Description

Joints of the Thoracic Cage (Ribs, Sternum & Vertebrae) | Anatomy

Structures covered in this video:

Joints Between Ribs and Vertebrae:
• Joint of the head of the rib (Articulatio capitis costae)
 • Superior costal facet (Fovea costalis superior)
 • Inferior costal facet (Fovea costalis inferior)
 • Intervertebral disc (Discus intervertebralis)
 • Radiate ligament (Ligamentum capitis costae radiatum)
 • Intra-articular ligament (Ligamentum capitis costae intraarticulare)
• Costotransverse joint (Articulatio costotransversaria)
 • Costotransverse ligament (Ligamentum costotransversarium)
 • Superior costotransverse ligament (Ligamentum costotransversarium superius)
 • Lateral costotransverse ligament (Ligamentum costotransversarium laterale)

Joints Along the Rib Shaft:
• Costochondral joints (Articulationes costochondrales)
• Interchondral joints (Articulationes interchondrales)

Associated Membranes and Muscles:
• External intercostal membrane
• Internal intercostal membrane
• External intercostal muscles (Musculi intercostales externi)
• Internal intercostal muscles (Musculi intercostales interni)

Joints Between Ribs and Sternum:
• Sternocostal joints (Articulationes sternocostales) – Ribs 2–7
• First sternocostal joint – Synchondrosis (Synchondrosis sternocostalis prima)
• Manubriosternal joint (Symphysis manubriosternalis)
• Xiphisternal joint (Symphysis xiphosternalis)

Supporting Structures:
• Radiate sternocostal ligament (Ligamentum sternocostale radiatum)
• Sternal membrane

Movements and Function:
• Rib cage expansion and contraction during respiration
• Gliding movements at synovial joints
• Stability and flexibility of thoracic wall
• Protection of thoracic organs

Clinical anatomy and conditions discussed:
• Rib fracture and costotransverse pain
• Thoracic stiffness with age (ossified interchondral joints)
• Thoracic trauma and ligament injury
• Use of sternal angle as a rib-counting landmark
• Relevance of intercostal spaces in respiration

