VERTEBRAL COLUMN ANATOMY Tom Grant and Marc Heymann

Vertebral body *I mistakenly confused terms for one group. To clarify: The vertebral canal (triangular foramen through which the spinal cord runs) is also known as the spinal canal or spinal cavity The CSF filled space running through the spinal cord is known as the central canal

Sections of the spine What type of joint is formed between atlas and axis? Atlas (C1) Axis (C2) Pivot joint What name is given to a fracture of both pedicles at C2? Hangman’s fracture

Which vertebral body is this? What quickly identifies this as a cervical vertebra? (3) C1 C3 T4 L1 L5 The presence of foramen transversarium Bifid spinous process Small body and large vertebral canal What runs through intervertebral foramina? We were asked what the anatomical purpose is of the bifid process of the cervical vertebrae. General consensus seems to be that it offers a greater surface area for muscle/ligament attachment (particularly the ligamentum nuchae) Vertebral artery (usually c6-c1) and vein Sympathetic nerve plexus

Which vertebral body is this? What identifies this as a lumbar vertebra? (2) C1 C3 T4 L1 S2 Large ‘kidney’ shaped body Relatively small vertebral canal Why is the vertebral canal smaller than in thoracic or cervical vertebrae? Less nerves are present in spinal cord (efferent and afferent nerves to arms and most of trunk don’t travel through lumbar vertebrae!)

Image – how thoracic vertebrae articulate with ribs Head of rib articulates with vertebral body Tubercle of rib articulates with transverse process

Which of the following is normal? One day you come across your good friend Pebbles Snodgrass. He is in tears, complaining that he has just realised he has a prominent bump on his lower neck, posteriorly (he’s had this for his whole life…) . What has he felt? He has felt C7 spinous process, a prominence in the back of the neck which is useful to mark the location of the lung apex Which of the following is normal? Cervical lordosis, thoracic lordosis, lumbar kyphosis, sacral kyphosis Cervical lordosis, thoracic kyphosis, lumbar lordosis, sacral rectus Cervical lordosis, thoracic kyphosis, lumbar lordosis, sacral kyphosis Cervical kyphosis, thoracic lordosis, lumbar lordosis, sacral kyphosis Cervical kyphosis, thoracic lordosis, lumbar kyphosis, sacral lordosis

How did we know it was the L5-S1 intervertebral disc? (2) Elvis Mcguire comes into your clinic. He complains of lower back pain and lack of sensation on the heel of his right ankle. On examination he notes that he is lacking the usual ankle reflex*, and suspects intervertebral disc herniation. Where is this most likely to have occurred? (2) *After block 4 you will know these symptoms indicate compression of S1 spinal nerve Right-sided posterolateral herniation of the L5-S1 intervertebral disc Why are intervertebral discs most likely to herniate posterolaterally? (1) Central support of posterior longitudinal ligament How did we know it was the L5-S1 intervertebral disc? (2) Poor ligament support to intervertebral disc here, posterolaterally A herniated/prolapsed intervertebral disc compresses the spinal nerve exiting the IVF one level below. Lack of ankle reflex and loss of sensation indicates compression of S1 spinal nerve The disc that would compress S1 spinal nerve is L5-S1

Be aware of supportive structure of anterior longitudinal ligament (compared to posterior longitudinal ligament) You can see here that the posterior longitudinal ligament is less structurally supportive than the anterior longitudinal ligament, since it has to wind around the bony pedicles.

Dan Wilkins is getting ready to resume his day at work putting caps on toothpaste tubes. As he gets out of bed he gets a severe back pain. The GP sends him for CT and MRI which reveals a central herniation of his L4/5 IV disc. What other symptoms may he notice? (6) Weakness of pelvic floor muscles Weakness of urinary and anal sphincter Lack of anal wink reflex Loss of bladder control Perineal sensory loss Loss of ankle-jerk reflex What is the collection of these symptoms known as? (1) Cauda equina syndrome L4 L5

BONUS: What are 4 other causes of CAUDA EQUINA syndrome? (4) Tumours Spinal stenosis Spondylolisthesis Vertebral canal stenosis (There are others, but these 4 are from your lecture, so more examinable!) What is spondylolisthesis? (1) Dislocation of the vertebral body What is spondylolysis? (1) Fracture of the vertebrae, which often leads to spondylolisthesis

Anatomy of the intervertebral disc… Can you label this? Knowing the anatomy of this allows us to define a “slipped disc”/ intervertebral disc herniation: The nucleus pulposus herniates through the damage annulus fibrosus

A woman goes into labor and is in need of an epidural anesthesia… Which spinal level would you access at (in an adult)? Why? L2/3 to L5/S1 (prefer higher up as there is more interspinous space Spinal cord terminates at L1/2 (can terminate down to L3) Where would you perform a lumbar puncture in a baby? Why? L4/5, L5/S1 Spinal cord terminates at L3/4

Performing an epidural… Which layers does one go through in order to reach the epidural space at the midline? Skin Supraspinous ligament (hold spinous processes together) Continues to become the ligamentum nuchae in cervical region (attaches to occipital protruberance) Interspinous ligament (hold spinous processes together) Ligament flavum (loss of resistance felt)- holds laminae together How many cm away from the midline does the epidural space lie? 4.5-5.5cm in 80% of people What two additional ligaments are there supporting the vertebral column? Anterior longitudinal (hold vertebral bodies together) Posterior longitudinal (hold vertebral bodies together)

During a lumbar tap, after the epidural space, what other layers need to be passed before collecting CSF? Dura mater (Subdural space) Arachnoid mater (Subarachnoid space) where CSF is contained