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.
In lordosis, the curve of the spine arches forward. The normal spine has a slight degree of lordosis in the neck and lower back regions. It bends forward in the chest area. In excessive lordosis, there is a greater arching of the spine, especially in the lower back. What are the causes and risks of the condition? Specific causes of excessive lordosis include: achondroplasia, which is the abnormal conversion of cartilage into bone that results in dwarfism spondylolisthesis, or the slipping forward of one vertebra on top of the one below Symptoms & Signs