Anatomical position

The anatomic position, also referred to as the standard anatomic position, is the consistent position of the human body in which positional reference is made for anatomical nomenclature. It is not reliant on whether the patient is standing, supine, prone, sitting, etc.

The position is defined as if the body is standing erect (hips and knees extended), head facing forward, eyes open and looking directly forwards and mouth closed. The arms are by the sides (shoulders adducted), the palms are facing forward (elbows extended and wrists supinated) and the feet parallel and together. In this position, the radius and ulna are parallel. Interestingly, due to the effect of gravity, the anatomic location of viscera is described when the patient is supine (e.g. surface anatomy of the liver).

{{youtube:http://youtu.be/JXPMla7Z8_k}}

The anatomic planes are then expressed in relation to the anatomic position when standing. The three standard planes are perpendicular to each other and are:

• the axial plane (transverse or transaxial plane): horizontal plane perpendicular to the long axis of the body
• the sagittal plane: vertical plane parallel to the median plane (or midsaggital plane which divides the body into two halves)
• the coronal plane: vertical plane perpendicular to the median plane

Anatomic description (adjectives) in regards to relationships are referenced to the anatomic position, in that:

• anterior: towards the front of the body (Latin: before)
• posterior: towards the back of the body (Latin: after)
• superior: towards the top of the body (Latin: above)
• inferior: towards the bottom of the body (Latin: below)
• medial: towards the midline (Latin: middle)
  • compared with median which is in the midline rather than towards the midline
• lateral: away from the midline (Latin: side)
• proximal: towards the centre of the body (Latin: near)
• distal: away from the centre of the body (Latin: far)
• superficial: towards the surface of the body
• deep: away from the surface of the body

Other older or traditional terms are still in use today, some of which are particularly relevant in embryology and include:

• dorsal: superior or posterior, can be used in structures that protrude away from the body (such as the tongue, penis, nose, foot); an embryological term that describes a structure's position during development which may be altered from the end position after development
• ventral: anterior
• caudal: towards the tail (feet); an embryological term derived from vertebrates with tails
• cephalad: towards the head
• rostral: anterior; used in brain development
• volar, palmar: anterior, used in relation to the hand
• plantar: sole of the foot
• radial: radial aspect of the forearm
• ulnar: ulnar aspect of the forearm
• tibial: tibial aspect of the anatomical leg
• fibular: fibular aspect of the anatomical leg

Dental anatomy

• mesial, distal: medial and lateral with regards to any tooth
• buccal: anterior surface of the tooth
• palatal: posterior surface of a maxillary tooth
• lingual: posterior surface of a mandibular tooth

Laterality

• unilateral: one side of the body
• bilateral: both sides of the body
• ipsilateral: on the same side of the body
• contralateral: on the opposite side of the body

Movement

Movement of parts of the body are described in relation to the anatomic position. They occur in opposing pairs and include:

• flexion: decrease in the angle of the joint
• extension: increase in the angle of the joint
• abduction: movement of limb away from midline
• adduction: movement of limb towards the midline
• pronation: movement of hand and forearm to bring the palm facing posterior
• supination: movement of hand and forearm to bring the palm facing anterior
• circumduction: circular movement of a joint using a combination of flexion, abduction, extension and adduction such that the distal limb describes a circle
• ulnar deviation: lateral movement of the wrist towards the midline
• radial deviation: lateral movement of the wrist away from the midline
• opposition: thumb brought to oppose another digit
• reposition: thumb repositioned back to the anatomic position
• elevation: movement of the scapular superiorly
• depression: movement of the scapular inferiorly
• eversion: movement of the sole of the foot away from the median plane
• inversion: movement of the sole of the foot towards from the median plane
• protrusion: movement of the mandible, lips or tongue anteriorly
• retraction: (retrusion) movement of the mandible, lips or tongue posteriorly