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214 Cards in this Set
- Front
- Back
Myofiber
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Muscle cell
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Sarcolemma
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Plasma membrane of muscle cell
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Sarcoplasm
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Cytoplasm of a muscle cell
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Sarcoplasmic reticulum
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Endoplasmic reticulum of muscle cell
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Myofilaments
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Long protein fibers within a muscle cell
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Skeletal muscle organization
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Myofiber -> Myofibrils -> Myofilaments
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Myofibril
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Bundle of myofilaments
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Myofilaments
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Long proteins
Actin & Myosin |
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Myosin
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Thick myofilament
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Actin
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Thin myofilament
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Ratio of actin:myosin in skeletal muscle
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2:1
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Sarcomere
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Basic unit of contraction in the myofiber
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Myofiber contraction
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Actin attached to protein fibers at each end (Z disc)
Actin slides over mysosin, sarcomere shortens Each myofiber contains many sarcomeres joined end-end |
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Z disc
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Region of the sarcomere that myofilaments are inserted to.
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Myosin globular heads
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Extensions off main myosin protein structure
Form cross-bridges with surrounding actin filaments Used to pull the actin filaments towards the center of the sarcomere |
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Myofiber contraction - mechanical
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1. Myosin globular heads are put in the "cocked" position (requires ATP)
2. Calcium is released and binds to troponin 3. Tropomyosin moves and uncovers binding sites on actin 4. Myosin globular heads cross-bridge with actin 5. Myosin globular heads release (de-cock) and pull actin towards the center of the sarcomere (Power Stroke) |
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Myofiber contraction - switch components
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1. Signal travels from brain along neurons to muscle
2. Signal reaches the muscle 3. Space between motor neuron and sarcolemma 4. Area of sarcolemma on the other side of the synapse |
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Motor End Plate
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Area of sarcolemma on the other side of the synapse (receives signal)
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Synapse
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Space between neuron and sarcolemma
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Motor Neuron
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Neurons that connect to myofibers (all skeletal muscles must have one)
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Neurotransmitter for skeletal muscle
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acetylcholine
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Neuromuscular junction
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Unit made of:
End of a motor neuron Synapse Motor End Plate |
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Muscle contraction
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1. Signal sent from the brain to myofiber
2. Motor neuron activated, causing release of acetylcholine into the synapse 3. Acetylcholine moves into the sarcoplasm 4. Acetylcholine causes Ca(2+) ions stored in the sarcoplasmic reticulum to be released into the sarcoplasm 5. Increased Ca(2+) concentration in sarcoplasm allows for cross-bridging between actin and myosin |
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Troponin
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Protein that is bound to actin and also to tropomyosin.
Receives Ca(2+) ions, which causes troponin to change shape. |
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Tropomyosin
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Protein that is bound to actin and also to troponin.
Covers cross-bridging sites on Actin Linked to troponin. When troponin changes shape, it moves tropomyosin away from the cross-bridging site |
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Muscle relaxation - requirements
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1. Signal from motor neuron must stop
2. Acetylcholine must be broken down 3. Ca(2+) ions must be moved back in SR from the sarcoplasm |
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Acetylcholine breakdown
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Done by enzyme found in sarcolemma called acelycholinesterase
Broken down into Acetyl CoA and Choline |
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Ca(2+) ion transport
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Ca(2+) ions moved back into sarcoplasmic reticulum
Done by enzymes in SR Against concentration gradient (requires ATP) |
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Areas where ATP is used in muscle contraction
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1. Cock myosin globular heads
2. Release the myosin globular head from actin 3. Move Ca(2+) ion back into sarcoplasmic reticulum 4. Generate signals through motor neurons |
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Skeletal muscle ATP supply
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1. Stored glycogen in muscle cells
2. Have own myoglobin (to carry extra O2) 3. Extensive blood supply (to get glucose & oxygen) |
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Oxygen debt
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amount of oxygen needed to get rid of the lactic acid buildup that occurs during anaerobic conditions
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Lactic acid cycle
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1. Muscle cells undergo anaerobic respiration, producing lactic acid
2. Lactic acid stored in muscle cells until activity is stopped 3. Lactic acid transported to liver 4. Liver converts lactic acid into pyruvate and then pyruvate is converted to glucose (requires ATP) 5. Oxygen is needed to make the ATP required to metabolise lactic acid |
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Types of muscle fibers
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Type I - Slow-twitch, oxidative
Type II - Fast-twitch, glycolitic Type IIa - Fast-twitch, oxidative |
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Slow-twitch muscles
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Conserves ATP
Found in muscles needed for endurance |
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Fast-twitch muscles
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Uses ATP quickly
Found in muscles that provide fast, quick movements |
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Oxidative muscles
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Energy pathway to make ATP
Multiple mitochondria Always aerobic (uses glycolysis / citric acid cycle / electron transport) |
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Glycolitic muscles
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Energy pathway to make ATP
Fewer mitochondria Always anaerobic |
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Type I muscle fibers
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Slow-twitch, oxidative
Resistant to fatigue Multiple mitochondria High level of myoglobin Extensive blood supply Referred to as "red" fibers |
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Type I muscles - examples
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Quads/hamstrings of marathon runners
Postural muscles for standing Pectoral muscles of migratory birds |
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Type II muscle fibers
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Fast-twitch, glycolytic
Easily fatigues Few mitochondria Low level of myoglobin Less blood supply Referred to as "white" fibers |
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Type II muscles - examples
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Muscles of hand/eye
Leg muscles of predators/sprinters |
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Type IIa muscle fibers
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Fast-twitch, oxidative
Intermediate type of fibers (Hybrid) Resists fatigues More mitochondria Intermediate level of myoglobin Moderate blood supply |
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Type IIa muscles - examples
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Seen when muscle fibers are being "trained" (one type is converted to another)
More prevalent in animals than humans |
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Types of muscle contraction
