The planes, axes, lines and regions of the body

Normal anatomy looks at the parts and organs of  human body standing erect and facing forwards, upper limbs by the side with the palms facing forwards, and the lower limbs together with the toes facing forwards. This standart is known as the anatomical position.

The human body consists of certain topographical parts where there are located organs, muscles, blood vessels, nerves and so on.

There are such parts of the body:

• Head (caput);
• Neck (cervix);
• Trunck (truncus) which consists of thorax (thorax), front of chest (pectus), abdomen (abdomen), back (dorsum), pelvis (pelvis);
• Upper limbs (membri superiores);
• Lower limbs (membri inferiores).

There are landmarks in anatomy: lines, axes and planes.

To determine the location and position of organs we can use three anatomical perpendicular planes (plana), which imaginary can divide any point of the organ or region of the human body: sagittal (sagittalis), planum sagittalia (from the Greek sagitta – arrow; in this case, arrow, that permeats through the body) – is imaginary vertical line which extends from the front of the body to the back; frontal (frontalis, from the Greek frons – forehead), planum frontalia, which is parallel to the forehead and is perpendicular to the saggital plane; horizontal, planum horizontalia, that is located perpendicular to the first two.

In the human body is possible to draw a lot of imaginary lines.

Sagittal plane, that divides the body into right and left halves, called medial plane (planum medianum), to indicate the location of organs in relation to the horizontal plane we can use terms: superior ( cranial, from the Greek cranium – brain box), inferior (caudal, from the Greek cauda – tail); concerning to the frontal plane we can use terms anterior  (ventral, from the Latin venter – abdomen) and posterior (dorsal, from the Latin dorsum – back).

There is also term lateral (lateralis) to indicate organs and body parts, which are located on the side and far away from the median plane, and medial (medialis) – which is closer to the median sagittal plane. To describe structures in the limb, taking the datum point as the attachment of the limb to the trunk  we can use terms proximal (proximalis), which is closer to the trunk than distal (distalis).  So proximal structure is closer to the attachment of the limb than a distal structure. Besides that,  in anatomy we can use such adjectives as right (dexter), left (sinister), big (major), small (minor), superficial (superficialis), deep (profundus).

The human body  is also divided into anatomical axes.  Axis of rotation is an imaginary line (point of rotation) that passes through a joint or the body to describe the movement.

Frontal axis (frontalis) is horizontal and located parallel to the frontal plane. Around it can be performed flexion (flexio) and extension (extensio) of limbs and other parts of the body. Sagittal axis (sagittalis) is also horizontal and is parallel to the sagittal plane. Around it is possible adduction (adductio) and abduction (abductio) limbs and other parts of the body. Around the vertical axis is possible to make rotation (rotatio) of  body parts. Besides that, is possible circumduction (circumductio), when a limb or other part of the body describes a cone, the tip of which is a specific joint.

The organs are projected on the surface of the body.

To determine the borders we can use some imaginary vertical lines, also anterior and posterior median lines (linea mediana anterior et linea mediana posterior). The first is in the middle of the front surface of the body, dividing it into two symmetrical halves – left and right, the second – along the tops of the spinous processes of the vertebras. The right and left sternal line (linea stemalis dextra et linea stemalis sinistra) pass along the appropriate edges of the sternum. Medclavicular line (linea medioclavicularis) passes through the middle of the clavicle. Between this two lines passes also parasternal line (linea parastemalis). Anterior, posterior and midaxillary lines (lineae axillares anterior, posterior et media) are passing through respective border and the middle of axillary fossa. Scapular line (linea scapularis) passes through inferior angle of scapula. Paravertebral line (linea paravertebralis) passes along vertebral column at the level of Costotransverse joints.

To accurately determine the projection of the internal abdominal organs on the front wall of the abdominal cavity we can use four lines that divide it into 9 areas.

The superior horizontal line which connects the lowest parts of the tenth ribs, called the costal line (linea costarum). Above this line is located the epigastric (epigastrium). Inferior horizontal line, which connects right and left anterior superior iliac spine, called spinous line (linea spinarum). Below of this line is located pubic region (hypogastrium). Two vertical lines are passing from the lowest point of left and right tenth rib along the medial border of the rectus abdominis to the pubic tubercle. These two lines divide the abdomen into 9 smaller regions.