complete lecture

1. Human Body Cavities
Ikramullah

2. At the end of the lecture, students will be able to
• Define body cavity
• Explain classification of various body cavities
• Describe body cavities in detail

3. Body Cavity
A body cavity is a space or compartment in the
body that houses organs or structures.
In other words, a body cavity is the space left
over when internal organs are removed.

5. Dorsal Cavity
• We know dorsal means back or posterior, so
the dorsal cavity is the cavity located in the
back of the body.
• The dorsal cavity is highlighted in red and
labeled with a star below.
• You can see how the dorsal cavity is situated
behind or posterior to the ventral cavity.
• The dorsal cavity houses the contents of the
central nervous system including the brain
and spinal cord.
• The dorsal cavity is located in the back of the
body (red/stars) and houses the central
nervous system including the brain and spinal
cord.

6. Ventral Cavity
• The ventral cavity is the cavity located in the
front of the body, which makes sense
because ventral means front or anterior.
• The ventral cavity is highlighted in red and
labeled with a star below.
• You can see how the ventral cavity is situated
in front of or anterior to the dorsal cavity.
• The ventral cavity houses the contents within
the chest, abdomen, and pelvis.
• The ventral cavity is located in the front of
the body (red/star) and houses the
organs/structures of the chest, abdomen,
and pelvis.

7. The dorsal cavity can be subdivided into 2 main parts:
1. Cranial Cavity
2. Spinal Cavity
We will first discuss the cranial cavity followed by the spinal cavity.
Cranial Cavity
• The cranial cavity is the superior portion of the dorsal
cavity, as we can see highlighted in red and labeled by
the star below.
• The cranial cavity is enclosed by the cranium or skull,
and it houses the brain.
• The cranial cavity is filled with fluid called cerebrospinal
fluid that helps protect and cushion the brain.
• Each cavity is also lined with thin sheets of tissue called
membranes.
• The cranial cavity is lined by a 3 layer membrane called
the meninges.
• The meninges also help protect and cover the brain.
• The 3 meningeal layers are the duramater, arachnoid, and
piamater.

9. Spinal Cavity
• The spinal cavity is also known as the vertebral cavity, and it is the inferior
portion of the dorsal cavity.
• The spinal cavity is continuous with the cranial cavity as we can see
highlighted in red and labeled by the stars below.
• The spinal cavity is enclosed by the vertebral column or spine, and it houses
the spinal cord.
• The spinal cavity also contains cerebrospinal fluid which helps protect the
spinal cord.
• Remember the cranial cavity and spinal cavity are continuous with one
another, so it makes sense they both contain CSF.
• Likewise, the meninges line the spinal cavity similar to the cranial cavity.

11. The ventral cavity can also be subdivided into 2 main parts:
1. Thoracic Cavity
2. Abdominopelvic Cavity
The thoracic cavity and abdominopelvic cavity are separated by the diaphragm.
• The thoracic cavity is the cavity in the chest.
• It is the superior portion of the ventral cavity located above the diaphragm, as
highlighted in red below.
• The thoracic cavity is enclosed mainly by the rib cage, vertebral column, and sternum.
• The main contents of the thoracic cavity include the heart, lungs, trachea, esophagus,
great vessels, and thymus gland.
• Similar to the cranial and spinal cavities, the thoracic cavity is also lined by a
membrane.
• The membrane that lines the majority of the thoracic cavity is the parietal pleura.

