Muscular System Flashcards
What are the three main types of muscle tissue?
How do they differ?
Smooth - Involuntary spindle-shaped, single nuclei, involuntary
Cardiac - Involuntary - Striated - Branched, intercalated disks
Skeletal - Voluntary - Striated - Attaches to Bone
What is the origin and insertion of a muscle?
The ORIGIN in the attachment to a main more STATIONARY bone.
The INSERTION is the attachment to a more MOVEABLE bone.
What is a tendon?
Tendons anchor muscles firmly to bones, made of fibrous connective tissue
How do a muscle’s myofilaments provide the mechanism for movement?
Two types, thick and thin, where the two sides come together to contract and relax by sliding past each other.
What are the 3 primary functions of the muscular system?
Movement - produce body movements
Heat (Homeostasis) - contraction of muscle fibers produces most of the heat required to maintain body temperature
Posture - Maintain body position because of a continuous, low-strength muscle contraction (Muscle Tone or Tonic Contraction)
When a prime mover muscle contracts, what does its antagonist do?
It relaxes or lengthens
Produce a movement in opposition
How would you define the term posture?
How your muscles work together to maintain alignment when you are sitting or standing.
Body parts are held in the position, balancing the distribution of weight.
What is oxygen debt?
The amount of oxygen the body needs to replace its oxygen reserves and remove lactic acid after exercise.
It occurs when the body uses oxygen faster than it can breathe it in.
What roles do the respiratory, circulatory, nervous and skeletal system play in producing normal movements?
Respiratory and Circulatory - provide oxygen and nutrients and eliminate waste.
Nervous - Provides the electrical stimuli and interpretation
Skeletal - Anchors connective tissues and muscles that work together (push/pull) to make your body move. Provides the framework, support, anchor, and movement.
What is a motor unit?
The basic units that produce the forces for all movement.
A single motor neuron with the muscle fibers it innervates.
When a motor unit is activated, all of its muscle fibers contract.
How does muscle exert varying levels of force?
The muscle fibers are all different with a threshold stimulus, therefore providing the body with ability to exert different levels of strength
What is the difference between isotonic and isometric muscle contractions?
Isometric - the muscle pulls forcefully against a load (changes tension) but does not change length
Isotonic - Changes length of muscles involved in contraction, producing movement
How does strength training affect a person’s muscles?
Increases the number of myofilaments in each muscle fiber.
“Make the muscles grow larger and stronger”.
What role does acetylcholine play in muscle contraction?
It’s a neurotransmitter that stimulates muscle nerve cells to contract.
When a person bends the knee, what movement is this?
Bending it
What happens when a person abducts his or her arm?
It moves away from the body.
How is dorsiflexion of the foot performed?
Pointing the toe up and the heel down.
What are the functions of the muscles of mastication?
- Closing the mouth
- Chewing movements
Name a muscle that dorsiflexes the foot.
Tibialis anterior
What action do the hamstring muscles perform?
Flex the leg
What are the two primary respiratory muscles?
Diaphragm and intercostals
Briefly describe the structure of skeletal muscle.
Striated (crosswise stripes) muscle tissue and moves voluntarily.
Many nuclei
Describe the microscopic structure of a skeletal muscle sarcomere and motor unit.
Sarcomere is made up of two main protein filaments (thin actin and thick myosin filaments) which is responsible for muscle contraction.
Motor Unit consists of a motor neuron, its axon, and muscle fibers.
When activated, all of its fibers contract at once.
Briefly describe the structure of cardiac muscle.
Cardiac muscle fibres (Branched)
1-2 nuclei
Involuntary movements
Briefly describe the structure of smooth muscle.
Appears “smooth”
1 nuclei in the center
Involuntary movements
Briefly describe the structure and give the functions of tendons, bursae, and synovial membranes.
Tendons - Made of dense, fibrous connective tissue. Anchors the muscles firmly to the bones
Bursae - sac of fluid
Lies between some tendons and bones, reducing friction making it easier for tendons to slide over bone
Synovial Membrane - Slippery lubricating fluid that fills the Bursae.
Explain how tonic contractions help to maintain posture.
They don’t contract but they hold muscles in position by this they maintain posture.
They help maintain posture by counteracting gravity and stabilizing the body’s segments.
