In order to avoid confusion when describing the body, it is always described in the anatomical position. In the anatomical position, a person stands erect, legs together and arms by their sides, with their head, eyes, toes and palms of the hands facing forward. It is important to remember that the palms face forward as their relaxed position is generally facing inwards.
The anatomical position allows us to describe the position of structures in relation to their surroundings, e.g. ‘the heart lies above the diaphragm’. The anatomical position avoids confusion as to whether the body is lying down or standing up.
You should also bear in mind that when looking at a person in the anatomical position, their right side will be on your left. The structures will always be described as they are to the subject rather than as they appear to you.
There are three major anatomical planes; axial, coronal, and sagittal.
If the body is cut in the sagittal plane, exactly along the middle of the body, it is known as the median sagittal line/plane.
Click here to view the thorax in the axial, coronal and sagittal planes.
Direction is used, when the body is in the anatomical position to explain the location of a structure relative to the structures surrounding it.
The body is split up into two main areas, the axial and appendicular regions. The axial region refers to the head, vertebral column and trunk, and the appendicular region refers to the pelvic girdles and the upper and lower limbs. Each area is further divided into descriptive regions.
There are two main cavities within the body, the ventral and the dorsal cavities.
The dorsal body cavity is at the back of the body and is the smaller of the two cavities. It can be further divided into the upper and lower portions, the cranial cavity and the vertebral canal respectively.
The ventral body cavity is at the front of the body and is the larger of the two cavities. It can be further divided into three cavities, the thoracic cavity, abdominal cavity and pelvic cavity. The thoracic and abdominal cavities are divided by the diaphragm and the abdominal and pelvic cavities are continuous with each other.
The abdomen can be divided by two lines into 4 quadrants or by 4 lines into 9 regions.
The two lines that divide the abdomen into quadrants form a cross, the centre of which is positioned over the umbilicus (belly button). These quadrants are often used to indicate the location of pain.
There are two vertical lines and two horizontal lines that divide the abdomen into a grid. The vertical lines also known as lateral lines are positioned using the middle of each clavicle as a reference. The upper horizontal line (also known as the transpyloric or subcostal line) is positioned at the level of the pylorus of the stomach close to the subcostal margin of the ribs. The lower horizontal line (also known as transtubercular line) is positioned at the level of the anterior superior iliac spines of the coxal (hip) bone.