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We finished with the bony part of the head which was the skull. Today, we will talkabout the bony framework in the neck, which is made by the cervical vertebrae and as you

all know, the cervical vertebrae are part of the vertebral column. The vertebral column is

made up of 33 vertebrae.

They are divided into:

- 7 in the cervical region

- 12 thoracic

- 5 lumbar

- 5 sacral

- 4 coccygeal

The last two -the sacral and coccygeal- usually fuse with each other. The 5 sacral

vertebrae fuse to form the sacrum, and the coccygeal fuse to form the coccyx.

So our lecture today will be related to those 7 cervical vertebrae. Before we start we

have to know some general information about the vertebral column to understand the

formation and the shape of the cervical vertebrae. When we look to the vertebral column

development during the fetal period, the fetus is sleeping over itself so all the vertebral

column will be carved more anteriorly, this is what we refer to as the primary curvature

of the vertebral column ( ) > when the kid starts to left his head up.

** Lumbar>> when the kid starts to stand up on his legs.

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The primary curvatures remain after birth in two regions:

- The thoracic region (it is still concave anteriorly)- The sacral region (pelvicregion sacrum + coccyx) concave anteriorly.

**thoracic & sacral (pelvic) >> PRIMARY curvatures

**cervical & lumbar >> SECONDARY curvatures

So the 7 cervical vertebrae are considered primary or secondary?

Answer: Secondary.

Those curvatures are normal because of the resilience of the vertebral column. It

must be resilient to allow the movement of the trunk (rotating left, right and

bowing).

In addition to these normal curvatures, there could be some abnormal curvatures as

well. Abnormal means it results from developmental anomalies or due to a

pathological process (Anomaly genetic abnormality) which leads to this kind of

abnormal curvatures.

Abnormal curvatures are mainly 3 in number:

1- Kyphosis :( ) increase in the thoracic curvature(hunch back) dueto the erosion of the anterior part of the vertebrae in the thoracic

region.

**This happens because of osteoporosis( ), which is apathological process that mainly happens in the geriatrics(elderly people).

2- Lordosis: increase in the lumbar curvature (secondary). When thecurvature increases, its called a hollow back (hollow= empty) the back

of the patient is too much concave posteriorly.

**Can be seen in temporary cases as in late pregnancies in women >> weight

of the fetus is very heavy producing pressure on the vertebral column

increasing this kind of curvature temporary lordosis because after

delivery it will be demolished.

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It can also be seen in some people who suffer from muscular weakness >>

especially in the anteriolateral abdominal muscles external oblique,

internal oblique, transversus abdominis those muscles come from the

vertebral column all the way back then turn anteriorly to reach the rectus

abdominis muscle. These are the muscles that pull the vertebral column>> When those muscles become weak they will relax the vertebral column

paralysis. So the vertebral column goes more anteriorly.

3- Scoliosis (curved back): Its a medical condition in which the vertebralcolumn is curved from side to side (one side will be longer than the

other). So the patients vertebral column might look like the letter S or

C.

Its caused by many reasons:

** Developmental anomaly: half of the vertebrae didnt develop.

** Asymmetric paralysis: in one side of the intrinsic path muscles muscles

that pull the vertebral column one side is paralyzed so it curves to the

opposite side.

** Difference in the lengths of the lower limbs.

So the vertebral column is made up of 33 vertebrae and the joints

between them are secondary cartilaginous, becausethere areintervertebral discs made up of fibrocartilage located between each

vertebra and the other.

Intervertebral discsare very important because they function in shock

absorption. When we look at it superiorly it is made up of two parts:

1-Annulus fibrosus (fibrous):External part is very rigid fibrocartilagenous.

Annulus >> circular, concentric >> rings with united centers, fibrosus >>

fibrous

So concentric layers of fibrocartilage strengthen the discs.2- Nucleus pulposus (gelatinous):

Internal pulp of the disc is made of gelatinous material ( ).Nucleus pulposus is located in this area which is empty because we have an

opening in the disc. It is the central coreofthe disc and it is moreelasticbecause of the watery content (high water content).