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
In the previous videos we covered the bone anatomy of the vertebral column,
0:04
Ribs, and the sternum. Together, they form a solid cage around the heart and lungs. But the
0:10
thorax also needs to move with every breath you take, it expands and contracts with every breath.
0:16
To let that happen safely, that’s where the joints come in. They connect these
0:19
bones while still allowing flexibility. So the way we’re gonna cover them is by
0:21
first look at the joints between the ribs and the vertebral column back there. We’re gonna
0:26
look at the joints along the rib shaft, and the joints between the ribs and the sternum.
0:30
What’s up everyone, my name is Taim. I’m a medical doctor, and I make animated medical lectures to
0:34
make different topics in medicine visually easier to understand. If you’d like a PDF version or a
0:39
quiz of this presentation, you can find it on my website, along with organized video lectures
0:43
to help with your studies. Alright, let’s get started.
Joints between Ribs and Vertebral Column
0:46
So let’s start with the joints between the ribs and the vertebral column. And for this,
0:50
let’s isolate the vertebra, two ribs, and look at the joints. In general, there are two major
0:56
joints here that we need to talk about, one is called the joint of the head of the rib,
1:00
and the other one is the costovertebral joint. Let’s look at this a little bit closer. The joint
Costovertebral Joint
1:06
of the head of the rib is here. This is a synovial joint, and the articulating surfaces are the head
1:12
of the rib, which usually has two articular facets as you see here. These connect to the
1:18
superior costal facet of the vertebra below, and the inferior costal facet of the vertebra above,
1:24
with the intervertebral disc sitting between them. So, one rib head typically touches two vertebrae.
1:31
This setup gives the thoracic cage its stability but, this joint is actually supported by two main
1:37
ligaments. First, we have the radiate ligament. It spreads out from the anterior surface of the
1:42
rib head and attaches to both vertebrae and the disc. It basically locks the joint down from the
1:48
front. Then there’s the intra-articular ligament, which connects the ridge between the two articular
1:54
facets of the rib to the intervertebral disc, and that divides the joint into two compartments.
2:09
Both of these ligaments work together to stabilize the joint but still allow for that slight
2:14
rotation the rib needs when you breathe. Now let’s move on to the second joint,
Costotransverse Joint
2:18
the costotransverse joint. This one is located between the tubercle of the rib and the transverse
2:24
process of the vertebra at the same level. So this is a simpler one-to-one articulation.
2:30
It’s also a synovial joint and allows slight gliding movements. That gliding varies though
2:35
depending on the rib, upper ribs rotate more, and lower ribs glide more. The costotransverse
2:42
joint is held in place by three supporting ligaments. First is the costotransverse ligament,
2:48
which connects the neck of the rib to the transverse process. Then we have the
2:52
superior costotransverse ligament, which runs up to the transverse process of the vertebra
2:57
above. And the lateral costotransverse ligament, that connects the tubercle of
3:03
the rib to the tip of the transverse process. If some of these ligaments are injured, like in
3:09
blunt trauma or rib fractures, pain in this area can often be mistaken for back or muscular pain.
3:15
So, that’s it for the joints between the ribs and the vertebral column. Next,
Joints along the Rib Shaft
3:20
let’s move on to the joints along the rib shaft. What does that mean? Basically, these are joints
3:25
located between different parts of the rib cage, not at the spine and not at the sternum,
3:30
but in between, along the rib itself. These joints help connect the ribs to their costal cartilages
3:37
and even connect the cartilages to each other, The first one on the list are costochondral
Costochondral Junction
3:42
joints. Where are the costochondral joints? Here you can see the costal cartilage, here’s the rib,
3:48
and in between them the costochondral joint, basically where these two meet.
3:54
These are synchondroses, so they’re cartilaginous joints. So the way this works is that essentially,
4:00
the rib and its cartilage are fused by hyaline cartilage. This type of joint doesn’t allow any
4:06
movement. It’s strong and rigid, which makes sense because we don’t want this part of the
4:10
rib cage flexing too much. All the ribs have these joints, so this connection exists from
4:16
the first rib all the way down to the tenth. After the tenth, the ribs are floating and don’t connect
4:22
to costal cartilage in the same way. Alright. Then we have the interchondral joints,
Interchondral Joints
4:28
and here you can see them highlighted. These are the joints between the costal cartilages of ribs
4:33
6 through 10. Unlike the costochondral joints, these are usually synovial, meaning they do
4:39
allow a bit of gliding movement that actually help your rib cage expand during breathing,
4:44
especially when taking deep breaths. Some of these joints can ossify with age, and that can
4:49
make the rib cage feel stiffer in older people. Now. I want to point out that there are also
External and Internal Intercostal Membranes
4:55
two membranes here that aren’t joints, but they’re still important in this area. In between the ribs,
5:02
we got something called the external intercostal membrane. This membrane is a continuation of the
5:08
external intercostal muscles and covers the front part of the intercostal space.
5:13
The external intercostal muscles themselves run obliquely downward and forward, and they
5:18
help lift the ribs during inspiration. Deep to them, we have the internal intercostal muscles,
5:24
which run in the opposite direction, so downward and backward, and help with forced expiration by
5:30
pulling the ribs downward. On the posterior end, we can see the internal intercostal membrane,
5:36
which is the posterior continuation of the internal muscles, near the vertebrae.
5:42
These membranes aren’t joints by definition, but they’re tightly linked to rib movement
5:46
and function, so definitely worth mentioning. So that was it for the joints along the rib shaft.
Joints between the Ribs and Sternum
5:52
Let’s now do the joints between the ribs and the sternum. So now we’re looking at the joints
5:57
where the front of the ribs meet the sternum, and we’ll just go through them one by one.
First Rib Joint
6:02
First is the first rib joint. This is a synchondrosis, so it’s a cartilaginous,
6:08
immovable joint, basically a firm, direct attachment between the first rib and the manubrium
6:13
of the sternum. This one is unique because the other ribs don’t use this type of joint.
Sternocostal Joints
6:18
The rest of the true ribs, that is ribs 2 through 7, connect to the sternum through what we call
6:24
the sternocostal joints. These are synovial joints, which means they do allow movement,
6:30
and that’s super helpful for the rib cage to expand and contract.
Manubriosternal Joint
6:34
Other joints in this area, we can see the manubriosternal joint,
6:38
located between the manubrium and the body of the sternum. This is a symphysis, so it’s a slightly
6:44
movable joint made of fibrocartilage. It forms the sternal angle, which you can often feel on
6:50
yourself. Fun fact, it’s used as a landmark in clinical exams to locate the second rib.
Xiphisternal joint
6:56
Below that is the xiphisternal joint. It’s also a symphysis and it’s between the body
7:00
of the sternum and the xiphoid process. This joint tends to ossify with age,
7:05
so it becomes less mobile over time. Now. There are also a couple of supporting
Radiate Sternocostal Ligaments
7:10
structures that are worth mentioning here as well. First up is the radiate sternocostal ligament, you
7:16
can see it here. It spreads out like a fan from the costal cartilage to the sternum, reinforcing
7:22
the front of the sternocostal joints. Then we have the sternal membrane, which covers the front of
Sternal Membrane
7:28
the sternum and helps stabilize all these joints. So that’s it for the joints between
7:34
the ribs and the breastbone. And with that, we’ve now covered
7:37
all the main joints of the thoracic cage. That means we’ve officially gone through
Outro
7:42
all the bones and joints of the axial skeleton in this skeletal video series, including the skull,
7:47
the thorax, and the vertebral column. Next up, we’re going to begin covering
7:52
the bones and joints of the upper limb. Starting from the top of the list, we’ll
7:56
go through the clavicle, scapula, humerus, radius, ulna, and the bones of the hand.
8:02
So the next video will be about the clavicle. Click on the next video
8:05
to continue learning, and I’ll see you there. And if you want a handmade PDF version of this
8:09
lecture, take a quiz to test your knowledge, or access an organized list of all my videos,
8:14
you can find everything on my website. Thanks for watching! See you in the next one.