Human body is a complex system that consists of various organs that function together to make a single unit. These organs belong to different body cavities, and work together and make the perfect machine in the universe - the human body. The whole human body is divided into body cavities and these are sub divided into dorsal body cavity and ventral body cavity. The dorsal body cavity comprises cranial and spinal cavity and the ventral body cavity is divided into thoracic, abdominal and pelvic cavity.
Body Cavities in the Human Body
The cranial cavity mainly consists of brain, meninges and cerebrospinal fluid. The cerebrospinal fluid is a clear and colorless fluid that is present in the brain and the spinal cord; meninges are membranes that enclose our central nervous system. The significance of meninges and cerebrospinal fluid is that they play an important role in protecting our central nervous system.
The volume of our cranial cavity is between 1,200-1,700 cm3. Cranial cavity is also called the intracranial space. The three main layers that constitute the meninges are dura mater, the arachnoid mater, and the pia mater. The dura mater consists of endosteal layer and meningeal layer. Arachnoid mater is a thin and transparent membrane in the meninges that forms the cushion like layer and protects the central nervous system. Pia mater is a thin membrane that forms the outer layer of the brain and the spinal cord. The blood capillaries and blood vessels pass through this membrane to reach the brain and the spinal cord.
Spinal cavity is the canal through which the spinal cord extends. Same like our cranial cavity, spinal cavity is also enveloped by meninges. The spinal cord extends from medulla oblongata of the brain to the coccyx and transfers the neural signals from the brain to the rest of our body. Coccyx or tailbone is the end of the vertebral column in human beings. The tissues enveloping the spinal cord is called disc and it is made up of cartilage. Anterior spinal artery and posterior spinal arteries are the vessels that supply cerebrospinal fluid to the spinal cord. Cerebrospinal fluid is supplied to the brain and spinal cord from subarachnoid space.
Thoracic cavity or chest cavity consists of a thoracic wall that protects the heart and lungs, which are the important organs of our body. Diaphragm, that separates the thoracic cavity from the abdominal cavity, forms the floor of the chest cavity and helps in the respiration process. Thoracic cavity consists of important blood vessels such as aorta, pulmonary artery, superior and inferior vena cava, that carry blood from the heart, lungs and to all parts of the body. The most important blood circulation called the 'double circulation', that occurs between the heart, lungs and the rest of the body, is enclosed by the thoracic cavity.
Abdominal cavity is located below the thoracic cavity and it primarily includes the important organs such as kidneys, stomach, liver, the small intestine, large intestine, gallbladder, spleen, and pancreas. The main function of the abdominal organs is to help in the process of digestion. The abdominal wall is made up of a double-layered membrane called peritoneum. Genitourinary system is also a part of the abdominal cavity.
Pelvic cavity mainly consists of the reproductive organs such as rectum and urinary bladder. The lower digestive tract and the reproductive system constitutes the pelvic cavity. The pelvic wall is divided into anterior pelvic wall and lateral pelvic wall. Pubic symphysis is a significant portion of the anterior pelvic wall. Pelvic fascia covers the important parts present near the pelvic brim. There is a pelvic diaphragm which is made up of levator ani and coccygeus muscles that form the floor of the pelvic cavity.
The coordination of the organs in these cavities is very important, as they are interlinked with each other. The improper function of an organ in a cavity will directly affect the functions of other organs in our body.