Week 1 Body Cavities

Introduction to Body Cavities, Planes, and Sections

To be able to have conversations about the human body between different people, it is important that we have a common language to know where to look. In an effort to provide this language, we divide the body up into:​

• Body Cavities​

• Body Sections ​

We will use planes throughout the body to identify common directions, which will help locate the described body part as well as give us a common language with which to view human anatomy. Imagine you are holding a heart one way and someone else is holding the heart upside down. If you have never seen a heart before, you would not know if you are looking at the same thing or not. Using body planes will help us avoid this confusion!

Body Planes and Sections

If an upright body in the anatomical position were to be sliced horizontally, in the transverse plane, which statement would be true?; The body would be divided into equal superior and inferior portions.

Imaging Techniques

Which imaging techniques rely on body planes?; All of these imaging techniques rely on body planes.

A CT scanner produces a series of images (slices) of the body in the transverse (axial) plane.​

MRI images can be obtained in any plane, and in most sequences, the images are typically viewed using the same principles as CT.​

PET scans are also transverse planes. ​

In a sonogram, the body structures are generally viewed longitudinally and axially using a Doppler ultrasound. Longitudinal views show the length and depth of a structure. Axial views demonstrate width and depth.

Body Cavities

The abdominopelvic cavity can be divided into; 4 Quadrants

Body Cavities Overview

Body cavities act as compartments in the human body. These compartments house and protect internal organs. The body’s two main compartments, the ventral and dorsal cavities, can be further subdivided based on the organs they surround. 

Body cavities, their location, associated organs, and subdivisions will be discussed.

Body Cavity Functions

Body cavities have two basic functions:​

• Protect vital internal organs from accidental shock​.

• Allow for possible changes in the shape and size of organs while still maintaining the organ system’s integrity​.

We can identify the location of body structures based on the cavity in which they are found. For example, the abdominopelvic cavity contains the organs of the abdomen cavity and the pelvic cavity. Clinicians and anatomists further divide the abdominopelvic cavity into four quadrants and nine regions, which we will examine further.​

Body Cavities: Dorsal and Ventral

The human body contains two major cavities, each of which has two major subdivisions:

• Dorsal cavity

  • Cranial: contains the brain and is surrounded by the skull

  • Vertebral: contains the spinal cord

• Ventral cavity

  • Thoracic: contains the heart and lungs

  • Abdominopelvic: contains all abdominal and pelvic organs

  • The thoracic and abdominopelvic cavities are separated by the diaphragm

Ventral Cavity: Thoracic

There are two pulmonary cavities, each of which surrounds a lung.​

• Right and left pulmonary cavities are bilateral compartments that contain the lungs and pleurae (lining membranes) and take up the majority of the thoracic cavity. ​

• The pleurae refers to the double-layered serous membrane. More specifically, it is the visceral pulmonary layer that abuts the surface of the lungs and is separated from the superficial parietal layer by the pleural cavity, which is a space filled with lubricant, aiding in reducing friction during inhalation and exhalation.​

• Each lung sits on either side of the mediastinum, which is an area in the middle of the thorax that contains the heart, portions of the trachea, the esophagus, and several important vessels.​

There is one pericardial cavity, which surrounds the heart.

• It is located in between the two pulmonary cavities.

• The pericardial cavity is made up of two layers; the visceral layer and the perietal layer.

Ventral Cavity: Abdominopelvic

The two subdivisions of the abdominopelvic cavity are the abdominal and pelvic cavities.​

• Abdominal cavity​

  • Contains the stomach, intestines, spleen, and liver​

  • Superior region of the cavity​

• Pelvic cavity​

  • Contains urinary bladder, reproductive organs, and rectum​

  • Inferior region of the cavity 

Which cavity is surrounded by the skull?;

 Dorsal cavity: 

• Cranial: contains the brain and is surrounded by the skull

• Vertebral: contains the spinal cord​

Ventral cavity:

• Thoracic: contains the heart and the lungs

• Abdominopelvic: contains all abdominal and pelvic organs

What is the cavity in the chest surrounded by the ribs?; Respiratory/Pulmonary 

Within the thoracic cavity, there are two pulmonary cavities, each of which contains a lung and is surrounded by the ribs. 

The thoracic and abdominopelvic cavities are separated by the diaphragm with the thoracic cavity superior and the abdominopelvic cavity inferior. The cranial cavity contains the brain and is surrounded by the skull, and the vertebral cavity contains the spinal cord and is surrounded by vertebrae.

