can because it’s coming out attaching on the
lesser tubercle. Okay. Now, we briefly
touched upon the nerve injuries. I’ll just
go back to other nerve injuries you can get.
Median nerve injury. So the median nerve, as
the name says, it’s
like the middle. That’s what we call median.
Imagine a median nerve is injured there, what
do you think the patient’s clinical presentation
will be? That’s the median nerve. When do
you think if somebody can get a median nerve
injury at this level, what’s the most common
Supracondylar fracture, commonly seen in children,
but, of course, you can get in adults.
But you have supracondylar fracture; the nerve
that is injured is median nerve. Of course
you can get the radial nerve, ulnar nerve,
in theory, but for the purpose of your exam,
they’ll ask you median nerve, supracondylar
fracture. So, let’s say this is a four-year-old
child. He doesn’t look four, but he’s
four. Supracondylar fracture, what do you
think this hand will be? What are things
he won’t be able to do?
Wrist drop? No, no, no, wrist drop is on
the other side,
it's on the radial. We’re talking about
So, unable to extend the wrist.
Flex you mean?
Flex the wrist. Okay. I think I’m just
working you towards
a clinical scenario. They won’t give you
that. What is the thing they will give you?
What does the patient unable to do if it is
a child? What does a classical thing a child
will be laying if you’re seeing a child
in any --
Grasp. The grasp. Okay. Grasp is lost.
the pointing index, the index finger won’t
flex. So if you see a four-year-old child
laying in any, this is a classical median
nerve injury. That’s called the pointing
index sign. Now, in a child, you can’t ask
him to make a fist. So that’s why it is
in that position. But in an adult, if they
are laying this, you ask them to make a fist,
again, they won’t be able to make a fist
but the hand will try to flex this way.
That’s called the hand of benediction. So this is
again a median nerve injury.
So if we have a median nerve injury at that
level, or even slightly lower down, you will
soon get this pointing index or the hand of
benediction. Okay. Now, let’s go to the
anatomy of that. Why do you get this? Going
back to your ulnar nerve, I said these two
are supplied by ulnar nerve, and these two
are by median. So that’s why when you have
a median nerve injury, these two don’t flex. But
classically, the middle finger can occasionally
be supplied by the ulnar from there or the
tendon is just pulling it down. But this finger will
never flex. So this is the classical one but
you can get this as well.
FPL, even this one flex because the FPL is
also by the median nerve. If you come to the
carpal tunnel and you have an injury of the
median nerve at this level, then you won’t
get pointing index, you won’t get hand of
benediction, what is lost? Thenar, I mean
wasting of thenar, but what does a patient
unable to do?
Abduction. Abduction of thumb. So that is
lost in the
median nerve injury. Well, clearly, if it
happens there, it will definitely be lost.
But if the patient has got a full fist but
unable to just abduct the thumb then it’s
the median nerve lower than the carpal tunnel.
Okay. So these are the levels of median nerve
injury that they will ask you. Ulnar nerve injury.
Ulnar nerve injury, they’ll ask you whether
it can be -- before the epicondyle or after.
If you have an ulnar nerve injury at this
level, what will you get? What will the patient
sign, acutely and chronically?
You get a drop. No, you won’t. In the
you’ll get clawing of the hand. Acutely,
what is the patient unable to do? These two
fingers, isn’t it? So if the patient makes
a fist, these won’t flex, these two.
But with the long standing ulnar nerve injury,
you will get wasting of the hypothenar eminence,
claw hand. Now, in your exam, what are the
other things they will expect you to know
about ulnar nerve in the hand? What are the
functions of ulnar nerve in the hand? Jay-P,
what are the other functions of ulnar nerve
in the hand? What are things you can ask
the patient to do to check for ulnar nerve
Flexion of the medial two digits.
Okay. So you can ask them to make a fist,
fine, that may be lost, what else? Very good,
spreading the fingers. So that is abduction
of the fingers, adduction of the fingers, as well as scissoring.
Then adduction of the thumb and then abduction
of the little finger. All of these are for
ulnar nerve injury. So if we have somebody
with an ulnar nerve injury -- so that is lost
in ulnar nerve injury. Then you do the Froment’s
sign, which is giving your card between the thumb
and index finger, and then you pull the card out.
So if the patient has got an ulnar nerve injury,
the adductor pollicis is affected and the
patient will be unable to hold the card but
they will try to hold the card by flexing
the IP joint. Your finger is in that
position. That’s your
positive Froment’s sign. That’s the
classical of ulnar nerve injury and you’re
testing for adductor pollicis. Okay. Back
to you. What’s the mechanism of claw hand?
