Vertebral Column

Osteology and Arthrology

Osteology

7 C, 12 T, 5 L, 5 S (Fused as Sacrum), 4 coccygeal

Primary Curves Secondary Curves Anterior/Posterior alignment

Primary Curve

Vertebral Segments

A-P View

Secondary Curves Lateral

Vertebral Column

Osteology Typical Vertebrae Body

• Superior and inferior surfaces of body (plateaus)• Thickened around the rim, location of epiphyseal plates• Cartilaginous end-plates

Vertebral Arch• Pedicles, Laminae• Transverse Processes• Spinous Process• Facets – superior articular and inferior articular

Spinal Foramen Intervertebral Foramen

Typical Vertebrae

Typical Vertebrae

Typical Lumbar

Typical Thoracic

Typical C

Sacrum and Coccyx

Vertebral Relationships

Arthrology

Intervertebral Discs Fibrocartilaginous joints Increase in size from C to L (3mm to 9

mm) Ratio remains the same Make up 20-30% of length of column

Intervertebal Discs

Discs

Discs

Arthrology

Two Components Outer rim of fibrocartilage called the

anulus fibrosus (attaches to cartilaginous end plate)

Connects vertebral bodies in a fibrocartilaginous joint (no capsule, little motion)

Arthrology

Anulus encloses a central mass called the nucleus pulposus

About 80-90% water, less with increased age

Contains a mucopolysaccharide matrix Changes shape, releases and absorbs

water. Thicker in AM than PM Neither blood vessels or nerves penetrate

nucleus

Arthrology

Structure deforms when pressure is put on vertebral column as in weight bearing

Acts as a shock absorber Annulus totally encloses the nucleus and

keeps it under constant pressure As you get older, the H2O content decreases

and the nucleus becomes more fibrocartilaginous, therefore less easily deformable and more easily damaged

Arthrology

Nucleus, when under extreme pressure, can herniate or extrude from the disc in a posterior or posterior-lateral direction

Usually occurs in cervical or lumbar region Nucleus can put pressure on spinal nerve

causing refereed symptoms (motor and sensory)

Can cause pressure on cord itself if true posterior

Vertebral Relationships

Facet Joints (C and T)

Arthrology

Facet Joints (Typical) Superior articular facets of one vertebrae with

inferior facets of vertebrae above Synovial gliding joints Surrounded by joint capsule and small capsular

ligaments The type and amount of motion in any given part

of the spine is dictated by the orientation of the articular facets as well as the fluidity, elasticity and thickness of the intervertebral discs

Facets L

Arthrology

Typical movements in sections of the spine

Lumbar Thoracic Cervical

Major Ligaments of the Spine

Anterior Longitudinal Ligament - ALL Dense band along anterior and lateral surface

of the vertebral bodies from C2 to sacrum• Superficial - bridge several vertebrae

• Deep – short, run from V to V, blends with fibers of anulus fibrosus

• Limits extension of V column

From C1 to skull, called Atlanto-Occipital Membrane

ALL

Atlanto-Occipital Membrane

A and P Longitudinal Ligament

Major Ligaments

Posterior Longitudinal Ligament• Runs along posterior surface of vertebral

bodies (anterior to spinal canal)

• C2 to Sacrum

• Short fibers attach ligament to posterior disc, reinforce disc posteriorly

Superiorly, continues to occiput, called Tectorial Membrane

Limits flexion

PLL

Tectorial Membrane

Ligaments

Supraspinous• Spinous process to spinous process – tip to

tip

• C7 to sacrum

Limits flexion In cervical region, becomes much thicker

with a greater elastic content Called Ligamentum Nuchae

Supraspinous

Ligamentum Nuchae

Ligaments

Interspinous Found between spinous processes Most well developed in lumbar region support

Interspinous

Interspinous

Ligaments

Ligamentum Flavum Connects lamina of one to lamina of the

other Found from axis to sacrum Limit flexion Continuation to the skull is called

Posterior Atlanto-Occipital membrane

Ligamentum Flavum

Atlanto-Occipital Membrane-Posterior

Ligaments

Intertransverse Only well-developed in Lumbar Region Between transverse processes Limit lateral flexion

Special Joints of Spine

Lumbo-Sacral• L5 and S1 (or sacrum)

• Drastic change from lordotic to kyphotic curve

• Strong “shearing forces”

• The sacral segment is inclined anteriorly and inferiorly forms an angel with the horizontal called the lumbo-sacral angle

Angle can be increased significantly with an increase in lumbar curve

During flexion/extension the greatest mobility of the spine occurs between L5 and S1

Lumbo-Sacral Jt.

L5/S1

L5/S1

Spondylolysis – a developmental anomaly of the lamina wherin a bony defect separates the sup. and inf. Articular processes thus separating the post. Part of the neural arch from the ant. Arch and the vertebral body

Usually asymptomatic, very common in males

S and S

L5/S1

Spondylolistheses – an anterior movement of the L5 vertebral body and can cause compression of the cauda equina which rests posteriorly

Sacralization

Where 5th lumbar vertebrae takes on characteristics of the sacrum and may be partially or completely fused with sacrum

Lumbarization

Superior aspect of the sacrum assumes characteristics of the 5th lumbar vertebrae

S-I Joint

Review Hip Bone AKA Innominate AKA Os Coxae

Ilium, Ischium and Pubis Fuse at Puberty Acetabulum Pelvis = 2 coxal bones the sacrum and

coccyx

Innominate Bone AKA Hip

Sacrum

Pelvis

Female Pelvis

S-I

Auricular surface of ilium with auricular surface of sacrum-Little movement

Joint under relatively constant pressure to rotate anteriorly based on anatomical design

Upper part of joint is not synovial, is fibrous held in place by tough Interrosseous S-I ligaments – helps limit anterior motion

S-I Joint

S-I Joint

S-I Joint

S-I – Synovial Aspect of Joint Major Ligaments – mostly designed to prevent ant.

motion Posterior S-I – runs down and medially from ilium to

sacrum Iliolumbar – L4 and 5 transverse processes to

posterior iliac crest Anterior S-I – ilium to sacrum Sacrotuberous – iliac tuberosity and post. Surface

of lower sacrum to ischial tuberosity Sacrospinous – lateral borders of lower sacrum and

coccyx to attach to the spine of ischium

S-I Joint

S-I Joint

Pubic Symphysis

Anterior connection of pelvis Fibrocartilaginous joint Limited motion Motion increase dramatically during

pregnancy, especially at the time of birth Similar increase in SI joint mobility at this

time Superior and Inferior Pubic Ligaments

Pubic Symphysis

Atlanto-Axial Joint

Atlas and Axis Pivot Two convex superior facets of axis with two

concave inferior facets of the atlas Atlas also posses a facet on the internal

surface of the anterior arch which articulates with the dens of the axis

Major ligaments from spine support – Ant. Atlanto-Occipital, Tectorial Membrane, Post. A-O

C1/C2

C1/C2

C1/C2

A-A Joint

Alar – from dens to occiput Transverse - around dens Cruciate

• Sup. Longitudinal Band

• Inferior Longitudinal Band

• Transverse

Atlanto-Occipital Joint

Two concave superior facets of atlas articulate with two convex surfaces of occipital condyles of the skull

Supported by major ligaments Small saddle joint Very limited motion – nodding type

motions in all directions.

Atlanto-Occipital

Atlanto-Occipital