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The synovial joints will form between the adjacent cartilage models, in an area called the joint interzone. Cells at the center of this interzone region undergo cell death to form the joint cavity, while surrounding mesenchyme cells will form the articular capsule and supporting ligaments.
Although joints can occur singly, they most frequently appear as joint sets and systems. A joint set is a family of parallel, evenly spaced joints that can be identified through mapping and analysis of their orientations, spacing, and physical properties. A joint system consists of two or more intersecting joint sets. [1] [2] [3]
The number of joints depends on if sesamoids are included, age of the human and the definition of joints. However, the number of sesamoids is the same in most people with variations being rare. [5] [6] [7] Joints are mainly classified structurally and functionally.
A synarthrosis is a type of joint which allows no movement under normal conditions. Sutures and gomphoses are both synarthroses. Joints which allow more movement are called amphiarthroses or diarthroses. Syndesmoses are considered to be amphiarthrotic, because they allow a small amount of movement. [1]
In amphiarthroses, the contiguous bony surfaces can be: A symphysis: connected by broad flattened disks of fibrocartilage, of a more or less complex structure, which adhere to the ends of each bone, as in the articulations between the bodies of the vertebrae or the inferior articulation of the two hip bones (aka the pubic symphysis).
The pubic symphysis is a nonsynovial amphiarthrodial joint. The width of the pubic symphysis at the front is 3–5 mm greater than its width at the back. This joint is connected by fibrocartilage and may contain a fluid-filled cavity; the center is avascular, possibly due to the nature of the compressive forces passing through this joint, which may lead to harmful vascular disease. [2]
The shoulder girdle is a complex of 5 joints that can be divided into two groups. 3 of these joints are true anatomical joints, while 2 are physiological ("false") joints. [explain 1] Within each group, the joints are mechanically linked so that both groups simultaneously contribute to the different movements of the shoulder to variable degrees.
This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, including Earth science, oceanography, cartography, and human geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic ...