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Muscular System Vocabulary 1. Agonist: (Primary Movers): 2. Antagonist: 3. Aponeuroses: 4. Buccinator: 5. Circumduction: 6. Endomysium: 7. Epimysium: 8. Fascia: 9. Fixators: 10. Gaster: 11. Insertion: 12. Oblique: 13. Origin: 14. Perimysium: 15. Pronation: 16. Protraction: (aka:scapular abduction) 17. Rectus: 18. Retraction: (aka:scapular adduction) 19. Smooth Muscle: 20. Sprain: 21. Strain: 22. Striated Muscle: 23. Supination: 24. Synergists: 25. Tendon: 26. Torticollis or Wryneck: 27. Naming skeletal Muscles: Muscles are named on the basis of several criteria, each focusing on a particular structural or functional characteristic: They include: 1. Direction of the Muscle Fibers: 2. Relative size of the Muscle: 3. Location of the Muscle. 4. Number of origins: 5. Location of the muscle’s origin & insertion. 6. Shape of the muscle. 7. Action of the muscle. 28. Types of Muscle Fiber Arrangement (6): 1) Parallel or Longitudinal 2) Radiate: 3) Multipennate 4) Bipennate 5) Unipennate 6) Circular 1 Gross Skeletal Muscles to Memorize Frontalis: Orbicularis Oculi: Orbicularis Oris: Buccinator: Zygomaticus: Masseter: Temporalis: Platysma: Sternocleidomastoid: Pectoralis Major: Intercostal Muscles: Rectus abdominis: External oblique: Internal oblique: Transversus abdominis: Trapezius: Latissimus Dorsi: Erector Spinae: Deltoid: Biceps Brachii: Brachialis: Brachioradialis: Triceps Brachii: Gluteus maximus: Gluteus medius: Iliopsoas: Biceps femoris: Semimemgbranosus: Semitendinosus: Sartorius: Rectus Femoris: Vastus Medialis: Vastus Lateralis: Vastus Intermedius: Tibialis Anterior: Extensor Digitorum Longus: Fibularis longus: Fibularis Brevis: Fibularis tertius: Gastrocnemius: Soleus: Muscles that move the shoulder: Muscle Function Trapezius Raises or lowers shoulder & shrugs them & Extends head when occiput acts as insertion Pectoralis Minor Pulls shoulder down & forward Serratus Anterior Pulls shoulder forward; abducts & rotates it upward. Muscles that move upper arm: Muscle Function Pectoralis Major Flexes & adducts humerus Latissimus Dorsi Extends upper arm, adducts upper arm posteriorly Deltoid Abducts upper arm; Assists in flexion & extension of upper arm Coracobrachialis Adduction; Assists in flexion & medial rotation of arm. Supraspinatus Assists in abducting arm Teres Major Assists in extension, adduction, & medial rotation of arm. Teres Minor Rotates arm outward Infraspinatus Rotates arm outward Muscles that move the lower arm: Muscle Function Biceps Brachii Flexes elbow & Supinates forearm & hand Brachialis Flexes elbow Brachioradialis Supinates forearm & hand:Flexes semipronated or semisupinated forearm Triceps Brachii Extends lower arm. (elbow) Pronator Teres Pronates & flexes forearm Supinator Supinates forearm Muscles that move the Hand: Muscle Flexor Carpi Radialis Flexor Carpi Ulnaris Flexor digitorum superficialis Extensor Carpi Radialis Longus Extensor Digitorum Extensor Carpi Ulnaris Function Flexes wrist & forearm; Abducts hand Adducts hand; Flexes wrist Flexes wrist & fingers Extends wrist; Abducts hand (moves toward thumb side when hand supinated) Extends fingers & wrist Extends hand; Adducts hand (move toward little finger side when hand supinated) Muscles of the pelvic floor: Muscle Function Levator Ani Together form floor of pelvic cavity; support pelvic organs; If these muscles are badly torn @ childbirth or become too relaxed, uterus or bladder my prolapse, that is drop out. Coccygeus (posterior continuation of levator ani) Same as levator ani Muscles that move the thigh: 2 Muscle Iliopsoas (iliacus & psoas mjr) Function Flexes hip; Flexes trunk (when femur acts as origin) Rectus Femoris Gluteus Maximus Gleuteus Medius Gleuteus Minimus Tensor Fasciae Lata: Piriformis Adductor Brevis, Longus, & Magnus Gracilis: Flexes hip; Extends lower leg Extends thigh – rotates outward Abducts thigh – rotates outward; Stabilizes pelvis of femur. Abducts thigh; stabilizes pelvis on femur; Rotates thigh medially. Abducts thigh; Tightens iliotibial