Appendix: Anatomic Positions and Directions

In orthopaedics, anatomic positions and directions are routinely used to provide an accurate description of specific anatomic locations. These basic directions may be compared to looking at a map to determine the longitude and latitude of an area. Humans are three-dimensional subjects with points of reference made in the orthograde (upright) position. The surface locations and anatomic planes are described as follows.

Surface Location

The location of a structure is described in reference to a standing person facing the examiner with outstretched hands in a palms-up position. The basic directional terms are:

anterior (ventral): forward or front surface (Fig. B-1)

inferior: lower area, below, toward the tail end

lateral: sides, away from midline

medial: middle, toward the midline

posterior (dorsal): back surface

superior: upper area, above, toward the head

These reference points may be combined to give a more precise location to a specific region on a surface or in structures deep within the body, for example, the exposed hip in a surgical procedure. When these terms are compounded and hyphen omitted, the combining forms may be:

anteroinferior: front and below

anterolateral: front and to outer side

anteromedial: front and to inner side

anteroposterior: front and toward back

anterosuperior: front and above

These can be used in combination with locations in reverse order, such as:

posteroinferior: back to below

posterolateral: back to outer side

posteromedial: back to inner side

posterosuperior: back to front toward head

In some cases, dorsal (back) may be used for posterior (e.g., dorsolateral).

Anatomic Planes

The term plane comes from the Latin word planus, meaning a flat, level surface. There are three directions of planes, all in reference to a standing person facing the examiner: vertical anterior to posterior (sagittal), vertical side to side (coronal or longitudinal), and horizontal (transverse).

anteroposterior planes

median (midsagittal) plane: vertical plane directly through the midline of the body, transecting the nose, navel, and spine, and dividing the body into left and right halves.

median or sagittal plane: any of the anteroposterior planes through the midaxis, dividing the body in half; the term sometimes implies the median plane only. If the word sagittal is used to denote the median plane, then other sagittal planes are called parasagittal planes.

Fig B-1 Anterior view of human figure demonstrating meaning of terms used in describing the body. (From Anthony CP, Kolthoff N: Textbook of anatomy and physiology, ed 9, St Louis, 1975, Mosby.)

horizontal (transverse) plane: any of the horizontal planes across the body at right angles to coronal and sagittal planes parallel to baseline.

neutral plane: the plane of a structure around which bending occurs.

vertical side to side planes

coronal (frontal plane): a plane parallel with long axis of body at right angles to median sagittal plane going through coronal sutures of the skull (approximately center of body) and dividing body into front and back parts.

longitudinal: lengthwise and parallel with long axis of body or part; any of the vertical side to side planes. Coronal and longitudinal planes have been used interchangeably to describe each other. In this case, the context of the sentence will indicate the reference point of the plane.

Specific Locations

When describing limb anatomy, the nomenclature is very specific. The four appendages are correctly referred to as the upper and lower limbs, two forelimbs, and two hind limbs. The thigh indicates that portion above the knee and the shank the portion between the knee and ankle. The calf is the posterior aspect and the shin the anterior aspect of the leg. The sole (bottom) of the foot is called the plantar surface, and the top is the dorsal surface. The brachium refers to that portion of the arm above the elbow and below the shoulder. The antebrachium refers to the portion of the arm below the elbow but above the wrist. The ventral side of the hand is the palm or volar surface, with the opposite side being the dorsum or dorsal surface. The forearm is similarly divided into volar and dorsal aspects.

Joint Motions ^∗ (Fig. B-2)

Ranges of joint motion refer to the extent of movement within a given joint. Joint motion may be active, passive, or active assistive. The major joint areas involve the shoulder (glenoid), elbow (cubitus), hip (coxa) (Fig. B-3), and knee (genu).

All the hinge joints have motion described in terms of flexion and extension. Except for the ankle, the 0-degree position occurs when the limb is held out straight, and the degree of flexion is then stated in terms of degrees from the 0-degree extended position. The knee and elbow will occasionally extend beyond the 0-degree limit, and this motion is expressed in degrees of hyperextension. The wrist has approximately 90 degrees of extension and 90 degrees of flexion (dorsiflexion and palmar flexion).

