Okay. So, that’s the spine of the scapula,
supraspinatus, infraspinatus, what supply
those muscles? Well, the suprascapular
Very good. Where does it come from?
From the first trunk.
Very good, from the upper trunk. From the
upper trunk, you also have something called
the suprascapular nerve. The suprascapular nerve supplies the
supraspinatus and the infraspinatus.So that’s the supraspinatus,
infraspinatus. Okay. That’s the edge
of the scapula, what muscles are these?
Teres minor and teres major. So teres minor is up
there and teres major is up here. Nerve supply
to teres minor?
Very good. Teres minor is by axillary, and
teres major is by-- Lower subscapular. So the
lower subscapular nerve supplies subscapularis,
as well as teres major. Axillary nerve supplies
deltoid, as well as teres minor. And then
you have radial nerve. So the radial nerve
supplies the triceps, I said. So the radial
nerve -- you can see the spiral groove in
him quite nicely. So there’s the spiral groove.
It comes down. That’s the brachioradialis.
In the cubital fossa, if you reflect the brachioradialis,
you will see the radial nerve there. Then it
lies between the two heads of the supinator
muscle. It runs between the two heads of the
supinator there. And about seven centimeters,
distal to the joined line, it divides into what?
Posterior interosseous nerve.
Posterior interosseous nerve, and superficial
brand of the radial nerve. Okay. So at this
point, it divides into a posterior interosseous
nerve, which is a deep branch similar to your
anterior interosseous nerve which is also deep
branch. And then you have the subcutaneous
nerve which is called the superficial branch
of the radial nerve. That’s what you’re
testing for sensation. Now, posterior interosseous
nerve. Nerve injuries. You will get a full
EMQ on nerve injuries. So the favorite questions
are related to levels
of nerve injuries. Imagine your radial nerve
is injured at this level, above the spiral
groove, then the entire extensor aspect is
paralyzed, quite obvious. If it is below the
spiral groove, triceps is spared. So the patient
will have extension of the elbow but wrist
drop, below the spiral groove. Okay. Let’s go
slightly lower down. At this
level, what muscles are spared? Triceps is
spared, fine, anything else? Which one?
Brachioradialis. Brachioradialis is spared
because the brachioradialis
is supplied earlier than that. Then you have
the anconeus which will be spared. Probably,
we’ll also have the extensor carpi radialis longus
and the brevis, which extends the wrist
this way. That is also spared. When it comes
down, the posterior -- before it gives off the
posterior interosseous nerve at this level,
always the extensor carpi radialis longus
extensor carpi radialis brevis, anconeus,
supinator, and brachioradialis. They’re
always supplied. So if the patient has got
a posterior interosseous
nerve injury following a laceration, the patient
would have a wrist-drop. The patient will
be able to lift the wrist-drop, but there
is loss of extension of the fingers. Okay.
So if you get a clinical scenario whereby
they have all these different nerves and then
the question says, “The patient is able
to extend the wrist but not the fingers, which
nerve is it?” It’s on the posterior interosseous
nerve. Okay. It’s the posterior interosseous
nerve. And the question will be a bit more
specific. It will say, “The patient is able
to extend the wrist but with radial deviation”
because only the extensor carpi radialis
longus and brevis is working. Now, the
extensor carpi ulnaris.
So when the patient extends the wrist, the
radial deviates. Because when you’re extending
the wrist, you have the extensor carpi radialis
on the radial side and extensor carpi ulnaris
on the ulnar side working to extend it. So
if posterior interosseous nerve is injured,
the extensor carpi ulnaris is affected but
not the radialis. So the patient can do this
but it will deviate to the radial side.
Staying on the radial nerve, it supplies all
the other muscles in the hand, the thumb.
What they’re going to ask you, you clearly
know the names, extensor pollicis longus,
extensor pollicis brevis, and then you have
the abductor pollicis longus in the base of
the snuffbox. Then to the digits, you should
know the names, extensor digitorum communis,
extensor indicis, and extensor digiti minimi.
There’s not really any EMQ question on that
but you can get a question on the snuffbox,
boundaries and contents of the snuffbox.
Boundaries of the snuffbox?
Yup, very good, on which side?
On the ulnar side. Ulnar side? On the ulnar
side, you have the
extensor pollicis longus.
And then there’s EPB on the medial side.
Extensor pollicis brevis and --
I can’t remember.
Abductor pollicis longus. So two longus and
one brevis. On the ulnar side, this one --
So that is your extensor pollicis longus on the ulnar
side. That’s the extensor pollicis brevis.
And then here is the abductor pollicis longus
which abducts the thumb. Those are the boundaries
of the snuffbox. Okay. What were the important
structures here out of the snuffbox? So, the
superficial brand of the radial nerve?
