7. Body Cavities and Viscera

Omental Bursa

- Extension of peritoneal cavity

Primitive gut

- A flat sheet of intraembryonic endoderm that will change into a tubular gut due to the folding of embryonic body-head, tail, and lateral body folds.

Anterior Mediastinum

- Anterior to middle mediastinum just below sternal angle - Fat depository

Retroperitoneal Cavity

- Behind the peritoneum - Extra-peritoneal space - Fat containing area with various organs scattered through it like the kidneys, pancreas, loops of bowel

Intraperitoneal Viscera

- Contains esophagus, stomach, spleen, liver, gallbladder, biliary tree, jejunum, ileum, transverse colon

Define the boundaries of the abdominopelvic walls

- Diaphragm (roof) - Posterior abdominal wall (back) - Anterolateral abdominal wall (sides) - Pelvic diaphragm (floor)

Explain the embryological basis for the arrangement of thoracic organs

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Name the three main body cavities

1. Cranial 2. Thoracic 3. Abdominopelvic

What are the four cavities in the trunk?

1. Thorax 2. Abdomen 3. Pelvis 4. Back

Describe the position of the pericardial cavities within the thoracic cavity

The heart lies in the pericardial cavity. The pericardial cavity is formed by the pericardium, or pericardial sac, tissues that surround the heart and anchor it within the mediastinum.

Describe the position of the mediastinum within the thoracic cavity

The mediastinum lies between the right and left pleural sacs in and near the median sagittal plane of the chest. It extends from the sternum anteriorly to the vertebral column posteriorly. The mediastinum contains the heart and its vessels, the esophagus, trachea, phrenic and cardiac nerves, the thoracic duct, thymus and lymph nodes of the central chest.

Define the thoracic body cavity

The thoracic cavity is the chamber of the body that is protected by the thoracic wall - The thoracic skeleton defines the limits of the thoracic cavity - The diaphragm forms the floor or base of thoracic cavity

Secondary Peritoneum Organs

- Duodenum, pancreas, caecum, ascending colon, descending colon

Posterior Mediastinum

- Esophagus on its way to the abdomen - Descending aorta

Sub (infra-)peritoneal Space

- Inferior to peritoneal lining - In pelvic cavity - Makes up most of the pelvic cavity - Superior boundary is the sacral promontory - Anterior boundary is the pubic synthesis - Inferior boundary is the pelvis diaphragm

Two parts of the Cranial Cavity

- Neural cranium (brain case) - Skeleton of mid face (between eyes and mouth, including upper jaws)

Superior Mediastinum

- Superior to middle mediastinum just above sternal angle - Arch of aorta, pulmonary arteries, trachea and its bifurcation

Retroperitoneum

- The retroperitoneal space (retroperitoneum) is the anatomical space (sometimes a potential space) in the abdominal cavity behind (retro) the peritoneum. It has no specific delineating anatomical structures. Organs are retroperitoneal if they have peritoneum on their anterior side only.

Describe the position of the pleural cavities within the thoracic cavity

- The right and left pleural cavities are separate compartments on either side of the mediastinum. - Each encloses a lung and its associated bron chial tree, and vessels, nerves and lymphatics.

Peritoneal Cavity

- The space within the abdomen - Contains the intestines, the stomach, and the liver (intraperitoneal organs) - Superior boundary is the diaphragm

Define the abdominopelvic cavity

The abdomen and pelvis form the largest continuous visceral cavity of the body.

Describe the locations of the heart, lungs, trachea and esophagus in the thoracic cavity.

Trachea: superior mediastinum Heart: middle mediastinum Lungs: middle mediastinum Esophagus: superior mediastinum