Thorax: Definition and Anatomy

Instructor: Sarah Phenix
The thorax is a structure found in humans, but it is not unique to humans- it exists in all mammals and arthropods. In this lesson you will learn what the thorax is and where it is located in the human body.

Anatomical Terminology: Useful & Important Tools

Anatomical terms may not sound like particularly important things, but think about how difficult it would be for a nurse to explain to a doctor where a patient was injured or what it might be like to discuss a surgical procedure without having a unified and universal set of terms. Yikes! If I were injured, I would much rather have the doctor know that it was, say, my 'upper limb' or my 'arm' rather than 'that long bendy thing off the top of my body'. Anatomical terms not only provide us with a universally accepted vocabulary but they also enable us to convey more specific, detailed, and succinct information much faster.

With that said, there are many different levels of regional classifications for the body. They can be general and refer to large regions of the body, such as the thorax, or they can be very specific and refer to a particular subregion, such as the oropharynx (the region of your throat between your soft palate and your epiglottis (the tissue flap that closes off your airway when you swallow food). See how much easier it was to name the oropharynx than it was to describe it? Thanks anatomical terminology! Here we are going to focus on the broad region of the body called the thorax.

Major Regions of the Human Body

Major regions of the body. See the thoracic cavity in purple.
Body cavities

What it is that determines the boundaries of a region varies with each particular region. Some regions identify structures off of the main trunk of the body, such as the upper limb region, lower limb region, cephalic region (head), or cervical region (neck), while others refer to subsections of the trunk and are delineated by either the walls of a body cavity or by the bone structures housed within those regions, such as the thoracic region (thorax), abdominal region, pubic region, and the pelvic region.

Thoracic Region, aka the Thorax

The thorax is a body region found in all mammals and refers to the upper area of the trunk, between the base of the neck and the diaphragm (the fibrous membrane that separates your lungs from your abdomen and helps you breathe).

Internally, this region houses your heart and lungs and is encased by your ribs. The long bony structure of your sternum (also known as the breast bone) supports your ribs at the front of your thorax, while specialized vertebrae of your spine, called thoracic vertebrae, support your ribs in the back.

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