Description

Vertebral Column (Bones, Regions, Curvatures & Landmarks) | Anatomy

Structures covered in this video:
Vertebral Column Regions:
• Cervical vertebrae (Vertebrae cervicales)
• Thoracic vertebrae (Vertebrae thoracicae)
• Lumbar vertebrae (Vertebrae lumbales)
• Sacral vertebrae (Vertebrae sacrales)
• Coccygeal vertebrae (Vertebrae coccygeae)

Physiological Curvatures:
• Cervical lordosis (Lordosis cervicalis)
• Thoracic kyphosis (Kyphosis thoracica)
• Lumbar lordosis (Lordosis lumbalis)
• Sacral kyphosis (Kyphosis sacralis)

Abnormal Spinal Curvatures (Clinical):
• Hyperlordosis
• Hyperkyphosis
• Scoliosis

General Vertebral Structures (Common):
• Vertebral body (Corpus vertebrae)
• Vertebral arch (Arcus vertebrae)
• Lamina (Lamina arcus vertebrae)
• Pedicle (Pediculus arcus vertebrae)
• Vertebral foramen (Foramen vertebrale)
• Spinous process (Processus spinosus)
• Transverse process (Processus transversus)
• Superior articular process (Processus articularis superior)
• Inferior articular process (Processus articularis inferior)
• Intervertebral foramen (Foramen intervertebrale)
• Vertebral canal (Canalis vertebralis)
• Intervertebral disc (Discus intervertebralis)
• Annular epiphysis (Epiphysis anularis)

Cervical Vertebrae Specifics:
• Carotid tubercle (Tuberculum caroticum)
• Anterior tubercle (Tuberculum anterius)
• Posterior tubercle (Tuberculum posterius)
• Groove for spinal nerve (Sulcus nervi spinalis)
• Bifid spinous process (Processus spinosus bifidus)
• Transverse foramen (Foramen transversarium)

Atlas (C1):
• Anterior arch (Arcus anterior atlantis)
• Posterior arch (Arcus posterior atlantis)
• Lateral mass (Massa lateralis atlantis)
• Superior articular facet (Facies articularis superior)
• Anterior tubercle (Tuberculum anterius)
• Posterior tubercle (Tuberculum posterius)
• Groove for vertebral artery (Sulcus arteriae vertebralis)
• Facet for dens (Fovea dentis)

Axis (C2):
• Dens (Dens axis)
• Anterior articular facet (Facies articularis anterior dentis)
• Posterior articular facet (Facies articularis posterior dentis)

Thoracic Vertebrae (Typical T2–T9):
• Superior costal facet (Fovea costalis superior)
• Inferior costal facet (Fovea costalis inferior)
• Transverse costal facet (Fovea costalis transversalis)

Thoracic Vertebrae (Atypical):
• T1: Single full facet (Fovea costalis totalis)
• T10–T12: Single full facet, rudimentary transverse facet

Lumbar Vertebrae:
• Costal process (Processus costalis)
• Kidney-shaped vertebral body (Corpus reniforme)
• Quadrate spinous process (Processus spinosus quadratus)

Sacrum:
• Sacral base (Basis ossis sacri)
• Sacral apex (Apex ossis sacri)
• Sacral promontory (Promontorium ossis sacri)
• Sacral wings (Ala ossis sacri)
• Auricular surface (Facies auricularis)
• Sacral tuberosity (Tuberositas sacralis)
• Anterior sacral foramina (Foramina sacralia anteriora)
• Transverse ridges (Lineae transversae)
• Posterior sacral foramina (Foramina sacralia posteriora)
• Median sacral crest (Crista sacralis mediana)
• Medial sacral crest (Crista sacralis medialis)
• Lateral sacral crest (Crista sacralis lateralis)
• Sacral canal (Canalis sacralis)
• Sacral hiatus (Hiatus sacralis)
• Sacral horns (Cornua sacralia)

Coccyx:
• Coccygeal cornua (Cornua coccygea)

