Facet joints (commonly called
spinal joints) join adjacent vertebrae. Facet joints are
hinge-like and allow adjacent vertebrae to move on one another
to allow bending and twisting and also keep the spine within
a normal range of motion. The surfaces of the bones that make
up the facet joints are coated with smooth cartilage that allows
the bones to glide smoothly against each other. Muscles, ligaments
and discs support the joints of the spine.
tough bands of connective tissue that connect the vertebrae.
Facet joints and ligaments help protect the spine by
limiting how far the spine can bend or twist. Muscles:
Muscles support the spine and allow movement. Muscles
of the back, abdomen and buttocks stabilize the spine
and maintain proper posture. Muscles protect the
spine by absorbing shock before it reaches the discs
and facet joints.
The spinal cord begins at the
brain and runs down to the level of the second lumbar vertebrae.
The lumbar spinal nerves join to form the sciatic nerve. Spinal
nerves branch out form the spinal cord. Sciatic nerve:
The sciatic nerve branches
off nerve roots off the lower end of the spinal cord. (The spinal
cord ends in the lower back) Two branches run through the pelvis,
deep into each side of the buttocks, through the hip, the backside
of the upper leg down to the foot. . The sciatic nerve is the
largest nerve in the human body - the diameter of a finger. Vertebrae:
The 24 vertebrae are named according to their location along
the spine. We start out with 33 vertebrae but the lowest nine
fuse together to form single bones- 5 fused vertebrae form the
sacrum and 4 tiny fused vertebrae form the coccyx (tailbone). The 24 vertebrae:
Cervical spine (neck area) with 7 vertebrae (labeled C1 - C7)
Thoracic spine (chest area) with 12 vertebrae (labeled T1 - T12)
Lumbar spine (lower back) with 5 vertebrae (labeled L1 - L5)
Below the lumbar spine:
Sacrum: a triangular shaped solid base with 5 fused vertebrae - connects
with the pelvis
Coccyx: (the tailbone) with 4 very small fused
The vertebrae are separated by shock absorbing intervertebral discs.
Theses discs have a tough outer coating with and contain a jelly-like
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