Knowledge base

Terminology

The basic language: planes, axes, directions, movements and the terms from arthrology.

Planes, axes and starting position

Anatomical position (Positio anatomica): Standing upright, face and eyes forward, arms by the sides with the palms facing forward, feet together with the toes forward. Every direction and movement is defined relative to this position, even when the patient is lying down.
Median plane (Planum medianum): The one sagittal plane that runs exactly through the middle and divides the body into a left and a right half.
Sagittal plane (Planum sagittale): Any plane parallel to the median plane. Movements in it (flexion, extension) turn around the transverse axis.
Frontal plane (Planum frontale (coronale)): Divides the body into a front and a back half. Movements in it (abduction, adduction, lateral flexion) turn around the sagittal axis.
Transverse plane (Planum transversale): Divides the body into an upper and a lower half. Movements in it (internal and external rotation) turn around the longitudinal axis.
Transverse axis (Axis transversalis): Runs from left to right, straight through the body. It is perpendicular to the sagittal plane, so flexion and extension turn around it.
Sagittal axis (Axis sagittalis): Runs from front to back. It is perpendicular to the frontal plane, so abduction and adduction turn around it.
Longitudinal axis (Axis longitudinalis): Runs from top to bottom, lengthwise. It is perpendicular to the transverse plane, so rotations turn around it.

Directions and position

Cranial (Cranialis (superior)): Towards the head, so higher up.
Caudal (Caudalis (inferior)): Towards the tail, so lower down.
Ventral (Ventralis (anterior)): Towards the belly side, so at the front.
Dorsal (Dorsalis (posterior)): Towards the back, so at the rear. On the hand and the foot, dorsal means the back of the hand and the top of the foot.
Medial (Medialis): Closer to the median plane.
Lateral (Lateralis): Further from the median plane, so more towards the side.
Proximal (Proximalis): Closer to the trunk or to the origin of a limb.
Distal (Distalis): Further from the trunk, so more towards the end of a limb.
Superficial (Superficialis): Closer to the body surface.
Deep (Profundus): Further from the body surface.
Palmar (Palmaris (volaris)): On the palm side of the hand.
Plantar (Plantaris): On the sole side of the foot.
Radial and ulnar (Radialis, ulnaris): On the thumb side and the little finger side of the forearm and hand respectively. Used instead of lateral and medial, because those would swap places during pronation and supination.
Tibial and fibular (Tibialis, fibularis): On the shin bone side and the calf bone side of the lower leg respectively.
Ipsilateral and contralateral: On the same side and on the opposite side of the body as the point you are talking about.

Movements

Flexion (Flexio): Bending: the angle in the joint gets smaller, in the sagittal plane around the transverse axis. At the trunk and the hip this is also called anteflexion.
Extension (Extensio): Straightening: the angle in the joint gets larger. Beyond the neutral position it is called hyperextension, and at the shoulder and hip retroflexion.
Abduction (Abductio): Moving away from the median plane, in the frontal plane around the sagittal axis. For the fingers and toes the axis of the hand or foot is the reference.
Adduction (Adductio): Moving towards the median plane.
Internal rotation (Rotatio interna): Turning inwards around the long axis of the bone.
External rotation (Rotatio externa): Turning outwards around the long axis of the bone.
Pronation (Pronatio): Of the forearm: the radius turns over the ulna so that the palm faces backwards or downwards. Of the foot: the combination of eversion, abduction and dorsiflexion.
Supination (Supinatio): Of the forearm: turning back until the palm faces forwards or upwards. Of the foot: the combination of inversion, adduction and plantar flexion.
Elevation and depression: Lifting and lowering, mainly of the shoulder girdle and the jaw.
Protraction and retraction: Sliding forwards and backwards, mainly of the scapula and the jaw.
Circumduction (Circumductio): The compound movement in which the end of a limb describes a cone: flexion, abduction, extension and adduction in sequence. It has no axis of its own.
Lateral flexion (Flexio lateralis): Bending the spine sideways, in the frontal plane.
Dorsiflexion and plantar flexion: Of the ankle: the top of the foot towards the shin, and the foot downwards, respectively. Dorsiflexion is also called extension, but that term is deliberately avoided at the ankle.
Inversion and eversion: Tilting the sole of the foot inwards and outwards respectively, mainly in the subtalar joint.
Opposition and reposition (Oppositio, repositio): Moving the thumb towards the little finger and back again. Only possible in the saddle joint of the thumb.