Structures Mentioned in Vertebral Canal:
• Spinal cord (Medulla spinalis)
• Meninges (Meninges spinales)
• Anterior spinal artery (Arteria spinalis anterior)
• Posterior spinal artery (Arteria spinalis posterior)
• Vertebral venous plexus (Plexus venosus vertebralis)
• Ligamentum flavum (Ligamentum flavum)
• Posterior longitudinal ligament (Ligamentum longitudinale posterius)
• Spinal nerve (Nervus spinalis)
• Spinal nerve root (Radix nervi spinalis)
• Sympathetic chain ganglia (Ganglia trunci sympathici)

Clinical anatomy and conditions discussed:
• Hyperlordosis and back pain
• Kyphosis and postural issues
• Scoliosis with vertebral wedging and rotation
• Compression of carotid artery at carotid tubercle
• Postural problems, muscle imbalance, and ligament stress

Transcript

Introduction & Content
0:00
Let’s talk about the vertebral column. It’s made up of bones called vertebrae,
0:04
stacked on top of each other – and even though they look similar,
0:08
they actually change shape and function depending on where you are in the spine.
0:12
So the way we’re going to understand the full anatomy of it is by first answering the questions,
0:17
How and why do we divide the spine into different regions? Why does the spine have curves,
0:23
and what happens when those curves go wrong? Then we’ll look at the basic structure of a vertebra,
0:28
which is common across the majority of the vertebra throughout the column. After
0:32
that we’ll talk specifically about the cervical vertebrae, thoracic vertebrae,
0:36
lumbar vertebrae and the sacrum and coccyx. What’s up everyone, my name is Taim. I’m a
0:41
medical doctor, and I make animated medical lectures to make different topics in medicine
0:45
visually easier to understand. If you’d like a PDF version or a quiz of this presentation, you can
0:50
find it on my website, along with organized video lectures to help with your studies.
Dividing the Spine
0:54
Alright, let’s get started. Look at this. The vertebral column, spine,
0:58
backbone. This is the core part of the axial skeleton in vertebrates. It goes from your skull,
1:04
all the way down to the tailbone. And when you look at it, really just don’t think anatomy right
1:09
now. Look at this. You’ll notice that at the top, it’s much smaller, this is to not limit the head,
1:16
neck and arm movement, as you go to the middle, the spine starts getting a little bit bigger,
1:21
curved outwards, this is to hold the ribs and protect your thorax. A bit more down,
1:26
it gets even bigger, large vertebrae responsible for holding the weight of your body, and allows
1:31
for a wide range of body motions. A little bit more down, and you’ll notice the bones are now
1:37
fused, into a shield looking unit that hold a lot of our muscles that help us keep our body upright.
1:44
Now, because the spine has different functions at different regions, we divide it into parts. We
1:50
have 7 cervical vertebrae, 12 Thoracic Vertebrae, 5 lumbar vertebrae, 5 fused sacral vertebrae,
1:58
and 3 to 5 coccygeal vertebrae, averaging to about 4 coccygeal vertebrae in human. This means that in
2:04
humans, our spine is composed of 33 vertebrae. Now let’s analyze the spine a little bit more,
Why Does the Spine have Curves?
2:12
this is really important. Why does your spine have curves?
2:16
For this, let’s put the spine back into this guy. In an upright position,
2:20
we humans have physiological curvatures. And we divide them into Primary curvatures, and Secondary
2:27
curvatures. Primary curvatures are present in the fetus, and remain the same in adults. We call
2:32
this type of curvatures ‘’kyphosis’’, outwards curvatures which is normal to a certain degree,
2:38
but it can be abnormal if it’s exaggerated. These are Thoracic kyphosis and sacral kyphosis
2:44
The thoracic and sacral curvatures are termed primary curves because they are present in
2:49
the fetus and remain the same in the adult. As the child grows, lifts the head, and begins to
2:54
assume an upright position, the secondary curves develop. These are known as lordosis, and you need
3:01
to separate this term because a normal lordosis is a gentle inward curve, and abnormal lordosis,
3:07
or also called hyperlordosis, is If the curve is too deep, causing lower back pain,
3:13
muscle imbalances, postural issues and so on. The cervical curve forms when the infant is
3:18
able to hold up his or her head (at three or four months) and sit upright (at nine months).
3:25
The lumbar lordosis forms between twelve to eighteen months when the child begins to walk.
3:31
