Applied Anatomy Glossary

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1

Abduction

Lateral movement away from the midline of the trunk, as in raising the arms or legs to the side horizontally.

2

Acceleration

The rate of change in velocity.

3

Accessory Motion

The actual change in relationship between the articular surface of one bone relative to another, characterized as roll, spin, and glide.

4

Action Potential

Electrical signal transmitted from the brain and spinal cord through axons to the muscle fibers in a particular motor unit providing the stimulus to contract.

5

Active Insufficiency

Point reached when a muscle becomes shortened to the point that it cannot generate or maintain active tension.

6

Active Tension

Tension in muscles that is generated via an active contraction of the respective muscle fibers in that muscle.

7

Adduction

Movement medially toward the midline of the trunk, as in lowering the arms to the side or legs back to the anatomical position.

8

Afferent Nerves

Nerves that bring impulses from receptors in the skin, joints, muscles, and other peripheral aspects of the body to the central nervous system.

9

Aggregate Muscle Action

Muscles working together in groups rather than independently to achieve given joint motions.

10

Agonist

A muscle or muscle group that is described as being primarily responsible for a specific joint movement when contracting.

11

All or None Principle

States that regardless of the number involved, the individual muscle fibers within a given motor unit will fire and contract either maximally or not at all.

12

amphiarthrodial (amphiarthrosis) joints

Joints that functionally allow only a very slight amount of movement such as synchondrosis (e.g., costochondral joint of the ribs with sternum), syndesmosis (e.g., distal tibiofibular), and symphysis (e.g., symphysis pubis) joints.

13

Amplitude

Range of muscle fiber length between maximal and minimal lengthening.

14

Anatomical Position

The position of reference in which the subject is in the standing position, with feet together and palms of hands facing forward.

15

Angle

Bend or protruding angular projection of a bone such as superior and inferior angle of scapula.

16

Angle of Pull

The angle between the muscle insertion and the bone on which it inserts.

17

Angular Displacement

The change in location of a rotating body.

18

Angular Motion

Motion involving rotation around an axis.

19

Antagonist

A muscle or muscle group that counteracts or opposes the contraction of another muscle or muscle group.

20

Anterior Axillary Line

A line parallel to the mid-axillary line which passes through the anterior axillary skin fold.

21

Anteroposterior axis

The axis that has the same directional orientation as the sagittal plane of motion and runs from front to back at a right angle to the frontal plane of motion. Also known as the sagittal or AP axis

22

Anteversion

Abnormal or excessive rotation forward of a structure, such as femoral ante version.

23

aponeurosis

A tendinous expansion of dense fibrous connective tissue, sheet- or ribbonlike in appearance and resembling a flattened tendon, which serves as a fascia to bind muscles together or as a means of connecting muscle to bone.

24

Appendicular Skeleton

The appendages, or the upper and lower extremities, and the shoulder and pelvic girdles.

25

Arthrodial Joint

Joints in which bones glide on each other in limited movement, as in the bones of the wrist (carpal) or the bones of the foot (tarsal).

26

Arthrokinematics

Motion between the actual articular sur- faces of the bones at a joint.

27

arthrosis

Joint or articulation between two or more bones.

28

Axial Skeleton

The skull, vertebral column, ribs, and sternum.

29

Axis of rotation

The point in a joint about which a bone moves or turns to accomplish joint motion.

30

Axon

An elongated projection that transmits impulses away
from the neuron cell body

31

Balance

The ability to control equilibrium, either static or
dynamic.

32

Biarticular muscles

Those muscles that, from origin to insertion, cross two different joints, allowing them to perform actions at each joint.

33

Bilateral

Relating to the right and left sides of the body or of a body structure such as the right and left extremities

34

Biomechanics

The study of mechanics as it relates to the functional and anatomical analysis of biological systems, especially humans

35

Bipennate

A type of pennate muscle with fibers running obliquely on both sides from a central tendon, such as the rectus femoris and flexor hallucis longus

36

Border or margin

Edge or boundary line of a bone such as lateral and medial border of scapula.

37

Brachial Plexus

Group of spinal nerves composed of cervical nerves 5 through 8, along with thoracic nerve 1; supplies motor and sensory function to the upper extrem- ity and most of the scapula.

38

Cancellous Bone

Spongy, porous bone that lies under cor- tical bone.

39

Cardinal Planes

Specific planes that divide the body exactly into two halves.

40

Carpal Tunnel

A three-sided arch, concave on the palmar side and formed by the trapezium, trapezoid, capitate, and hamate. It is spanned by the transverse carpal and volar carpal ligaments creating a tunnel.

41

Carpal tunnel syndrome

A condition characterized by swelling and inflammation with resultant increased pressure in the carpal tunnel, which interferes with nor- mal function of the median nerve, leading to reduced motor and sensory function of its distribution; particu- larly common with repetitive use of the hand and wrist in manual labor and clerical work such as typing and keyboarding.

