Proper functioning of our hand and
wrist is vital for everyday living.
So, it is important that as physicians, we understand the
basic anatomy and function to better help our patients
'cause our patients will come to us with any sort
of complaint that they have with the wrist and hand.
So taking a closer look at the anatomy of the fingers
here, we have 14 phalanges and 5 metacarpal bones
These articulate with our wrist
which is composed of 8 carpal bones
In our wrist, these 8 bones start with the
scaphoid which articulates with the radius.
The scaphoid is one of the
most commonly fractured bones.
The scaphoid articulates then with the
lunate and this relationship is important
because the scaphoid-lunate articulation
is a commonly injured articulation
due to strain on the different
ligaments in the hand.
The lunate then articulates
with the triquetrum,
and on the palmar surface of the triquetrum
you could find the pisiform bone.
The base of our thumb is the trapezium and
so this first metacarpal phalangeal joint
is a commonly irritated and inflammed joint
that could occur with osteoarthritis.
You also have your trapezoid which
articulates with the 2nd metacarpal
and your capitate is a large bone which then articulates
with the metacarpal bone of your middle finger.
On the palmar surface of the hand,
we have our extensor tendons.
These extensor tendons attach to our
fingers which help with finger extension.
These tendons usually will combine
and attach to the different muscles
which then attaches to
your lateral epicondyle
On your palmer surface, you
have your flexor tendons.
The flexor tendons attach to the muscles
which then attach to your medial epicondyle.
It's important to understand the innervation
of the nerves that go to the hand and wrist.
and so our radial nerve is responsible
for wrist and finger extension.
It also supplies innervation
to the extrinsic hand muscles.
It also does sensation for the thumb.
The ulnar nerve is
important for power grip.
The ulnar nerve innervates the flexor carpi ulnaris,
the ulnar half of the flexor digitorum profundus,
your lumbricals, and the dorsal and palmer
interossei and your hypothenar muscles.
You have your median nerve which is important
because it controls the pincer grip
and you want to, it innervates the extrinsic flexors
of the hand and the intrinsic thenar muscles.
In order to check for, whether or not a
nerve has been damaged or compromised,
one of the things that we could do
is to check for sensation testing.
So with sensation testing, you could check
whether or not the patient feels any pressure
but another thing you could check for
is to check for 2 point discrimination.
So what that means is the patient's able to
tell the difference between one point or two.
So what I do in the office is
usually have open paper clip
with 2 ends and what I do is I
put the tip of that paper clip
at the distal end of my patient's fingers
and ask them if they feel one point or two
and I alternate one or two points
to see if they could tell the difference,
It's important to know the nerve root
innervation and to understand the dermatomes
So understanding the different dermatomes, you
know where to place and check for sensation.
So when you look at the dermatome map in
your wrist and hand, there's a correlation
between the nerve root and which
region of the hand you are testing.
And so, if I wanted to test the different nerve roots, I
could check for whether or not the sensation's intact
and whether or not the patient could tell
between one and two point discrimination.
The nerve root sometimes be compromised
whether it be at the cervical region
or distal to it the elbow or
wrist or in the fingers itself.
And so when we are checking
the different nerve roots,
we have to think about what is
the region that we are checking.
So, if I wanted to check the C6 nerve root, what I
want to do is to check the distal portion of the thumb.
In order to check the c7 nerve root, we're gonna
be checking the distal aspect of the middle finger
and to check for the C8, we're
checking the distal and the pinkie.
Since some of these dermatomes overlap, to
check the distal ends of the finger here,
would be the most isolating
and the most precise.
The vascularity of the hand is applied by
the radial artery and the ulnar artery
These two arteries meet in the hand and form a
superficial palmar arch and a deep palmar arch.
Sometimes vascular compromise of
the hand can lead to discoloration
or patient's complaining of a
numbness and tingling or even
having a feeling of a coldness in the extremities.