Any exaggeration of these natural curves causes problems, and is often due to postural problems,
3:37
muscle atrophy, or weakening of bones. Now. Let’s turn our guy to the front. Turn on the
3:43
xray machine, and then give him a little injury. If there is a lateral curve of the
3:48
vertebral column, any wedging and rotation of vertebrae, we call this condition scoliosis.
3:54
So, that was the curvatures of the spine. Now, let’s go ahead and remove the spine for this guy
Basic Structures of Vertebra
4:00
again. The vertebrae across different regions of the spine may differ, but the majority of
4:05
them share some basic structure. And I wanna remind you again, remember we got cervical
4:10
vertebrae in the neck, we got vertebrae in the thorax, lumbar vertebrae, sacrum and the coccyx.
4:15
The majority of vertebrae in the cervical region look like this. In the thoracic region,
4:20
they look like this. And in the lumbar region, this is what they look like.
4:24
Pay close attention now. They all have a vertebral body. They all have a vertebral arch, and they all
4:31
have processes. This is interesting, you see now they do have common basic structures, but notice
4:37
they do differ slightly from one another depending on the function of that specific vertebra.
4:42
Let’s look at these three structures a little bit more detailed. Focus on the
4:46
vertebral body for a moment. Here we can see the intervertebral surface, which connects with the
4:51
intervertebral disc. Surrounding the surface is the anular epiphysis, which is a ring of compact
4:57
bone on the external margin of the body, containing a secondary ossification centre.
5:03
Now, let’s move on to the Vertebral arch. The vertebral arch is typically
5:08
divided into two regions. It’s the posterior part of the
5:12
vertebral arch called Lamina, and the anterior narrowest part of the vertebral arch, that
5:18
connect to the vertebral body, called Pedicle. Throughout all vertebrae in the spine, there’ll
5:24
also be a large hole in the middle called the vertebral foramen, bordered by the body and arch.
5:29
Now, let’s do the processes. The process are simple, there’s the spinous process that’s
5:35
pointing backwards, and it’s the one you often can see and feel on a person’s back. On the sides we
5:40
can see the transverse processes which differs in size across the vertebrae, and we can see the
5:45
superior and inferior articular processes. To understand these, let’s look at a sideview of
5:51
the spine. The Superior articular process is the bony part on the vertebra that faces upward and
5:58
forms a joint with the vertebra above, whereas the Inferior articular process goes downward and
6:04
connects with the vertebra below. When those vertebra go together,
6:08
they form the intervertebral foramen, and the vertebral canal. Why are they significant?
6:14
Let me show you why. Within the vertebral canal is going to be a lot of different structures,
6:19
and the noticeable ones are the spinal cord as you see here, along with meninges around them.
6:24
There are Blood vessels (e.g. anterior and posterior spinal arteries, venous plexuses).
6:30
There are ligaments like the ligamentum flava, and the posterior longitudinal ligament.
6:35
The spinal cord is going to give off some spinal nerves, that unite to form the spinal nerve root,
6:41
that exit through the intervertebral foramen. Not of significance for the foramina here,
6:46
but on this model we can also see the sympathetic chain ganglia.
6:50
Alright, what else can we see? Between the vertebral bodies of the spine, you’ll find
6:55
intervertebral disks highlighted here in blue. They allow the vertebral column to be flexible
7:00
and act as shock absorbers during activities. So, we saw that the vertebrae across the spine
7:06
share some common basic structures. But there are specific structures that make vertebrae districts
7:12
based on where they’re located. Most of the 7 cervical vertebrae share specific structures,
7:17
thoracic vertebra has some specific structures for the ribs, Lumbar vertebrae has some specific
7:22
structure, and even, the sacrum and coccyx. Now, the cervical vertebral column consists
Cervical Vertebrae
7:28
of 7 vertebrae and forms the cervical lordosis. The cervical vertebrae generally share similar
7:35
morphological features across C3-C7. The first cervical vertebrae C1, is called atlas,
7:41
and it greatly differs from the basic structure of the vertebrae as it does not have a vertebral
7:46
body. During development, its body fuses with the dens of the second cervical vertebrae,
7:52
