Body CavitiesChapter 1

Mr. Knowles

Anatomy and Physiology

Liberty Senior High School

Body Cavities

Body Cavities• Internal chambers that suspend vital organs.• Functions:

1. Protect delicate organs from shock and cushions them.

2. Allow internal organs to change size and shape without distorting other organs.

Body Cavities

Dorsal Body Cavity

Ventral Body

Cavity

Two Major Divisions

• Dorsal Body Cavity- contain brain and spinal cord.

• Ventral Body Cavity- much larger; contains all of the major organs.

I. Doral Body Cavity

• Subdivided into:

1. Cranial Cavity- contains the brain.

2. Spinal Cavity- contains the spinal cord.

A. Cranial Cavity

• Within the bony skull.

• Protects the brain.

B. Spinal Cavity• extends from the

cranial cavity to the end of the vertebral column

• protects the spinal cord.

II. Ventral Body Cavity• The diaphragm divides this cavity

into:A. Thoracic Cavity- a superior cavity in the chest.B. Abdominopelvic Cavity- an inferior cavity containing the organs of the abdomen and the pelvis.

Body Cavities• Provide moist, internal spaces

that allow expansion and prevent friction.

• Viscera: organs that project into the cavities.

How do the body cavities protect organs?

• Serous membranes line the walls of the cavities and cover the surface of the organs.

• Membranes secrete a fluid (serous fluid) that reduces friction within the cavity.

Naming the Two Layers• Visceral- the layer of membrane

that covers the organ.

• Parietal- the layer of membrane that lines the cavity.

• Both layers secrete a fluid that fills the space between.

Ventral Body Cavity

•Surrounds respiratory, cardiovascular, digestive, urinary, reproductive

II. Ventral Body CavityThe diaphragm separates the Ventral into 2 sub cavitiesThoracic Cavity (superior)

Abdominopelvic Cavity (inferior)

A. Thoracic Cavity

• Contains three internal chambers:

1. Pericardial Cavity- surrounds and protects the heart.

2. Two Pleural Cavities- surround the left and right lung.

1. Pericardium• Made of two layers:

a. Visceral pericardium- membrane covering the heart.b. Parietal pericardium- membrane on the outside.c. Pericardial Cavity- is the fluid-filled space between.

Mediastinum• The region within the thoracic

cavity between the pleural cavities.• Contains the pericardium +

esophagus + trachea.• It is only a region and not a cavity.

Mediastinum

2. Pleural Cavity

• Cavity around each lung.

• Made by the a. visceral pleura and b. parietal pleura.

Abdominopelvic Cavity

AbdominalCavity (Superior)

Pelvic Cavity(Inferior)

B. Abdominopelvic Cavity

• Divided into:1. Abdominal Cavity-

superior; from diaphragm to lowest vertebra.

2. Pelvic Cavity- inferior to the above; pelvic bones form wall and muscles form its floor.

Abdominal Cavity•Lined by a serous membrane- peritoneum which protects the liver, stomach, spleen, small intestine and most of the large intestine.•Kidneys are retroperitoneal- behind the peritoneum.

Peritoneum• Two membranes:

1. Visceral Peritoneum- covers the organs.2. Parietal Peritoneum- lines the abdominopelvic cavity.3. Peritoneal Cavity- is the fluid-filled space between.

Pelvic Cavity• Inferior portion of the abdominopelvic

cavity.• Contains the last segments of large

intestine, urinary bladder, and reproductive organs.

• Only the most superior organs in the pelvic cavity are covered in peritoneum (uterus, uterine tubes, ovaries, and bladder.

Inflammation of Peritoneum-Peritonitis

A Weakened Abdominal Wall-Hernia

Parasites of the Peritoneum