42

Carrying angle

In the anatomical position, the angle formed by the forearm deviating laterally from the arm, typically 5 to 15 degrees.

43

Cartilaginous Joints

Joints joined together by hyaline cartilage or fibrocartilage, allowing very slight movement, such as synchondrosis and symphysis.

44

Center of Gravity

The point at which all of the body’s mass and weight are equally balanced or equally distributed in all directions.

45

Center of Rotation

The point or line around which all other points in the body move.

46

Central Nervous System (CNS)

The cerebral cortex, basal ganglia, cerebellum, brain stem, and spinal cord

47

Cervical Plexus

Group of spinal nerves composed of cervical nerves 1 through 4; generally responsible for sensory and motor function from the upper part of the shoulders to the back of the head and front of the neck.

48

Circumduction

Circular movement of a bone at the joint, as in movement of the hip, shoulder, or trunk around a fixed point. Combination of flexion, extension, abduction, and adduction.

49

Closed Kinetic Chain

When the distal end of an extremity is fixed, preventing movement of any one joint unless predictable movements of the other joints in the extrem- ity occur.

50

Coefficient Friction

The ratio between the force needed to overcome friction over the force holding the surfaces together.

51

Collagen

A protein in the body that forms fibrous con- nective tissues such as ligaments, tendons, cartilage, bone, and skin. Its elongated fibrils provide strength and flexibility to these tissues.

52

Concentric Contraction

A contraction in which there is a shortening of the muscle that causes motion to occur at the joints it crosses.

53

Concurrent

Movement pattern allowing the involved biar- ticular muscle to maintain a relatively consistent length because of the same action at both of its joints.

54

Condyle

Large, rounded projection that usually articulates with another bone, such as the medial or lateral condyle of the femur.

55

Condyloid Joint

Type of joint in which the bones permit movement in two planes without rotation, as in the wrist between the radius and the proximal row of the carpal bones or the second, third, fourth, and fifth metacarpo- phalangeal joint

56

Contractility

The ability of muscle to contract and develop tension or internal force against resistance when stimulated

57

Contraction Phase

In a single muscle fiber contraction, it is the phase following the latent period in which the muscle fiber actually begins shortening; lasts about 40 milliseconds.

58

Core training

Strengthening and conditioning that focuses on the diaphragm, transversus abdominis, lumbar mul- tifidus, and the muscles of the pelvic floor as well as the rectus abdominis, external obliques, internal obliques, and erector spinae.

59

Coronal Axis

Runs from side to side through the body and is at a right angle to the sagittal plane of motion. Also known as the frontal or lateral axi

60

Cortex

Diaphyseal wall of long bones, formed from hard, dense compact bone.

61

Cortical Bone

Harder, more compact bone that forms the outer bony surface of the diaphysis

62

Counterconcurrent

Movement pattern resulting from opposite actions occurring simultaneously at both joints of a bi-articular muscle resulting in substantial shortening of the biarticular muscle.

63

Cranial Nerves

The group of 12 pairs of nerves originating from the undersurface of the brain and exiting from the cranial cavity through skull openings.

64

Curvilinear motion

Motion along a curved line

65

Davis' law

States that ligaments, muscle, and other soft tissue when placed under appropriate tension will adapt over time by lengthening and conversely when main- tained in a loose or shortened state over a period of time will gradually shorten.

66

Dendrite

One or more branching projections from the neuron cell body that transmit impulses to the neuron and cell body

67

Depression

Inferior movement of the shoulder girdle, as in returning to the normal position from a shoulder shrug

68

Dermatome

A defined area of skin supplied by a specific spinal nerve

69

Dexter

Relating to, or situated to the right or on the right side of something

70

Diagonal Abduction

Movement by a limb through a diagonal plane away from the midline of the body such as in the hip or glenohumeral joint.

71

Diagonal Adduction

Movement by a limb through a diago- nal plane toward and across the midline of the body such as in the hip or glenohumeral joint.

72

Diagonal or Oblique Axis

Axis that runs at a right angle to the diagonal plane. As the glenohumeral joint moves from diagonal abduction to diagonal adduction in over- hand throwing, its axis runs perpendicular to the plane through the humeral head.

73

Diagonal Plane

A combination of more than one plane. Less than parallel or perpendicular to the sagittal, frontal, or transverse plane. Also known as oblique plane.

74

Diaphysis

The long cylindrical portion or shaft of long bones.

75

Diarthrodial Joints

Freely movable synovial joints containing a joint capsule and hyaline cartilage and lubricated by synovial fluid.

76

Displacement

A change in position or location of an object from its original point of reference.

77

Distal

Farthest from the midline or point or reference; the fingertips are the most distal part of the upper extremity.

78

Dislocating Component

When the angle of pull is greater than 90 degrees, the force pulls the bone away from its joint axis, thereby increasing joint distraction forces.

