Question | Answer |
Contractility | the ability of skeletal muscle to shorten with force. |
Excitability | the capacity of skeletal muscle to respond to a stimulus. |
Extensibility | the ability to be stretched. |
Elasticity | ability to recoil to their original resting length after they have been stretched. |
Each skeletal muscle is surrounded by a connective tissue sheath called the _________ | Epimysium |
_______ is another connective tissue located outside the epimysium. It surrounds and separates muscles. | Fascia |
The fasciculi are composed of single muscle cells called ______. | Fibers |
Each fiber is surrounded by a connective tissue sheath called the _______. | Endomysium |
Cytoplasm of each fiber is filled with. | Myofibrils |
2 Major Kinds of Protein Fibers | Actin Myofilaments and Myosin Myofilaments |
Sarcomere | basic structural and functional unit of the muscle. |
An A Band extends length of _______. | myosin |
Is Myosin thick or thin? | thick |
Resting Membrane Potential | The outside of most cell membranes is positively charged compared to the inside of the cell membrane, which is negatively charged. The charge difference across the membrane |
Motor Neurons | nerve cells that carry action potentials to skeletal muscle fibers. |
Motor Unit | A single motor neuron and all the skeletal muscle fibers it innervates |
Presynaptic Terminal | enlarged nerve terminal |
Synaptic Cleft | space between the presynaptic terminal and the muscle cell |
Postsynaptic Terminal | the muscle fiber |
Muscle Twitch | contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers. |
Contraction Phase | The time of contraction |
Relaxation Phase | The time during which the muscle relaxes |
Threshold | A muscle fiber will not respond to stimulus until that stimulus reaches a level |
Lag Phase | The time between application of a stimulus to a motor neuron and the beginning of a contraction |
Tetany | Where the muscle remains contracted without relaxing. |
Recruitment | The increase in number of motor units being activated |
ATP | needed for energy for muscle contraction and produced in mitochondria. |
Anaerobic Respiration | without oxygen |
Aerobic Respiration | with oxygen (more efficient) |
Muscle Fatigue | results when ATP is used during muscle contraction faster than it can be produced in the muscle cells. |
2 types of muscle contractions | Isometric and Isotonic |
Muscle Tone | Muscle tone refers to constant tension produced by muscles of the body for long periods of time. |
Fast-Twitch Fibers | contract quickly and fatigue quickly. Well adapted to perform anaerobic metabolism. |
Slow-Twitch Fibers | contract more slowly and are more resistant to fatigue. They are better suited for aerobic metabolism. |
Origin (head) | most stationary end of the muscle. |
Insertion | the end of the muscle undergoing the greatest movement. |
Belly | The portion of the muscle between the origin and the insertion |
Synergists | Muscles that work together to accomplish specific movements |
Antagonists | Muscles that work in opposition to one another |
Prime Mover | Among a group of synergists, if one muscle plays the major role in accomplishing the desired movement |
Occipitofrontal | raises the eyebrows |
Orbicularis Oculi | closes the eyelids and causes “crows feet” wrinkles in the skin at the lateral corners of the eye. |
Orbicularis Oris | puckers the lips. |
Buccinator | flattens the cheeks. |
Zygomaticus | smiling muscle. |
Depressor Anguli Oris | frowning. |
Mastication | chewing |
Intrinsic Tongue Muscles | change the shape of the tongue. |
Extrinsic Tongue Muscles | move the tongue. |
Sternocleidomastoid | lateral neck muscle and prime mover. |
Trapezius | rotates scapula. |
Serratus Anterior | pulls scapula anteriorly. |
Pectoralis | adducts and flexes the arm |
Latissimus Dorsi | medially rotates, adducts, and powerfully extends the arm. |
Deltoid | attaches the humerus to the scapula and clavicle, and is the major abductor of the
upper limb. |
Triceps Brachii | extends the forearm. |
Biceps Brachii | flexes the forearm. |
Brachioradialis | flexes and supinates the forearm. |
Flexor Carpi | flexes the wrist. |
Extensor Carpi | extends the wrist. |
Flexor Digitorum | flexes the fingers. |
Extensor Digitorum | extends the fingers. |
Quadriceps Femoris | extends the leg; anterior thigh muscles |
Satorius | “tailors muscle”; flexes the thigh |
Hamstring Muscle | posterior thigh muscles; flexes the leg and extends the thigh. |
Linea Alba | This tendinous area of the abdominal wall |
Erector Spinae | group of muscles on each side of the back. Responsible for keeping the back straight and the body erect. |
External Intercostals | elevate the ribs during inspiration |
Internal Intercostals | contract during forced expiration. |
4 pairs of mastication muscles | 2 pair of pterygoids, temporalis, and masseter. |
Gluteus maximus | buttocks. |
Gluteus medius | hip muscle and common injection site. |
Tendinous Inscriptions | cross the rectus abdominis at three or more locations, causing the abdominal wall of a well-muscled person to appear segmented. |
Rectus Abdominis | On each side of the linea alba |
Diaphragm | accomplishes quiet breathing |