The Vertebral Column and the Vertebral Canal

THE VERTEBRAL COLUMN AND THE VERTEBRAL CANAL

THE VERTEBRAL COLUMN

• The central bony pillar of the body

• Functions:1. To support the skull, pectoral girdle, upper limbs,

thoracic cage and the pelvic girdle

2. To protect the spinal cord, roots of the spinal nerves, ad the meninges (coverings) located in the vertebral cavity

3. For posture and locomotion

4. To support the body

The Vertebral Column• COMPOSITION: 33 vertebrae• The regions in the vertebral column are as follows:

Cervical (7)

Lumbar (5)

Sacral (5)

Coccygeal (4)

Thoracic (12)

Fused to form the sacrum

Last 3 fused to form the coccyx

The Vertebral Column

• Flexible structure due to – Segmented– Made up of vertebrae, joints, intervertebral

disk

• Stabilized by ligaments, muscles and the intervertebral discs

CURVES

• SAGITTAL PLANE– Due to upright posture

and weight-bearing musculature

• CORONAL PLANE– Due to the use of the

upper limbs

Curves in the Sagittal Plane

In the fetus, the curve is one continuous

anterior cavity.

At birth, the lumbosacral angle appears.


At 3-4 months, when the infant starts to raise his head,

the cervical part becomes concave.


At around 1 year old, the child begins to stand upright.

The lumbar part becomes concave posteriorly.

The secondary curves are due to the shape of the intervertebral disks.


In an adult, the regional curves are identifiable: cervical (posterior concavity) thoracic (posterior convexity) lumbar (posterior concavity) sacral (posterior convexity – to preserve the center of gravity)


Primary Curves

Secondary Curves

Curves in the Coronal Plane

Late Childhood:

Minor lateral curves (thoracic area) – NORMAL

Compensatory curves above and below the lateral curve.

PARTS OF A VERTEBRA

• GENERAL DESIGN

Vertebral Body

Vertebral Arch

Anterior

Posterior

PARTS OF A VERTEBRA

• GENERAL DESIGN

Pedicle

Laminae – flattened

Vertebral foramen – enclosed by the arch and the body - where the spinal cord and its coverings are

VERTEBRAL CANAL – formed by the succession of foramina

Anterior

Posterior

PARTS OF A VERTEBRA

• GENERAL DESIGN

Spinous Process

Transverse processes (2)

Anterior

Processes (7)

Articular process (Superior - 2)

Articular process (Inferior - 2)

AnteriorPosterior

Superior vertebral notch

Posterior

Inferior vertebral notch

Intervertebral Foramen

Transmits the spinal nerves and blood vessels

THE CERVICAL VERTEBRAEParts Cervical

A. BODY •Small, •broad from side to side

B. VERTEBRAL ARCH with Vertebral Canal/ Foramen

Large, triangular

D. PROCESSES

1. spinous Small and bifid

2. transverse Has a transverse foramen (vertebral artery and vein)

3. Superior Articular Facets face upward and backward

4. Inferior Articular Facets face downward and forward

THE CERVICAL VERTEBRAE Parts Typical Cervical

Vertebrae

(C2-C7)

C1-Atlas

(Atypical)

C2- Axis

(Atypical)

C7

(Atypical ?)


•Absent Body of C1 fused with body of C2 to form the odontoid process

B. VERTEBRAL ARCH with

Vertebral Canal/ Foramen

Large, triangular Has an anterior and posterior arch

Each with a tubercle and a lateral mass

D. PROCESSES

1. spinous Small and bifid Absent Not bifid, Long (vertebral prominens)

2. transverse Has a transverse foramen

(vertebral art. & vein)

3. Superior

Articular

Facets face upward and backward

Kidney-shaped facet is large to articulate with the occipital condyle

4. Inferior

Articular

Facets face downward and forward

?

?

