Description

This video is about the joints of the wrist and hand.

In this video I break down every major articulation from the wrist to the fingertips – their anatomy, movement, and supporting ligaments.

Radiocarpal joint (Articulatio radiocarpea)
• Formed by the carpal articular surface of the radius and the articular disc (part of the triangular fibrocartilage complex)
• Articulates with: Scaphoid (os scaphoideum), Lunate (os lunatum), and Triquetrum (os triquetrum)
• Type: Ellipsoid (biaxial) joint
• Movements: Flexion (palmar flexion), extension (dorsiflexion), abduction (radial deviation), adduction (ulnar deviation)
• Ligaments:
 – Palmar radiocarpal ligament
 – Palmar ulnocarpal ligament
 – Dorsal radiocarpal ligament
 – Dorsal ulnocarpal ligament
 – Radial collateral ligament
 – Ulnar collateral ligament
• Capsule: Fibrous capsule reinforced by synovial membrane

Intercarpal joints (Articulationes intercarpeae)
• Between neighboring carpal bones in each row
• Type: Plane joints
• Ligaments:
 – Palmar intercarpal ligaments
 – Dorsal intercarpal ligaments
 – Interosseous intercarpal ligaments
• Function: Stabilize the carpal arch and assist in force transmission during load-bearing tasks

Midcarpal joint (Articulatio mediocarpea)
• Located between the proximal row and distal row of carpal bones
• Not a single joint cavity; rather, a composite joint with an S-shaped contour
• Movements: Augments wrist extension and radial/ulnar deviation
• Ligaments: Shares palmar and dorsal intercarpal ligaments with adjacent joints

Carpometacarpal joints (Articulationes carpometacarpeae)
• Between distal carpal row and bases of metacarpals (ossa metacarpi)
• Joints of digits II–V: Plane joints with limited motion
• Thumb (CMC I):
 – Saddle joint
 – Movements: Flexion, extension, abduction, adduction, opposition
• Ligaments:
 – Palmar and dorsal carpometacarpal ligaments

Intermetacarpal joints (Articulationes intermetacarpeae)
• Between bases of metacarpals II–V
• Ligaments:
 – Dorsal metacarpal ligaments
 – Palmar metacarpal ligaments
 – Interosseous metacarpal ligaments
• Function: Stabilize hand posture and allow slight gliding

Metacarpophalangeal joints (Articulationes metacarpophalangeae)
• Between heads of metacarpals and bases of proximal phalanges (phalanges proximales)
• Type: Condyloid joints (biaxial)
• Movements: Flexion, extension, abduction, adduction, circumduction
• Ligaments:
 – Medial and lateral collateral ligaments
 – Palmar ligaments (volar plates)
 – Deep transverse metacarpal ligament

Interphalangeal joints (Articulationes interphalangeae)
• Digits II–V:
 – Proximal interphalangeal joint (PIP)
 – Distal interphalangeal joint (DIP)
• Thumb:
 – One interphalangeal joint only
• Type: Hinge joints (uniaxial)
• Ligaments:
 – Medial and lateral collateral ligaments
 – Palmar ligaments (volar plates)
• Function: Allow flexion and extension with strong lateral support

Additional ligamentous and fascial structures (not primary joint stabilizers):
• Palmar aponeurosis – Protects flexor tendons and stabilizes soft tissue during grip
• Superficial transverse metacarpal ligament – Located at distal edge of palmar aponeurosis
• Palmar carpal ligament – Forms superficial component of the flexor retinaculum

Clinical notes covered:
• TFCC injury
• Thumb CMC osteoarthritis
• Ligament sprains and dislocations
• PIP joint instability and hyperextension
• Volar plate injury
• MCP collateral ligament rupture (Gamekeeper’s thumb)
• Joint movement during grasp, grip, and fine motor control

Sources:
• Kozlowski, T. (2017). Memorix Anatomy, 2nd ed.
• Standring, S. (2020). Gray’s Anatomy, 42nd ed.
• Platzer, W. (2004). Color Atlas of Human Anatomy Vol. 1: Locomotor System
• White TD, Folkens PA. (2005). The Human Bone Manual

Programs used: Complete Anatomy, Powerpoint, Canva, Camtasia

Transcript

0:00:00.080,0:00:04.480
In the last video, we looked at all the bones
in the wrist and hand, but bones on their own

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would just fall apart. So how do they stay
connected and move with such control when

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you make a fist or flex your fingers?
It all comes down to this – the joints.