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Isometric
Isotonic |
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Isometric muscle contraction
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Muscle generates force,
Sarcomeres DO NOT change length |
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Isotonic muscle contraction
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Muscle generates force
Sarcomeres DO change length (2) Types of Isotonic contractions: A. Concentric B. Eccentric |
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Concentric isotonic contractions
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Sarcomeres shorten
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Eccentric isotonic contractions
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Sarcomeres lengthen
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Origin
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immovable end of a muscle
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Insertion
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movable end of a muscle
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Prime mover
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Muscle primarily responsible for movement
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Synergists
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Muscle that assists prime mover
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Antagonist
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Muscle that resists prime mover's action and cause movement in the opposite direction
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Flexion
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angle decreases between bones on either side
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Extension
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angle increases between bones on either side
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Adbuction
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Moving a part away from the midline
(as if that structure were "abducted" from the body) |
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Adduction
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Moving a part towards the midline
("adding" that structure back to the body) |
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Rotation
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Moving a part around an axis
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Dorsiflexion
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Movement at the ankle that brings the toes closer to the tibia
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Plantar flexion
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movement at the ankle that brings the heel closer to the tibia
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Frontalis - location
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Over the frontal bone
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Frontalis - function
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Raises the eyebrows
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Occipitalis - location
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Over the occipital bone
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Occipitalis - function
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Connected to the frontalis by tendonous membrane
Aids the frontalis |
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Temporalis - location
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Over the temporal bone of skull
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Temporalis - function
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aids in chewing
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Buccinator - location
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Side of cheeks
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Buccinator - origin
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Mandible, maxilla
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Buccinator - insertion
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angle of mouth
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Buccinator - function
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aids in chewing, blowing air out
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Platysma - location
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From upper chest to jaw
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Platysma - origin
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CT in the upper chest
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Platysma - insertion
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inferior edge of the mandible
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Platysma - function
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pulls angles of mouth down
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Masseter - location
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cheeks (posterior)
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Masseter - origin
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Inferior edge of zygomatic bone
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Masseter - insertion
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Mandible
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Masseter - function
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Prime mover in mastication
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Zygomaticus Major - location
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cheek
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Zygomaticus Major - function
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pulls the corner of the mouth upward
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Trapezius - location
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Upper back
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Trapezius - function
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Rotates, raises or lowers Scapula
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Rhomboid - location
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Upper back - below trapezius
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Rhomboid - function
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Retracts, elevates & rotates Scapula
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Levator scapulae - location
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posterior neck and shoulder
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Levator scapulae - origin
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cervical vertebrae
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Levator scapulae - insertion
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Medial edge of scapula
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Levator scapulae - function
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Elevates scapula
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Serratus anterior - location
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posterior ribs
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Serratus anterior - function
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Pulls Scapula anteriorly & downward
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Pectoralis major - location
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Upper chest
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Pectoralis major - function
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Flexes & Adducts
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Muscles that move the arm
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Pectoralis major
Lattismus dorsi Deltoid |
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Muscles that move the pectoral girdle
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Trapezius
Rhomboid Levator scapulae Serratus anterior |
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Latissimus dorsi - location
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flanks to lower back
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Latissimus dorsi - function
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Extends, Adducts, Rotates
Pulling arms down & back “Rowing” motion |
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Deltoid - location
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shoulder
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Deltoid - origin
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Scapula & clavicle
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Deltoid - insertion
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Humerus
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Deltoid - function
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Abducts, Extends & Flexes
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Deltoid - parts
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Anterior (flexes)
Middle (abducts) Posterior (extends) |
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Muscles that move the forearm
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Insertion on the ulna/radius
Biceps brachii Brachialis Brachioradialis Triceps brachii Supinator Pronator teres |
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Biceps brachii - location
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anterior arm
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Biceps brachii - origin
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Scapula - 2 points
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Biceps brachii - insertion
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Radius
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Biceps brachii - function