Parts Thoracic

A. BODY •Medium – sized, •heart-shaped•Has costal facets on sides to articulate with the head of the ribs


Small, circular

D. PROCESSES

1. spinous Long, inclined forward

2. transverse Has costal facets to articulate with the tubercle of the ribs

3. Superior Articular Facets that face backward and laterally

4. Inferior Articular Facets that face forward and medially

THE THORACIC VERTEBRAE

Parts Thoracic



Small, circular

D. PROCESSES

1. spinous Long, inclined forward


3. Superior Articular Facets that face backward and laterally

4. Inferior Articular Facets that face forward and medially

THE THORACIC VERTEBRAE

THE THORACIC VERTEBRAE Parts Typical Thoracic

Vertebrae

(T5-T8)

Atypical Thoracic Vertebrae

(T1 to T4)With features of

cervical vertebrae

Atypical Thoracic Vertebrae

(T9 to T12)

With tubercles similar to lumbar vertebrae


•T1 – has a complete ocstal facet on its body and a demifacet on its inferior edge

B. VERTEBRAL ARCH with

Vertebral Canal/ Foramen

Small, circular

D. PROCESSES

1. spinous Long, inclined forward T1 – long, horizontal spine


T11 – T12

No costal facets to articulate with ribs

3. Superior

Articular

4. Inferior

Articular

T12 – facets face laterally

Parts Lumbar

A. BODY Large,

Kidney-shaped


•triangular•Pedicles are strong and directed backwards.•Laminae are thick.

D. PROCESSES

1. spinous Short, flat quadrangular, projects backward

2. transverse Long, slender,

no costal facets

3. Superior Articular Faces medially

No facets for ribs

4. Inferior Articular Faces laterally

THE LUMBAR VERTEBRAE

PECULIAR FEATURES OF THE VERTEBRAE IN EACH REGION

Parts Cervical Thoracic Lumbar


•Medium – sized, •heart-shaped•Has costal facets on sides to articulate with the head of the ribs

Large,

Kidney-shaped


Large, triangular Small, circular •triangular•Pedicles are strong and directed backwards.•Laminae are thick.

D. PROCESSES

1. spinous Small and bifid Long, inclined forward Short, flat quadrangular projects backward

2. transverse Has a transverse foramen (vertebral artery and vein)

Has costal facets to articulate with the tubercle of the ribs

Long, slender, no costal facets

3. Superior Articular Facets face upward and backward

Facets that face backward and laterally

Faces medially

No facets for ribs

4. Inferior Articular Facets face downward and forward

Facets that face forward and medially

Faces laterally

SACRAL BONE• 5 rudimentary vertebrae fused to form a

wedge-shaped bone concaved anteriorly

• Articulations*

Promontory

Vertebral foramina forms the sacral canal, contains the subarachnoid space

Laminae fail to meet at the midline

(sacral hiatus)

Where sacral nerves pass throughSacral canal•Sacral n.•Coccygeal n.•Filum terminale•Fibrofatty material

THE COCCYX

The first coccygeal bone is usuallyFused or incompletely fused with the Second coccygeal bone.

LIGAMENTS• Anterior Longitudinal Ligament

Strong, broad fibrous band

Covers and connects the anterior aspects fo the verterbral bodies and intervertebral discs

From the anterior tubercle of C1 and the occipital bone of the skull anterior to the foramen magnum to the sacrum

pelvic surface of the sacrum to the Prevents hyperextension of the vertebral column

• Posterior Longitudinal Ligament

Weaker, narrower band

Runs along the posterior bodies of the vertebral bodies within the vertebral canal

From C2 to the sacrum

Prevents hyperextension of the vertebral colmn

LIGAMENTS• Anterior Longitudinal Ligament

Strong, broad fibrous band

Covers and connects the anterior aspects fo the verterbral bodies and intervertebral discs

