Now, musculocutaneous, other bit. It’s
called musculocutaneous. So, what is the cutaneous
component in the neck and what is the nerve called?
The intercostobrachial nerve. No, not intercostobrachial.
Why is it called musculocutaneous?
Where is the cutaneous part?
It’s the skin, is that what you ask?
Yes, yes. Tell me more.
Musculocutaneous -- Yes. So which part of
the skin? Okay. So the
musculocutaneous nerve comes lateral to the
artery, then it lies between the coracobrachialis
muscle. You have the coracobrachialis here.
It lies between the coracobrachialis.
Then it does separate all the three BBC muscles
and then it becomes cutaneous. At this point,
it’s called the lateral cutaneous nerve
of the forearm. That’s why it’s called
musculocutaneous. Your medial cutaneous nerve
of the forearm comes directly from brachial
plexus. The lateral cutaneous nerve of the
forearm is the continuation of the musculocutaneous
nerve. Okay. Coming down here for now
to get our
median nerve and the ulnar nerve covered in
the forearm. We discover the cubital fossa.
Very good. Quite important question
in the exam. You can take it, boundaries of
the cubital fossa. The boundaries of cubital
fossa are, one side
is the floor which is the brachialis. Floor is
the brachialis. What is on the lateral
side? Which muscle is this?
Coracobrachialis is coming from here. This
Brachioradialis. If you sort of semi pronate
your forearm, semi pronate, and then you readily
extend the wrist this way, the muscle you’re
feeling is the brachioradialis. So semi pronate
your forearm and lift your wrist up, that’s
the brachioradialis. So that is your lateral
boundary -- yeah, that’s the one, yeah.
So that’s the lateral border of the cubital fossa.
What is the medial side? Pronator teres.
So pronator teres, brachioradialis and an
imaginary line between the two condyles.
So those are the boundaries of the cubital fossa.
The floor is formed by the brachialis muscle.
What’s on the roof? On the roof, you have
the skin, then you have some subcutaneous tissue.
On the medial side, you have the medial cutaneous
nerve of the forearm. And the lateral side,
you have the lateral cutaneous nerve of the
forearm. Then the vein you can see here, which
vein is that? What is that called?
It was a median cubital vein.
Median cubital vein. Median cubital vein is
a union of the cephalic vein from here and
the basilic vein from the medial side. So
that’s the median cubital vein. The roof
is also reinforced by the tendon of biceps.
This is the biceps. From the biceps tendon,
there is an aponeurosis which comes up that
reinforces the roof. So if you reflect the
skin, what are the structures you see from
medial to lateral? What’s the most median
structure? You’re always cannulating here --
Median nerve. Median nerve. First is at
the most median
section of the median nerve, after that
is -- No. Median cubital vein is on the skin.
But now we are reflecting the skin. We've
gone into the cubital fossa. Median nerve,
brachial artery. Second is the brachial artery,
and the third structure is the tendon of biceps.
So these are the three important structures
in the cubital fossa and the floor is by the
brachialis muscle. So, if you imagine
the hand, there are eight
forearm muscles. As I said, the things we’re
covering are quite relevant to your exam.
Eight forearm muscles in the hand, out of
which, the five are arranged superficial and
three are deep in the forearm. So if you tighten
and flex your forearm, the muscles you feel,
there are eight in total. The first one here
is the pronator teres. The next one is flexor
carpi radialis. Third one is palmaris longus.
Fourth one is flexor digitorum superficialis.
And the fifth one is flexor carpi ulnaris.
Now, sometimes you know that flexor digitorum
superficialis is classified as an intermediate
layer. So in exam, if you get the superficial
ones, make sure that this one, if at all it
is asked separately, just remember that is
an intermediate layer, not necessarily the
superficial layer, which is called the flexor
digitorum superficialis. Now, you go deeper,
what do you find? You got three muscles.
So you got five muscles superficial, three deep.
The three deep muscles are flexor pollicis
longus to the thumb, flexor digitorum profundus
to the distal interphalangeal joints and the
pronator quadratus. So the pronator teres
works more proximally,
and pronator quadratus more distally. Well,
these are the eight muscles out of which the
flexor carpi ulnaris and the flexor digitorum
profundus to these two fingers are supplied
by ulnar nerve. Everything else is by median nerve.
So this is clearly our first-year anatomy
level. One specific question in your exam
will be the anterior interosseous nerve.