Fig B-2 A, Elbow. Flexion: 0 to 150 degrees. Extension: 150 degrees to 0 (from angle of greatest flexion to 0 position). Hyperextension: measured in degrees beyond the 0 starting point. This motion is not present in all individuals; when it is, it may vary from 5 to 15 degrees. B, Elbow and wrist, Pronation: 0 to 80 or 90 degrees. Supination: 0 to 80 or 90 degrees. Total forearm motion: 160 to 180 degrees. C, Wrist. Flexion (palmar flexion): 0 to about 80 degrees. Extension (dorsiflexion): 0 to about 70 degrees, D, Wrist. Radial deviation: 0 to 20 degrees. Ulnar deviation: 0 to 30 degrees. (From American Academy of Orthopaedic Surgeons: Joint motion—method of measuring and recording, Chicago, 1985, The Academy.)

The Neutral Zone Method is used for measuring joint motion. The anatomic position of the joint defines the starting position at zero, and motion is measured in degrees of a circle. Other measured motions include:

circumduction: a maneuver or movement of a ball-and-socket joint in a circular motion; for example, the shoulder can circumduct 180 degrees with six movements possible.

flexion: to bend from the joint as in flexion movements of the spine at the waist (anterior or lateral). In the foot or hand is expressed as:

dorsiflexion: the toe-up motion of the ankle expressed in degrees from the 0-degree position of the foot at rest on the ground in standing position.

plantar flexion: the toe-down motion of the foot at the ankle expressed in degrees from 0-degree position of the foot at rest on the ground in standing position.

palmar flexion: of the wrist with palm up in flexion.

extension: extending distally away from body as in the limbs, or bending back posteriorly as in the spine.

pronation: palm-down position of hand with elbow at a 90-degree angle, brought about by the motion of the radius around the ulna (posterior rotation). In the foot, the plantar surface is turned down.

supinate, supination: palm-up position of the hand with elbow flexed at a 90-degree angle, brought about by motion of the radius around the ulna (anterior rotation). In the foot, the plantar surface is turned inward.

Fig B-3 The hip. A, Inward rotation: measured by rotating leg outward. Outward rotation: measured by rotating leg inward. B, Inward rotation (internal): measured by rotating leg away from midline of trunk with thigh as the axis of rotation, thus producing inward rotation of the hip. Outward rotation (external): measured by rotating leg toward midline of trunk with thigh as the axis of rotation, thus producing outward rotation of the hip. C, Abduction: outward motion of the extremity is measured in degrees from 0 starting position. Adduction: to measure, examiner should elevate opposite extremity a few degrees to allow leg to pass under it. (From American Academy of Orthopaedic Surgeons: Joint motion—method of measuring and recording, Chicago, 1985, The Academy.)

ulnar deviation: of the hand at the wrist such that the hand is directed in an ulnar direction; measured in degrees from 0 with hand in midline.

radial deviation: of the hand at the wrist such that the hand is directed radially; measured in degrees from 0 with hand in midline.

abduction: movement away from midline of body in frontal plane; applied to hip, shoulder, fingers, thumb, and foot. The midline reference point is a central line in the body for proximal joints and the central part of a limb for distal joints (Figs. B-4 and B-5).

adduction: movement toward the midline in frontal plane as in abduction. On verbal transcription in clinical notes the person dictating will sometimes say 8220a-b-duction8221 or 8220a-d-duction8221 to clarify distinction between abduction and adduction (see Fig. B-4).

anteversion: to lean forward at an angle; in reference to the neck of humerus or femur, an anterior rotation.

anteroflexion: bending forward.

eversion: turning outward, when applied to the heel, describes the degree of motion of the heel pushed outward with ankle in neutral position; when applied to the foot, describes the combined motions of dorsiflexion, pronation, and abduction (Fig. B-6).

inversion: when applied to the heel, describes the degree of motion of the heel pushed inward with ankle in neutral position; when applied to the foot, describes the combined motions of plantar flexion, supination, and adduction (see Fig. B-6).

retroflexion: bending backward.

retroversion: turned toward the back; in reference to the neck of femur or humerus, a posterior rotation.

apposition: contact of two adjacent parts; bringing together as in a finger movement, the thumb to index finger.

opposition: applied mostly to the thumb but also to little finger; describes the motion required to bring about opposition, or the setting opposite, of thumb against little finger (pulp surfaces). For the thumb, opposition is the combined action of abduction, rotation, and flexion.

external rotation: in frontal plane is away from midline.

internal rotation: in a frontal plane is toward the midline.

valgus: turned outward; the distal part is bent away from the midline; for example, genu valgus (knock-kneed).

varus: turned inward; the distal part is toward the midline; for example, genu varus (bow-legged).