Give an example of how two body systems other than the muscular system contribute to body movement.
Skeletal System - Maintains structure and is something the muscles can attach to.
Nervous System - Sends the orders to move the limbs/muscles.
Describe how a muscle is stimulated.
Muscles is stimulated by a nerve impulse sending a message from the brain to the muscle through the nervous system.
Explain twitch and tetanic contractions.
Twitch is a quick, jerky response to a stimulus, in isolated muscles.
Tetanic is a series of stimuli bombarding the muscle rapidly causing a more sustained contraction.
Explain isotonic contractions.
Produces movement at a joint. Muscle changes length and moves relative to the point of origin.
Explain isometric contractions.
Muscle contracts and no movement results.
Describe “strength training” and explain the expected results.
Strength training is lifting heavy weights causing the muscles to contract against heavy resistance.
The expected result is to increase numbers of myofilaments in each muscle fiber. The muscle fiber number stays the same.
Increase # of myofilaments = bigger muscles
Describe “endurance training” and explain the expected results.
Endurance training is an activity that increases your breathing and heart rate.
Increase the # of blood vessels in the muscles without increasing in size.
Describe the following movements:
Flexion
Extension
Abduction
Adduction
Rotation
- Flexion—decreasing an angle
- Extension—increasing an angle
- Abduction—moving away from the midline
- Adduction—moving toward the midline
- Rotation—moving around an axis
Name 2 muscles of the trunk and give their function, insertion, and origin.
External Oblique: Compress Abdomen - Midline of abdomen - Lower thoracic cage
Internal Oblique: Compress Abdomen - Midline of abdomen - Pelvis
Transversus Abdominis: Compress Abdomen - Midline of abdomen - Ribs, vertebrae, pelvis
Rectus abdominis: Flexes trunk - Lower rib cage - Pubis
Diaphragm: Expand thoracic cavity during inspiration - Fibrous tissue at center of diaphragm - circumference or lower rib cage
Name 2 muscles of the head or neck and give their origin, insertion and function.
Frontal: Raises eyebrow - Skin of eyebrow - Occipital bone
Orbicularis oculi: Closes eye - Maxilla and frontal bone - Maxilla and frontal bone (encircles eye)
Orbicularis oris: Encircles lips and draws lips together - Lips - Maxilla and mandible
Zygomaticus: Elevates corners of mouth and lips - Angle of mouth and upper lip - Zygomatic
Masseter: Closes jaw - Mandible - Zygomatic arch
Temporal: Closes jaw - Mandible - Temporal region of the skull
Sternocleidomastoid: Rotates and flexes head and neck - Mastoid process - Sternum and clavicle
Trapezius: Extends head and neck, Moves or stabilizes scapula - Scapula - Skull and upper vertebrae
Name 2 muscles that move the upper extremity and give their origin, insertion, function.
Pectoralis major: Flexes and helps adduct arm - Humerus - Sternum, clavicle, and upper rib cartilages
Latissimus dorsi: Extends and helps adduct arm - Humerus - Vertebrae and ilium
Deltoid: Abducts arm - Humerus - Clavicle and scapula
Biceps brachii: Flexes elbow - Radius - Scapula
Triceps brachii: Extends elbow - Ulna - Scapula and humerus
Name 3 muscles that move the lower extremity and give their origin, insertion, and function.
Iliopsoas: Flexes thigh or trunk - Femur - Ilium and vertebrae
Sartorius: Flexes thigh and rotates leg - Tibia - Ilium
Gluteus maximus: Extends thigh - Femur - Ilium, sacrum, coccyx
Explain the interaction of the prime mover, synergist, and antagonist in efficient movement.
Prime mover is the muscle doing the most contracting, Synergist muscles are the helper muscles, Antagonist muscles don’t move (relaxed position)
Describe the conditions that cause a muscle to develop an “oxygen debt.” How is the oxygen debt “paid off”?
Caused by a temporary shortage of oxygen in the body’s tissues after exercise.
Homeostasis - The body takes in the amount of oxygen needed to remove the lactate and replace the body’s oxygen reserves to normal resting levels.
How does cardiac muscle tissue demonstrate the principle that “structure fits function”?
Cardiac muscle fibers allow the heart to contract efficiently as a unit increasing efficiency of the heart pumping blood.
