Vertebral Column Anatomy

A 52-year-old male presents to the orthopedic clinic with severe lower back pain radiating to the left leg for 3 weeks. On examination, he has positive straight leg raise test at 40 degrees on the left side and diminished left ankle reflex. MRI of the lumbar spine shows a large central disc herniation at the L4–L5 level compressing the nerve root. Which nerve root is most likely being compressed at this level?

Which vertebra is characterized by the presence of a dens (odontoid process) that articulates with the anterior arch of the atlas?

A 48-year-old woman presents with acute onset neck pain and right upper limb radiculopathy after a motor vehicle accident. Physical examination reveals weakness of shoulder abduction and external rotation, sensory loss over the lateral shoulder and arm, and diminished biceps reflex on the right. Plain radiographs show a unilateral facet joint dislocation at C5–C6 on the right side. Which vertebral structure is primarily responsible for preventing excessive forward displacement of C5 on C6 in this injury?

In the lumbar vertebrae, which anatomical feature is located between the superior and inferior articular processes and forms part of the lateral wall of the vertebral foramen?