SPINE ANATOMY

Question 1

Types of cartilaginous joints

Answer 1

bones are united by fibrocartilage or hyaline cartilage

1” cartilaginous - synchondroses
2” cartilaginous - symphyses

Synchondrosis
- bones connected by hyaline cartilage. immovable
e.g. joint b/w diaphysis and epiphysis of a growing lone bone

Symphyses
- bones are united by a layer of fibrocartilage. slightly movable
e.g. pubic symphysis, intervertebral body joints

Question 2

Synovial joints

Answer 2

Synovial joint
- Defined by the presence of a fluid-filled joint cavity contained within a fibrous capsule.

They are freely movable and are the most common type of joint found in the body.

Synovial joints can be sub-classified into several different types, depending on the shape of their articular surfaces and the movements permitted:

Hinge
Saddle
E.g. carpometacarpal joints.
Plane – the articular surfaces are relatively flat, allowing the bones to glide over one another.
E.g. acromioclavicular joint, subtalar joint.
Pivot – allows for rotation only. It is formed by a central bony pivot, which is surrounded by a bony-ligamentous ring
E.g. proximal and distal radioulnar joints, atlantoaxial joint.
Condyloid – contains a convex surface which articulates with a concave elliptical cavity. They are also known as ellipsoid joints.
E.g. wrist joint, metacarpophalangeal joint, metatarsophalangeal joint.
Ball and Socket – where the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. It permits free movement in numerous axes.
E.g. hip joint, shoulder joint.

Question 3

What makes an intervertebral disc

Answer 3

Annulus fibrosus of fibrocartilage
Internal nucleus pulposus - semi liquid gelatinous substance from embryonic notochord

this annulus can deteriorate and weaken with age causing extrusion of the nucleus puposus (often posterolaterally)

Question 4

Where does the spinal cord end? What is the clinical relevance of this

Answer 4

The spinal cord ends at L1-2, after which are the nerve roots ie cauda equina

It is safe to perform a lumbar puncture @ L3/4 or L4/5

The dural sac containing CSF does not end until S2W

Question 5

Which layers are passed during a lumbar puncture?

Answer 5

Skin
Superficial fascia
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
Epidural space (loose areolar tissue containing internal vertebral venous plexus)
Dura mater
Arachnoid mater
CSF in subarachnoid space