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.