Abdominopelvic Quadrants

The abdominopelvic cavity is divided into four quadrants. Here is important information to remember about the abdominopelvic quadrants:

• There are imaginary lines that separate parts of the abdominopelvic cavity​ (see image)

• Provides an easy means of identifying the location of body structures​

• Four abdominopelvic quadrants​:

  • Right upper quadrant (RUQ)

    • Liver and gallbladder pain presents as RUQ pain.​

  • Left upper quadrant (LUQ)​

  • Right lower quadrant (RLQ)​

  • Left lower quadrant (LLQ)

Study note:

When deciding between which side is left or right, always go with the client’s left side and right side.

Abdominopelvic Regions

Review the tabs to learn about the abdominopelvic regions and their associated organs as well as the clinical presentation of the abdominopelvic quadrant concerns. 

The umbilical region: ​

• Located at the center of the abdomen, surrounding the umbilicus (navel).​

• Associated organs: duodenum, small intestine, transverse colon

​The epigastric region: ​

• Located superiorly (above) the umbilical region. ​

• Epi = Above

• Associated organs: liver, stomach, pancreas, duodenum, spleen, adrenal glands

​The hypogastric (pubic) region: ​

• Located inferiorly (below) the umbilical region.​

• Hypo = below

• Associated organs: urinary bladder, portions of the sigmoid colon, small intestine, reproductive organs

​Right & left lumbar (flank) regions: ​

• Located laterally to the umbilical region. ​

• Lumbar refers to the lower back. ​

• Associated organs:

  • Right: portions of the ascending colon, portions of the small intestine, right kidney

  • Left: portions of the descending colon, portions of the small intestine, left kidney

​Right & left hypochondriac regions: ​

• The upper region of the abdomen below the cartilage of the lower ribs. ​

• Hypochondriac literally means “below the cartilage of the ribs.” ​

• Associated organs:

  • Right: liver, gallbladder, right kidney, portions of small and large intestines

  • Left: spleen, large and small intestines, left kidney, pancreas, stomach, small portion of the liver

​Right & left iliac (inguinal) regions: ​

• Region near the groin (inguin/o = groin), which is the area where the legs join the trunk of the body. ​

• The term Iliac is derived from the ilium, a wide bone forming the upper part of each side of the hip bone or pelvis. 

• Associated organs:

  • Right: appendix, cecum, ascending colon, small intestine

  • Left: portions of the sigmoid colon, descending colon, small intestine

Clinical presentations of abdominopelvic quadrant concerns include:​

Appendicitis: ​

• Suspect appendicitis, inflammation of the appendix, in a young male client who complains about the right lower quadrant (RLQ Abdomina) because the appendix is found in the RLQ. ​

• Upon palpation of this client's RLQ, you will notice tenderness. ​

Pelvic Inflammatory Disease: ​

• Inflammation of ovaries. ​

• To know where the pain will be felt, think in which abdominal region and in which abdominal quadrant the ovaries are found. ​

• clients will have RLQ or right iliac/inguinal abdominal pain. ​

Diverticulitis: ​

• Diverticula are pouchlike herniations through the walls of an organ, most commonly affecting the sigmoid colon of the large intestine.​

• The weakened colonic muscular wall is due to constant straining and severe chronic constipation precipitated by a low fiber diet and excessive consumption of red meat. ​

• Common clinical presentation:​

  • A Caucasian male in his mid 60s presenting with lower left quadrant (LLQ) abdominal pain accompanied by LLQ tenderness on physical examination. ​

  • Past medical history is consistent with severe constipation and straining during defecation. ​

  • Social history reveals a diet that is poor in fiber and rich in red meat.​

Peptic Ulcer Disease:

• A sore on the lining of the stomach or the small intestine. ​

• Clients with peptic ulcer disease complain of epigastric pain + vomiting. ​

• A clue to diagnosis is a history of taking a lot of nonsteroidal anti-inflammatory drugs (NSAIDs). 