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So nucleus pulposus is the main part responsible for shock absorption.

So the intervertebral disc is made up of 2 parts:

The Annulus fibrosus & Nucleus pulposus which is a whole space containing

the gelatinous material.

Disc herniation:

Tearing in annulus fibrosus >> as a result the nucleus pulposus will be

drained out of the annulus fibrosus.

**The disc is made of a very thick layer of annulus fibrosus anteriorly

however the posterior layer is thinner.

So the herniation is more prone to take place posteriorly. Then the

nucleus pulposus will start to leak posteriorly where the vertebral canal

which contains the spinal cord is located.

So when the nucleus pulposus enter the vertebral canal it will press on the

spinal cord producing pain in the nerve that originates from that area of

the spinal cord.

Herniation usually happens between L4-L5 and L5-S1 >> because they are

the last two discsand most of the weight lies on them.

The more weight applied on the disc, the greater the susceptibility of the

rupture of annulus fibrosus becomes

**Why are there no discs between the sacral vertebrae?

- Answer: Because they are fused & form the sacrum. They all work as one piece ofbone.

So the last disc is between L5 S1 .

Sciatic nerve: originates from L4,L5,S1,S2,S3.

Sciatica:

) (.

It happens because of pain in the sciatic nerve root. That pain usually

happens because of disc herniation in the disc between L4-L5 OR L5-S1.

The pain extends from the back to the lower limbs.

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IV Ligaments(intervertebral ligaments):

To FIX the vertebrae and the discs in their positions, there are ligaments

supporting the vertebral bodiesand ligaments supporting the vertebral

arches.

Structure of the vertebra: It has a body from the front that differs from

one region to another. It is rectangularin the cervical region, archshaped

in the thoracic region, kidneyshaped in the lumbar region.

Behind the body there is an arch composed of 2 pedicels & 2 laminae.

Over them there are 7 processes: 2 transverse, 1 spinous, 2 sub articular

processes and 2 inf articular processes.

Ligaments between Vertebral Bodies:

1. Ant. longitudinal ligament: From the front along the spine. Its verystrong and broadband, and it extends along the anterior surface of the

vertebral column from top to bottom.

2. Posterior longitudinal ligament: Very narrow ligament locatedposteriorly on the middle aspect of the posterior vertebral bodies.

The anterior Ligament is stronger than the posterior Ligament.

Ligaments between arches & processes:

1. Ligamentum flavum: Or flavae plural.

flavum means yellowish >> because it has elastic connective tissue

between the laminae of the vertebra above and below.

2. Intertransverse lig. :Located between the transverse processabove and the transverse process below.

3. Interspinous lig. : Between spinous processes.

4. Supraspinous lig. : On the tip of the spinous processes (between

tips of the spines).

2 ligaments for the bodies and 4 ligaments for the arches**There is an additional ligament seen ONLY in the cervical region:

5. Nuchal Ligament: or ligamentum nochae.

Nuchais the French word for the back of the neck.

*Occipitis the back of the head.

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So this ligament as you see it here is located in the back of the neck

extends from the skull (from the external occipital protuberance) a

very clear point at the end of the head.

Starts from the nuchal ligament and extends down along the half of

the occipital bone external occipital crest OR median nuchal line.

So it extends from the external occipital protuberance and median

nuchal line. Descends all the way down and merges with the

supraspinous ligament, only in the cervical region. So it ends at C7

*Nuchal lig. >> Supports the cervical vertebrae because they are small

in size posteriorly.

Cervical Vertebrae:

There are 7 cervical vertebrae. We classify them to typical and

atypical, depending on specific characteristics such as the ribs.

The typical vertebrae have 4 main charecteristics. If we miss one

of them it will be considered atypical.

Atypical vertebrae:

C1 the Atlas

C2 the Axis

C7

Typical vertebrae:

C3, C4, C5, C6

**Because they have a:

1-rectangular shaped body.

2-transverse foramina Holes in transverse Processes

3-Bifid: (2 heads) ONLY exception is C7 it has a Long process

and a unifid (1 head) process.