So if it’s a proximal injury, you get a
claw hand and if it’s distally, you don't
because you got a compensation. It’s
because if it's a proximal injury, you get --
Well, maybe I should just correct you there.
You will get a claw hand in both. Both in high
lesion as well as low lesion, you’ll get
a claw hand, but there’s a difference.
What’s the principle behind the claw hand? What’s
claw hand? Show me how does claw hand look. No.
How do you distinguish a claw hand from
Dupuytren's contracture or the Volkmann's
contracture? Okay. No, just by looking at
it. In a claw hand, the classical feature
is hyperextension of the MCP joint and flexion
of the IP joint.
So this is claw hand. These two joints have
to be hyperextended. That’s claw hand, because
if you get this, then you’re getting a number
of conditions. You can get Dupuytren's bone
contracture, Volkmann’s contracture, etc.
But in a claw hand, that’s claw
hand. So, that brings us to the muscles in
the hand. To understand claw hand, you need
to understand action of muscles. I said this
action, abduction of the fingers. That is
by, what interossei? Palmar or dorsal?
Dorsal, DAB. PAD AND DAB isn’t it? DAB is
dorsal interossei. So dorsal interossei abducts,
palmar interossei adducts. So there are four
and four, so eight muscles. Then you have
four hypothenar muscles, four thenar muscles.
So that’s 16, and finally, your lumbricals.
What is the action of lumbricals? This is
the action of lumbricals. That’s when you
put somebody on a plastic cast, you put them in
this position. Because in your normal resting
position of the hand, the lumbricals will
help in flexion of the MCP and extension of
the interphalangeal joints. That’s the
Now, spread your fingers, that’s all ulnar
nerve, bring it together, all ulnar nerve.
What about that? Which nerve is this? Radial?
Extension of the --
No, this action.
Median and ulnar.
Very good, yes. So these two are by ulnar
and these two are by median. I will explain
that bit of anatomy now. In the hand, we discuss
about 20 muscles, four thenar, four hypothenar,
four palmar interossei, four dorsal interossei,
and four lumbricals. All these are supplied
by the ulnar nerve except those on the radial
site which are called the LOAF muscles.
So the LOAF is supplied by the median nerve.
L stands for lateral to lumbricals, opponens
pollicis, abductor pollicis brevis, and flexor
pollicis brevis. These four are supplied -- well,
these four means these five, the lateral two
lumbricals; opponens pollicis, abductor pollicis
brevis, and flexor pollicis. These are supplied
by the median nerve. Everything else is by
ulnar. So this action, these two are by
two are by ulnar. So, what happens? If you
have an ulnar nerve injury, these two are
spared. That’s where you get the clawing.
So what happens in clawing? If you have your
hand in this position, when you have a nerve
injury, the opposite of that happens.
So, the opposite will be hyperextension of the
MCP and flexion of the interphalangeal joint.
These two are not affected. It will get clawing
only in those two. This is your claw hand.
Now, what you said was high lesion and low
lesion. If you have a high ulnar nerve injury,
then these two FDPs are also affected on there
because the FDP is supplied by ulnar nerve
quite higher up here. So your clawing will
be less because they’re also affected.
The hand is clawed less. But if there’s a low
injury, this nerve is intact, so it's
pulling it more. Okay. So that is your
ulnar nerve paradox. If you have a high lesion,
the clawing is less. If you have a low lesion
here, the clawing is more. That’s your ulnar
nerve injury, ulnar nerve paradox.
So if you got anything related to this in
your EMQs, usually, high lesion, low lesion.
They like high lesion for ulnar nerve
and radial nerve because it’s got quite a bit
of clinical significance. Did you understand
the clawing concepts, and the high lesion
and the low lesion? Okay. So that’s all
you need to know about the hand. At this level,
you don’t have to know about the arches.
You don’t have to know about the pulley
system or the other detailed anatomy. If you
want to ask me anything at this point of what
you’re wasting in other MCQs, if you want
to ask me anything at this point, I can answer
you but I’m not going to any more detailed
high anatomy because that will be too
much for you.
Is anybody wanting to know about pulleys?
No, I don’t think so. You need to know where
is the insertion of the FDP and FDS. Where
does the FDP insert, flexor digitorum profundus
insert? Base of the distal phalanx. And FDS?