called Atlas. Let’s cover the specific features across those vertebrae. Now, if we look at a
7:57
superior view of the normal cervical vertebrae, The first noticeable difference from a normal
8:03
vertebra, is that the transverse process is different. It contain an extra hole
8:07
here called the vertebral foramen. This exists because the vertebral artery goes through it,
8:11
that supplies our brain. A little side note here, on the transverse process of the 6th
8:16
cervical vertebra, there’s an anterior tubercle specifically called the “carotid” tubercle.
8:21
This one is prominent and palpable in the neck. And clinically, it’s important because the common
8:26
carotid artery can be compressed against it to control bleeding or check the pulse.
8:31
That’s why it’s called the “carotid” tubercle. Alright. Other things here on the transverse
8:36
process are the anterior tubercles, which are remnant of the cervical ribs. Posterior
8:42
tubercle, and the Groove for spinal nerve. We can also see the articular processes,
8:47
superior articular process points dorsocranially, and inferior articular
8:51
process points ventrocaudally. And the spinous process is distinct here in this region as well
8:57
in that it’s bifid, with the exception of C1 and C7. It is shaped this way because it increases
9:04
the surface area for muscle and ligament attachment, especially since neck muscles
9:08
are involved in fine movements and posture. Now let’s do the C1 Atlas. For this one,
9:14
let’s start by looking at it from a superior view, as you see here. It’ll make sense in a moment. So,
9:19
what do we see? Remember we said that C1 greatly differs from the basic structure
9:24
of the vertebrae as it does not have a vertebral body. Instead, it has an anterior and a posterior
9:31
arch. There’s a lateral mass, which contain the articulating surfaces. And since we’re looking at
9:37
a superior view, we’re looking at the superior articulating surface, which articulates with
9:42
the occipital condyle on the occipital bone. Usually at the tip of the posterior end we got
9:48
a spinous process, right? Here we only got a posterior tubercle, which is the embryological
9:54
remnant of the spinous process, and acts as the origin of the rectus capitis posterior
9:59
minor and the attachment of the nuchal ligament. Anteriorly is the anterior tubercle, and on the
10:05
inside of the arch, is the facet for dens, which articulated with the dens of C2. There is one more
10:12
structure we can’t really see from this view, and it’s a groove associated with the posterior
10:17
arch. If we go back to looking at th vertebral artery again. This artery actually winds around
10:23
the posterior parts of the lateral mass, forming the groove for vertebral artery, as it head up to
10:29
your brain, helping form the circle of willis. Now, let’s look at C2. Just for orientation.
10:36
Here is the anterior part, here is the posterior part. C2 Axis is distinct in that it has a dens
10:42
that fits perfectly on the facet of C1. Now this is really interesting, The reason why C2 has Dens,
10:49
is that this is actually the embryological remnant of the body of atlas, somewhere along
10:54
the development, the body of C1 separated, and fused with C2 giving an apex. And this resulted
11:00
in C1 having just an arch on the anterior and posterior sides. This Dens has an anterior
11:07
articular facet which articulates with the atlas, and a Posterior articular facet, articulating with
11:12
the transverse ligament of the atlas. So that was the cervical vertebra. Now let’s do the specific
Thoracic Vertebrae
11:19
structures associated with the thoracic vertebra. The thoracic vertebral column consists of 12
11:24
vertebrae and form the thoracic kyphosis. Thorax has ribs, right? Because the ribs are connected
11:31
to the thoracic vertebrae, they restrict the movements of the thoracic vertebral column. Now,
11:37
we can divide the thoracic vertebra into typical vertebrae, usually 2nd to 9th,
11:42
and atypical vertebra, which are T1, T10, T11 and T12. The typical vertebra is distinct because
11:50
it has a superior costal facet, inferior costal facet and a transverse costal facet.
11:57
The superior and transverse facet both provide a point of attachment for the same rib,
12:02
while the inferior facet is usually for the rib below. So, this is the typical
12:08
general usual thoracic vertebrae. Why do we have atypical vertebra? It’s a very subtle difference.
12:15
But T1 is atypical because it has a single ‘full’ facet for the head of the first rib,
12:21
and it has an Inferior demi facet for the head of the second rib, and just morphologically, T1 bears