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Flexion and lateral rotation of the forearm
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Brachialis - location
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anterior, distal arm
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Brachialis - function
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Flexion of forearm
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Brachioradialis - location
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lateral, proximal, anterior forearm
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Brachioradialis - origin
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Distal humerus
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Brachioradialis - insertion
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Distal radius
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Brachioradialis - function
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Flexes
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Triceps brachii - location
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posterior arm
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Triceps brachii - origin
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Scapula & humerus - 3 points
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Triceps brachii - insertion
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Olecranon process of ulna
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Triceps brachii - function
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Extends
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Supinator - location
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proximal lateral forearm
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Supinator - function
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laterally rotates
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Pronator teres - location
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anterior proximal, medial forearm
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Pronator teres - function
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medially rotates
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Gracilis - origin
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Inferior edge of the pubic bone
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Gracilis - Insertion
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Medial surface of the tibia
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Biceps femoris - origin
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Ischium, femur
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Biceps femoris - insertion
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Head of the fibula, lateral condyle of tibia
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Biceps femoris - function
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flexion and lateral rotation of leg, extends thigh
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Sartorius - origin
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anterior ilium
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Sartorius - insertion
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Medial surface of tibia
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Sartorius - function
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Flexes leg & thigh, abducts and rotates thigh
** crosses 2 joints ** ** flexes 2 structures ** Longest muscle in the body |
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Rectus femoris - origin
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illium, margin of acetabulum
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Rectus femoris - insertion
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Anterior tibia (over patella)
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Rectus femoris - function
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Extends the leg
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Tibialis anterior - origin
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Lateral condyle and surface of the tibia
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Tibialis anterior - insertion
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Tarsal bones & 1st metatarsal
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Tibialis anterior - function
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Dorsiflexion
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Extensor digitorum longus - origin
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lateral condyle of tibia & fibula
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Extensor digitorum longus - insertion
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Dorsal surfaces of toes 2-5
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Extensor digitorum longus - function
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Dorsiflextion and extension of toes
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Extensor hallucis longus - origin
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anterior fibula
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Extensor hallucis - insertion
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distal phalanx of great toe
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Extensor hallucis - function
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extends greatt toe
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Gastrocnemius - origin
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Lateral and medial condyles of femur
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Gastrocnemius - insertion
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Posterior surface of calcaneus
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Gastrocnemius - function
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Plantar flexion
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Muscles that move the hand
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Flexor digitorum superficialis
Flexor pollicis longus Flexor carpi radialis Flexor carpi ulnaris Extensor digitorum Extensor pollicis longus Extensor carpi ulnaris Extensor carpi radialis |
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Flexor digitorum superficialis - location
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forearm
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Flexor digitorum superficialis - origin
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Distal humerus
Proximal ulna & radius |
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Flexor digitorum superficialis - insertion
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Tendons of the fingers
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Flexor digitorum superficialis - function
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flexes the fingers and the hand
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Flexor pollicis longus - location
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anterior lateral radius
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Flexor pollicis longus - origin
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anterior surface of radius
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Flexor pollicis longus - insertion
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distal phalanx of thumb
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Flexor pollicis longus - function
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flexes thumb
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Flexor carpi radialis - location
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medial forearm
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Flexor carpi radialis - function
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flexes wrist, abducts hand
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Flexor carpi ulnaris - location
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medial forearm
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Flexor carpi ulnaris - function
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flexes wrist, adducts hand
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Extensor digitorum - location
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forearm
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Extensor digitorum - origin
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distal humerus
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Extensor digitorum - insertion
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Posterior surface of phalanges in digits 2-5
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Extensor digitorum - function
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Extends fingers
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Extensor pollicis longus - location
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lower forearm
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Extensor pollicis longus - origin
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Middle of ulna
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Extensor pollicis longus - insertion
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Distal phalanx of the thumb
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Extensor pollicis longus - function
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Extends the thumb
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Extensor carpi ulnaris - function
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Extends wrist, adducts hand
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Extensor carpi radialis - function
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Extends wrist, abducts hand
