Full Ball & Socket Joint Description. [Continued from above] . . . In the shoulder joint, the spherical head of the humerus (upper arm bone) fits into the glenoid cavity of the scapula (shoulder blade). The glenoid cavity is a small and shallow cavity that permits the shoulder joint the greatest range of motion in the human body.
Lumbar lordosis refers to the inward curvature of the spine just above the buttocks. The National Institutes of Health reports that lordosis is caused by spondylolisthesis. Spondylolisthesis is a condition in which a spinal bone slips out of its normal space and onto the bone below it.
Lordosis â Abnormal lordosis is an abnormal curvature of the normal curvature of the spine. This can occur when the lumbar and cervical curvatures are over-pronounced, and can cause extreme pain or discomfort. Lordosis itself can refer to either normal or abnormal curvature of the spine. Scoliosis â Scoliosis is the complete abnormality of the curvature of the spine. With this condition, the spine curves from side to side, often resulting in unbalanced posture and muscle development.