Muscular System PDF

MUSCULAR SYSTEM  MUSCULAR SYSTEM → Some scientist long ago dubbed muscles from the Latin “mus” meaning "little mouse" Muscle → The dominant tissue in the heart and in the walls of other hollow organs → Makes up nearly half the body's mass ...

MUSCULAR SYSTEM  MUSCULAR SYSTEM → Some scientist long ago dubbed muscles from the Latin “mus” meaning "little mouse" Muscle → The dominant tissue in the heart and in the walls of other hollow organs → Makes up nearly half the body's mass  FUNCTION OF MUSCLES 1. Produce movement → Responsible for all locomotion and manipulation (e.g., smile or frown) 2. Maintain posture and body position → Make one tiny adjustment after another to counteract the never-ending downward pull of gravity 3. Stabilize joints → Strengthen and stabilize the joints of the skeleton 4. Generate heat → Generate heat as they contract, maintaining a normal body temperature  TYPES OF MUSCLE TISSUE 1. Skeletal Muscle → Are organs attached to and cover the bony skeleton → Longest muscle cells and have obvious stripes called striation → Contain muscle fiber, nerves, and blood Fascia – Layer of fibrous tissue that separates muscles from each other and from the skin Function: Responsible for overall body mobility Exert tremendous power  TYPES OF MUSCLE TISSUE 2. Cardiac Muscle → Occurs only in the heart, where it constitutes the bulk of the heart walls → Can contract without being stimulated by the nervous system Neural controls → Allow the heart to speed up for brief periods  TYPES OF MUSCLE TISSUE 3. Smooth Muscle → Found in the walls of hollow visceral organs, such as the stomach, urinary bladder, and respiratory passages → Its contractions are slow and sustained Function: To force fluids and other substances through internal body channels  TYPES OF MUSCLE TISSUES Skeletal Muscle Cardiac Muscle Smooth Muscle Striated Striated Nonstriated Voluntary Involuntary Involuntary Elongated cells Elongated cells  FUNCTIONAL GROUPS OF MUSCLES → Muscles can only pull; they never push 1. Prime mover or Agonist → A muscle that has the major responsibility for producing a specific movement 2. Antagonists → Muscles that oppose, or reverse, a particular movement are antagonists → When a prime mover is active, the antagonist muscles may stretch or remain relaxed → Prime mover and its antagonist are located on opposite sides of the joint across  FUNCTIONAL GROUPS OF MUSCLES → Muscles can only pull; they never push 3. Synergists → Most movements involve the action of one or more synergists → Help prime movers by adding a little force to the same movement or by reducing undesirable or unnecessary movements  MUSCLE AND BODY MOVEMENTS → Movement is attained due to a muscle moving an attached bone Muscles are attached to at least two points 1. Insertion – attachment to a moveable bone 2. Origin – attachment to an immovable bone  TYPES OF ORDINARY BODY MOVEMENTS 1. Flexion → Decreases the angle of the joint and brings two bones closer together 2. Extension → Increases the angle of the joint 3. Rotation → Movement of a bone in the longitudinal axis, shaking head “no”  TYPES OF ORDINARY BODY MOVEMENTS 4. Abduction → Moving away from the midline 5. Adduction → Moving toward the midline 6. Circumduction → Cone-shaped movement, the proximal end doesn’t move, while the distal end moves in a circle  NAMING OF SKELETAL MUSCLES 1. Muscle location → Names indicate the body region with which the muscle is associated Examples: Temporalis (temporal bone), external (outside) 2. Muscle shape → Named for their distinctive shapes Examples: Deltoid (triangle), trapezius (trapezoid) 3. Muscle size → Maximus (largest), minimus (smallest), longus (long), and brevis (short) 4. Direction of muscle fibers  NAMING OF SKELETAL MUSCLES 5. Number of origins → Biceps (two heads), triceps (three), quadriceps (four) 6. Location of the attachments → Named according to their points of origin and insertion Example: Sternum (sterno), clavicle (cleido) 7. Muscle action → Named for the movement they produce Example: Flexor (flexes), extensor (extends)  MUSCLES OF THE HEAD 1. Temporalis → Closes jaw, elevates and retracts mandible 2. Masseter → “Chewer”, prime mover of jaw closure 1 2  MUSCLES OF THE FACE 1. Epicranius → Raises eyebrow when surprised 2. Orbicularis oculi → Close eyes, blinking and squinting 3. Zygomaticus → Smiling muscle 4. Orbicularis oris → Closes lips, purses and protrudes lips, kissing, whistling  MUSCLES OF THE ABDOMEN 1. Rectus abdominis → Flex and rotate the lumbar region of the vertebral column 2. External oblique → Flex the vertebral column and compress the abdominal wall, rotating trunk and curls 3. Internal oblique → Same as external oblique 4. Transversus abdominis → Compresses abdominal contents  MUSCLES OF THE ANTERIOR AND POSTERIOR THORAX 1. Trapezius → Stabilizes, elevates, retracts, and rotates scapula 2. Pectoralis minor → With ribs fixed, it draws the scapula forward and downward 3. Rhomboids → Stabilize scapula 4. Intercostals → Draw ribs together and depress rib cage  MUSCLES OF THE SHOULDER 1. Pectoralis major → Adducts and medially rotates arm against resistance 2. Deltoid → Prime mover of arm abduction when all its fibers contract simultaneously 3. Latissimus dorsi → Prime mover of arm extension, powerful arm adductor  MUSCLES OF THE FOREARM 1. Triceps brachii → Powerful forearm extensor 2. Biceps brachii → Flexes and supinates forearm 3. Brachialis → A major forearm flexor 4. Pronator teres → Pronates forearm  MUSCLES OF THE FOREARM 5. Flexor carpi radialis → Powerful flexor and abductor of hand 7. Palmaris longus → Tenses skin and fascia of palm during hand movements  MUSCLES OF THE THIGH 1. Tensor fascia lata → Steadies the leg and trunk on the thigh by making the iliotibial tract taut 2. Sartorius → Flexes, abducts and laterally rotates thigh 3. Adductor longus → Adducts, flexes, and medially rotates thigh 4. Gracilis → Adducts thigh, flexes, and medially rotates leg  MUSCLES OF THE THIGH 5. Rectus femoris → Extends leg and flexes thigh at the hip 6. Vastus lateralis → Extends and stabilizes leg 7. Vastus medialis → Extends leg  MUSCLES OF THE LEG 1. Fibularis longus → Plantar flexes and everts foot 2. Extensor digitorum longus → Prime mover of toe extension 3. Tibialis anterior → Prime mover of dorsiflexion 4. Gastrocnemius → Plantar flexes foot