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In this video, we’re going to go through every
major joint in the wrist and hand. So we will

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cover the radiocarpal joint, intercarpal joints,
and the midcarpal joint. Then we will move on to

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the carpometacarpal joints, intermetacarpal
joints, metacarpophalangeal joints,

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and finally, the interphalangeal joints.
What’s up everyone, my name is Taim. I’m

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a medical doctor, and I make animated medical
lectures to make different topics in medicine

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visually easier to understand. If you’d like a PDF
version or a quiz of this presentation, you can

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find it on my website, along with organized
video lectures to help with your studies.

0:00:45.840,0:00:48.800
Alright, let’s get started.
Let’s set the ground properly

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first and build brick by brick. So, for
orientation, we’re looking at the front

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of the hand now. In the previous video on the
radius and ulna, we covered the interosseous

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membrane and the distal radioulnar joint. We
have followed the joints down to this point.

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The next joint after that is the radiocarpal
joint, or simply, the wrist joint. Makes sense?

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Let’s start here.
The wrist joint is where the forearm meets the

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hand. And it’s not just a simple hinge. It’s made
up of several parts coming together. First we have

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the carpal articular surface of the radius.And
on the other side, interestingly, the ulna does

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not directly articulate with the carpal bones.
Instead there’s something called the articular

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disc that lies here, in some sources referred
to as the triangular fibrocartilage complex,

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or TFCC for short. It’s a thin but strong piece
of fibrocartilage, think of it as a shock absorber

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that also helps distribute forces across the
wrist and stabilize the ulnar side. Pretty cool.

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Now, distally, we’ve got three carpal
bones forming the other half of this joint:

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the scaphoid, lunate, and triquetrum. These
articulate with the radius and the articular

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disc to complete the radiocarpal joint.
And all of this is enclosed within a joint

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capsule. Like most synovial joints, we’ve
got a synovial membrane lining the inside,

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which secretes that nice lubricating synovial
fluid, and around it, a fibrous capsule that

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gives the joint its strength. You’ll see some
sources refer to this fibrous capsule as part

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of the general ligamentous support, and that’s
fair, because it does add passive stability.

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But in addition to the capsule, the wrist joint
is reinforced by a whole set of ligaments that

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support it from all directions. These ligaments
are typically grouped based on their position,

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on the palmar side we’ve got the palmar
radiocarpal ligament, and right next to it,

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the palmar ulnocarpal ligament. These two help
stabilize the joint from the front, connecting

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the radius and ulna to the carpal bones.
On the sides, there’s the ulnar collateral

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ligament, which runs from the styloid process of
the ulna to the triquetrum and pisiform. And on

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the other side, there’s the radial collateral
ligament, which goes from the styloid process

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of the radius to the scaphoid. These two
help prevent excessive sideways movement.

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Now let’s flip around and take a look at
the back of the wrist. Here, you’ll see the

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dorsal radiocarpal ligament, which is basically
the posterior counterpart to the palmar one,

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stabilizing the joint from behind. And we can also
see the dorsal ulnocarpal ligament here as well.

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So that’s the radiocarpal joint. And what makes
it really useful is what it can do. It allows

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palmar flexion, that’s bending the wrist forward,
and dorsiflexion, which is just extension. Then

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we also have adduction, or ulnar deviation,
where the hand moves toward the pinky side,

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and abduction, or radial deviation, when it moves
toward the thumb. It’s a biaxial ellipsoid joint,

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which just means it can move in
two planes, and that makes it

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perfect for those smooth wrist circles.
Alright, let’s now move a little bit down

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to the intercarpal joints. These are the joints
between the individual carpal bones themselves,

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like little articulations between
neighbors in the same row.

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And just like the wrist, they’re held together
by ligaments. On the palmar side, these are

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collectively referred to as the palmar intercarpal
ligaments, and on the back, they’re reinforced by

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the dorsal intercarpal ligaments. These ligaments
don’t just stabilize, they also help with force

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distribution across the wrist when the hand is
under load, like during push-ups or gripping.

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Another joint in this region is the midcarpal
joint. So, if we look at the carpal bones again,

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remember they’re arranged into two rows,
a proximal row and a distal row. And the

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joint formed between these two rows
is what we call the midcarpal joint.

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Now, it’s not one single joint space,
but a collection of articulations between

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the proximal and distal carpal bones. And
because of the way these bones are shaped,

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the midcarpal joint as a whole has a bit
of an S-shape when viewed from the side.

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It’s not a huge contributor to movement on its
own, but combined with the radiocarpal joint,

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it significantly increases
the wrist’s range of motion,

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especially in extension, or wrist bending back.
Functionally and anatomically, the midcarpal

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joint is closely related to the intercarpal
joints. In fact, it is reinforced by the same

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sets of ligaments we just talked about, the
palmar and dorsal intercarpal ligaments. So

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although they’re named differently, they
more or less cover almost the same area.

