Joint Types, Ligaments & Range of Motion by Region

Musculoskeletal Test 1 - Back, Spine & Abdominal Wall

How many joints are in between each vertebra and what do they do?

Two joints between every pair of vertebrae, one disc, and a set of ligaments running the length of the column:

• those are what turn 33 separate bones into a structure that moves in a controlled way

Two Kinds of Joint in One Column

1. Between the bodies

2. Between the arches

Between the bodies

Secondary cartilaginous joints — symphyses.

• The intervertebral disc is the joint.

• C2 down to the lumbosacral junction.

• Built for load transfer with a little movement at each level.

Between the arches

Synovial joints — the zygapophysial, or facet, joints, between the articular processes.

Also C2 to S1.

Built for guided movement; they decide which direction a region can travel.

The exception:

the craniovertebral joints at the top have no disc at all

— none between the occiput and C1, or between C1 and C2.

Zygapophysial (Facet) Joints → What kind of joint

Synovial.

• The articular surfaces are covered in hyaline cartilage, and each joint is enclosed by a capsule containing synovial fluid

Zygapophysial (Facet) Joints → What movement they allow

Gliding between the articular processes.

• A single level gives very little; thirty-odd levels together give the column its range

Zygapophysial (Facet) Joints - Why they matter clinically

They are true synovial joints, so they are subject to the same

degenerative changes as any other — which is half of the cervical

spondylosis story from Presentation 2

What Determines Range of Motion (5)

1) Intervertebral disc

• Its composition and its height. A taller, well-hydrated disc allows more movement.

2) Facet joint morphology

• The plane the articular surfaces sit in — the previous slide.

3) Resistance from muscles & ligaments

• Passive tension in the soft tissue crossing the joint.

4) Whether the vertebra carries a rib

• Costal articulations tie the thoracic vertebrae down.

5) Surrounding soft tissue

• Bulk of tissue around the column limits travel at the extremes

The Intervertebral Disc (3)

1. Anulus fibrosus

2. Nucleus pulposus

3. Where and how numbered

Anulus fibrosus

Concentric fibrocartilaginous rings

forming the outer wall.

Nucleus pulposus

Gelatinous, high water content,

sitting slightly posterior to centre.

Its shape and position shift with

movement

Where and how numbered

C2 to the lumbosacral junction.

Each disc is numbered for the

vertebral body immediately above

it.

The Intervertebral Disc (Nucleus)

Off-centre nucleus

Ligaments: Three Groups

1. Occiput to cervical vertebrae

2. Between vertebrae

3. Spine & sacrum to ilium

The continuity rule:

Occiput to cervical vertebrae

.

Several group 1 ligaments simply change name as they run down the column —

• the anterior atlanto-occipital membrane becomes the anterior longitudinal ligament,

• the tectorial membrane becomes the posterior longitudinal ligament

• the ligamentum nuchae becomes the supraspinous ligament.

Craniocervical Ligaments: External (3)

1. Anterior

2. Posterior

3. Ligamentum nuchae

Anterior (Craniocervical Ligaments: External)

Anterior atlanto-occipital and atlantoaxial membranes

→ continue below as the anterior longitudinal ligament.

Posterior (Craniocervical Ligaments: External)

Posterior atlanto-occipital and atlantoaxial

membranes — continue below as the

ligamentum flavum

Ligamentum nuchae (Craniocervical Ligaments: External)

A midline sheet from the external occipital

protuberance to the C7 spinous process;

continues as the supraspinous ligament

Craniocervical Ligaments: Internal (3)

1. Cruciform ligament

2. Alar ligaments

3. Apical ligament

Cruciform ligament

The transverse ligament plus superior and inferior longitudinal bands — together they form a cross.

• Transverse band/ligament holds the dens against the anterior arch of C1

Alar ligaments

Paired; dens to the margins of the foramen magnum.

• Limit rotation of the head.

Apical ligament

Tip of the dens to the anterior margin of the foramen magnum

Tectorial membrane

Covering the dens and its ligaments from behind.

It is the upward continuation of the posterior longitudinal ligament

the third of the three continuities

Anterior Longitudinal Ligament (Where it runs)

Down the anterior and lateral surfaces of the vertebral bodies, from the occiput and C2 all the way to the sacrum.

• It is firmly attached to the anterior aspect of each intervertebral disc

Anterior Longitudinal Ligament (What it is like)

Broad and strong — the most substantial ligament of the

column, and it gets wider as it descends.

