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.
A condition which is characterized by an exaggerated inward curve of the lower back, is known as lordosis. This article helps you understand what causes this condition. Also known by other names such as 'swayback' or 'saddle back', lordosis is defined as an increases curvature of the normally curved lumbar spine.