79

Dorsal

Relating to the back, being or located near, on, or toward the back, posterior part, or upper surface of; also relating to the top of the foot.

80

Dorsiflexion

Flexion movement of the ankle resulting in the top of foot moving toward the anterior tibia.

81

Duration

An exercise variable usually referring to the number of minutes per exercise bout.

82

Dynamic equillibrium

Occurs when all of the applied and inertial forces acting on the moving body are in balance, resulting in movement with unchanging speed or direction.

83

Dynamics

The study of mechanics involving systems in motion with acceleration.

84

Eccentric Contraction

A contraction in which the muscle lengthens in an attempt to control the motion occurring at the joints that it crosses, characterized by the force of gravity or applied resistance being greater than the con- tractile force.

85

Eccentric Force

Force that is applied in a direction not in line with the center of rotation of an object with a fixed axis. In objects without a fixed axis, it is an applied force that is not in line with the object’s center of gravity.

86

Efferent Nerves

Nerves that carry impulses to the outlying regions of the body from the central nervous system.

87

Elasticity

The ability of muscle to return to its original length following stretching.

88

Elastin

A protein in the body that forms connective tissue. It has a highly elastic quality and will return to its original state after stress, whether compressed or stretched.

89

Electromyography

A method utilizing either sur- face electrodes or fine wire/needle electrodes to detect the action potentials of muscles and provide an electronic readout of the contraction intensity and duration.

90

Elevation

Superior movement of the shoulder girdle, as in shrugging the shoulders.

91

Enarthrodial joint

Type of joint that permits movement in all planes, as in the shoulder (glenohumeral) and hip joints.

92

Endochondral bones

Long bones that develop from hyaline cartilage masses after the embryonic stage.

93

Endosteum

Dense, fibrous membrane covering the inside of the cortex of long bones.

94

Epicondyle

Projection located above a condyle, such as the medial or lateral epicondyle of the humerus.

95

Epiphyseal Plate

Thin cartilage plate separating the diaphysis and epiphysis during bony growth; commonly referred to as growth plate.

96

Epiphysis

The end of a long bone, usually enlarged and shaped to join the epiphysis of an adjacent bone, formed from cancellous or trabecular bone.

97

Equillibrium

State of zero acceleration in which there is no change in the speed or direction of the body.

98

Eversion

Turning of the sole of the foot outward or later- ally, as in standing with the weight on the inner edge of the foot.

99

Extensibility

The ability of muscle to be stretched back to its original length following contraction.

100

Extension

Straightening movement resulting in an increase of the angle in a joint by moving bones apart, as when the hand moves away from shoulder during extension of the elbow joint.

101

External Rotation

Rotary movement around the longitudi- nal axis of a bone away from the midline of the body. Also known as rotation laterally, outward rotation, and lateral rotation.

102

Extrinsic Muscles

Muscles that arise or originate outside of (proximal to) the body part on which they act.

103

Fascia

Sheet or band of fibrous connective tissue that envel- ops, separates, or binds together parts of the body such as muscles, organs, and other soft tissue structures of the body.

104

Fibrous Joints

Joints joined together by connective tis- sue fibers and generally immovable, such as gomphosis, sutures, and syndesmosis.

105

Fibular

Relating to the fibular (lateral) side of the lower extremity.

106

First-class lever

A lever in which the axis (fulcrum) is between the force and the resistance, as in the extension of the elbow joint.

107

Flat muscles

A type of parallel muscle that is usually thin and broad, with fibers originating from broad, fibrous, sheetlike aponeuroses such as the rectus abdominus and external oblique.

108

Flexion

Movement of the bones toward each other at a joint by decreasing the angle, as in moving the hand toward the shoulder during elbow flexion.

109

Follow-through phase

Phase that begins immediately after the climax of the movement phase, in order to bring about negative acceleration of the involved limb or body segment; often referred to as the deceleration phase. The velocity of the body segment progressively decreases, usually over a wide range of motion.

110

Foramen

Rounded hole or opening in bone, such as the foramen magnum in the base of the skull.

111

Force

The product of mass times acceleration.

112

Force-Arm

The perpendicular distance between the loca- tion of force application and the axis. The shortest dis- tance from the axis of rotation to the line of action of the force. Also known as the moment arm or torque arm.

113

Force Couple

Occurs when two or more forces are pulling in different directions on an object, causing the object to rotate about its axis.

114

Force Magnitude

Amount of force usually expressed in newtons.

115

Fossa

Hollow, depressed, or flattened surface of bone, such as the supraspinous fossa or iliac fossa.

116

Fovea

Very small pit or depression in bone, such as the fovea capitis of the femur.

117

Frequency

An exercise variable usually referring to the number of times exercise is conducted per week.

118

Friction

Force that results from the resistance between the surfaces of two objects moving upon one another.

