Description

Elbow Joint (Ligaments, Movements & Common Injuries) | Anatomy

This video covers the anatomy of the elbow joint. We look visually at the three joints that make up the elbow, including their articulating surfaces, ligaments, synovial membrane, capsule, and bursae.

Bones Involved in the Elbow Joint:
• Humerus (humerus)
• Radius (radius) – lateral bone of the forearm (thumb side)
• Ulna (ulna) – medial bone of the forearm (pinky side)

Joints within the Elbow Joint:

Humeroulnar joint (articulatio humeroulnaris)
 • Classic hinge joint
 • Trochlea of humerus (trochlea humeri) + Trochlear notch of ulna (incisura trochlearis ulnae)
 • Allows flexion and extension

Proximal radioulnar joint (articulatio radioulnaris proximalis)
 • Pivot joint
 • Articular circumference of radius (circumferentia articularis radii) + Radial notch of ulna (incisura radialis ulnae)
 • Enables pronation and supination

Humeroradial joint (articulatio humeroradialis)
 • Ball-and-socket joint (functionally part of hinge system)
 • Capitulum of humerus (capitulum humeri) + Articular facet of radius (fovea articularis radii)

Synovial Features & Capsule:
• Synovial membrane (membrana synovialis) – surrounds all 3 joints in a single cavity
• Fibrous capsule (capsula fibrosa) – encloses and stabilizes the joint
• Sacciform recess (recessus sacciformis) – synovial fold over neck of radius to allow rotation

Ligaments of the Elbow Joint:
• Ulnar collateral ligament (ligamentum collaterale ulnare)
 • From medial epicondyle (epicondylus medialis) to ulna
 • Consists of anterior, posterior, and oblique bands
 • Stabilizes against valgus stress

• Radial collateral ligament (ligamentum collaterale radiale)
 • From lateral epicondyle (epicondylus lateralis)
 • Blends with annular ligament

• Annular ligament of radius (ligamentum anulare radii)
 • Encircles the head of radius and holds it in the radial notch
 • Allows pronation and supination

• Quadrate ligament (ligamentum quadratum)
 • Short band between neck of radius and radial notch of ulna
 • Adds rotational stability

Common Elbow Joint Injuries & Conditions:
• Nursemaid’s elbow (radial head subluxation) – common in children
• Olecranon bursitis – inflammation of the subcutaneous olecranon bursa
• Valgus overload injuries – from throwing or trauma
• Dislocation of the radial head – due to annular ligament weakness in toddlers
• Elbow arthritis – affects the entire joint capsule due to shared synovial cavity

Bursae of the Elbow Joint:
• Subcutaneous olecranon bursa (bursa subcutanea olecrani) – between skin and olecranon (olecranon)
• Subtendinous triceps bursa – beneath triceps tendon
• Function: reduce friction during movement

Movements of the Elbow Joint:
• Flexion / Extension – at humeroulnar and humeroradial joints
• Pronation / Supination – at proximal radioulnar joint

Structures Mentioned in the Video:
• Trochlea of humerus (trochlea humeri)
• Capitulum of humerus (capitulum humeri)
• Radial notch of ulna (incisura radialis ulnae)
• Articular circumference of radius (circumferentia articularis radii)
• Articular facet of radius (fovea articularis radii)
• Olecranon of ulna (olecranon)
• Medial epicondyle (epicondylus medialis)
• Lateral epicondyle (epicondylus lateralis)
• Neck of radius (collum radii)
• Radial head (caput radii)

Clinical Relevance Summary:
• Joint stability maintained by ligaments and capsule
• Joint motion involves coordinated action of all three articulations
• Common injuries include ligament tears, bursitis, and nursemaid’s elbow
• Ligaments and bursae are frequent sources of pain in overuse or trauma

Sources:
• Kozlowski, T. (2017). Memorix Anatomy, 2nd ed.
• Standring S. (2020). Gray’s Anatomy, 42nd edition
• Tubbs RS, Shoja MM, Loukas M. (2016). Bergman’s Encyclopedia of Human Anatomic Variation
• White TD, Folkens PA. (2005). The Human Bone Manual