Transverse processes of cervical

vertebrae have foramina that dont

exist in the other vertebrae of the

body, because of a very important

artery ascending from the root of

the neck up into the skull to providblood supply to the post. inf. part o

the brain especially the cerebellum

which is called the vertebral arter

inside the vertebral column within

the cervical vertebrae. Its a direc

branch of the subclavian artery th

enters the transverse foramina and

after passing the first one it goes

foramen magnum of the brain.

This vertebral artery passes through cervical transverse foramina except C7.

Although C7 has transverse foramen, the artery passes anterior to the

transverse process, and then it enters C6 foramen up to the brain.

The cause of that >> If the artery is going to pass in the transverse foramen of

C7 it has to make a sharp angle, so it will block the blood supply to the brain

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4- Large triangular vertebral foramen.The spinal cord passes through the vertebral foramen between the body

and the arch of the vertebrae. The vertebral foramen is biggest in the

neck cervical vertebrae then it becomes narrower as you go down the

thoracic, lumbar then sacrum, because of tapering of the spinal cord.

Because C7 has a long spinous process the physicians count the vertebrae from the spinous

processes of C7. In the root of the neck theres a very clear area (bony prominent

palpated easily) which is the tip of the spinous process of C7.

**So C7 has a long spinous process with one head. It is very easily palpated (bulging

beneath the skin) and thats why we depend on this spinous process in counting the

vertebrae.

Four main characteristics of the typical cervical vertebrae:

1- Rectangular body2- Transverse foramina3- Bifid spinous process and short4- Triangular and large vertebral foramenException C7 >> long unifid spinous process and has a foramen but the vertebral artery

doesnt pass in this foramen.

Atlas C1:

The first cervical vertebra:

Atypical >> It has no body. It is a ring shaped bone (). So it has no body and nospinous process. Instead it has only an anterior arch and a posterior arch and two

lateral masses of bone to allow articulation up and down. So its a ring with 2 small

masses of bone for articulation.

Why do they call it Atlas?

In the Greek mythology, theres a Greek gad called ATLAS whos holding the whole

earth in his hands. So referring to this kind of mythology or resembling, the Atlas is the

first vertebra holding the whole skull up.

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Atlas communicates superiorly by 2 joints (the most important 2 joints in the cervical

region). The first one with the skull superiorly with the occipital condyles occipital

bone forming atlanto occipital >> it allows the head to move in anterior posterior

directions flexion and extension signifying yes. This is between the atlas and the

skull.

The other joint which is inferior to the atlas (atlanto axial joint) is for the rotational

movement of the head signifying no. It has nothing to do with the skull; it takes place

inside the cervical vertebrae. There is no movement for the skull there (between atlas

and axis).

Most two important joint in the cervical vertebrae:

1- Atlanto_occipital >> flexion & extension.2- Atlanto_axial >> lateral movement.

Axis C2:

It is Atypical because of one reason >> on its body it has a dense, tooth, axis, Odontoid

process.

It is thought by some anatomists that the dense of axis actually used to be the body ofatlas but with development and with timeit has lost its communication and fusion withatlas to go and fuse with the axis to allow the rotational movement.

Atlas is a ring shape and this is the axis, and the dense extending from it. The atlas is

connected to the dense and it wraps around it. So the dense or the odontoid process acts

as an axis for the atlas producing rotational movement saying NO >> so atlas rotates over

the dense of the axis on the atlanto-axial joint .

Atlanto-Occipital Joint:

You have to know the type, articulation, supporting ligaments and the movement.

**NOTE: The special characteristics of it are not included.

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Type: condyloid synovial joint >> condyloid because of occipital condyles are part of the

articulation.

Articulations: atlas with occipital condyles.

Movement: flexion and extension, also helps in Lateral flexion.

(Distinguish from the rotational flexion).

**Lateral flexion: atlas wraps around the axis, and the axis wraps

around the C3, the C3 wraps around the C4 together.

It starts with the atlanto-occipital and continues within the cervical

vertebrae in the bending of your head.

Ligaments:

Two important membranes:

1. Ant. atlanto-occipital membrane:

Starts from the anterior arch of atlas to the anterior margin of foramen magnum.

