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Anatomy Ch. 6
Muscle
| Term | Definition |
|---|---|
| 4 major functional characteristics of skeletal muscle | Contractility, excitibility, extensibility, & elasticity |
| 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 |
| Epimysium | Connective tissue sheath that surrounds each skeletal muscle |
| Fascia | Another connective tissue located outside the epimysium |
| Perimysium | Loose connective tissue that surrounds the muscle fasciculi |
| Fibers | Single muscle cells |
| Endomysium | Connective tissue sheath that surrounds each fiber |
| Myofibrils | A threadlike structure that extends from one end of the fiber to the other |
| Actin myofilaments | Thin myofilaments |
| Myosin myofilaments | Thick myofilaments |
| Sarcomeres | Highly ordered units which are joined end to end to form the myofibril |
| Resting membrane potential | The charge difference across the membrane |
| Action potential | The brief reversal back of the charge |
| Motor neurons | Nerve cells that carry action potentials to skeletal muscle fibers |
| Neuromusclular junction/synapse | Formed from each branch that connects to the muscle |
| Motor unit | A single motor neuron and all the skeletal muscle fibers it innervates |
| Presynaptic terminal | The enlarged nerve terminal |
| Synaptic cleft | The space between the presynaptic terminal and the muscle cell |
| Postsynaptic terminal | The muscle fiber |
| Synaptic vesicles | Secretes neurotransmitters in the presynaptic terminal |
| Acetylcholine | Diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell |
| Acetylcholinesterase | Ensures that one action potential in the neuron yields only one action potential in the skeletal muscle, and only one contraction of the muscle cell |
| Sliding filament mechanism | Sliding of actin myofilaments past myosin myofilaments during contraction |
| Muscle twitch | Contraction of an entire muscle in response to a stimulus that causes action potential |
| Threshold | The maximum a muscle can contract |
| All-or-none response | A muscle fiber will not respond to stimulus until it reaches the threshold |
| Lag phase | Time between application of a stimulus to the beginning of a contraction |
| Contraction phase | Time of contraction |
| Relaxation phase | Time when the muscle relaxes |
| Tetany | Where the muscle remains contracted without relaxing |
| Recruitment | The increase if motor units being activated |
| ATP | Needed for energy for muscle contraction |
| ADP | More stable ATP |
| Creatine phosphate | A high-energy molecule |
| Anaerobic respiration | Without oxygen |
| Aerobic respiration | With oxygen |
| Oxygen debt | Amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creating phosphate in muscle cells |
| Muscle fatigue | Results when ATP is used during muscle contraction faster than it can be produced in the muscle cells |
| Isometric and isotonic | 2 types of muscle contractions |
| Isometric | Equal distance |
| Isotonic | Equal tension |
| Muscle tone | Constant tension produced by muscles of the body for long periods of time |
| Fast-twitch fibers | Contract quickly and fatigue quickly |
| Slow-twitch fibers | Contract more slowly and are more resistant to fatigue |
| Origin | The 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, it's the one muscle that plays the major role in accomplishing the desired movement |
| Occipitofrontalis | Raises eyebrows |
| Orbicularis oculi | Closes eyelids |
| Orbicularis oris | Puckers lips |
| Buccinator | Flattens cheeks |
| Kissing muscles | Orbicularis oris and buccinator |
| Zygomaticus | Smiling muscle |
| Levator labii superioris | Sneering |
| Depressor anguli oris | Frowning |
| Mastication | Chewing |
| Temporalis and masseter | 4 pairs of pterygoids, ,and . |
| Intrinsic | Change the shape of the tongue |
| Extrinsic | Move the tongue |
| Strenocleidomastiod | Lateral neck muscle and prime mover. Rotates and abducts the head |
| 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. |
| Diaphragm | Accomplishes quiet breathing. Dome-shaped muscle. Aids in breathing. |
| Linea alba | This tendinous area of the abdominal wall |
| Rectus abdominis | On each side of the linea alba |
| Tendinous inscriptions | Cross the rectus abdominis at three or more locations, causing the abdominal wall of a well-muscled person to appear segmented |
| Trapezius | Rotates scapula |
| Serratus anterior | Pulls scapula anteriorly |
| Pectoralis major | Adducts and flexes the arm |
| Latissimus dorsi | Medially rotates, adducts, and powerfully extends the arm.“Swimmer muscles” |
| Deltoid | Attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb. |
| Triceps brachii | Extends the forearm. Occupies the posterior compartment of the arm. |
| Biceps brachii | Flexes the forearm. Occupies the anterior compartment of the arm. |
| Brachialis | Flexes forearm |
| Brachioradialis | Flexes and supinates the forearm. |
| Retinaculum (bracelet) | Strong band of fibrous connective tissue that covers the flexor and extensor tendons and holds them in place around the wrist so that they do not “bowstring” during muscle contraction. |
| Flexor carpi | Flexes the wrist. |
| Extensor carpi | Extends the wrist |
| Flexor digitorum | Flexes the fingers. |
| Extensor digitorum | Extends the fingers. |
| Intrinsic hand muscles | Located within the hand |
| Interossi | Located between the metacarpals, are responsible for abduction and adduction of the fingers. |
| Gluteus maximus | Buttocks. Contributes most of the mass of the buttocks. Gluteus medius,hip muscle and common injection site. |
| Quadriceps femoris | Extends the leg; anterior thigh muscles |
| Sartorius | “Tailors muscle”; flexes the thigh |
| Hamstring muscles | Posterior thigh muscles; flexes the leg and extends the thigh. |
| Gastrocnemius and soleus | Form the calf muscle |
| Calcaneal tendon (Achilles tendon) | Flex the foot and toes |
| Peroneus | Muscles are primarily everters (turning the lateral side of the foot outward) of the foot, but they also aid in plantar flexion. |
| Intrinsic foot muscles | 20 muscles that flex extend, abduct, and adduct the toes. |
Created by:
meganpreece
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