Arthrology of the Spine

Question 1

Intervertebral disc

Answer 1

Separate the VERTEBRAL BODIES (between C2 and S1).
Pads of fibrocartilage.
Allow the vertebral column to bend and twist.
Three main components:
- Nucleus pulposus
- Annulus fibrosus
- Cartilaginous endplate

Question 2

Nucleus pulposus (central)

Answer 2

Composed majorly of water (decreases with age,
90% to 70 %).
Gelatinous structure (40-50%)
Composed of proteoglycan (35-65%) , type II collagen (5-20%), water.

Question 3

Annulus fibrosus (periphral)

Answer 3

15 to 25 concentric layers (lamellae).
Composed of Proteoglycan (20%), Collagen (50-70%), Elastin (2%).
Inner zone: Fibrocartilaginous made of type II collagen fibers
and provides compressive strength.
Outer zone: Much thicker, fibrous sheath, high tensile strength, type 1 collagen. Connects marginal ridges of two successive vertebrae.

Question 4

Cartilaginous endplate

Answer 4

Hyaline cartilage that bind the disc superiorly and
inferiorly.
60% of water, type II collagen, proteoglycans.
Permit osmosis.
Protect the vertebra from pressure.

Question 5

Intervertebral joint

Answer 5

“Water cushion” to absorb transient axial load. Adapts to different movement.
Resilient under pressure.

Question 6

Hernia

Answer 6

When the nucleus is severely degenerated, it looses its ability to cushion the load on the intervertebral disc.

Question 7

Intradiscal pressure in different positions.

Answer 7

(Kg)
Laying on back              20
Laying on side               75
Standing straight           100
Sitting down                   140 (L5-S1 is getting all the pressure)
Standing, bending over 150
Sitting, bending over     195
Stand., bend. w/load      215
Sitting, bending w/load 275

Question 8

Anterior longitudinal ligament

Answer 8

• Origin + insertion: Anterior surface of the vertebral bodies
  and intervertebral discs from the skull bases to the sacrum.
• Role: Limits extension of the vertebral column and
  reinforces the intervertebral disc.

Question 9

Posterior longitudinal ligament

Answer 9

• Origin + insertion: Posterior surface of vertebral bodies and
  intervertebral discs. From the clivus to the sacral canal.
• Role: Limits flexion of the vertebral column and reinforces
  the intervertebral disc. Weaker, lower down the spine, not as
  strong as other ligaments.

Question 10

Zygapophyseal joint

Answer 10

Paired facet joints formed by the articular processes:
- Inferior articular facets of the superior vertebra.
- Superior articular facets (concave) of the inferior vertebra.
From top to L5. Much more movement in cervical region.

Question 11

Articular capsule of zygapophyseal joint

Answer 11

thin fibrous capsule.
attached to the ligament flavum.
- Origin + insertion: cover the synovial membrane located
around articular processes of 2 adjacent vertebrae.
- Role: Prevent extreme sliding movements of vertebrae.

Question 12

Uncoverable joints

Answer 12

Small synovial joints situated between the lateral parts of
adjacent vertebral bodies. On each side of the lateral joint capsule.
Movement of joint in cervical region.
Role: Control movements and stabilize the neck. IVD protected and staying inside.

Question 13

Ligament Flavum

Answer 13

Truly elastic, yellow. Thick and powerful.
- Origin + insertion: Between the laminae of 2 adjacent
vertebrae on each side (right and left).
- Role: Preserve spinal curvature, limits spinal flexion. Helps
erector muscles stabilize the spine in upright position.

Question 14

Intertransverse ligament

Answer 14

• Origin + insertion: Between the transverse processes of 2
  adjacent vertebrae.
• Role: Limits rotational movement, lateral movement of the
  trunk.
  Some have intertransverse muscle instead of ligament in cervical part.

Question 15

Nuchal ligament

Answer 15

• Origin: Occipital protuberance + nuchal line of the occipital
  bone.
• Insertion: Spinous processes + ligament flava of cervical
  vertebrae from C1 to C7.
• Role: Limit cervical flexion.
  Interspinous ligament of the cervical spine.

Question 16

Interspinous ligament

Answer 16

• Origin + insertion: From the base to the apex of 2 adjacent
  spinous processes.
• Role: Limit trunk flexion.
  From C7 to L5.
  Longer and stronger in the lumbar region.

Question 17

Supraspinous ligament

Answer 17

• Origin + insertion: Attached to the apex of spinous
  processes.
• Role: Limit trunk flexion.
  From C7 to L4 (L5) some don’t have it on L5.
  More posterior to the interspinous ligament.

Question 18

Joints between two spinous processes

Answer 18

Nuchal Ligament (cervical spine)
Interspinal Ligament (thoracic and lumbar)
Supraspinal Ligament (more posterior on thoracic and lumbar)

Question 19

Atlas and axis: 5 joints

Answer 19

Atlanto-occipital joint (paired joints)
Atlanto-axial Lateral (paired joints)
Atlanto-axial Medial

Question 20

Cruciform ligaments

Answer 20

Atlanto-axial joints.

Longitudinal fascicles

• Origin: Skull (foramen magnum)
• Insertion: Posterior surface of the body of the axis (C2).

Transverse ligament
- Origin + Insertion: Links the 2 lateral masses of the atlas.

• Role: Holds the dens of the axis in articulation anterior
  arch of the atlas.

Question 21

Apical ligament of the dens

Answer 21

Atlanto-axial joint.
- Origin: Apex of the dens.
- Insertion: Skull (foramen magnum).
- Role: Prevents extreme sliding and circumduction 
  movements of the joint.

Question 22

Alar ligaments

Answer 22

Atlanto-axial joint

• Origin: Apex of the dens.
• Insertion: Occipital condyles.
• Role: Limit the rotation of the dens into the atlas.

Question 23

Atlanto-occipital capsule

Answer 23

• Origin + Insertion : Covers the synovial membrane, located
  around the occipital condyle and the lateral mass of C1.
• Role: Prevents extreme sliding and circumduction
  movements of the joint.

Question 24

Anterior atlanto-occipital ligament

Answer 24

• Origin: Anterior arch of the atlas.

- Insertion: Basilar part of the occipital bone.

Question 25

Posterior atlanto-occipital membrane

Answer 25

• Origin: Posterior arch of the atlas.
• Insertion: Posterior margin of the foramen magnum.
• Role: Limits extreme cervical flexion.