From the anterior tubercle of C1 and the occipital bone of the skull anterior to the foramen magnum to the sacrum

pelvic surface of the sacrum to the Prevents hyperextension of the vertebral column

LIGAMENTS• Posterior Longitudinal

Ligament

Weaker, narrower band

Runs along the posterior bodies of the vertebral bodies within the vertebral canal

From C2 to the sacrum

Prevents hyperextension of the vertebral colmn

THE INTERVERTEBRAL DISC

• LOCATION– ¼ the entire length of the vertebra– Thickest at the cervical and lumbar regions– Shock absorbers

– In between vertebrae EXCEPT• Between C1 and C2• In the sacrum• In the coccyx

First disc is between C2 and C3.Last functional disc is between L5 and S1.

Total= 18

Annulus Fibrosus fibrocartilage and collagen fibers

Nucleus Pulposus In children: gelatinous, with large amount of water little amount of cells

In adults: replaced by collagen fibers discs becomes thin and less elastic

cannot distinguish it from annulus fibrosus

HERNIATION OF THE INTERVERTEBRAL DISC

• A sudden increase in the compression load of the vertebra causes the semifluid nucleus pulposus to become more flattened.

• At times the outward thrust is too great, the annulus fibrosus ruptures and the nucleus pulposus herniates and protrudes into the vertebral canal (compressing the spinal cord, roots or nerves).

HERNIATION OF THE INTERVERTEBRAL DISC

• A sudden increase in the compression load of the vertebra causes the semifluid nucleus pulposus to become more flattened.

• At times the outward thrust is too great, the annulus fibrosus ruptures and the nucleus pulposus herniates and protrudes into the vertebral canal (compressing the spinal cord, roots or nerves).

ATLANTO-OCCIPITAL JOINTSynovial Joint (condyloid)

• ARTICULATING BONES

Occipitalcondyles

MOVEMENTS: flexion, extension, lateral flexion NO ROTATION!

ATLANTO-AXIAL JOINT

• JOINT CLASSIFICATION• Synovial Joint (Pivot Joint)

• 3 synovial joints:– between the odontoid

process and the anterior arch of the atlas

– 2 joints between the lateral masses of the bones

ATLANTO-AXIAL JOINT

• JOINT CLASSIFICATION:• Synovial Joint (Pivot Joint)

• 3 synovial joints:– between the odontoid

process and the anterior arch of the atlas

– 2 joints between the lateral masses of the bones

MOVEMENTS: extensive rotation of the atlas and of the head.

LUMBAR TAP

• A procedure to withdraw cerebrospinal fluid for examination

• For clinical diagnosis• Introduce drugs• Remove “excess

spinal fuid” (headache)

The patient lies on his side with hisVertebrae well flexed.

This widens the space between the adjoining laminae.

The level of t he fourth lumbar spine is determined by drawing an imaginary line joining the highest points of the iliac crest. the vertebrae

The lumbar puncture needle is passed into the vertebral canalAbove or below the fourth lumbar spine.

Structures:1. Skin2. Superficial fascia3. Supraspinous ligament4. Interspinous ligament5. Ligamentum flavum6. Areolar tissue containing the internal vertebral venous plexus in the epidural space7. Dura matter8. Arachnoid matter9. Subarachnoid space

SPONDYLOLYSIS

• Spinous process, laminae and inferior articular process

separate from

the body pedicles and the superior articular process

• NO ANTERIOR DISPLACEMENT

SPONDYLOLISTHESIS

• Spinous process, laminae and inferior articular process

separate from

the body pedicles and the superior articular process

• THERE IS ANTERIOR DISPLACEMENT

SPONDYLOLISTHESIS

• The body of a lower lumbar vertebra (usually of L5) moves forward to the body of the vertebra below and carries with it the whole upper portion of the vertebral column

• The nerve roots may be compressed.

THE VERTEBRAL COLUMN AND THE VERTEBRAL CANAL

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The Vertebral Column and the Vertebral Canal