Spine

• Function of the spine:

  • Stability to the thorax
  • Movement in all directions
  • Support the head, shoulder, and rib cage
  • Protect the spinal cord
  • Force transference
  • Shock absorber
  • Attachment point for muscles and ligaments

  
• Vertebral column consists of;

  • 7 cervical vertebrae
  • 12 thoracic vertebrae
  • 5 lumbar vertebrae
  • Sacrum - 5 fused sacral vertebrae
  • Coccyx - 3-5 fused vertebrae

  
• There are 4 spinal curves;

  2 primary - thoracic and sacro-coccygeal

  2 secondary - cervical and lumbar
• the vertebrae differ in size, shape, and facet orientation which means their function differs throughout the spinal column
• Cervical vertebrae characteristics:

  • 7 vertebrae (C1-C7) are the smallest and lightest
  • C3-C7 are distinguished with an oval body, short spinous processes, and large foramen
  • Each transverse process contains a transverse foramen for blood vessel travelling to the head/ brain

  
• Cervical vertebrae: The Atlas and Axis

  • The atlas (C1) has no body and no spinous process which helps to keep the head in place

  
• Cervical vertebrae: The atlas and axis

  • The axis (C2) has a body, spine, and vertebral arches like other vertebrae
  • Unique to the axis is the dens, which is a process thay projects superiorly from the body

  
• Thoracic vertebrae:

  • 12 thoracic vertebrae (T1-T12)
  • All articulate with ribs
  • Heart shaped body, circular foramen, transverse processes, and long spinous process
  • Articular facets limit flex/ext movements, but allow rotation

  
• Lumbar vertebrae:

  • 5 lumbar vertebrae (L1-L5), enhanced weight-bearing function
  • They allow flexion and extension
  • Short, thick pedicles and laminae, flat spinous processes and triangular shaped foramen
  • Facets lock to provide stability

  
• Sacral vertebrae:

  • Sacrum: 5 fused vertebrae (S1-S5)
  • Articulate with the innominates to form pelvic girdle
  • Coccyx (tailbone): 3-5 fused vertebrae

  
• Intervertebral joints:

  • There are 2 types of intervertebral joints
  • Vertebral body articulations
  • Bodies of the vertebrae are united by a fibrocartilaginous intervertebral disc (Ampiarthosis:symphysis)
  • Vertebral facet articulations:
  • Joint between articular facets of vertebral, non axial diarthrodial joints, movements determined largely by direction the articular facets face

  
• Intervertebral discs:

  Vary in thickness depending on location and relative to vertebral body size

  • constitute 1/4 of the length of spinal column
  • Made up of:
  • Annulus fibrousus - outer fibrous ring
  • Nucleus pulposus - inner ball of firmly compressed elastic material
  • Allow for compression and rotation and act as an important shock absorber
  • Discs made up of 80-90% water

  
• Vertebral ligaments:

  • anterior and posterior longitudinal ligaments: connects vertebral bodies
  • ligamentum flavum: connects the laminae from the axis to the sacrum
  • Interspinous ligament: connects spinous processes
  • Supraspinous ligament: connects apices of the spinous processes
  • Intertransverse: connects transverse processes
• Ligamentum flavum: limits flexion

  Intertransverse ligament: limits lateral flexion

  Posterior longitudinal ligament: limits flexion

  Anterior longitudinal ligament: limits extension

  Supraspinous ligament: limits flexion

  Interspinous ligament: limits flexion

  
• Vertebral ligaments