119

Frontal Plane

Plane that bisects the body laterally from side to side, dividing it into front and back halves. Also known as the lateral or coronal plane.

120

Fundamental Position

Reference position essentially the same as the anatomical position, except that the arms are at the sides and the palms are facing the body.

121

Fusiform Muscle

A type of parallel muscle with fibers shaped together like a spindle with a central belly that tapers to tendons on each end, such as the brachialis and the biceps brachii.

122

Gaster

The central, fleshy, contractile portion of the muscle that generally increases in diameter as the muscle contracts.

123

Ginglymus joint

Type of joint that permits a wide range of movement in only one plane, as in the elbow, ankle, and knee joints.

124

Golgi Tendon Organ

A proprioceptor, sensitive to both muscle tension and active contraction, found in the tendon close to the muscle tendon junction.

125

Gomphosis

A type of immovable articulation, as of a tooth inserted into its bony socket.

126

Goniometer

Instrument used to measure joint angles or compare the changes in joint angles

127

Goniometry

Measuring the available range of motion in a joint or the angles created by the bones of a joint.

128

Ground Reaction Force

The force of the surface reacting to the force placed on it, as in the reaction force between the body and the ground when running across a surface.

129

Hamstrings

A common name given to the group of poste- rior thigh muscles: biceps femoris, semitendinosus, and semimembranosus.

130

Head

Prominent, rounded projection of the proximal end of a bone, usually articulating, such as the humeral or femoral head.

131

Heel-strike

First portion of the walking or running stance phase characterized by landing on the heel with the foot in supination and the leg in external rotation.

132

Horizontal Abduction

Movement of the humerus in the horizontal plane away from the midline of the body.

133

Horizontal Adduction

Movement of the humerus in the horizontal plane toward the midline of the body.

134

Hyaline Cartilage

Articular cartilage; covers the end of bones at diarthrodial joints to provide a cushioning effect and reduce friction during movement.

135

Hyperextension

Extension beyond the normal range of extension.

136

Impingement Syndrome

Occurs when the tendons of the rotator cuff muscles, particularly the supraspinatus and infraspinatus, become irritated and inflamed as they pass through the subacromial space between the acromion process of the scapula and the head of the humerus, typi- cally resulting in pain, weakness, and loss of movement.

137

Impulse

The product of force and time.

138

Inertia

Resistance to action or change; resistance to acceleration or deceleration. Inertia is the tendency for the current state of motion to be maintained, regardless of whether the body segment is moving at a particular velocity or is motionless.

139

Innervation

The supplying of a muscle, organ, or body part with nerves.

140

Insertion

The distal attachment or point of attachment of a muscle farthest from the midline or center of the body, generally considered the most movable part.

141

Instantaneous Center of Rotation

The center of rotation at a specific instant in time during movement.

142

Intensity

An exercise variable usually referring to a certain percentage of the absolute maximum that a person can sustain.

143

Internal Rotation

Rotary movement around the longitudi- nal axis of a bone toward the midline of the body. Also known as rotation medially, inward rotation, and medial rotation.

144

Interneurons

Central or connecting neurons that conduct impulses from sensory neurons to motor neurons.

145

Intrinsic Muscles

Muscles that are entirely contained within a specified body part; usually refers to the small, deep muscles found in the foot and hand.

146

Inversion

Turning of the sole of the foot inward or medially, as in standing with the weight on the outer edge of the foot.

147

Irritability

The property of muscle being sensitive or responsive to chemical, electrical, or mechanical stimuli.

148

Isokinetic

Type of dynamic exercise usually using concen- tric and/or eccentric muscle contractions in which the speed (or velocity) of movement is constant and mus- cular contraction (usually maximal contraction) occurs throughout the movement.

149

Isometric Contraction

A type of contraction with little or no shortening of the muscle resulting in no appreciable change in the joint angle.

150

Isotonic Contraction

Contraction occurring in which there is either shortening or lengthening in the muscle under tension; also known as a dynamic contraction, and classified as being either concentric or eccentric.

151

Kinematics

The description of motion, including consid- eration of time, displacement, velocity, acceleration, and space factors of a system’s motion.

152

Kinesiology

The science of movement, which includes anatomical (structural) and biomechanical (mechanical) aspects of movement.

153

Kinesthesis

The awareness of the position and movement of the body in space; sense that provides awareness of bodily position, weight, or movement of the muscles, ten- dons, and joints.

154

Kinetic Friction

The amount of friction occurring between two objects that are sliding upon one another.

155

Kinetics

The study of forces associated with the motion of a body.

156

Krause's end bulbs

A proprioceptor sensitive to touch and thermal changes found in the skin, subcutaneous tis- sue, lip and eyelid mucosa, and external genitals.

157

Kyphosis

Increased curving of the spine outward or back- ward in the sagittal plane.

