The Basics-Anatomical Terminology

The Basics-Anatomical Terminology

1. The Anatomical Position

   • A person standing upright, facing forward.
   • Arms straight and hands held by the hips, palms facing forward.
   • Feet parallel and toes pointing forward.

2. Anatomical Planes

   • Sagittal plane
     • a vertical line which divides the body into a left section and a right section.
   • Coronal plane
     • a vertical line which divides the body into a front (anterior) section and back (posterior) section
   • Transverse plane
     • a horizontal line which divides the body into an upper (superior) section and a lower (inferior) section.

3. Anatomical Terms of Movement

   • Flexion and Extension
     • Flexion and extension are movements that occur in the sagittal plane. They refer to increasing and decreasing the angle between two body parts:
       • Flexion refers to a movement that decreases the angle between two body parts.
       • Extension refers to a movement that increases the angle between two body parts.
   • Abduction and Adduction
     • Abduction and adduction are two terms that are used to describe movements towards or away from the midline of the body.
       • Abduction is a movement away from the midline
       • Adduction is a movement towards the midline.
       • In fingers and toes, the midline used is not the midline of the body, but of the hand and foot respectively. Therefore, abducting the fingers spreads them out.
   • Medial and Lateral Rotation
     • Medial and lateral rotation describe movement of the limbs around their long axis:
       • Medial rotation is a rotational movement towards the midline. It is sometimes referred to as internal rotation.
       • Lateral rotation is a rotating movement away from the midline.
   • Elevation and Depression
     • Elevation refers to movement in a superior direction
     • depression refers to movement in an inferior direction.
   • Pronation and Supination
     • keeping your shoulder and elbow still, turn your hand into its back, palm up. This is the supine position, and so this movement is supination.
     • keeping the elbow and shoulder still, flip your hand into its front, palm down. This is the prone position, and so this movement is named pronation.
     • These terms also apply to the whole body – when lying flat on the back, the body is supine. When lying flat on the front, the body is prone.
   • Dorsiflexion and Plantarflexion
     • Dorsiflexion and plantarflexion are terms used to describe movements at the ankle. They refer to the two surfaces of the foot; the dorsum (superior surface) and the plantar surface (the sole).
     • Dorsiflexion refers to flexion at the ankle, so that the foot points more superiorly. Dorsiflexion of the hand is a confusing term, and so is rarely used. The dorsum of the hand is the posterior surface, and so movement in that direction is extension. Therefore we can say that dorsiflexion of the wrist is the same as extension.
     • Plantarflexion refers extension at the ankle, so that the foot points inferiorly. Similarly there is a term for the hand, which is palmarflexion.
   • Inversion and Eversion
     • Inversion and eversion are movements which occur at the ankle joint, referring to the rotation of the foot around its long axis.
     • Inversion involves the movement of the sole towards the median plane – so that the sole faces in a medial direction.
     • Eversion involves the movement of the sole away from the median plane – so that the sole faces in a lateral direction.
   • Opposition and Reposition
     • A pair of movements that are limited to humans and some great apes, these terms apply to the additional movements that the hand and thumb can perform in these species.
     • Opposition brings the thumb and little finger together
     • Reposition is a movement that moves the thumb and the little finger away from each other, effectively reversing opposition.
   • Circumduction
     • Circumduction can be defined as a conical movement of a limb extending from the joint at which the movement is controlled. It is sometimes talked about as a circular motion, but is more accurately conical due to the ‘cone’ formed by the moving limb.

4. Anatomical terms of location

   • Medial and Lateral
     • Imagine a line in the sagittal plane, splitting the right and left halves evenly. This is the midline. Medial means towards the midline, lateral means away from the midline.
   • Anterior and Posterior
     • Anterior (ventral) refers to the ‘front’, and posterior (dorsal) refers to the ‘back’.
   • Superior and Inferior
     • These terms refer to the vertical axis. Superior means ‘higher’, inferior means ‘lower’.
   • Proximal and Distal
     • The terms proximal and distal are used in structures that are considered to have a beginning and an end (such as the upper limb, lower limb and blood vessels). They describe the position of a structure with reference to its origin – proximal means closer to its origin, distal means further away.

5. Terms of Location in Embryology

   • Cephalic and Caudal
     • Cephalic refers to the head of the embryo, while caudal refers to the tail (inferior) end. Cranial is often used instead of cephalic when describing a location of one structure relative to another.
   • Ventral and Dorsal
     • The term ventral refers to the anterior (front) aspect of the embryo, while dorsal refers to the posterior (back).
   • Neuroembryological terms
     • Rostral and caudal are only used to describe structures within the central nervous system, above the level of the spinal cord (e.g brainstem, cerebrum and cerebellum). They are more commonly used in neuroanatomy, but can be applied to embryology.
     • Rostral and Caudal
       • Rostral is taken from the Latin rostrum, to mean towards the nose/beak. Rostral therefore refers to the anterior (front) aspect of the head. In this context, caudal refers to the posterior (back) of the head.
     • Ventral and Dorsal
       • As described above, ventral and dorsal refer to the anterior and posterior aspects of the body respectively. However in the context of the central nervous system, they have slightly different meanings. Ventral refers to the inferior region of the brain, while dorsal refers to the superior region (towards the scalp).