Anterior Longitudinal Ligament (What it limits)

Extension — and it is the only ligament of the vertebral

column that does. Every other one on the next few slides

limits flexion.

Anterior Longitudinal Ligament

Posterior Longitudinal Ligament (Where it runs)

Down the posterior surface of the vertebral bodies, C2 to the

sacrum — which places it inside the vertebral canal, immediately

in front of the spinal cord.

• Continuous above with the tectorial membrane

Posterior Longitudinal Ligament (What it is like)

Narrower and weaker than the anterior longitudinal ligament. It

has lateral expansions where it crosses each disc, so it is broad at

the disc and narrow over the body — giving it a scalloped outline

Posterior Longitudinal Ligament (What it limits)

Flexion — but weakly, given its size.

• That scalloped shape is the point. Where the ligament narrows, the disc behind it is least supported.

Posterior Longitudinal Ligament

Ligamentum Flavum Diagram

Ligamentum Flavum (Where it runs)

Paired, connecting the lamina of one vertebra to the lamina of

the next. Together the pairs form the posterior wall of the

vertebral canal

Ligamentum Flavum (What it is made of)

High elastin content — which is where the yellow colour and the

name come from. Flavum means yellow.

Ligamentum Flavum (What it limits)

Flexion — it stretches as the laminae separate, then recoils to

resting length without buckling into folds.

Ligamentum Flavum & Sustained Flexion (Why elasticity, and not just strength)

A ligament forming the back wall of the vertebral canal has a design

problem. It must lengthen when you flex, and it must shorten again

when you straighten — but if it shortened by buckling, it would fold

inward, into the canal, toward the cord.

Ligamentum Flavum & Sustained Flexion (Elastin solves it)

• Elastic recoil returns the ligament to resting length under its own tension, so it stays taut rather than folding.

• The canal keeps its dimensions through the whole range of flexion and extension.

Interspinous, Intertransverse & Supraspinous Location

Interspinous

• Between adjacent spinous processes, in the

  sagittal plane

• Limits: Flexion

Intertransverse

• Between adjacent transverse processes, in the frontal plane

• Limits: Lateral flexion

Supraspinous

Along the posterior tips of the spinous processes; continuation of the ligamentum nuchae

• The supraspinous ligament becomes very thin in the lumbar region — the part of the column where flexion loads are highest

Limits: Flexion

Ligaments: What Each One Limits (6)

1. Anterior longitudinal

2. Posterior longitudinal

3. Ligamentum flavum

4. Interspinous

5. Supraspinous

6. Intertransverse

Anterior longitudinal

Where it runs: Anterior & lateral surfaces of the bodies;

attached to each disc

Extent: Occiput / C2 → sacrum

Limits: EXTENSION — the only one

Posterior longitudinal

Where it runs: Posterior surface of the bodies, inside the

vertebral canal

Extent: C2 → sacrum

Limits: Flexion (weakly)

Ligamentum flavum

Where it runs: Lamina to lamina; posterior wall of the vertebral canal

Extent: C2 → S1

Limits: Flexion

Interspinous

Where it runs: Between spinous processes, sagittal plane

Extent: Whole column

Limits: Flexion

Supraspinous

Where it runs: Along the tips of the spinous processes

Extent: C7 → sacrum

Limits: Flexion

Intertransverse

Where it runs: Between transverse processes, frontal plane

Extent: Whole column

Limits: Lateral flexion

Costovertebral joint

Head of the rib to the superior costal facet of its own vertebra and the inferior costal facet of the vertebra above — with the intervertebral disc between them.

Costotransverse joint

Tubercle of the rib to the transverse process of the vertebra of the same number.

Spine to Pelvis: Lumbosacral & Sacroiliac Ligaments (5)

1) Iliolumbar

2) Sacroiliac (ant., post., interosseous)

3) Sacrospinous

4) Sacrotuberous

5) Sacrococcygeal

Iliolumbar

Transverse processes of L4 and L5 to the iliac crest

Sacroiliac (ant., post., interosseous)

Sacrum to ilium across the sacroiliac joint

Sacrospinous

Sacrum to the ischial spine

Sacrotuberous

Sacrum to the ischial tuberosity

Sacrococcygeal

Sacrum to the coccyx

Why Discs Herniate Posterolaterally (3)

1) The nucleus already sits posteriorly

2) The anulus is thinnest behind

3) The PLL reinforces the centre, not the corner

Range of Motion by Region