Programs used: Complete Anatomy, Biorender, PowerPoint

Transcript

Introduction & Content
0:00
This is a video about the elbow joint. How it bends,
0:03
its articulations, and supporting structures. We are going to cover it by going through the
0:07
Joints within the elbow joint. It sounds weird but there are three bones to this
0:11
joint that provide different movement. After this we’ll briefly cover the common
0:16
parts of this joint, like its capsule, different ligaments and the bursae.
0:20
What’s up everyone, my name is Taim. I’m a medical doctor, and I make animated medical lectures to
0:24
make different topics in medicine visually easier to understand. If you’d like a PDF version or a
0:28
quiz of this presentation, you can find it on my website, along with organized video lectures
0:32
to help with your studies. Alright, let’s get started.
Joints within the elbow joint
0:35
Joints within the elbow joint. Feels so weird to say it, but let me show you specifically what I
0:40
mean. We will first strip away all the connective tissue until we see the bones. What we see now
0:46
is the humerus of your upper arm, and radius and ulna of the lower arm. Radius on the side of the
0:52
thumb, and ulna on the side of the pinky. Now, usually a joint has two articulating
Proximal Humerus
0:58
surfaces. However, this joint is special because there are different articulating
1:03
surfaces that make up three joints within. Let me show you how. Each of these bones are
1:09
shaped in a way that allow the joint to move in a specific way. So first,
1:13
we have the trochlea of the humerus. This is the distal end of the humerus, and its specifically
1:18
shaped to match the trochlear notch of the ulna, which hugs around it to form a tight hinge.
1:24
Then, just lateral to that, we’ve got the capitulum of the humerus, a rounded structure
1:29
that articulates with the head of the radius, or the articular area of the proximal part of
1:34
the radius if you wanna sound correct. The head of the radius has two parts here. A
1:39
shallow articular facet on top, and the articular circumference along its edge. Just beside that,
1:45
on the ulna, we find the radial notch. These are the pieces we’ll need to define all three joints.
Humeroulnar joint
1:52
First one is called the humeroulnar joint. This is a classic hinge joint, like a door hinge,
1:58
and it allows flexion and extension of the elbow. Pretty straightforward, but very stable thanks
2:03
to the deep trochlear notch wrapping around the trochlea. That close fit is also why this
2:08
joint doesn’t allow any side-to-side movement. Next, we move to the joint between the articular
Proximal Radioulnar Joint
2:14
circumference of the radius and the radial notch of the ulna, this is the proximal radioulnar
2:19
joint. It’s a pivot joint, and this means that the head of the radius spins against the ulna.
2:26
That’s how pronation and supination happen. Watch as we rotate the radius over the ulna,
2:32
this is pronation, basically palm facing down. When it rotates back, this is supination,
2:38
palm facing up. Both of these are pure rotational movements happening at this joint.
Humeroradial Joint
2:44
The third articulation is between the capitulum of the humerus and the articular facet of the
2:49
radial head. This is the humeroradial joint. Technically, it’s a ball-and-socket joint,
2:55
but in practice, it mostly follows the movement of the humeroulnar joint, so it flexes and extends
3:01
along with it. It also helps transmit compressive force from the hand and radius into the humerus,
3:07
like when you push yourself up off the ground. So, those are the three joints that make
3:12
up the elbow, and they’re all packed into one functional unit.
Synovial Membrane
3:16
By a synovial membrane that surrounds them. This synovial lining produces something called synovial
3:22
fluid, which lubricates the articulating surfaces, reduces friction, and allows smooth movement.
3:28
Just to clear any confusion you might have, even though we’ve been talking about three joints,
3:33
there are no physical walls or septae dividing them. It’s all one continuous synovial cavity,
3:39
wrapped inside a single membrane. So if inflammation happens, like in arthritis,
3:44
it affects the entire joint capsule, not just one of the compartments.
3:49
Let’s now look at the joint also from the posterior view to be able to understand it
3:52
from all angles. Around the joint capsule, there are supporting structures called
