Ch. 10 Vocab – Flashcards

A muscle that has the major responsibility for producing a specific movement is a prime mover, or agonist, of that movement. *The pectoralis major muscle, which fleshes out the anterior chest (and inserts on the humerus), is a prime mover of arm flexion. *When a prime mover is active, the antagonist muscles may stretch or remain relaxed.

A muscle that opposes or reverses a particular movement is an antagonist. *When a prime mover is active, the antagonist muscles may stretch or remain relaxed. *Usually, however, antagonists help to regulate the action of a prime mover by contracting slightly to provide some resistance, thus helping to prevent overshooting the mark or to slow or stop the movement.

Synergists are muscles that aid prime movers in one of two ways (they add a little extra force to the same movement, or reduce undesirable/unnecessary movements that might occur as the prime mover contracts). *When synergists immobilize a bone, or a muscle's origin so that the prime mover has a stable base on which to act, they are called fixators. *Muscles can be classified into four functional groups: prime movers, antagonists, synergists, and fixators.

Fixators are synergists that immobilize a bone, or a muscle's origin so that the prime mover has a stable base on which to act. *Muscles can be classified into four functional groups: prime movers, antagonists, synergists, and fixators. *The fixator muscles that run from the axial skeleton to the scapula can immobilize the scapula so that only the desired movements occur at the mobile shoulder joint.

Angular movements are movements that increase or decrease the angle between two bones. *These movements may occur in any plane of the body and include flexion, extension, hyperextension, abduction, adduction, and circumduction.

Flexion is a bending movement, usually along the sagittal plane, that decreases the angle of the joint and brings the articulating bones closer together. *Examples include bending the head forward on the chest and bending the body trunk or the knee from a straight to an angled position.

Extension is the reverse of flexion and occurs at the same joints. *It involves movement along the sagittal plane that increases the angle between the articulating bones and typically straightens a flexed limb or body part. *Examples include straightening a flexed neck, body trunk, elbow, or knee.

Hyperextension is continued extension beyond the anatomical position. *The anterior cruciate ligament prevents forward sliding of the tibia on the femur and checks hyperextension of the knee.

Abduction ("moving away") is movement of a limb away from the midline or median plane of the body, along the frontal plane. *Raising the arm or thigh laterally is an example of abduction. *For the fingers or toes, abduction means spreading them apart.

Adduction is the movement of a limb toward the body midline or, in the case of the digits, toward the midline of the hand or foot. *Because circumduction consists of flexion, abduction, extension, and adduction performed in succession, it is the quickest way to exercise the many muscles that move the hip and shoulder ball-and-socket joints.

Circumduction is moving a limb so that it describes a cone in space. *The distal end of the limb moves in a circle, while the point of the cone (the shoulder or hip joint) is more or less stationary. *Because circumduction consists of flexion, abduction, extension, and adduction performed in succession, it is the quickest way to exercise the many muscles that move the hip and shoulder ball-and-socket joints.

Rotation is the turning of a bone around its own long axis. *It is the only movement allowed between the first two cervical vertebrae and is common at the hip and shoulder joints. *Rotation may be directed from the midline or away from it.

Special movements are movements that do not fit into any of the other categories (gliding movements, angular movements, and rotation), and they occur at only a few joints. *Inversion and eversion are special movements of the foot.

Supination is rotating the forearm laterally so that the palm faces anteriorly or superiorly. *In the anatomical position, the hand is supinated and the radius and ulna are parallel. *Pronation is a much weaker movement than supination.

Pronation is the rotation of the forearm medially so that the palm faces posteriorly or inferiorly. *Pronation moves the distal end of the radius across the ulna so that the two bones form an X. *Pronation is a much weaker movement than supination.

Dorsiflexion is lifting the foot so that its superior surface approaches the shin. *Although dorsiflexion is not a powerful movement, it is important in preventing the toes from dragging during walking.

Plantar flexion is depressing the foot (pointing the toes). *Plantar flexion is the most powerful movement of the ankle (and foot) because it lifts the entire weight of our body.

Inversion is a movement in which the sole of the foot turns medially. *Inversion and eversion are special movements of the foot.

Eversion is a movement in which the sole of the foot turns laterally. *Inversion and eversion are special movements of the foot.

Protraction is a nonangular anterior movement in a transvere plane. *The mandible is protracted when you jut out your jaw and retracted when you bring it back.

Retraction is a nonangular posterior movement in a transverse plane. *The mandible is protracted when you jut out your jaw and retracted when you bring it back.

Elevation means lifting a body part superiorly. *For example, the scapulae are elevated when you shrug your shoulders.

Depression is moving the elevated part inferiorly. *During chewing, the mandible is alternately elevated and depressed.

Opposition is the action taken when you touch your thumb to the tips of the other fingers on the same hand. *The saddle joint between metacarpal I and the trapezium allows a movement called opposition of the thumb. *It is opposition that makes the human hand such a fine tool for grasping and manipulating objects.