Anatomy of the vertebral column

Objectives Describe the general structure of the vertebra Describe the structure of the atypical cervical vertebrae Describe the structure of typical cervical vertebrae Describe the structure of the thoracic vertebra Describe the structure of the lumbar vertebra Describe the structure of the sacrum List the differences between vertebrae in different regions of the vertebral column

Vertebral Column Consists of 31 vertebrae and the intervening discs It appears as straight line anteroposteriorly, and with multiple curves laterally According to shape and location, vertebrae can be divided into: Cervical Thoracic Lumbar Sacral Primary vs Secondary curve Spine abnormalities

Vertebral Column 7 C, 12 T, 5 L, 5 S (Fused as Sacrum), 4 coccygeal Primary Curves Secondary Curves

Secondary Curves (Lateral view)

Vertebral Column General structure of vertebra : Body Pedicle Lamina Spine Transverse process Vertebral foramen Vertebral notch Superior articulating process Inferior articulating process

Typical Vertebrae Body Superior and inferior surfaces of body (plateaus) Thickened around the rim, location of epiphyseal plates Cartilaginous end-plates Vertebral Arch Pedicles, Laminae Transverse Processes Spinous Process Facets – superior articular and inferior articular

Vertebral Foramen Vertebral notch Intervertebral Foramen

Typical Vertebrae

Ligaments of the Spine Anterior longitudinal Posterior longitudinal Supraspinous Interspinous Ligamentum flavum

Vertebral Relationships

Intervertebal Discs Intervertebral Discs Fibrocartilaginous joints Increase in size from C to L (3mm to 9 mm) Make up 20-30% of length of column

Discs

Discs Outer rim of fibrocartilage called the anulus fibrosus (attaches to cartilaginous end plate) Connects vertebral bodies in a fibrocartilaginous joint (no capsule, little motion) Anulus encloses a central mass called the nucleus pulposus About 80-90% water, less with increased age Contains a mucopolysaccharide matrix Changes shape, releases and absorbs water. Neither blood vessels or nerves penetrate nucleus

Discs Structure deforms when pressure is put on vertebral column as in weight bearing Acts as a shock absorber Annulus totally encloses the nucleus and keeps it under constant pressure With increased age, the H2O content decreases and the nucleus becomes more fibro cartilaginous, therefore less easily deformable and more easily damaged

Discs Nucleus, when under extreme pressure, can herniate or extrude from the disc in a posterior or posterior-lateral direction Usually occurs in cervical or lumbar region Nucleus can put pressure on spinal nerve causing referred symptoms (motor and sensory) Can cause pressure on cord itself if true posterior

Cervical Vertebrae 1st cervical vertebra(Atlas) No body No spine Anterior arch Posterior arch 2nd cervical vertebra (Axis) Looks like typical vertebra It has odontoid process (Dens)

Typical Cervical Vertebrae Characterized by the general structure of vertebra but each has a bifid spine 7th cervical vertebra: Characterized by general structure of vertebra but it has NO bifid spine

Thoracic Vertebra

Thoracic Vertebra Heart-shaped body Long, thin, vertical spine Round vertebral foramen Body/foramen ratio almost 2 Superior articulating facets facing posteriorly Body has impression for rib articulation( COSTAL facet)

Lumbar Vertebra

Lumbar Vertebra Kidney-shaped body Short, thick, horizontal spine Triangular vertebral foramen Body/foramen ratio almost 3-4 No impression for rib articulation

Sacrum and Coccyx

The Sacrum Identify the following: - Anterior sacral foramina - Transverse lines - Promontory - Ala - Posterior sacral foramina - Median sacral crest - Medial (Intermediate) sacral crest - Lateral sacral crest - Sacral hiatus - Cornu - Sacral canal

Ligaments of the Spine Anterior longitudinal Posterior longitudinal Supraspinous Interspinous Ligamentum flavum

Ligaments of the Spine Tectorial membrane Interspinous ligaments Supraspinous ligament Ligamentum flavum

Atlanto-Occipital Joint Two concave superior facets of atlas articulate with two convex surfaces of occipital condyles of the skull Supported by major ligaments: 1- Ant. Atlanto-Occipital, 2- Tectorial Membrane, 3- Post. A-O Small saddle joint Very limited motion nodding type motions in all directions.

Atlanto-Axial Joint Cruciate ligament Superior longitudinal Atlas and Axis Pivot Two convex superior facets of axis with two concave inferior facets of the atlas Atlas also posses a facet on the internal surface of the anterior arch which articulates with the dens of the axis Major ligaments from spine support – alar ligament and cruciate ligament Cruciate ligament Superior longitudinal Inferior longitudinal Transverse

C1/C2