Joint science

Osteokinematics: The movement of the bones relative to each other, as you see it from the outside and measure it with a goniometer: flexion, abduction, rotation.
Arthrokinematics: The movement of the joint surfaces relative to each other, inside the joint: rolling, gliding and spinning. Not visible from the outside, but palpable during mobilisation.
Roll and glide: Rolling is one surface unwinding over the other; gliding is it sliding across. In a healthy joint both happen at once; without the glide the joint jams on one side.
Convex-concave rule: When a convex surface moves over a concave one, roll and glide run in opposite directions. When a concave surface moves over a convex one, they run the same way. It determines the direction in which you mobilise.
Range of motion (ROM): The excursion of a joint, in degrees. Active is what the patient reaches alone, passive is what the therapist adds; passive is normally slightly larger.
End feel: What you feel at the end of the passive movement. Normal: soft (soft tissue), elastic (capsule and ligaments) or hard (bone against bone). Abnormal: empty (pain stops the movement), springy (a block) or hard too early.
Capsular pattern: The fixed pattern in which the movements of a joint become limited when the whole capsule is affected. At the hip internal rotation is limited first, at the shoulder external rotation. A limitation that does not fit that pattern points at something other than a capsular problem.
Close-packed position: The position in which the joint surfaces fit together maximally and the capsule and ligaments are taut. The joint is then at its most stable and least suitable for mobilisation.
Loose-packed position: The resting position: capsule and ligaments are at their slackest and there is the most play. The position in which you examine and mobilise.
Form closure and force closure: Stability from the shape of the joint surfaces themselves, as opposed to stability from tension in muscles, ligaments and fascia. The SI joint is the textbook example of the two together.

Muscle action and biomechanics

Agonist: The muscle that performs the movement in question.
Antagonist: The muscle that makes the opposite movement and brakes the agonist.
Synergist: A muscle that helps the agonist or prevents an unwanted side movement of it.
Stabiliser: A muscle that holds a bone or a joint in place so that another muscle has something to work from.
Moment arm: The perpendicular distance from the line of action of a muscle to the axis the joint turns around. The larger the moment arm, the more turning force the same muscle force produces.
Line of action: The line along which a muscle pulls, from origin to insertion. When the tendon wraps around a bony edge or over a pulley, the line of action bends there and the moment arm changes with it.
Open and closed chain: In an open chain the distal segment moves freely (swinging a leg); in a closed chain it is fixed and the rest moves around it (a squat). The same muscle does something different in each.
Concentric, eccentric, isometric: The muscle shortens while contracting, lengthens while braking, or holds its length. Eccentric loading is what most tendon complaints are treated with.
Active insufficiency: A muscle crossing two joints cannot shorten maximally in both at once: the hamstrings cannot fully bend the knee while the hip is already extended.
Passive insufficiency: That same muscle cannot be lengthened maximally over both joints at once either; that is what limits a straight leg raise.

Neurology

Myotome: The muscles supplied by one spinal segment. Tested clinically with a strength test per level: C5 shoulder abduction, L4 ankle dorsiflexion, S1 plantar flexion.
Dermatome: The area of skin whose sensory information enters through one spinal segment.
Radiculopathy: Irritation or loss of function of a nerve root, with pain, sensory loss or weakness in the corresponding dermatome and myotome.
Referred pain: Pain felt somewhere other than where it comes from, because the information enters at the same segment. Shoulder pain in gallbladder disease is the classic example.