Chapter 1 Organization of the Human Body – Body Cavities and Membranes

Chapter 1

Organization of the Human Body – Body Cavities and Membranes

Major Parts of Human Body

• The human body consists of three major parts:– Cavities– Membranes– Organ Systems

Major Divisions of the Human Body

• The human body can be separated into:– Axial portion• Includes the head, neck, and trunk

– Appendicular portion• Includes the upper and lower limbs

Cavities of the Axial Portion

• Cranial cavity– Houses the brain


• Vertebral canal– Contains the spinal cord surrounded by portions

of the backbone (vertebrae)


• Thoracic cavity– Contains organs called viscera:• Lungs, heart, esophagus, trachea, and thymus gland

– The wall of the thoracic cavity consists of skin, skeletal muscles, and bones.

– The region between the left and the right lungs is called the mediastinum.• The mediastinum contains the heart, esophagus,

trachea, and thymus gland• Separates the thorax into two compartments (one

containing the right lung and one containing the left lung).


• Abdomino-pelvic cavity– Includes an upper abdominal portion and a lower pelvic

portion– Contains organs called viscera

• The viscera within the abdominal cavity include the stomach, liver, spleen, gallbladder, and the small and large intestines

• The pelvic cavity (which is the area enclosed by the pelvic bones) contains the terminal end of the large intestine, the urinary bladder, and the internal reproductive organs

– The wall of the abdomino-pelvic cavity primarily consists of skin, skeletal muscles, and bones

– Separated from the thoracic cavity by the diaphragm• The diaphragm is a broad thin muscle that curves upward into the

thorax like a dome when it is at rest and presses down on the abdominal viscera when it contracts during inhalation

Cavities of the Axial Portion• Smaller cavities within the head:– Oral cavity

• Contains the teeth and tongue– Nasal cavity

• Located within the nose• Divided into right and left portion by a nasal septum• Several air-filled sinuses (including sphenoidal and frontal

sinuses) are connected to the nasal cavity.– Orbital cavities

• Contain the eyes and associated muscles and nerves– Middle ear cavities

• Contain the middle ear bones




Thoracic and Abdominopelvic Membranes

• Serous membranes– Thin membranes that line the walls of the thoracic

and abdominal cavities– Fold back to cover organs within both cavities– Secrete a slippery serous fluid that separates the

layer lining the wall (called the parietal layer) from the layer covering the organ (called the visceral layer)


• Thoracic membranes– Parietal pleura – serous membrane that lines the

right and left thoracic compartments, which contain the lungs

– Visceral pleura – part of the parietal pleura that folds back to cover the lungs• A thin film of serous fluid separates the parietal and

visceral pleural membranes.– Pleural cavity• The potential space between the membranes


• Pericardial membranes– Surround the heart (which is located in the

broadest portion of the mediastinum)• Visceral pericardium

– Cover’s the surface of the heart

• Parietal pericardium– Layer that covers the visceral pericardium but that is

separated from the visceral pericardium by a small amount of serous fluid.» The potential space between the two membranes is

called the pericardial cavity

• Fibrous pericardium– Much thicker layer that covers the parietal pericardium



• Abdominopelvic membranes– Peritoneal membranes• Parietal peritoneum

– Lines the wall

• Visceral peritoneum– Covers each organ in the abdominal cavity

• Peritoneal cavity– The potential space between the parietal peritoneum and the

visceral peritoneum


Documents

Chapter 1 Organization of the Human Body – Body Cavities and Membranes