2. Post. atlanto-occipital membrane:

From the posterior arch of atlas to the posterior margin of foramen magnum occipital

bone It protects the joint posteriorly.

***So both of them extend from the arches of atlas to the margins of foramen magnum.

Atlanto-Axial Joints: 3

Atlas articulates with the axis in the 3 joints.

**First 2 lateral atlanto_axial

They are Laterally located between the lateral masses of atlas with the superior articular

facets of axis.

Type >> they are synovial gliding joints.

*Atlas with lateral masses and Axis with facets .

Condyle: is a smooth round

surface that helps in

articulation of the joint.Its always present in the

joints e.g:

tempromandebular joint

there is a condyler process

in the mandible

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**Median atlanto-axial joint:

It is located in the middle and it is the most important. Its classified as a pivot synovial

joint. Pivot means axial, so the movement is rotational. The rotation starts between the

anterior arch of atlas along with the dense of axis.

Articulation:

Anterior arch of atlas, the dense of axis and posterior there is a ligament >> transverse

ligament of atlas.

The transverse ligament of atlas begins from the lateral mass of atlas in one side to the

lateral mass of atlas in the other side. So its the stick that keeps the dense attached

firmly against the anterior arch of atlas, and thats why it considered a part of

articulation.

So:

1- Anterior arch of atlas2- The dense of axis3- Transverse ligament of atlas

Imagine this ligament is ruptured. If there is a tearing in this ligament, this means the

dense will leave the anterior arch of atlas, so there will be a posterior displacement of the

dense of axis and that is the dangerous situation.

If it was posteriorly displaced this is what we call Atlanto-axial dislocation sometimes if

its minor, we call it subluxation

(Again dense of axis goes posteriorly away from the atlas)

Behind the dense of axis there is the spinal cord, and above the atlas directly theres the

skull (foramen magnum). At the level of foramen magnum, the last part of the brain is

usually found medulla oblongata ( ). It ends at the foramen magnum and the

spinal cord starts. So if that tearing happens the dense will go more posterior and it willeither hit the medulla oblongata or it will injure the spinal cord.

Medulla oblongata has very important centers >> the cardiovascular center and the

respiratory center. If the tear hits those two centers that will result in direct death.

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Quadriplegia :( )

A luckier situation if the dense goes backwards and hit the spinal cord only, that willresult in paralysis in all the nerves that the spinal cord supplies. All the limbs become

paralyzed.

80% of car accidents death happens because of tearing in transverse ligament of atlas.

Web lash injuries ): If the driver is driving in a very high speed and he )

suddenly hits the breaks, his head will go ant. and post.

web lashing when the head comes back, huge force is gathered causing a tearing in the

transverse ligament and the dense hit the medulla oblongata .

Supporting Ligaments of atlanto_axial joint:

1- Cruciate LigOr cross ligament is located posteriorly. The horizontal part of it is the transverse

ligament of atlas. But in order to strengthen it, 2 vertical branches extend from it

(2 lig. Attach to the skull, the ant. Margin of foramen magnum). One of them

descends to attach to the body of the dense post. So one from above and the other

from below.

Just remember that this ligament mainly is an expansion of transverse ligament of

atlas.

2- Apical LigYou cant see it here. You have to cut the cruciate lig. Its at the apex of the axis,

attached to the tip of the dense along with the ant. border of foramen magnum.

3-Alar Ligaments

They go to the sides. A ligament extends from the tip of the dense of axis and

goes to the top, called apical. 2 ligaments extend from it, one to the right and oneto the left. Those are called the Alars. So we have 1 apical and 2 alars.

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4-Tectorial MembraneCovers all the ligaments. So if you cut it you will see posteriorly the cruciate lig. and

when you cut the cruciate you will see the alars and the apical.

**The Tectorial membrane is a continuation of the posterior longitudinal ligament

of the vertebral column. When the posterior longitudinal ligament reaches the back

of C2 and C1, it will be named tectorial.

***NOTE: The Tectorial ligament is the posterior longitudinal ligament itself.

Your colleague :)

Malak abuaqulah