The brain and spinal cord are protected by the bones of the skull and vertebral column and by cerebrospinal fluid, a colorless fluid produced by the brain, which cushions the brain and spinal cord within the posterior dorsal cavity. The anterior ventral cavity has two main subdivisions: the thoracic cavity and the abdominopelvic cavity see Figure 1.
The thoracic cavity is the more superior subdivision of the anterior cavity, and it is enclosed by the rib cage. The thoracic cavity contains the lungs and the heart, which is located in the mediastinum.
The diaphragm forms the floor of the thoracic cavity and separates it from the more inferior abdominopelvic cavity. The abdominopelvic cavity is the largest cavity in the body. Although no membrane physically divides the abdominopelvic cavity, it can be useful to distinguish between the abdominal cavity, the division that houses the digestive organs, and the pelvic cavity, the division that houses the organs of reproduction. The more detailed regional approach subdivides the cavity with one horizontal line immediately inferior to the ribs and one immediately superior to the pelvis, and two vertical lines drawn as if dropped from the midpoint of each clavicle collarbone.
There are nine resulting regions. A s erous membrane also referred to a serosa is one of the thin membranes that cover the walls and organs in the thoracic and abdominopelvic cavities. The parietal layers of the membranes line the walls of the body cavity pariet- refers to a cavity wall.
The visceral layer of the membrane covers the organs the viscera. Between the parietal and visceral layers is a very thin, fluid-filled serous space, or cavity Figure 1. There are three serous cavities and their associated membranes.
The pleura is the serous membrane that surrounds the lungs in the pleural cavity. The visceral pleura is located on the surface of the lungs, the parietal pleura lines the wall of the thoracic cavity. Figure 1. The pericardium is the serous membrane that surrounds the heart in the pericardial cavity. The visceral pericardium is located on the heart wall, the parietal pericardium lines the wall of the pericardial sac Figure 1.
The peritoneum is the serous membrane that surrounds several organs in the abdominopelvic cavity. The visceral peritoneum lines the surface of many organs, the parietal peritoneum lines the wall of the abdominopelvic cavity. The serous fluid produced by the serous membranes reduces friction between the walls of the cavities and the internal organs when they move, such as when the lungs inflate or the heart beats. Both the parietal and visceral serosa secrete the thin, slippery serous fluid that prevents friction when an organ slides past the walls of a cavity.
In the pleural cavities, pleural fluid prevents friction between the lungs and the walls of the cavity. In the pericardial sac, pericardial fluid prevents friction between the heart and the walls of the pericardial sac. And in the peritoneal cavity, peritoneal fluid prevents friction between abdominal and pelvic organs and the wall of the cavity.
The serous membranes therefore provide additional protection to the viscera they enclose by reducing friction that could lead to inflammation of the organs. Privacy Policy. Skip to main content. Module 1: Body Plan and Organization. Search for:.
Anatomical Terminology Learning Objectives Demonstrate the anatomical position Describe the human body using directional and regional terms Identify three planes most commonly used in the study of anatomy Distinguish between the posterior dorsal and the anterior ventral body cavities, identifying their subdivisions and representative organs found in each Describe serous membrane and explain its function.
Distal - away from or farthest from the trunk or the point or origin of a part example, the hand is located at the distal end of the forearm. Coronal Plane Frontal Plane - A vertical plane running from side to side; divides the body or any of its parts into anterior and posterior portions. Sagittal Plane Lateral Plane - A vertical plane running from front to back; divides the body or any of its parts into right and left sides.
Axial Plane Transverse Plane - A horizontal plane; divides the body or any of its parts into upper and lower parts. Median plane - Sagittal plane through the midline of the body; divides the body or any of its parts into right and left halves.
The cavities, or spaces, of the body contain the internal organs, or viscera. The two main cavities are called the ventral and dorsal cavities.
The ventral is the larger cavity and is subdivided into two parts thoracic and abdominopelvic cavities by the diaphragm, a dome-shaped respiratory muscle. The upper ventral, thoracic, or chest cavity contains the heart , lungs, trachea , esophagus , large blood vessels, and nerves.
The thoracic cavity is bound laterally by the ribs covered by costal pleura and the diaphragm caudally covered by diaphragmatic pleura. Examples include the superior and inferior vena cava, which carry deoxygenated blood away from the head superior and from the lower body inferior to the heart. Anterior and posterior are sometimes used in place of superior and inferior, respectively.
These words are used more often for animal anatomy and rarely and only with very specific meaning in human anatomy. Anterior refers to the side of the structure facing up in the standard anatomical position while posterior refers to the bottom side. For example, the pituitary gland has an anterior and posterior side, each of which secretes different types of hormones.
Dorsal and ventral are sometimes used in place of anterior and posterior, respectively. Dorsal means the back side or upper side, while ventral means the frontal or lower side. These are mostly used with animal anatomy, but can be used in human anatomy as long as they are describing the side of an appendage. Lateral is used to describe anything closer to the sides of the body toward the arms, in the standard anatomical position , while medial is used to describe anything toward the middle of the body.
0コメント