158

Latent Period

In a single muscle fiber contraction, it is the brief period of a few milliseconds following the stimulus before the contraction phase begins.

159

Lateral Axis

Axis that has the same directional orienta- tion as the frontal plane of motion and runs from side to side at a right angle to the sagittal plane of motion. Also known as the frontal or coronal axis.

160

Lateral Epicondylitis

A common problem quite frequently associated with gripping and lifting activities that usually involves the extensor digitorum muscle near its origin on the lateral epicondyle; commonly known as tennis elbow.

161

Lateral Flexion

Movement of the head and/or trunk later- ally away from the midline; abduction of spine.

162

Law of Acceleration

A change in the acceleration of a body occurs in the same direction as the force that caused it and is directly proportional to the force causing it and inversely proportional to the mass of the body.

163

Law of Reaction

For every action there is an opposite and equal reaction.

164

Lever

A rigid bar (bone) that moves about an axis.

165

Ligament

A type of tough connective tissue that attaches bone to bone to provide static stability to joints.

166

Linear Displacement

The distance that a system moves in a straight line.

167

Linear Motion

Motion along a line; also referred to as translatory motion.

168

Lordosis

Increased curving of the spine inward or forward in the sagittal plane.

169

Lumbar Kyphosis

A reduction of its normal lordotic curve, resulting in a flat-back appearance.

170

Lumbar Plexus

Group of spinal nerves composed of L1 through L4 and some fibers from T12, generally respon- sible for motor and sensory function of the lower abdo- men and the anterior and medial portions of the lower extremity.

171

Mass

The amount of matter in a body

172

Maximal Stimulus

A stimulus strong enough to produce action potentials in all of the motor units of a particular muscle

173

Mechanical Advantage

The advantage gained through the use of machines to increase or multiply the applied force in performing a task; enables a relatively small force to be applied to move a much greater resistance; determined by dividing the load by the effort.

174

Mechanics

The study of physical actions of forces; can be subdivided into statics and dynamics

175

Medial Epicondylitis

An elbow problem associated with the medial wrist flexor and pronator group near their ori- gin on the medial epicondyle; frequently referred to as golfer’s elbow.

176

Medullary Cavity

Marrow cavity between the walls of the diaphysis, containing yellow or fatty marrow.

177

Meissner's Corpuscle

A proprioceptor sensitive to fine touch and vibration found in the skin.

178

Mid-Axillary Line

A line running vertically down the sur- face of the body passing through the apex of the axilla (armpit).

179

Mid-clavicular line

A line running vertically down the sur- face of the body passing through the midpoint of the clavicle.

180

Mid-sagittal Plane

Cardinal plane that bisects the body from front to back, dividing it into right and left symmetrical halves.

181

Midstance Phase

Middle portion of the walking or running stance phase characterized by pronation and internal rotation of the foot and leg; may be divided into loading response, midstance, and terminal stan

182

Mid-sternal line

A line running vertically down the surface of the body passing through the middle of the sternum.

183

Momentum

The quality of motion, which is equal to mass times velocity.

184

Motor Neurons

Neurons that transmit impulses away from the brain and spinal cord to muscle and glandular tissue.

185

Motor Unit

Consists of a single motor neuron and all of the muscle fibers it innervates.

186

Movement Phase

The action part of a skill, sometimes known as the acceleration, action, motion, or contact phase. Phase in which the summation of force is gener- ated directly to the ball, sport object, or opponent, and is usually characterized by near-maximal concentric activity in the involved muscles.

187

Multi-articular joints

Those muscles that, from origin to insertion, cross three or more different joints, allowing them to perform actions at each joint.

188

Multi-pennate muscle

A type of pennate muscle that has several tendons with fibers running diagonally between them, such as the deltoid.

189

Muscle Spindle

A proprioceptor sensitive to stretch and the rate of stretch that is concentrated primarily in the muscle belly between the fibers.

190

Myotatic/Stretch Reflex

The reflexive contraction that occurs as a result of the motor neurons of a muscle being activated from the CNS secondarily to a rapid stretch occurring in the same muscle; the knee jerk or patella tendon reflex is an example.

191

Myotome

A muscle or group of muscles supplied by a spe- cific spinal nerve.

192

Neuromuscular Junction

Connection between the ner- vous system and the muscular system via synapses between efferent nerve fibers and muscle fibers.

193

Neuron

Nerve cell that is the basic functional unit of the nervous system responsible for generating and transmit- ting impulses.

194

Neuron Cell Body

Portion of a neuron containing the nucleus but not including the axon and dendrites.

195

Neutralizers

Muscles that counteract or neutralize the action of other muscles to prevent undesirable move- ments; referred to as neutralizing, they contract to resist specific actions of other muscles.

196

Non-rotatory Component

Compo- nent (either stabilizing or dislocating) of muscular force acting parallel to the long axis of the bone (lever).