The appendix is in what quadrant?; Right lower quadrant

A patient reports liver pain. You would suspect the location of pain to be in which abdominopelvic quadrant?; Right Upper Quadrant 

Body Planes and Sections Overview

• Body planes are invisible flat surfaces (dividing lines) that separate organs, structures, or the human body into sections.​

• Anatomists utilize three standard planes to describe the location or direction of body structures (see image):

  • Transverse plane

  • Coronal plane

  • Sagittal plane

• Sectional anatomy refers to invisible flat surfaces that separate organs, structures, or the body into distinct planes and sections as described below. ​

• This is useful when studying structures/organs from various aspects or views. ​

• It is used to visualize internal organization and structure and is important for medical imaging techniques.

 Plane

• Refers to an axis​

• Three planes are needed to describe any three-dimensional object.

Section

• The portion or slice of the body formed by cutting along the plane.

RECAP

A plane is an imaginary line, while a section is the portion or slice of the body formed by the cutting of the plane. 

Sagittal Plane 

• A sagittal plane is a slice that is parallel to the long axis of the body or structure. ​

• It runs vertically from top to bottom. ​

• This plane separates a body or structure into left and right portions.

• The midsagittal plane is a sagittal plane that runs perfectly down the midline of the body (or structure).

• It divides the body (or structure) into equal left and right portions.

• In the image, the midsagittal plane is illustrated in blue.

• The parasagittal plane is a sagittal plane that is lateral to the midline of the body (or structure).

• It divides the body into unequal left and right portions​.

• The prefix "para-" means "next to, beside, or alongside."

• In the image, the parasagittal plane is illustrated in yellow.

Coronal Plane

The coronal plane ​is also known as the frontal plane. 

• A frontal plane is a slice that is parallel to the long axis of the body or structure. ​

• It runs vertically, from top to bottom. ​

• This plane separates the body or structure into anterior (front) and posterior (back) portions. ​

• In the image, the frontal plane is illustrated in blue.

What does the prefix “para” mean?; Beside

Transverse Plane

The transverse plane is also known as the axial or horizontal plane.

• A transverse plane is a slice that is perpendicular to the long axis of the body or structure. ​

• The prefix “trans” means “across.”​

• The transverse plane is a plane that runs horizontally. ​

• It separates the body or structure into superior (above) and inferior (below) portions.​

• In the image, the transverse plane is illustrated in blue.

Recap of the Three Planes

To remember the 3 main types of planes, use SCT, which is an abbreviation of the word “section.” ​

• ​SCT = Sagittal, Coronal, Transverse​

  • Sagittal

    • Vertical plane

    • Divides into right and left sections

    • In the image, illustrated in orange

  • Coronal

    • Vertical plane

    • Divides into anterior (front) and posterior (back) sections

    • In the image, illustrated in blue

  • Transverse

    • Horizontal plane

    • Divides into superior (above) and inferior (below) sections

    • In the image, illustrated in green

Within the thoracic cavity, two compartments exist, inside of which the organs partaking in inhalation and exhalation reside. The two compartments are called what?; Pulmonary Cavities

Which is not one of the four main body cavities?; The human body contains four main body cavities: cranial, vertebral, thoracic, and abdominopelvic.

The heart is contained within the pericardial cavity, while each lung is contained within the pulmonary cavity. The pancreas is found within the abdominal cavity, and the female ovaries lie within the pelvic cavity. Inside the cranial cavity is the brain.

The liver is found in the RUQ

A 22-year-old male client presents to the emergency room with abdominal pain, anorexia (loss of appetite), nausea, and fever. Pain started in the mid-abdominal region 6 hours ago and is now in the right lower quadrant of the abdomen. The physical exam reveals a febrile young adult in severe distress with a temperature of 102 °F and pain on palpation in the right lower quadrant.​

Based on what you know about which organs are in each abdominopelvic quadrant, which disease do you think the client would most likely have?

The client most likely has appendicitis. 

• Appendicitis is most commonly seen in males between ages 10 and 25. ​

• The abdominal pain begins in the central abdomen (periumbilical abdominal pain) and migrates to the right lower quadrant (RLQ) over the course of a few hours.​

• Severe tenderness on palpation of RLQ on abdominal examination is a classic physical examination finding of appendicitis. 

A client has left lower quadrant (LLQ) abdominal tenderness present on palpation. Which is the most likely diagnosis?; diverticulitis

Which is a correct description of a transverse plane?; Transverse planes separate into superior (above) and inferior (below) portions and run perpendicular to the long axis of the body.

Sagittal planes separate into left and right.

Frontal planes separate into anterior (front) and posterior (back).