Ligaments of the Elbow Joint
3:57
ligaments. These ligaments wrap around the capsule and help hold everything together.
Ulnar Collateral Ligament
4:03
First we can see the ulnar collateral ligament. This is a strong triangular ligament on the medial
4:08
side, connecting the medial epicondyle of the humerus to the ulna. It’s made of three parts:
4:14
the anterior, posterior, and oblique bands. And it plays a huge role in resisting valgus stress,
4:22
that’s force pushing the forearm laterally, like what happens in overhead throwing.
Radial Collateral Ligament
4:27
Then we’ve got the radial collateral ligament on the lateral side. This ligament extends
4:32
from the lateral epicondyle of the humerus, but unlike the ulnar collateral, it doesn’t
4:36
attach directly to a bone on the forearm. Instead, it blends with the annular ligament,
4:42
helping reinforce the lateral elbow without limiting rotation. This connection helps keep
4:47
the radius stable during supination and pronation, working together with
4:51
the annular ligament like one functional unit The annular ligament in its own though is special,
Annular Ligament of Radius
4:58
this ligament wraps around the head of the radius and anchors it to the ulna at the radial notch,
5:03
keeping the radius in place while still allowing it to rotate during pronation and supination.
5:09
Clinical note here, in kids under 2, the annular ligament isn’t fully developed.
5:14
So if you pull on their forearm too hard, like yanking them up by the arm, the radial head can
5:18
slip out partially. This is called nursemaid’s elbow, or radial head subluxation. It’s the
5:24
most common upper limb injury in preschool-aged children. It usually presents with sudden refusal
5:30
to use the arm, but it reduces easily with a little supination and flexion. It’s a very
5:34
common reason for visits to the emergency room. Anyways, then we have the quadrate ligament,
Quadrate Ligament
5:40
this is a short, thick structure between the neck of the radius and the radial notch of the ulna.
5:45
It’s small, but it helps limit excessive rotation and adds a bit of stability between those bones.
Fibrous Capsule & Sacciform Recess
5:52
Now apart from the ligaments, this joint is also enclosed in a tough outer layer called the fibrous
5:58
capsule, or fibrous layer. It reinforces the joint externally and attaches to the humerus
6:04
just below the epicondyles, and to the ulna and radius around their articular margins.
6:09
At the front, you’ll also notice this little pouch-looking extension, this is the sacciform
6:15
recess. It’s basically a fold in the synovial membrane that extends over the neck of the radius,
6:20
to allow free rotation during pronation and supination without pinching the capsule.
6:26
Now, in addition to all the ligaments, synovial membranes and all the other
6:30
structures supporting the elbow. The elbow joint actually has another
Bursae of the Elbow Joint
6:34
supporting system, called bursae. These are small, friction-reducing pillows we refer to as bursae.
6:40
Think of these as synovial-fluid filled cushions that reduce friction between soft
6:44
tissues and bone during movement. The most well-known here is the
Subcutaneous Olecranon Bursa
6:48
subcutaneous olecranon bursa, located right over the tip of the elbow, between the skin
6:53
and the olecranon. You can’t see it normally, but when it gets inflamed, it’s very obvious.
6:59
This condition is called olecranon bursitis, and you’ll usually see it as a swollen,
7:04
red, and tender elbow. Could be from repetitive pressure, like leaning on your
7:08
elbows too much, or from trauma or infection. There are also other bursae around the elbow,
7:13
like the subtendinous bursa of the triceps brachii, which sits deeper near the insertion
7:18
of the triceps, but the one you’ll see most clinically is the subcutaneous olecranon bursa.
Next Topic
7:23
So that was everything I had for the elbow joint, I really hope it all made sense.
7:28
In the next video in the upper limb skeletal series, we’ll talk about the bones and joints
7:32
of the forearm. The ulna and radius, and how they’re held together. Click
7:36
the next video, and I’ll see you there. If you want a handmade PDF version of this
7:40
lecture, take a quiz to test your knowledge, or access an organized list of all my videos,
7:44
you can find everything on my website. Thanks for watching! See you in the next one.