197

Open Kinetic Chain

When the distal end of an extremity is not fixed to any surface, allowing any one joint in the extremity to move or function separately without neces- sitating movement of other joints in the extremity.

198

Opposition

Diagonal movement of the thumb across the palmar surface of the hand to make contact with the hand and/or fingers.

199

Origin

The proximal attachment or point of attachment of a muscle closest to the midline or center of the body, gen- erally considered the least movable part.

200

Osteoblasts

Specialized cells that form new bone.

201

Osteoclasts

Specialized cells that resorb new bone.

202

Osteokinematic motion

Motion of the bones relative to
the three cardinal planes, resulting from physiological
movements.

203

Pacinian Corpuscle

A proprioceptor sensitive to pressure and vibration found in the subcutaneous, submucosa, subserous tissues around joints, external genitals, and mammary glands.

204

Palmar Flexion

Flexion movement of the wrist in the sagittal plane with the volar or anterior side of the hand moving toward the anterior side of the forearm.

205

Palpation

Using the sense of touch to feel or examine a
muscle or other tissue.

206

Parallel Muscles

Muscles that have their fibers arranged parallel to the length of the muscle, such as flat, fusiform, strap, radiate, or sphincter muscles.

207

Parasagittal Plane

Planes parallel to the midsagittal plane.

208

Passive Insufficiency

State reached when an opposing muscle becomes stretched to the point where it can no longer lengthen and allow movement.

209

Passive Tension

Tension in muscles that is due to externally applied forces and is developed as a muscle is stretched beyond its normal resting length.

210

Pennate Muscles

Muscles that have their fibers arranged obliquely to their tendons in a manner similar to a feather, such as unipennate, bipennate, and multi-pennate muscles.

211

Periodization

The intentional variance of overload through a prescriptive reduction or increase in a training program to bring about optimal gains in physical performance.

212

Periosteum

The dense, fibrous membrane covering the outer surface of the diaphysis.

213

Peripheral Nervous System

Portion of the nervous system containing the sensory and motor divisions of all the nerves throughout the body except those found in the central nervous system.

214

Physiological Movement

Normal movements of joints such as flexion, extension, abduction, adduction, and rotation, accomplished by bones moving through planes of motion about an axis of rotation at the joint.

215

Plane of Motion

An imaginary two-dimensional surface through which a limb or body segment is moved.

216

Plantar

Relating to the sole or undersurface of the foot.

217

Plantarflexion

Extension movement of the ankle, resulting in the foot and/or toes moving away from the body.

218

Plica

An anatomical variant of synovial tissue folds that may be irritated or inflamed with injuries or overuse of the knee.

219

Posterior Axillary Line

A line parallel to the mid-axillary line which passes through the posterior axillary skinfold.

220

Preparatory Phase

Skill analysis phase, often referred to as the cocking or wind-up phase, used to lengthen the appropriate muscles so that they will be in position to generate more force and momentum as they concentrically contract in the next phase.

221

Primary Mover

Muscles that contribute significantly to causing a specific joint movement when contracting concentrically.

222

Pronation

Internally rotating the radius so that it lies diag- onally across the ulna, resulting in the palm-down posi- tion of the forearm; term also refers to a combination of ankle dorsiflexion, subtalar eversion, and forefoot abduc- tion (toe-out).

223

Proprioception

Feedback relative to the tension, length, and contraction state of muscle, the position of the body and limbs, and movements of the joints provided by internal receptors located in the skin, joints, muscles, and tendons.

224

Protraction

Forward movement of the shoulder girdle away from the spine; abduction of the scapula.

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Proximal

Nearest to the midline or point of reference; the forearm is proximal to the hand.

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Q Angle (Quadricep Femoris)

The angle at the patella formed by the intersection of the line of pull of quadriceps with the line of pull of the patella tendon.

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Quadriceps

A common name given to the four muscles of the anterior aspect of the thigh: rectus femoris, vastus medialis, vastus intermedius, and vastus lateralis.

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Radial

Relating to the radial (lateral) side of the forearm or hand.

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Radial Deviation (Radial Flexion)

Abduction movement at the wrist of the thumb side of the hand toward the forearm.

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Radiate Muscles

A type of parallel muscle with a combined arrangement of flat and fusiform muscle in that they origi- nate on broad aponeuroses and converge onto a tendon such as the pectoralis major or trapezius. Also described sometimes as being triangular, fan-shaped, or convergent.

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Range of Motion

The specific amount of move- ment possible in a joint.

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Reciprocal Inhibition

Activation of the motor units of the agonists, causing a reciprocal neural inhibition of the motor units of the antagonists, which allows them to sub- sequently lengthen under less tension. Also referred to as reciprocal innervation.

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Recovery Phase

Skill analysis phase used after follow- through to regain balance and positioning to be ready for the next sport demand.

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Rectilinear Motion

Motion along a straight line.