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Alright. So we’ve now covered all the joints
up until this region, the radiocarpal joint,

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the intercarpal joints, and the midcarpal joint.
The next two are the carpometacarpal joints

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and the intermetacarpal joints.
Now before we jump into those,

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let’s orientate. Here are your carpal
bones. These are your metacarpal bones,

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and these are the phalanges, or finger bones. That
way, the carpometacarpal joints, or CMC joints,

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are right here, between the carpal bones
and the metacarpal bases, hence the name.

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These joints are strongly supported by ligaments,
named, as you’d expect, the palmar and dorsal

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carpometacarpal ligaments. They keep the bases of
the hand bones securely linked to the wrist bones.

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But now look at this one, the CMC joint of the
thumb. Notice how different it looks? That’s

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because it is different. This joint is a saddle
joint, which gives it way more mobility than the

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other CMC joints. It allows not just flexion
and extension, but also abduction, adduction,

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and that cool thumb movement called opposition,
where you touch your thumb to your fingertips.

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That’s all thanks to the CMC joint of the thumb.
So that was the CMC joints. Right next to them,

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we’ve got the intermetacarpal joints. These
are the joints between the bases of the 2nd

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to 5th metacarpals, so, between the
long bones of the hand themselves.

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They’re held together by another set
of ligaments called the dorsal, palmar,

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and interosseous metacarpal ligaments.
Alright, moving further down, we get to the

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metacarpophalangeal joints, or MCP joints. These
are the joints between the metacarpals and the

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proximal phalanges. Basically, your knuckles.
What’s interesting with these is just how

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well-protected they are. They’ve got
dorsal, palmar, and interosseous ligaments,

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just like the intermetacarpal joints, but also
the medial and lateral collateral ligaments,

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and the deep transverse metacarpal ligament.
These work together to stabilize the

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fingers during flexion, especially when
gripping or pushing against something.

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The next joints lie between the finger bones
themselves, we have the interphalangeal joints,

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or IP joints. In each finger, you’ve got
a proximal interphalangeal joint, or PIP,

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and a distal interphalangeal joint, or DIP.
Now, the thumb only has one interphalangeal joint,

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not two like the rest of the fingers.
That’s because the thumb has only two

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phalanges instead of three. So we just call it the
interphalangeal joint of the thumb. Easy enough.

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Now what’s cool about these joints is how
compact but stable they are. They’re supported

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by medial and lateral collateral ligaments,
which keep the joint from wiggling sideways,

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and also by palmar ligaments, which help resist
hyperextension. You’ll sometimes hear these

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referred to as volar plates in clinical settings.
So that is it for the joints. We’ve gone through

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all the major articulations of the
wrist and hand, and also all the

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ligaments that support these joints.
But you might be wondering, what about

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these other ligaments you’re seeing here?
Like the palmar aponeurosis, the superficial

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transverse metacarpal ligament,
and the palmar carpal ligament?

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These structures are absolutely important,
but they’re not primarily responsible

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for stabilizing joints. Instead, they help
define the shape and structure of the hand,

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and more importantly, they guide and protect the
tendons of the muscles that move your fingers.

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For example, the palmar aponeurosis is that
thick triangular sheet in the middle of the palm,

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and it functions like a stabilizing roof for
the flexor tendons. The superficial transverse

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metacarpal ligament, sitting at the base of the
palmar aponeurosis, helps keep the soft tissue

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in place when you grip something tightly.
And the palmar carpal ligament, up here,

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is part of the flexor retinaculum complex that
maintains the tendons’ alignment across the wrist.

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So, these structures are more about soft
tissue organization and tendon protection,

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rather than joint mechanics. But if you’re
curious about how all of this ties together

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with hand movement, I’ve made a full video just
on the muscles of the hand, and I’ve also created

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a detailed visual PDF study note that breaks
down the tendinous sheaths and support ligaments

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layer by layer if you’re interested.
Before we finish, here’s one final tip.

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The names of the joints we’ve covered are directly
tied to their locations. Radiocarpal = radius to

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carpus. Carpometacarpal = carpus to metacarpal.
Metacarpophalangeal = metacarpals to phalanges.

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And so on. Once you grasp the naming logic, the
anatomy gets a whole lot easier to remember.

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And with that, we’ve officially covered all the
bones and joints of the upper limb. We covered

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the axial and appendicular upper skeleton.
So what’s next? In the next couple videos,

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we are going to cover the lower limb. We’ll look
at the bones and ligaments of the pelvis, femur,

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fibula, tibia, and foot, starting
with the hip bone, or pelvis.

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Click the next video, and I’ll see you there.
If you want a handmade PDF version of this

0:10:07.440,0:10:11.440
lecture, take a quiz to test your knowledge,
or access an organized list of all my videos,

0:10:11.440,0:10:14.480
you can find everything on my website.
Thanks for watching! See you in the next one.