Radial artery. Radial nerve is deep. Okay. Radial
artery is deep and cephalic vein. They’re on
the snuffbox. What are the bony prominences
you can feel in the snuffbox? If you feel
your snuffbox, clearly, you will feel the
scaphoid. What else can you feel?
Trapezium. Scaphoid, trapezium. Four bones,
scaphoid, trapezium, anything else? Base of
the first metacarpal and the radial styloid.
These are the four bones in the snuffbox.
That’s the radial styloid --
Those clusters in the snuffbox, isn’t it? Yeah, that is it.
Because if you look at the anatomical specimen,
these tendons lie on these sites.
Okay. So that’s the snuffbox.
So that’s all about the radial nerve.
If you go back here, that’s your teres minor.
Where does the teres minor insert?
Radial tuberosity of the humerus, okay. What
else inserts along with the teres minor in
the great --
Very good. So supraspinatus, infraspinatus,
teres minor. The rotator cuff muscles, so
SITS, supraspinatus, infraspinatus, teres
minor, they are attached the greater tubercle.
And the subscapularis is attached to the lesser
tubercle. Those are the rotator cuff muscles.
So this is the teres minor. Where does the
teres major insert? Think about it.
I’m sure you know this. If you can see the arm,
the teres major coming from there, where can it
insert? Think about it. It has to be in the
shaft of the humerus. Where else can it go
to? It has to, isn’t it? Because if it
does not go into the shoulder, it has to be
coming here. So it inserts into the medial
lip of the bicipital groove of the humerus.
What else attaches there? That’s the biceps
and that’s the bicipital groove. What are
the muscles that are attached there? I’m
sure you know this. Not biceps.
Triceps. No, no, no. Triceps all go to the
You have the teres major, pectoralis
major, and then your latissimus dorsi.
So that is a lady between the two majors; latissimus
dorsi, pectoralis major, and teres major.
So your action of latissimus dorsi, pectoralis
major, and teres major would have to be adduction
of the arm. Okay. So these are your three
here. So that’s the teres minor and teres major.
I’ve drawn a quadrangle here. That is called
the quadrangular space. Quadrangular space is
essentially bounded laterally by the humerus,
medially by the long head of triceps, teres
major, teres minor. Okay. What comes out through
this quadrangular space?
Axillary nerve, very good, axillary nerve,
along with an artery. Go on.
Posterior -- Posterior circumflex humeral
artery. So, the
axillary nerve is accompanied by the posterior
circumflex humeral artery. Whenever I try
to emphasize something, that’s because this
is what comes up; axillary nerve, posterior
circumflex humeral artery. Then this comes
down and then it becomes a triangular interval.
So the triangular interval is bounded superiorly
by the teres major, along with the triceps,
humerus. And what comes out through that?
Radial nerve. So that is the radial nerve
which is coming out through there and lying in the
spiral groove. Which artery accompanies
The profunda brachii.
Profunda brachii artery, very good. Where
does the profunda brachii artery come from?
The axillary, the brachial --
Brachial artery. I think at this point, I’ll
tell you something which is of quite relevance.
I said this is the teres major, right? The
anatomical significance of that point is your
axillary artery comes there. At this point,
it changes name, and then it becomes the brachial
artery. So that’s an anatomical point where
the name changes. So the moment it becomes the
brachial artery, it immediately gives off
the profunda brachii branch. So if you go
back to this image here, that’s
where you get the profunda brachii immediately
coming off below the teres major. So axillary artery
runs down, comes below the teres major, and
immediately given off the profunda brachii
branch, and then the brachial artery just
continues into the arm. Whenever you say profunda,
profunda is deep. So it supplies the deep muscles
in the arm. Okay, So don't refer to your quadrangular
interval, boundaries, contents. Sorry, quadrangular
space. Triangular interval, boundaries, contents.
So, going back here, radial nerve, we
discuss axillary. Axillary nerve, just remember
your deltoid. You have the anterior fibers,
lateral fibers, and the posterior fibers.
They’re all supplied by the axillary nerve,
and this is a little bit more detail. Axillary
nerve has got an anterior and the posterior
division. That’s why one-off it supplies
the teres minor. But for part A, don’t confuse
which is anterior and which is posterior.
Just remember that teres minor is also supplied
by the axillary nerve. And the axillary nerve
sensory is the regimental badge area, which
I’m sure you know this. That’s your sensory
distribution for axillary. It’s very difficult
to test for teres minor
in isolation because it’s a part of the
rotator cuff. So, whenever you’re asked
any shoulder pathology, this always comes
along with supraspinatus, infraspinatus, and
teres minor is part of it. It’s because you just
can’t isolate spontaneously. Subscapularis, you
can because it’s coming out attaching on the
lesser tubercle. Okay. Now, we briefly