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Recurvatum

Bending backward, as in knee hyperextension.

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Reduction

Return of the spinal column to the anatomic position from lateral flexion; spine adduction.

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Relaxation Phase

In a single muscle fiber contraction, it is the phase following the contraction phase in which the muscle fiber begins relaxing; lasts about 50 milliseconds.

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Reposition

Diagonal movement of the thumb as it returns to the anatomical position from opposition with the hand and/or fingers.

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Resistance

Component of the lever that is typically being attempted to be moved, usually referred to as load, weight, or mass.

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Resistance Arm

The distance between the axis and the point of resistance application.

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Retinaculum

Fascial tissue that retains tendons close to the body in certain places such as around joints like the wrist and ankle.

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Retraction

Backward movement of the shoulder girdle toward the spine; adduction of the scapula.

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Retroversion

Abnormal or excessive rotation backward of a structure, such as femoral retroversion.

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Rolling friction

The resistance to an object rolling across a surface, such as a ball rolling across a court or a tire roll- ing across the ground.

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Rotation

Movement around the axis of a bone, such as the turning inward, outward, downward, or upward of a bone.

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Rotary Component

Component of muscular force acting perpendicular to the long axis of the bone (lever).

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Rotator Cuff

Group of muscles intrinsic to the glenohu- meral joint, consisting of the subscapularis, supraspi- natus, infraspinatus, and teres minor, that is critical in maintaining dynamic stability of the joint.

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Ruffini's Corpuscles

A proprioceptor sensitive to touch and pressure found in the skin, subcutaneous tissue of fingers, and collagenous fibers of the joint capsule.

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Sacral Plexus

Group of spinal nerves composed of L4, L5, and S1 through S4, generally responsible for motor and sensory function of the lower back, pelvis, perineum, posterior surface of the thigh and leg, and dorsal and plantar surfaces of the foot.

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Sagittal Plane

Plane that bisects the body from front to back, dividing it into right and left symmetrical halves. Also known as the anteroposterior, or AP plane.

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Scalar

Mathematical quantities are described by a magni- tude (or numerical value) alone such as speed, length, area, volume, mass, time, density, temperature, pressure, energy, work, and power.

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Scaption

Movement of the humerus away from the body in the scapula plane. Glenohumeral abduction in a plane halfway between the sagittal and frontal plane.

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Scapula Line

A line running vertically down the posterior surface of the body passing through inferior angle of the scapula.
scapular plan

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Scoliosis

Lateral curving of the spine.

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Second-class lever

A lever in which the resistance is between the axis (fulcrum) and the force (effort), as in plantarflexing the foot to raise up on the toes.

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Sensory Neurons

Neurons that transmit impulses to the
spinal cord and brain from all parts of the body.

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Shin Splints

Slang term frequently used to describe an often chronic condition in which the tibialis posterior, tib- ialis anterior, and extensor digitorum longus muscles are inflamed, typically a tendinitis of one or more of these structures.

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Sinister

Relating to, or situated to the left or on the left side of something.

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Sinus

Cavity or hollow space within a bone, such as the frontal or maxillary sinus.

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Somatic Nerves

Afferent nerves, which are under conscious control and carry impulses to skeletal muscles.

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Speed

How fast an object is moving, or the distance an object travels in a specific amount of time.

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Sphincter Muscles

A type of parallel muscle that is a tech- nically endless strap muscle with fibers arranged to sur- round and close openings upon contraction, such as the orbicularis oris. Also referred to as circular muscles.

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Spin

A type of accessory motion characterized by a sin- gle point on one articular surface rotating clockwise or counterclockwise about a single point on another articular surface.

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Spinal nerves

The group of 31 pairs of nerves that origi- nate from the spinal cord and exit the spinal column on each side through openings between the vertebrae. They run directly to specific anatomical locations, form different plexuses, and eventually become peripheral nerve branches.

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Stability

The resistance to a change in the body’s accel- eration; the resistance to a disturbance of the body’s equilibrium.

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Stabilizers

Muscles that surround the joint or body part and contract to fixate or stabilize the area to enable another limb or body segment to exert force and move; known as fixators, they are essential in establishing a relatively firm base for the more distal joints to work from when carry- ing out movements.

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Stabilizing Component

When the angle of pull is less than 90 degrees, the force pulls the bone toward its joint axis, thereby increasing joint compression forces.

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Static Equilibrium

The body at complete rest or motionless.

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Static Friction

The amount of friction between two objects that have not yet begun to move.

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Stretch-shortening cycle

An active stretch via an eccentric contraction of a muscle followed by an immediate con- centric contraction of the same muscle.

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Submaximal Stimuli

Stimuli that are strong enough to pro- duce action potentials in multiple motor units, but not all motor units of a particular muscle.

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Sub-threshold stimulus

Stimulus not strong enough to cause an action potential and therefore does not result in a contraction.

