04:16
And that's really the armpit region.
And this forms the floor of the axilla.
04:21
Passing through the axilla as I've mentioned
before, there's a whole series of structures.
04:28
And we can see now, within that space
that's being formed by these various landmarks,
we have the brachial plexus, the subclavian artery and the
subclavian vein, and some important lymphatic structures.