No, because the FDS has got two strands coming
off. So the FDP and FDS comes here. FDS splits
into two. It’s called the Camper’s chiasm,
and it’s attached to the sides of the middle
phalanx. The FDP comes to the middle and attaches
to the distal phalanx. That’s your FDP and
Okay. The last bit here is the carpal tunnel,
extremely important. Attachments of the flexor
retinaculum. Do you want to say that? Attachment,
yup. Anyone, attachments of the flexor retinaculum.
Scaphoid? Scaphoid, on the radial
Trapezium. Trapezium, pisiform, and
what’s the bony
figure in your hand?
Oh no, hamate, hook of hamate. Okay. Something
like the flexor retinaculum, you need to know
the attachments because it’s quite an important
thing in the exam. This is your flexor retinaculum.
The proximal part of your flexor retinaculum
is your distal wrist crease. If you see your
distal wrist crease in your hand, that is
the proximal part of the retinaculum.
Then if you ask a patient to extend the thumb fully,
extend it fully, then the ulnar border of
the thumb forms the distal part of the retinaculum.
You extend it fully then identify the ulnar
border of the thumb. That’s your distal part
of the retinaculum. So this is your retinaculum.
The attachment here is the tubercle of the
scaphoid. Just remember that the carpal bones
are in a concave shape such that the retinaculum
does not attach to the entire bone. It just
attach to specific points. So on the scaphoid,
it’s called the tubercle of the scaphoid.
Pisiform. The pisiform is a small bone so
it attaches to the pisiform. Here, it is a
hook of the hamate, not the entire hamate,
hook of the hamate. And here, it’s a ridge
of the trapezium. So this is where the
So if you feel the bony prominence here, that
is your hook of hamate. Okay. Structures going
under the retinaculum, this is very important.
So you have the median nerve then you have
the FDP and FDS to this finger, so eight of
them, and FPL. So ten structures. Ten structures
go under the retinaculum, and what goes over
the retinaculum? Anyone? You know what, the
flexor carpi ulnaris, what did you say, is
that radialis? No. You know, some of the books
do say that but it’s not strictly accurate.
The flexor carpi radialis, does not go
under or over the retinaculum because it just
attaches to the base of the second metacarpal.
So it has nothing to do with the retinaculum.
Yeah, palmaris longus goes over the retinaculum.
What else? Ulnar nerve, ulnar artery, anything
else? If you have a patient coming with carpal
tunnel, carpal tunnel syndrome, what is
it classically feature? They’ll have tingling
and numbness in the lateral three digits,
right? If you test for sensation, can that be
affected? It can be. But what about sensation
here, can it be affected? No. Why not?
No. Here. It’s a branch.
Once it comes up before the --
That’s right. Okay. So, that’s the median
nerve. Approximately five centimeters before
the wrist crease, there is a branch called
the palmar cutaneous branch of the median
nerve, which supplies the thenar eminence.
So if we have a patient with carpal tunnel,
because this is running over the retinaculum,
that area is spared. How it work? After you
operate and see them postoperatively, you
need to test this because if that is lost,
then you have iatrogenically damaged the palmar
cutaneous branch. Okay. What is radial
artery? The radial artery comes here just
lateral to your FCR tendon. The deep branch
goes to the snuffbox, and then it comes out
through the thenar eminence to form the palmar
arch. But you have a superficial branch
which goes over the retinaculum, and anastomosis
with the ulnar artery and other side to form
the other part of the palmar arch. Essentially,
you have a superficial branch of the radial
artery, palmar cutaneous branch of the median
nerve, palmaris longus, ulnar nerve, ulnar
artery. So these are all structures going
over the retinaculum. Okay. So, we have covered
the entire upper
limb on this. Couple of nerves we haven’t
covered, one is the long thoracic nerve which
comes from C5, C6, and C7. So, root value
is C5, C6, C7. It lies in the midaxillary
line in the chest or the thorax, and it can
be damaged when you put in a chest drain or
do any surgery in the axillary region. So
that’s the long thoracic. Then a couple
of more nerves just for completion, we have
the nerve to subclavius from there and the
nerve to rhomboid. But I don’t think you
need to know for the part A, you just need
to -- if at all you’re asked, you just need
to get in your head that it has nothing to
do with the cords. It is just an isolated
nerve coming off the root, nerve to subclavius
and the nerve to rhomboid. Okay. I think
that pretty much covers everything.
We are spot on time. What I’m going to do
is go through the slides. As I said, all these
slides are going to be available for you online.
So you don’t have to worry. The purpose
of going to the slides is just to reinforce
what you have learned and for you to just
have a quick revision. Okay. I’ll come to
the axillary artery when
we do the thorax and axilla as well. The shoulder
joint, a lot of theory. I haven't cover