Joints and Cavities

JOINTS

By connecting one structure to another, joints enable motion. They allow different structures to work with each other in delivering body functions. There are various types of joints, which would be described in the succeeding paragraphs.

Pivot joints enable rotation. An example of pivot joints is the one connecting the atlas and axis vertebrae, which allow the rotation of the head to left or right.

Hinge joints enable flexion and extension. An example of which is the hinge joint of the elbow.

Saddle joints are highly flexible joints in various parts of the body which allow reciprocal reception. Saddle joints allow people to wave their hands.

Plane joints enable eversion and inversion and dorsiflexion and plantarflexion. An example of which is the plane joint between the tarsal bones.

Condyloid joints enable twisting the hand from one side to another. An example of which is the condyloid joint between the radius and carpal bones of the muscles.

Lastly, ball and socket joints enable circumduction, including the sideways, backward-forward, and rotating movements.

CAVITIES

There are several types of body cavities. In this portion, we will be focusing on the following: cranial, spinal, dorsal, thoracic, abdominal, and pelvic.

The cranial cavity houses the brain and some parts of the spinal cord. The spinal cavity, from the name itself, protects the spinal cord. The general term for the area that includes the cranial and spinal cavities is known as the dorsal cavity.

The thoracic cavity protects the heart, lungs, and trachea. This basically pertains to the space occupied by the ventral internal organs above the diaphragm. The thoracic cavity is divided into three: the mediastinum, which is the space between the lungs; the pericardial cavity which houses the heart; and the superior mediastinum.

The abdominal cavity pertains to the space occupied by the ventral internal organs below the diaphragm and above the pelvic cavity. This houses the stomach, liver, pancreas, kidneys, and other parts needed for digestion.

The pelvic cavity houses the different types of muscle such as the abdominal muscles, muscles of the spine, urinary, excretory, and reproductive systems.

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