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Muscles of the abdominal wall
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External oblique
Rectus abdominis Linea alba (connective tissue structure) |
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Linea alba
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Band of dense connective tissue that extends from the xiphoid process of the sternum to the superior edge of the symphysis pubis
Serves as a site of attachment for several of the abdominal wall muscles |
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External oblique - location
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flanks, outer surface of lower ribs
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External oblique - function
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tenses abdominal wall
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Rectus abdominis - location
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abdominal wall
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Rectus abdominis - origin
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Superior edge of the pubis
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Rectus abdominis - insertion
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Xiphoid process of the sternum, lower ribs
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Rectus abdominis - function
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Tenses abdominal wall
Flexes vertebral column Has dense connective tissue running transversely for support |
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Muscles that move the thigh
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Psoas major
Gluteus maximus Adductors group Gracilis |
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Psoas major - location
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Lumbar vertebra to lesser trochanter of femur
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Psoas major - function
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Flexion of thigh
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Gluteus maximus - location
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Butt
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Gluteus maximus - function
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extends the thigh
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Adductors (group) - location
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pubic bones to later edge of femur
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Adductors (group) - function
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Adducts, flexes thigh
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Gracilis - function
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Adducts thigh
Flexes thigh Flexes leg at the knee ** performs actions at 2 different joints ** |
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Muscles that move the leg
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Hamstring group
Sartorius Quadriceps group |
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Hamstring group
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Biceps fermoris
Semitendinosus Semimembranosus |
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Semitendinosus - function
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flexes & medial rotates leg
extends thigh |
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Semimembranosus - function
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flexes & medial rotates leg
extends thigh |
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Quadriceps femoris group
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Rectus femoris
Vastus lateralis Vastus medialis Vastus intermedius |
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Muscles that move the foot
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Tibialis anterior
Extensor digitorum longus Extensor hallucis longus Gastrocnemius Soleus Tibialis posterior Flexor digitorum longus Fibularis longus |
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Soleus - location
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Calf (deep to the gastrocnemius)
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Soleus - function
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Plantar flexion
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Flexor digitorum longus - origin
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Posterior tibia
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Flexor digitorum longus - insertion
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Plantar surface of distal phalanges of 2nd-5th digit
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Flexor digitorum longus - function
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flexion of the toes
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Tibialis posterior - location
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posterior leg
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Tibialis posterior - function
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Plantar flexion
Inversion |
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Fibularis longus - location
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lateral leg
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Fibularis longus - function
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Plantar flexion
Eversion |
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Comparison of smooth muscle to skeletal muscle
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Smaller cells
Single, centrally located nuclei Less developed sarcoplasmic reticulum Contains actin & myosin, but the filaments are thinner, more randomly distributed, not organized in true sarcomeres |
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Smooth muscle structure - compared to skeletal muscle
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Fewer overall myofilaments
Actin/myosin ratio - 16:1 Myofilaments not as well organized Have longer actin filaments Do not attach to Z lines Attach to the sarcolemma or to sarcoplasmic proteins called dense bodies |
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Dense bodies
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Structures in smooth muscle that are analagous to Z discs
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Smooth muscles are found in:
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Viscera
Glands Blood vessels Others |
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Smooth muscles are controlled by:
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autonomic nervous system
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Smooth muscle neurotransmitters
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acetylcholine
norepinepherine |
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Accomodation
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As smooth muscles stretch, muscle fibers relax to accomodate the increase in length
Able to maintain tension while being stretched |
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Major divisions of smooth muscle
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Unitary (visceral)
Multi-unit |
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Unitary smooth muscle
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Cell contracts as a single unit
Only some of the cells have direct connectio with a neuron Have gap junctions between cells to allow nerve impulses to spread All the cells in the unit work simultaneously |
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Unitary smooth muscle - example
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Stomach, Intestines, Bladder
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Peristalsis
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Alternation between contraction and relaxation in the different layers of smooth muscle in an organ
Can produce a "wave" that propogates in a single direction |
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Multi-unit smooth muscle
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Contains units similar to skeletal muscle
All cells must be stimulated by individual nerve fibers Units can work independently |
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Multi-unit smooth muscle examples
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Walls of blood vessels
Iris |
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Unitary smooth muscle summary
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single-unit smooth muscle
• sheets of muscle myofibers • have & use gap junctions • exhibit rhythmicity • exhibit peristalsis • Found: – walls of most hollow organs |
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Multi-unit smooth muscle summary
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less organized
function as separate units myofibers function separately Found: – irises of eye – walls of blood vessels |
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Smooth muscle compared to skeletal muscle - similarities
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Contraction resembles skeletal muscles
- interaction between actin and myosin - both use calcium & ATP - both triggered by impulses from nervous system |
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Smooth muscle compared to skeletal muscle - differences
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- smooth muscle lacks troponin
– two neurotransmitters affect smooth muscle • Acetylcholine and Norepinephrine – stretching can trigger smooth muscle contraction – smooth muscle slower to contract and relax – smooth muscle more resistant to fatigue – smooth muscle can change length without losing tension • Accommodation |