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Summation

When successive stimuli are provided before the relaxation phase of the first twitch is complete allow- ing the subsequent twitches to combine with the first to produce a sustained contraction generating greater ten- sion than a single contraction would produce on its own.

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Supination

Externally rotating the radius to where it lies parallel to the ulna, resulting in the palm-up position of the forearm; term is also used in referring to the com- bined movements of inversion, adduction, and internal rotation of the foot and ankle.

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Suture

Line of union between bones, such as the sagittal suture between the parietal bones of the skull.

276

Syndesmosis Joint

Type of joint held together by strong ligamentous structures that allow minimal movement between the bones, such as the coracoclavicular joint and the inferior tibiofibular joint.

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Synergists

Muscles that assist in the action of the agonists but are not primarily responsible for the action; known as guiding muscles, they assist in refined movement and rule out undesired motions.

278

Synergists (helping)

Muscles that have an action common to each other, but also have actions antagonistic to each other; they help another muscle move the joint in the desired manner and simultaneously prevent undesired actions.

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Synergists (true)

Muscles that contract to prevent an undesired joint action of the agonist and have no direct effect on the agonist action.

280

Synovial Joints

Freely movable diarthrodial joints contain- ing a joint capsule and hyaline cartilage and lubricated by synovial fluid.

281

Tendinous Inscriptions

Horizontal indentations that tran- sect the rectus abdominus at three or more locations, giv- ing the muscle its segmented appearance.

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Tendons

Fibrous connective tissue, often cordlike in appear- ance, that connects muscles to bones and other structures.

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Tetanus

When stimuli are provided at a frequency high enough that no relaxation can occur between muscle contractions.

284

Third-class lever

A lever in which the force (effort) is between the axis (fulcrum) and the resistance, as in flex- ion of the elbow joint.

285

Threshold Stimulus

When the stimulus is strong enough to produce an action potential in a single motor unit axon and all of the muscle fibers in the motor unit contract.

286

Tibial

Relating to the tibial (medial) side of the lower extremity.

287

Toe-off

Last portion of the walking or running stance phase characterized by the foot returning to supination and the
leg returning to external rotation.

288

Torque

Moment of force; the turning effect of an eccentric
force.

289

Transverse Plane

Plane that divides the body horizontally into superior and inferior halves; also known as the axial or horizontal plane.

290

treppe

A staircase effect phenomenon of muscle contraction that occurs when rested muscle is stimulated repeatedly with a maximal stimulus at a frequency that allows complete relaxation between stimuli, the second contraction produces a slightly greater tension than the first, and the third contraction produces greater tension than the second.

291

Triceps Surae

The gastrocnemius and soleus together; tri- ceps referring to the heads of the medial and lateral gas- trocnemius and the soleus; surae referring to the calf.

292

Trochanter

A very large bony projection, such as the greater or lesser trochanter of the femur.

293

Trochoidal Joint

Type of joint with a rotational movement around a long axis, as in rotation of the radius at the radioulnar joint.

294

Tubercle

A small, rounded, bony projection, such as the greater and lesser tubercles of the humerus.

295

Tuberosity

A large, rounded, or roughened, bony projec- tion, such as the radial tuberosity or tibial tuberosity

296

Ulnar

Relating to the ulnar (medial) side of the forearm or hand.

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Ulnar Deviation (Ulnar Flexion)

Adduction movement at the wrist of the little finger side of the hand toward the forearm.

298

Uni-articular Muscles

Those muscles that, from origin to insertion, cross only one joint, allowing them to perform actions only on the single joint that they cross.

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Uni-pennate Muscles

A type of pennate muscle with fibers that run obliquely from a tendon on one side only, such as the biceps femoris, extensor digitorum longus, and tibialis posterior.

300

Valgus

Outward angulation of the distal segment of a bone or joint, as in knock-knee

301

Varus

Inward angulation of the distal segment of a bone or joint, as in bowlegs.

302

Vector

Mathematical quantity described by both a magni- tude and a direction such as velocity, acceleration, direc- tion, displacement, force, drag, momentum, lift, weight, and thrust.

303

Velocity

Includes the direction and describes the rate of displacement.

304

Ventral

Relating to the belly or abdomen, on or toward the front, anterior part of.

305

Vertebral Line

A line running vertically down through the spinous processes of the spine.

306

Vertical Axis

Axis that runs straight down through the top of the head and spinal column and is at a right angle to the transverse plane of motion. Also known as the longi- tudinal or long axis.

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Visceral Nerves

Nerves that carry impulses to the heart, smooth muscles, and glands; referred to as the autonomic nervous system.

308

Volar

Relating to the palm of the hand or the sole of the foot.

309

Wolff's Law

States that bone in a healthy individual will adapt to the loads it is placed under. When a particu- lar bone is subjected to increased loading, the bone will remodel itself over time to become stronger to resist that particular type of loading.