Considerations of the Wrist and Hand

00:00 Proper functioning of our hand and wrist is vital for everyday living.

00:05 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.

00:17 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.

00:33 The scaphoid is one of the most commonly fractured bones.

00:37 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.

00:50 The lunate then articulates with the triquetrum, and on the palmar surface of the triquetrum you could find the pisiform bone.

00:59 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.

01:12 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.

01:24 On the dorsal surface of the hand, we have our extensor tendons.

01:28 These extensor tendons attach to our fingers which help with finger extension.

01:32 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.

01:44 The flexor tendons attach to the muscles which then attach to your medial epicondyle.

01:50 It's important to understand the innervation of the nerves that go to the hand and wrist.

01:55 and so our radial nerve is responsible for wrist and finger extension.

02:01 It also supplies innervation to the extrinsic hand muscles.

02:06 It also does sensation for the thumb.

02:11 The ulnar nerve is important for power grip.

02:14 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.

02:27 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.

02:39 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.

02:47 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.

02:56 So what that means is the patient's able to tell the difference between one point or two.

03:00 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.

03:30 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.

03:39 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.

03:51 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.

03:59 And so when we are checking the different nerve roots, we have to think about what is the region that we are checking.

04:06 So, if I wanted to check the C6 nerve root, what I want to do is to check the distal portion of the thumb.

04:12 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.

04:21 Since some of these dermatomes overlap, to check the distal ends of the finger here, would be the most isolating and the most precise.

04:31 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.

04:44 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.