13. Thoracic Body Cavity: Labeled diagram of the thoracic cavity (red) along
with its features, such as its structures (heart, lungs, trachea, esophagus, great
vessels, thymus gland), and membrane (parietal pleura).
In order to better understand the parietal
pleura, as well as the fluid within the
thoracic cavity, we can subdivide the
thoracic cavity even further.
• The thoracic cavity can be subdivided
into 2 main parts:
• Pleural Cavities
• Mediastinum

14. Pleural Cavities
• There are 2 pleural cavities in the thorax, a right and a left.
• Each pleural cavity surrounds a lung.
• The right pleural cavity surrounds the right lung and is located in the right side of the thoracic cavity.
• The left pleural cavity surrounds the left lung and is located in the left side of the thoracic cavity.
• The right lung is highlighted in red with the right pleural cavity surrounding it shown in yellow below.
• The left lung is uncolored as a reference.
• Each pleural cavity contains a small amount of fluid, called pleural fluid.
• The pleural fluid helps lubricate the membranes lining the pleural cavity and lungs when breathing in
and out.
• The pleural fluid is located in the pleural cavity, also known as the pleural space, which is the potential
space between the lungs and chest wall shown in yellow.
• Each pleural cavity is lined by a serous membrane called the pleura.
• The pleura folds on itself to create a double-layered membrane shown in green and purple below.
• The inner green membrane that lines the lung is called the visceral pleura, and the outer purple
membrane that lines the thoracic cavity is called the parietal pleura.
• The potential space between the visceral and parietal pleura is the pleural cavity/space shown in
yellow.

16. Mediastinum
• The mediastinum is located in the middle
portion of the thoracic cavity.
• You can use the “M” in “Middle” and
“Mediastinum” to help you remember this.
• The main contents of the mediastinum include
the heart, trachea, esophagus, great vessels,
and thymus gland.
• The outer parietal pleura we discussed earlier
lines the mediastinum, as shown in the image
below.

18. Pericardial Cavity
• The pericardial cavity is located in the
mediastinum within the thoracic cavity, and it
surrounds the heart as well as the roots of the
great vessels.
• Similar to how the pleural cavity contained
pleural fluid, the pericardial cavity contains a
small amount of fluid called pericardial fluid.

19. Abdominopelvic Cavity
• The abdominopelvic cavity is the inferior
portion of the ventral cavity located below
the diaphragm, as highlighted in red
below.
• As the name suggests, the abdominopelvic
cavity is in the abdomen and pelvis and
consists of both the abdominal cavity and
pelvic cavity.
• Abdominopelvic Body Cavity: Labeled
diagram of the abdominopelvic cavity
(red), which is the inferior portion of the
ventral cavity below the diaphragm. It
consists of the abdominal and pelvic
cavities.

21. Abdominal Cavity
• The abdominal cavity is the middle portion of the ventral cavity (or the superior portion of the
abdominopelvic cavity) as highlighted in red below.
• The abdominal cavity is enclosed mainly by the rib cage, abdominal muscles, and the vertebral
column.
• The diaphragm forms the superior boundary of the abdominal cavity, and an imaginary line at
the pelvic inlet forms the inferior boundary between the abdominal and pelvic cavities.
• Some of the main contents of the abdominal cavity include the liver, stomach, pancreas, spleen,
kidneys, and intestines.
•

22. Conti…………….
• Similar to the pleura and pericardium, the abdominal cavity is lined
with a double-layered serous membrane called the peritoneum.
• The inner visceral peritoneum lines most of the internal abdominal
organs or viscera, and the outer parietal peritoneum lines the walls of
the abdominal cavity.
• The peritoneal cavity is the potential space between the visceral and
parietal peritoneal layers, and it contains a small amount of fluid called
peritoneal fluid.
• The peritoneal fluid helps lubricate the membranes that line the
peritoneal cavity and most of the abdominal organs.

24. Pelvic Cavity
• The pelvic cavity is the inferior portion of the ventral cavity.
• It is enclosed by the pelvis and pelvic floor muscles.
• The pelvic cavity is continuous with the abdominal cavity superiorly at the pelvic
inlet.
• The pelvic cavity mainly houses the urinary bladder, reproductive organs, pelvic
portion of the colon, and rectum.
• Since the pelvic cavity is continuous with the abdominal cavity, the fluid and
membranes are the same.

26. Thanks
Any Question