Spine
Atlanto-axial joint
joint between the atlas(C1) and axis (C2), which provides a large range of axial rotation (75%)
Spinal rotation
largest ROM in Cervical Region C1-C2 Thoracis also free to rotate (~9deg) < Lumbar spine because there is no space
Facet Joints (R) and (L)
lie between the superior and inferior articular processes, are diarthroses of the gliding type that are lined with articular cartilage.
Flexion/ Extension of spine
more flexion/extension at Cervical and Lumbar regions compared thoracic because of the orientation of facet joints
Functional structure of intervertebral discs
*Annulus fibrosus *Nucleus pulposus
Atlas (C1)
- first cervical vertebra has a specialized shape and function. - provides a reciprocally shaped receptacle to support the skull.
Forward Torque: Anterior to spinal Column
-Create constant bending movement -Tension must be counteracted by back extensor muscles -Compression Increases with sitting at the lumbar spine
Why does vertebral size change from the cervical region down through he lumbar region?
-This serves as a functional purpose, since when the body is in an upright position, each vertebra must support the weight of not only the arms and head but all the trunk positioned above it. -The increased surface are of the lumbar vertebrae reduces the amount of stress to which these vertebrae would other wise be subject to. -The weight-bearing surface of the intervertebral disk also increases with the weight supported
Vertebral Canal
-this is a protective passageway for the spinal cord and associated blood vessels. -This canal is made up of the neural arches, posterior sides of the bodies, and the intervertebral discs.
Intervertebral discs in Geriatrics
A geriatric discs fluid content is reduced by approximately 35% change causes abnormal movements which cause more of the compressive, tensile, and shear loads on the spine to be assumed by the facets and joint capsules
At what point are contact forces the largest in the spine?
At the L5-S1 Facet Joints 15-40% of chronic low back pain emanates from these facet joints
Motion Segment
Composed of 2 adjacent vertebrae and the soft tissues between them -The motion segment is the functional unit of the spine -can only exist in the cervical, thoracic and lumbar portions of the spine. - each segment contains 3 joints: The vertebral bodies, the right and left facet joints.
Vertebra
Consists of a body, a hallow ring (neural arch), and several bony processess Serve as the primary weight-bearing components of the spine
Lateral Flexion of spine
Frontal plane movement away from anatomical position Largest ROM at Cervical Region 9-10 deg at c4-c5
Does the Vertebral size increase or decrease from the cervical region down through the lumbar region?
Increased
Atlanto-occipital Joint
Joint between atlas (C1) and the occipital condyles of the skull. extremely stable joint, with flexion/extension of ~14-15% permitted, but with no motion occurring in any other plane.
Scoliosis
Lateral and rotational deformity may appear as either C or S curve involvung the thoracic or lumbar spine. idiopathic commonly diagnosed in children age 10-13 years old
Secondary spinal curves
Lumbar and Cervical- Concave posteriorly Develop from supporting body(not present at birth)
Why lift with your legs?
Minimizing trunk flexion reduces torque generated on spine.
Structure of the Spine
Provides mechanical linkage between the upper and lower extremities, and enables motion in all three planes, yet still functions as a bony protector of the delicate spinal cord.
Axis (C2)
Second cervical vertebrae
When is stress on intervertebral discs higher?
Stress is significantly higher with flexion as compared to rotation. - compression is the most common form of loading on the spine
What happens when spine is flexed
The discs are compressed, and they simultaneously lose water and absorb sodium and potassium throughout the day until its internal electrolyte concentration is sufficient to prevent further water loss. *causes spine to decrease 2cm by end of the day*
Vertebral Column
The spine consists of a curved stack of 33 vertebrae divided structurally into 5 regions 7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 5 fused sacral vertebrae 4 small fused coccygeal vertebrae
Primary Curves
Thoracic and sacral- Concave anteriorly Present at birth
Complex trunk muscular activation
antagonist muscle increase load on spine 3X more load than lifting in the sagital plane
Spondylolisthesis
complete fracture resulting in anterior slippage of the vertebra
Causes of Lordosis
congenital spinal deformity, weakness of the abdominal muscles, poor posture, overtraining in sports requiring repeated lumber hyperextension such as gymnastics
Kyphosis
exaggerated thoracic curve - seen in swimmers who train in butterfly stroke
Lordosis
exaggeration of the lumbar curve - associated with weakened abdominal muscles and anterior pelvic tilt
Hyperextension of spine
extension past anatomical position spinal hyperextension is considerable in cervical and lumbar regions
Spondoylolysis
presence of fracture int he pars interarticularis of the vertebral neural arch
The vertebral bodies
separated by the intervertebral disk, form a symphysis type of amphiarthrosis.
Intervertebral Discs
these are fibrocartilaginous discs that act as cushions between adjacent vertebral bodies.
Facet Joints
these are joints between the superior articular process of one vertebra and the inferior articular process of the vertebra directly above it. The facet joints and discs provide about 80% of the spine's ability to resist rotational torsion and shear. -The facet joints also sustain up to ~30% of the compressive loads on the spine, particularly when the spine is in hyperextension.
Nucleus pulposus
this is a gelatinous material that is located inside the annulus fibrosus.
Annulus fibrosus
this is a this fibrocartilaginous ring that forms the exterior of the intervertebral disc
Low back Pain
up to 85% of people have low back pain at some point in their life.