12:28
some resemblance to low cervical vertebrae. For the other atypical ones. T9 is highly variable,
12:35
some sources mention it as atypical as well just because it might not have an inferior demifacet.
12:40
But generally T10-T12 are the main ones. T10 has a singe full facet. While T11 and T12 both have
12:49
a single full facet while also the facet on the transverse process is rudimentary. So, those are
12:56
the specific features of the thoracic vertebra. The lumbar vertebral column consists of 5 large
Lumbar Vertebrae
13:02
vertebrae that share morphological characteristics and form the lumbar lordosis. These vertebrae are
13:09
huge, have strong body and processes that support the weight of your body. There’s a lot of heavy
13:14
stress on your lower back as you move, so these bones have to be able to support that. The special
13:19
thing here is that the transverse processes are less well developed on the lumbar vertebrae. They
13:25
rather have something called costal process, which are the lumbar equivalents of the ribs.
13:30
So they’re the embryological remnant of the lumbar ribs. Otherwise the body is tall, wide and kidney
13:37
shaped, and the spinous process is flat and quadrate shaped when viewed from the side.
13:42
That was the lumbar vertebral column. Now, let’s do the Sacrum and Coccyx.
Sacrum
13:47
These are interesting. The sacrum is formed by fusion of the 5 sacral vertebrae. The coccyx
13:53
consists of 3–5 fused rudimentary vertebrae. Very variable. They form the sacral kyphosis.
13:59
Let’s isolate them and look at an anterior view. Again here we see that there were
14:02
initially 5 sacral vertebrae that fused. How do we generally divide the sacrum?
14:07
We have a base at the top, and an apex at the bottom, connecting
14:11
to the coccyx via an intervertebral disk. The base. If you look here. Has a promontory,
14:17
which is a part of the terminal line of the pelvis. And we got the Superior articular process,
14:23
which articulated with the corresponding inferior articular process of the 5th lumbar vertebra. From
14:30
this view we can also see the sacral wings. These are the lateral parts of the sacrum, and contain
14:35
the auricular surface which is articulates with the ilium. And if we look from the backside, we
14:40
can see the sacral tuberosity, which serves as the attachment for the posterior sacroiliac ligament.
14:46
Alright. What else can we see? On the pelvic surface, we can see
14:50
the anterior sacral foramina, which are 4 pairs of opening that transmit the anterior rami of
14:57
the sacral spinal nerves. And we can see the transverse ridges, those are lines that formed
15:03
due to the fusion of vertebrae. Now, let’s look at the sacrum from a posterior view.
15:09
Here we can see the posterior sacral foramina, which are 4 pairs of openings that transmit the
15:14
posterior branches of the sacral spinal nerves S1–S4. Apart from this we can also see the lateral
15:21
sacral crest, which is due to the fusion of the transverse processes. Median sacral crest, due
15:26
to fused spinous processes, and the medial sacral crest, due to fusion of the articular processes.
15:33
Within the sacrum, there’s a canal called the sacral canal. This is an extension of
15:38
the vertebral canal, and it goes all the way down to open at the sacral hiatus,
15:43
transmitting the spinal nerves S5 and coccygeal nerve. This opening
15:47
is bordered laterally by the sacral horns, which are remnants of the articular processes.
Coccyx
15:53
Now, Coccyx. This small tailbone is the end of the vertebral column. It’s highly variable between
16:00
people, but in average there are 4 vertebrae here that fused and made this bone. If we turn
16:06
it around. We can see something called coccygeal cornua, which are horns pointing cranially,
16:12
and are remnants of the articular processes. So that was all I had for the bones of the
Outro
16:17
vertebral column. The vertebral column don’t work alone, they are connected by a network
16:22
of ligaments and membranes that stabilize it during movement and help prevent injuries.
16:27
And interestingly, a lot of back problems start right there,
16:30
with the ligaments. If you want to understand how those ligaments are arranged and what they do,
16:36
check out the next video. I’ll see you there. If you want a handmade PDF version of this
16:40
lecture, take a quiz to test your knowledge, or access an organized list of all my videos,
16:44
you can find everything on my website. Thanks for watching! See you in the next one.