There is a “language” used by medical practitioners of all kinds (podiatrists, chiropractors, orthopaedic surgeons, etc.). When discussing the body and its ailments, the basic terms you will need to know are:
1. proximal and distal: “proximal” means closer to the heart and “distal”
means further away from the heart. Thus, each toe has three bones: the
proximal phalanx, the middle phalanx, and the distal phalanx (except the big toe, which has two bones).
2. The three anatomical planes: transverse, frontal and sagittal – there are three planes which divide the body and are used as points of reference.
A. transverse: divides top and bottom.
B. frontal: divides front and back.::
C. sagittal: divides left from right.
When dealing with the foot, the midline is relative to the foot itself. Therefore, the midline of the foot divides the 2nd and 3rd toe.
3. The single plane motions of the foot:
A. Abduction and adduction: These movements occur in the transverse plane. The foot abducts when it rotates laterally (i.e. away from the centre). It adducts when it rotates medially (i.e. towards the centre.)
B. Inversion and eversion: These movements occur in the frontal plane. The foot inverts when it rotates inward and upward (the sole toward the midline), and everts when it rotates outward and upward (the sole away from the midline).
C. Plantarflexion and dorsiflexion: These movements occur in the sagittal plane. The foot plantar flexes when it moves downwards away from the tibia and dorsiflexes when it moves upwards toward the tibia.
4. Pronation and supination: There are two motions of the foot, pronation and supination, which include simultaneous movement in the frontal, sagittal, and transverse planes. These are termed tri-plane movements.
Pronation is a tri-plane motion consisting of simultaneous movements of abduction, dorsiflexion, eversion.
Supination is a tri-plane motion which combines the movements of adduction, plantarflexion, inversion.
It is difficult to clinically measure a tri-plane motion in the ankle at the subtalar joint (“STJ”). Therefore, frontal plane motion is used as an index to measure tri-plane motion at the STJ. The number of degrees of inversion or eversion in the frontal plane signifies the amount of pronation and supination. As the foot strikes the ground it immediately begins pronating to absorb shock and acts as a “mobile adaptor” (“loose bag of bones”) for variance in the terrain. It must then serve as a “rigid lever” to propel the body forward in locomotion. The latter occurs when the foot is supinated, as the foot structure becomes more rigid when supinated.
a) The STJ and foot in a supinated position.
b) the STJ and foot in the neutral position.
c) the STJ and foot in a pronated position.
5. lateral and medial - Lateral means on the side away from the mid-line sagittal plane and medial means on the side closer to the mid-line sagittal plane.
6. dorsum and plantar surfaces - The dorsum is the top part of the foot. The plantar surface is the sole of the foot.
7. positions of the foot:
a. dorsiflexed and plantarflexed: In the normal foot, the reference point for a dorsiflexed or plantarflexed position is a transverse plane which runs through the heel. If the foot is positioned below this transverse plane, it is said to be plantarflexed; above this transverse plane, it is said to be dorsiflexed.
b. Everted and inverted: A foot or part of a foot is said to be inverted when it is tilted parallel to the frontal plane so that the plantar surface of the foot or part of the foot faces toward the midline of the body. A foot or part of the foot is said to be everted when it is tilted parallel to a frontal plane so that the plantar surface faces away from the midline of the body.
c. abducted and adducted: The two transverse plane positions of the foot are abducted and adducted. The reference point is the mid-line sagittal plane.
8. Fixed structural positions of the foot can occur due to the inherent structure of bone, ligament, etc. of a particular foot.
a. Adductus and Abductus: Adductus denotes a fixed structural position in which the foot is held in an adducted position in the transverse plane. Abductus denotes a fixed structural position in which the foot is held in an abducted position in the transverse plane.
b. Varus and Valgus: the two frontal plane fixed structural positions which the foot may assume relative to the inverted and everted positions. The fixed structural position in which the foot or part of the foot appears inverted is classified as varus. The fixed structural position in which the foot or part of the foot appears everted is classified as valgus.