tract Rotates thigh outward; Abducts thigh; Extends thigh. Adducts thigh Adducts thigh & Flexes knee Muscles that move the lower leg: Muscle Quadriceps Femoris Group: Rectus Femoris: Vastus Lateralis, Medialis & intermedius Sartorius Hamstring Group: Biceps Femoris Semitendinosus & Semimembranosus Muscles that move the foot: Muscle Tibialis Anterior Gastroccnemius Soleus Extensor Digirorum Longus Peroneus Longus(fibularis longus) Peroneus Brevis (fibularis Brevis) Tibialis Posterior Peroneus Tertius (fibularis tertius) Muscles that move the head: Muscle Sternocleidomastoid Semispinalis Capitis Splenius Capitis Longissimus Capitis Function Extends knee, flexes hip Extends knee Adducts & flexes leg; Permits crossing of legs tailor fashion. Flexes leg.; Extends thigh Extends thigh Function Dorsiflex foot; Inverts foot Plantar flexes foot; Flexes lower leg Plantar flexes foot Toe extension & dorsiflexor of foot Plantarflexes foot; Everts foot. Everts foot; Flexes foot Extends foot (plantar flexion); Inverts foot Flexes foot; Everts foot Function Flexes head (prayer muscle); One muscle alone, rotates head toward opposite side; spasm of this muscle alone or associated w/trapezius called torticollis or wry-neck Extends head; Bends it laterally Extends head; Bends & rotates head toward same side as contracting muscle. Extends Head; Bends & rotates head toward contracting side. Muscles that move the chest wall: Muscle Function External Intercostals Elevate ribs Internal Intercostals Probably depress ribs Diaphragm Enlarges thorax, cuasing inspiration. Muscles that move the abdominal wall: Muscle Function External Oblique Flexes & rotates vertebral column; when these muscles lose their tone, common figure faults of protruding abdomen & lordosis develop. Internal Oblique Trunk Flexion; Same as external oblique Transversalis Same as external oblique Rectus Abdominis Trunk Flexion; Same as external oblique; because abdominal muscles compress abdominal cavity, they aid in straining, defecation, forced expiration, childbirth, etc.; abdominal muscles are antagonists of diaphragm, relaxing as it contracts & vice versa. Muscles of Facial Expression & Mastication 3 Muscle Masseter & Temporalis Epicranius (occiput frontalis) Orbicularis Oculi Orbicularis Oris Platysma Zygomaticus Buccinator Function Closes jaw Pulls scalp forward & wackward Draws corners of mouth down - pouting Raises corner of mouth Permits smiling, blowing, sucking, & holding food b/w teeth during chewing. Muscles that move the trunk: Muscle Sacrospinalis (Ercector Spinae) Function Extend Back; Maintain erect posture of trunk. Lateral Portion: Iliocostalis Lumborum Iliocostalis Dorsi Iliocostalis Cervicis Medial Portion: Longissimus Dorsi Longissimus Cervicis & Capitis Quadratus Lumborum (forms part of posterior abdominal wall) Iliposoas Trunk extension; Elevation of pelvis Trunk Extension Neck Extension Trunk rotation Neck Extension Elevates pelvis; Both muscles together extend spine; One muscle alone abducts trunk toward side of contracting muscle Flexes trunk & hip 4 Physiology of the Muscular System Vocabulary Actin: Action Potential: Axon: Clonic Muscle Spasm: Concentric Contraction Contractility: Dark A Band: Fast Fast Twitch Irritability: Isometric Contraction Light I Band: Motor Unit: Myofibrils: Myofilaments: Myosin: Neurotransmitter: Acetylocholine: Nueromuscular Junction: Sarcomere: Sarcoplasmic Reticulum: Sliding Filament Theory: Slow Twitch Synaptic Cleft: Tonic Muscle Spasm: Z Disc: Cartilaginous Joint: Condyloid Joint: Ball & Socket Joint: Fibrous Joint: Pivot Joint: Plane Joint: Saddle Joint: Hinge Joint: Amphiarthroses: Synarthroses: Synovial Joint: Diathroses: Muscular System Vocabulary KEY 1. Agonist: (Primary Movers): Muscle(s) whose contraction actually produces movement. 2. Antagonist: One or more muscles that oppose the action of another group of muscles or the pull of gravity. Ex. The antagonist of a flexor muscle is an extensor muscle. 3. Aponeuroses: sheet like tendinous expansion, mainly serving to connect a muscle w/ the parts it moves. 