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)

Thoracic (12)

Lumbar (5) Sacral (5) Coccygeal (4)

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.

Curves in the Sagittal Plane

At 3-4 months, when the infant starts to raise his head, the cervical part becomes concave.

Curves in the Sagittal Plane

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.

Curves in the Sagittal Plane 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)

Curves in the Sagittal Plane

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 Posterior

Vertebral Arch Vertebral Body

Anterior

PARTS OF A VERTEBRA • GENERAL DESIGN Posterior Laminae – flattened Vertebral foramen – enclosed by the arch and the body - where the spinal cord and its coverings are Pedicle VERTEBRAL CANAL – formed by the succession of foramina

Anterior

PARTS OF A VERTEBRA • GENERAL DESIGN Posterior

Processes (7) Spinous Process Transverse processes (2) Articular process (Inferior - 2) Articular process (Superior - 2)

Anterior

Superior vertebral notch Posterior

Anterior

Inferior vertebral notch

Intervertebral Foramen Transmits the spinal nerves and blood vessels

THE CERVICAL VERTEBRAE Parts

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)

A. BODY

•Small, •broad from side to side

•Absent

B. VERTEBRAL ARCH with Vertebral Canal/ Foramen

Large, triangular

Has an anterior and posterior arch Each with a tubercle and a lateral mass

1. spinous

Small and bifid

Absent

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

?

C2- Axis (Atypical)

C7 (Atypical ?)

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

D. PROCESSES Not bifid, Long (vertebral prominens)

?

THE THORACIC VERTEBRAE Parts

Thoracic

A. BODY

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

B. VERTEBRAL ARCH with Vertebral Canal/ Foramen

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

A. BODY

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

B. VERTEBRAL ARCH with Vertebral Canal/ Foramen

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

Typical Thoracic Vertebrae (T5-T8)

Atypical Thoracic Vertebrae (T1 to T4) With features of cervical vertebrae

A. BODY

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

B. VERTEBRAL ARCH with Vertebral Canal/ Foramen

Small, circular

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

D. PROCESSES 1. spinous

Long, inclined forward

2. transverse

Has costal facets to articulate with the tubercle of the ribs

T1 – long, horizontal spine T11 – T12 No costal facets to articulate with ribs

3. Superior Articular 4. Inferior Articular

T12 – facets face laterally

THE LUMBAR VERTEBRAE Parts

Lumbar

A. BODY

Large, Kidney-shaped

B. VERTEBRAL ARCH with Vertebral Canal/ Foramen

•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

PECULIAR FEATURES OF THE VERTEBRAE IN EACH REGION Parts

Cervical

Thoracic

Lumbar

A. BODY

•Small, •broad from side to side

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

Large, Kidney-shaped

B. VERTEBRAL ARCH with Vertebral Canal/ Foramen

Large, triangular

Small, circular

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

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

D. PROCESSES

SACRAL BONE • 5 rudimentary vertebrae fused to form a wedge-shaped bone concaved anteriorly • Articulations* Where sacral nerves pass through Sacral canal •Sacral n. •Coccygeal n. •Filum terminale •Fibrofatty material

Promontory

Laminae fail to meet at the midline (sacral hiatus)

Vertebral foramina forms the sacral canal, contains the subarachnoid space

THE COCCYX

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

LIGAMENTS •

Anterior Longitudinal Ligament

•

Posterior Longitudinal Ligament

 Strong, broad fibrous band

 Weaker, narrower band

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

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

 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

 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 JOINT Synovial Joint (condyloid) • ARTICULATING BONES Occipital condyles

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 his Vertebrae 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 canal Above or below the fourth lumbar spine. Structures: 6. Skin 7. Superficial fascia 8. Supraspinous ligament 9. Interspinous ligament 10. Ligamentum flavum 11. Areolar tissue containing the internal vertebral venous plexus in the epidural space 7. Dura matter 8. Arachnoid matter 9. 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