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Vertebral Column
Consists of:
• Body
• Spinous process
• Transverse process
• Pedicle
• Laminae
These act to form the vertebral canal, which encases and protects the spinal cord. The
posterior components are called the vertebral arch (everything except the body).
Considered triaxial as a whole - flex/exten; hyperexten; lateral bending and rotation.
There are three normal curves in the vertebral column. A lordosis in the cervical and
lumbar areas and kyphosis in the thoracic.
Articulation is through the articular facets referred to as superior and inferior articular
facets. Facet joints are synovial gliding joints so there is a little bit of motion at each
segment called translatory movement (they all move). Called apophyseal or
zygapophyseal joints.
Two Main Functions of the Facets
• Permit intervetebral movement and dictate the direction of the movement
• Share in the weight bearing duties with the bodies of the vertebrae for maintenance of
the longitudinal axis of the body
The Intervetebral Disk acts like a ball between two blocks of wood; the wood can tilt,
rotate and/or glide if the ball rolls. If the size of the "ball" increases or decreases it will
change the amount of movement allowed at the joint. During flexion, the anterior portion
of the annulus fibrosus is compressed and bulges posteriorily, while the posterior portion
is stretched and vice versa. There are 23 discs for shock absorption and flexibility. They
comprise about 25% of the vertebral column length.
When we discuss intervetebral motions we are talking about a motion segment. A
motion segment consists of the two facet joints and the intervertebral disk inbetween.
Example: C 1 C2; T5 T6
Because the direction of the facets change from cervical to lumbar, the motions allowed
at each area of the neck and trunk also changes.
Facets are more superior/inferior or horizontal in direction; a diagonal direction
Because of their position, the cervical area produces a great deal of motion on all three
planes. Half of the rotation occurs at the C1C2 motion segment. An average of 10-12
degrees comes from the other motion segments. Vertebrae in this region support the head,
allow motion, allow for nervous tissue and vascular supply to enter canal.
Facets are more anterior/posterior or vertical in direction
The direction of these facets means that the primary movement in this area is rotation and
lateral bending. Less motion due to attachment to ribs.
Facets are more medial/lateral or sagittal plane
Not much mobility is allowed in the lumbar area, but its primary movement is
flexion/extension which mostly occurs at L 4L5; L5 S1
Anterior longitudinal located down the vertebral column on the anterior surface of the
bodies and checks excessive hyperextension. This ligament is stronger/thicker distally
and fuses to sacrum
Posterior longitudinal located along the vertebral bodies posteriorly inside the vertebral
foramen and checks excessive flexion. This ligament is stronger/thicker in the cervical
area to support head/neck. Lumbar area more vulnerable to injury.
Supraspinal ligament located from the seventh cervical to the sacrum posteriorly along
the tips of the spinous processes
Interspinous ligament runs between successive spinous processes
Nuchal ligament replaces the supraspinal and interspinous ligaments in the cervical area