4. Buccinator: Muscle found around the cheek 4. Circumduction: a combination of flexion, extension, abduction & adduction commonly seen in ball & socket joints like the shoulder. 5 5. Deep Fascia: Sheet of fibrous connective tissue investing the trunk, limbs, & muscles. 6. Endomysium: A fine meshwork of loose connective tissue that surrounds each muscle fiber. 7. Epimysium: a thicker, outer connective tissue sheath which covers the entire muscle. 8. Fasiculi: Groups of 15 – 40 fibers are bound into bundles & is covered by the perimysium. 9. Fixators: Muscles that serve to fix or stabilize a joint to augment the effectiveness of a primary mover (agonist). 10. Gaster: The central fleshy, or meaty contractile position of a muscle also called the belly of a muscle. 11. Insertion: A tendonous extremityby which the muscle is attached to a bone & allows for motion at the distal end of a bone. 12. Oblique: when the muscles fibers run oblique or slanted the name includes oblique. 13. Origin: A tendonous extremityby which the muscle is attached to a bone at the proximal end of a bone & usually remains fixed or stationary when the muscle contracts. 14. Perimysium: a coarse fibrous connective tissue sheath that covers the fassiculi. 15. Pronation: describes the inward rotation of the supinated forearm & hand which causes the palm of the hand to face posteriorly. 16. Protraction: refers to motion that moves a part forward. Reaching for an object involves protraction of the shoulder girdle. Also known as scapular abduction. 17. Rectus: when a muscle fibers are parallel it’s name includes rectus. 18. Retraction: is the motion that returns a protracted body part to its original or usual position . also known as scapular adduction. 19. Smooth Muscle: has no striation & is involuntary (not consciously controlled). Found mainly in the walls of hollow visceral organs ex stomach & bladder & along a definite tract w/in the body. Also called visceral, nonstriated or involuntary muscle. 20. Sprain: a tear in a ligament. The severity is grades as 1st, 2nd, or 3rd degree or mild, moderate, & severe. 21. Strain: a tear in a muscle or tendon. The severity is grades as 1st, 2nd, or 3rd degree or mild, moderate, & severe. 22. Striated Muscle: also called skeletal muscle because its fibers appear to be striped. It is a voluntary muscle 23. Superficial Fascia: a continuous sheet of loose connective tissue lies directly under the skin. 24. Supination: occurs at the radioulnar joint. In the anatomical position the hands & forearms are already supinated (palms forward). Outward rotation of hand & forearm. 25. Synergists: Muscles that contract at the same time as the prime mover, assisting or supplementing a primary mover in producing a particular movement. 26. Tendon: a strong, fibrous, extension of the muscle that connects muscles to muscles or muscles to bone. 27. Torticollis or Wryneck: a spasm of one of the neck muscles alone or associated w/the trapezius 6 28. Naming skeletal Muscles: Muscles are named on the basis of several criteria, each focusing on a particular structural or functional characteristic: They include: 1. Direction of the Muscle Fibers: 2. Relative size of the Muscle: 3. Location of the Muscle. 4. Number of origins: 5. Location of the muscle’s origin & insertion. 6. Shape of the muscle. 7. Action of the muscle. 29. Types of Muscle Fiber Arrangement (6): 1) Parallel or Longitudinal fibers align along the long axis of the muscle ex. Rectus abdominis or Sartorious 2) Radiate : fiber arrangement that converge from a broad area of origin to a narrow insertion ex. Pectoralis major; 3) Multipennate the convergence of fibers in several muscular components ex. Deltoid muscle; 4) Bipennate with fibers directed obliquely from both sides of a central tendon ex. Rectus femoris; (produces strongest contractions) 5) Unipennate exhibits fibers inserting diagonally or slanted on only one side of a similar tendon that runs the entire length of the muscle, much like the feathers in an old fashioned plume