Clinical anatomy of the spine

Question 1

Review the structure of a typical vertebrae

Answer 1

Question 2

In terms of the spine what are the 3 key vertebrae ?

Answer 2

C1 - atlas, C2 - axis, C7 - vertebrae prominens

Question 3

Where do most disc prolapses occur ?

Answer 3

MOST AT L4/5 or L5/S1

Question 4

How do disc prolapses commonly occur ?

Answer 4

Lifting heavy object ===> Annulus tear ===>“twang”

Question 5

In terms of the spine where do motor neurones originate and come from and where do sensory neurones originate and come from ?

Answer 5

• Motor neurons originate anteriorly – bodies in anterior grey horn
• Sensory neurons originate dorsally – bodies in dorsal root ganglion

Question 6

Anterior & posterior (dorsal) roots form mixed spinal nerve which exits via what in terms of the spine ?

Answer 6

The intervertberal foramen

Question 7

Where does the spinal cord end and what does it become ?

Answer 7

Spinal cord ends at L1 and becomes the cauda equina (horses tail)

Question 8

What does nerve root compression result in ?

Answer 8

Causes a radiculopathy resulting in pain down the sensory distribution of the nerve root (dermatome), which in the lower leg is known as Sciatica

Also weakness in any muscle supplied (myotome) and reduced or absent reflexes (LMN signs)

Question 9

What does the T4 dermatome represent ?

Answer 9

Male nipple level

Question 10

What does T10 dermatome represent ?

Answer 10

Umbilical cord level

Question 11

Define what is meant by sciatica ?

Answer 11

Pain along sensory distribution of the sciatic nerve - pain affecting the back, hip, and outer side of the leg

Note mechanical back pain can go down to the buttock and thigh - need to remember that the sciatica should go below the knee

Question 12

What are the characteristic signs of cauda equina syndrome ?

Answer 12

Bilateral lower motor neuron signs, bladder and bowel dysfunction, saddle anaesthesia and loss of anal tone