pen ex. (produces strongest contractions) 6) Circular fibers bundles are curved to encircle an opening & are typical in sphincter muscles such as the Orbicularis oris. Muscles that move the shoulder: Muscle Origin Trapezius Occipital bone Vertebrae (cervical & thoracic) Pectoralis Minor Ribs (2nd to 5th ) Serratus Anterior Ribs (upper 8 or 9) Muscles that move upper arm: Muscle Origin Pectoralis Major Clavicle (medial half) Sternum Costal Cartilages of true ribs Latissimus Dorsi Vertebrae (spines of lower thoracic, lumbar & sacral) Ilium (crest) Lumbodorsal fascia Deltoid Clavicle Scapula(spine & acromion Coracobrachialis Scapula (coracoid process) Supraspinatus Teres Major Teres Minor Scapula (supraspinous fossa) Scapula (lower part, axillary border) Scapula (axillary border) Infraspinatus Scapula (infraspinatus border) Muscles that move the lower arm: Muscle Origin Biceps Brachii Scapula (supraglenoid tuberosity) Scapula (coracoid) Brachialis Humerus (distal ½ , anterior surface) Brachioradialis Humerus (above lateral epicondyle) Insertion Clavicle Scapula (spine & acromion) Scapula (coracoid) Scapula (anterior surface, vertebral border) Function Raises or lowers shoulder & shrugs them & Extends head when occiput acts as insertion Pulls shoulder down & forward Pulls shoulder forward; abducts & rotates it upward. Insertion Humerus (greater tubercle) Function Flexes & adducts humerus Humerus (intertubercular groove) Extends upper arm, adducts upper arm posteriorly Humerus (deltoid tuberosity) Humerus (middle 3rd, medial surface) Humerus (greater tubercle Humerus (upper part, anterior surface) Humerus (greater tubercle) Humerus (greater tubercle) Abducts upper arm; Assists in flexion & extension of upper arm Adduction; Assists in flexion & medial rotation of arm. Assists in abducting arm Assists in extension, adduction, & medial rotation of arm. Rotates arm outward Rotates arm outward Insertion Radius (tubercle at proximal end) Ulna (front of coronoid process Function Flexes elbow & Supinates forearm & hand Flexes elbow Radius (styloid process) Supinates forearm & hand:Flexes semipronated or 7 Triceps Brachii Pronator Teres Supinator Scapula (infraglenoid tubrerosity) Proximal Humeral head Humerus (medial epicondyle) Ulna (coronoid process) Humerus (lateral epicondyle) Ulna (proximal 5th ) Muscles that move the Hand: Muscle Origin Flexor Carpi Radialis Humerus (medial epicondyle) Flexor Carpi Ulnaris Humerus (medial epicondyle) Ulna (posterior) Flexor digitorum Distal Humerus, ulna & superficialis radius Extensor Carpi Radialis Humerus Longus Extensor Digitorum Distal Humerus Extensor Carpi Ulnaris Humerus (lateral epicondyle) Ulna (proximal ¾ ) semisupinated forearm Extends lower arm. (elbow) Ulna (olecranon process) Radius (middle 3rd of lateral surface) Raduis (proximal 3rd ) Insertion 2nd & 3rd Metacarpal Supinates forearm Function Flexes wrist & forearm Abducts hand Adducts hand Flexes wrist Pisiform bone 3rd ,4th & 5th Metacarpal Middle phalanges of 2nd – 5th metacarpal 2nd & 3rd Metacarpal (base of) Flexes wrist & fingers Extends wrist; Abducts hand (moves toward thumb side when hand supinated) Extends fingers & wrist Distal phalanges of 2nd to 5th fingers 5th Metacarpal (base of) Muscles that move the thigh: Muscle Origin Iliopsoas (iliacus & Ilium (iliac fossa) psoas major) Vertebrae (bodies of 12th thoracic to 5th lumbar) Pronates & flexes forearm Extends hand; Adducts hand (move toward little finger side when hand supinated) Insertion Femur (small trochanter) Function Flexes hip; Flexes trunk (when femur acts as origin) Tibia (by way of patellar tendon) Femur (proximal) Iliotibial tract Flexes hip; Extends lower leg Extends thigh – rotates outward Femur (greater trochanter) Abducts thigh – rotates outward; Stabilizes pelvis of femur. Abducts thigh; stabilizes pelvis on femur; Rotates thigh medially. Abducts thigh; Tightens iliotibial tract Rotates thigh outward; Abducts thigh; Extends thigh. Adducts thigh Adducts thigh Adducts thigh Adducts thigh & Flexes knee Rectus Femoris Ilium (anterior, inferior spine) Gluteus Maximus Gleuteus Medius Ilium (crest & posterior surface) Sacrum & Coccyx Sacrotuberous ligament Ilium (lateral surface) Gleuteus Minimus Ilium (lateral surface) Femur (greater trochanter) Tensor Fasciae Lata: Ilium (anterior part of crest) Piriformis Vertebrae (front of sacrum) Adductor Brevis Adductor Longus Adductor Magnus Gracilis: Pubic bone Pubic bone Pubic bone Pubic bone (just below symphysis) Tibia (by way of Iliotibial tract) Femur (medial aspect of greater trochanter) Proximal Femur Proximal Femur Proximal Femur Tibia (medial surface behind sartorius) Muscles of the pelvic floor: Muscle Levator Ani Origin Pubis (posterior surface) Ischium (spine) Insertion Coccyx Function Together form floor of pelvic cavity; support pelvic organs; If these muscles are badly torn @ childbirth or become too relaxed, uterus or bladder my prolapse, 8 Coccygeus (posterior continuation of levator ani) Muscles that move the lower leg: Muscle Quadriceps Femoris Group: Rectus Femoris: Vastus Lateralis Vastus Medialis Vastus Intermedius: Sartorius Ischium (spine) Origin Ilium (anterior, inferior spine) Femur (linea aspera) Femur Femur (anterior surface) Os Innominatum (ilium) Hamstring Group: Biceps Femoris Semitendinosus Ischium (tuberosity) Femur (linea aspera) Ischium (tuberosity) Semimembranosus Ischium (tuberosity) Muscles that move the foot: Muscle Tibialis Anterior Gastroccnemius Soleus Extensor Digirorum Longus Origin Tibia (proximal lateral condyle) Femur (distal condyles) Tibia (proximal) Fibula Lateral tibial condyle Coccyx Sacrum that is drop out. Same as levator ani Insertion Tibia (by way of patellar tendon) Tibia (by way of patellar tendon) Tibia (by way of patellar tendon) Tibia (by way of patellar tendon) Proximal tibia Fibula (head of ) Tibia (lateral condyle) Tibia (proximal end, medial surface) Tibia (medial condyle) Insertion 1st Cuneiform &base of 1st Metatarsal Calcaneus by way of Achilles tendon) Calcaneus by way of Achilles tendon) Phalanges of 2-5 toes Function Extends knee, flexes hip Extends knee Extends knee Extends knee Adducts & flexes leg; Permits crossing of legs tailor fashion. Flexes leg. Extends thigh Extends thigh Extends thigh. Function Dorsiflex foot Inverts foot Plantar flexes foot Flexes lower leg Plantar flexes foot Toe extension & dorsiflexor of foot Plantarflexes foot Everts foot. Everts foot Flexes foot Extends foot (plantar flexion) Inverts foot Peroneus Longus (fibularis longus) Peroneus Brevis (fibularis Brevis) Tibialis Posterior Tibia (lateral condyle Fibula (head & shaft) Fibula (lower 2/3 of lateral surface of shaft) Tibia (posterior surface) Fibula (posterior surface) Peroneus Tertius (fibularis tertius) Fibula (distal third) 1st Cuneiform Base of 1st metatarsal 5th Metatarsal (tubercle, dorsal surface) Navicular Bone Cuboid Bone All 3 Cuneiforms 2nd & 4th Metatarsals 4th & 5th Metatarsals (bases of) Origin Sternum Clavicle Insertion Temporal Bone (mastoid process) Vertebrae (transverse processes of upper 6 thoracic, articular processes of lower 4 cervical) Ligamentum Nuchae Vertebrae (spinous processes of upper 3 or 4 thoracic) Occipital Bone (b/w superior & inferior nuchal lines) Function Flexes head (prayer muscle); One muscle alone, rotates head toward opposite side; spasm of this muscle alone or associated w/trapezius called torticollis or wry-neck Extends head; Bends it laterally Temporal Bone (mastoid process) Occipital Bone Extends head; Bends & rotates head toward same side as contracting Muscles that move the head: Muscle Sternocleidomastoid Semispinalis Capitis Splenius Capitis Flexes foot Everts foot 9 Longissimus Capitis Vertebrae (transverse processes of upper 6 thoracic, articular processes of lower 4 cervical) Muscles that move the chest wall: Muscle Origin External Intercostals Rib (lower border; forward fibers) Temporal Bone (mastoid process) muscle. Extends Head; Bends & rotates head toward contracting side. Insertion Rib (upper border of rib below origin) Function Elevate ribs Internal Intercostals Rib (inner surface, lower border; backward fibers) Rib (upper border of rib below origin) Probably depress ribs Diaphragm Lower circumference of Thorax (of rib cage) Central tendon of Diaphragm Enlarges thorax, cuasing inspiration. Insertion Ossa Coxae (iliac crest & pubis by way of inguinal ligament) Linea alba by way of an aponeurosis Ribs (lower 3) Pubic bone Linea Alba Pubic bone; Linea Alba Function Flexes & rotates vertebral column; when these muscles lose their tone, common figure faults of protruding abdomen & lordosis develop. Trunk Flexion Same as external oblique Ribs (costal cartilage of 5th, 6th, & 7th ribs) Sternum (xiphoid process) Trunk Flexion; Same as external oblique; because abdominal muscles compress abdominal cavity, they aid in straining, defecation, forced expiration, childbirth, etc.; abdominal muscles are antagonists of diaphragm, relaxing as it contracts & vice versa. Insertion Mandible Mandible Skin of eyebrows & root of nose Tissues of the eyelid Function Closes jaw Closes jaw Pulls scalp forward & wackward. Blinking, squinting, draws eyebrows downward, closes eyelids Closes lips, purses lips, kissing muscle Draws corners of mouth down - pouting Raises corner of mouth Muscles that move the abdominal wall: Muscle Origin External Oblique Ribs (lower 8) Internal Oblique Transversalis Rectus Abdominis Ossa Coxae (iliac crest & inguinal ligament) Lumbodorsal Fascia Ribs (lower 6) Ossa Coxae (iliac crest, inguinal ligament) Lumbodorsal Fascia Ossa Coxae (pubic bone & symphysis pubis) Muscles of Facial Expression & Mastication Muscle Origin Zygomatic Arch Masseter Temporal bone Temporalis Occipital & frontal bones Epicranius (occiput frontalis) Frontal & maxillary bones Orbicularis Oculi Orbicularis Oris Maxilla & mandible Encircles mouth Platysma Fascia of upper part of deltoid & pectoralis major Zygomatic bone Mandible (lower border) Skin around corners of mouth Skin & muscles @ corner of Zygomaticus Same as external oblique 10 Buccinator Muscles that move the trunk: Muscle Sacrospinalis (Ercector Spinae) Lateral Portion: Iliocostalis Lumborum Iliocostalis Dorsi Iliocostalis Cervicis Medial Portion: Longissimus Dorsi Longissimus Cervicis Longissimus Capitis Quadratus Lumborum (forms part of posterior abdominal wall) Iliposoas Maxillae & mandible near molars lips Orbicularis oris Permits smiling, blowing, sucking, & holding food b/w teeth during chewing. Origin Iliac crests, ribs 3-12, & vertebrae Insertion Ribs, thoracic & cervical vertebrae Function Extend Back; Maintain erect posture of trunk. Iliac crest: sacrum (posterior surface), & Lumbar vertebrae (spinous processes) Ribs, lower 6 Ribs, upper 6 Same as Iliocostalis Lumborum Vertebrae, upper 6 thoracic Vertebrae, upper 6 thoracic & last 4 cervical Ilium (posterior part of crest) Vertebrae (lower 3 lumbar) Ribs, lower six Trunk extension Elevation of pelvis Ribs, upper 6 Vertebrae, 4th to 6th cervical Vertebrae, thoracic ribs Trunk Extension Neck Extension Trunk rotation Vertebrae, 2nd to 6th cervical Temporal bone, mastoid process Ribs (12th ) Vertebrae (transverse processes of 1st 4 lumbar) Neck Extension Neck Extension Ilium & lumbar vertebrae Femur Elevates pelvis Both muscles together extend spine; One muscle alone abducts trunk toward side of contracting muscle Flexes trunk & hip Information from: Athletic Injury Assessment by James M. Booher, & Gary A. Thibodeau, Times Mirror / Mosby College Publishing 11 Physiology of the Muscular System Vocabulary Actin: Action Potential: Axon: Clonic Muscle Spasm: Concentric Contraction Contractility: Dark A Band: Fast Fast Twitch Irritability: Isometric Contraction Light I Band: Motor Unit: Myofibrils: Myofilaments: Myosin: Neurotransmitter: Acetylocholine: Nueromuscular Junction: Sarcomere: Sarcoplasmic Reticulum: Sliding Filament Theory: Slow Twitch Synaptic Cleft: Tonic Muscle Spasm: Z Disc: Cartilaginous Joint: Condyloid Joint: Ball & Socket Joint: Fibrous Joint: Pivot Joint: Plane Joint: Saddle Joint: Hinge Joint: Amphiarthroses: Synarthroses: Synovial Joint: Diathroses: 12