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U2: Muscles II
Question | Answer |
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Muscles that act on the Anterior and Lateral abdominal wall and trunk | walls have fascia, 4 pairs of sheet-like muscles-rectus abdominus, external oblique, internal oblique, transversus abdominis. Offer support, flex of trunk & column, lateral bend & rotate, increase pressure. |
Rectus abdominis | most medial & anterior of ab wall/trunk muscles. Runs vertically along anterior abdomen; compression of abdomen (childbirth, vomiting, defecation, situps) |
External oblique | most superficial of anterolateral aspect of ab wall; fibers run at an angle; compresses abdomen, helps rotate and laterally bend trunk. |
Internal oblique | anterolateral ab wall between external oblique & transversus abdominis; fibers run at an angle; compresses abdomen, helps rotate and laterally bend trunk. |
Transversus abdominis | deepest of anterolateral ab muscles; fibers run horizontally; compresses abdomen |
Muscles used in breathing | diaphragm, external intercostals, internal intercostals |
Diaphragm | used in breathing; thoracic cavity floor. Relaxed=dome shaped;contracted=flat,primary muscle for inhalation/inspiration;voluntary (forced breath)/involuntary. Phrenic nerve innervation. Can increase intra-abdominal pressure |
External intercostals | between ribs; elevate ribs, thus increasing volume of thoracic & pleural cavities & facilitating inspiration; synergists of diaphragm |
Internal intercostals | between ribs, but run at opposite angle of external intercostals; depress ribs during forced expiration (exhalation) |
Muscles of Pelvic Floor | include pelvic diaphragm, urogentical diaphragm, both are sheets of muscles that support pelvic organs (uterus, urinary bladder) |
Muscles that move the shoulder | pectoralis minor, serratus anterior, trapezius, rhomboids |
Pectoralis minor | deep to pectoralis major in upper chest; insertion is scapula; protracts (pulls forward) shoulder, specifically the scapula |
Serratus anterior | “boxer’s muscle”-deep and inferior to pectoral muscles on lateral aspect of rib cage; runs from lateral chest toward shoulder; insertion is scapula. Protracts (pulls forward) shoulder, esp. scapula |
Trapezius | large, superficial muscle in upper & middle back; upper fibers run inferiorly toward scapula, middle run horizontally toward scapula, lower run superiorly toward scapula. Insertion-scapula. Elevates, depresses, adducts, retracts scapula and shoulder |
Rhomboids | two rectangular muscles lying deep to trapezius; insertion is scapula; along with middle fibers of trapezius, retract scapula thereby “squaring shoulders” |
Muscles that move arm (humerus) | pectoralis major, latissimus dorsi, deltoid, rotator cuff muscles |
Pectoralis major | large, superficial muscle of chest; insertion is humerus; flexes & adducts arm; pulls arm forward across chest |
Latissimus dorsi | broad, flat, superficial muscle that extends from lower back to upper arm; insertion humerus; extends and adducts arm; draws arm backward and downward |
Deltoid | forms much of fleshy portion of the shoulder area; common site for intramuscular injections. Insertion-deltoid tuberosity of humerus; abducts arm |
Rotator cuff | four different specific muscles-supraspinatus, infraspinatus, teres minor, subscapularis; muscles & tendons strengthen, stabilize shoulder joint; form nearly complete circle around shoulder joint |
Supraspinatus | muscle of rotator cuff; lies superior to scapular spine on posterior scapula; deep to trapezius; helps hold head of humerus in glenoid cavity of scapula and thereby stabilizes shoulder joint |
Infraspinatus | muscle of rotator cuff; lies inferior to scapular spine on posterior scapula; helps hold head of humerus in glenoid cavity of scapula and thereby stabilizes shoulder joint. |
Teres minor | muscle of rotator cuff; small muscle inferior to infraspinatus; helps hold head of humerus in glenoid cavity of scapula and thereby stabilizes shoulder joint |
Subscapularis | muscle of rotator cuff; lies against anterior aspect of scapula; helps hold head of humerus in glenoid cavity of scapula and thereby stabilizes shoulder joint |
Muscles that move forearm | insert on radius or ulna; sheets of fascia separate the muscles in arm into anterior & posterior compartments; anterior-flexors of forearm; posterior-extend. Biceps brachii, brachialis, triceps brachii, brachioradialis, supinator, pronator teres |
Biceps brachii | two-headed superficial muscle in anterior arm; origin-2 parts of scapula, one of which is coracoid process; insertion-radial tuberosity; action-flexes forearm |
Brachialis | lies deep to biceps brachii in anterior arm; flexes forearm, synergist of biceps brachii. |
Triceps brachii | three headed muscle in posterior arm; insertion is olecranon process of ulna; extends forearm |
Brachioradialis | superficial, lateral forearm; forms lateral border of cubital fossa; extends from distal humerus to distal radius; insertion is styloid process on distal radius; flexes forearm; synergist of biceps brachii and brachialis |
Supinator | deep forearm; insertion is radius; supination (turns forward and palm forward or upward) |
Pronator teres | located in anterior forearm; insertion is radius; pronation (turns forearms and palm backward or downward) |
Muscles that move the hand (wrist/carpals, palm/metacarpals, fingers/phalanges) | most muscles located in forearm; have long tendons that extend to hand, primarily allowing them to flex and extend wrist and fingers. |
Flexors of the wrist and fingers | in anterior forearm; mainly innervated by median nerve; include flexor carpi radialis, palmaris longus, flexor carpi ulnaris |
Extensors of the wrist and fingers | located in posterior forearm; innervated by radial nerve; include extensor carpi radialis (extends wrist); extensor digitorum (digits except thumb); extensor carpi ulnaris (wrist) |
Muscles that move the thigh (femur) and/or leg (tibia) | iliopsoas, Sartorius, quadriceps femoris muscle group, tensor fascia latae, gracilis, adductor muscle group, gluteus maximus, gluteus medius, hamstring muscle group |
Iliopsoas | muscle that moves thigh and/or leg. Composite of 2 muscles, iliacus & psoas major, which exten from the ilium and vertebral column, respectively, to the anterior thigh. |
Iliacus | origin-ilium of hip bone; insertion-femur; action-flexion of thigh |
Psoas major | origin-lumar vertebrae; insertion-femur; action-flexion of thigh; cut of meat-tenderloin |
Sartorius | strap-like superficial muscle that runs obliquely across anterior surface of thigh to knee. Action-helps produce cross legged position |
Quadriceps femoris muscle group | 4 muscles that form bulk of front & sides of thigh; all have a common tendon that extends to patella, then patellar ligament extends to tibial tuberosity. Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius |
Rectus femoris | part of quadriceps femoris muscle group; superficial muscle of anterior thigh; runs straight down thigh; insertion-tibial tuberosity via patellar ligament; extends leg; innervation-femoral nerve |
Vastus lateralis | part of quadriceps femoris muscle group;forms lateral aspect of thigh; common site for intramuscular injections, esp. in children; insertion-tibial tuberosity via patellar ligament; extends leg; innervation-femoral nerve |
Vastus medialis | part of quadriceps femoris muscle group; forms inferomedial aspect of thigh; insertion-tibial tuberosity via patellar ligament; extends leg; innervation-femoral nerve |
Vasus intermedius | part of quadriceps femoris muscle group; lies between vastus lateralis & vastus medialis; deep to rectus femoris; insertion-tibial tuberosity via patellar ligament; extends leg; innervation-femoral nerve |
Tensor fasciae latae | located in anterolateral thigh, insertion-iliotibial tract/band |
Gracilis | long, thin, superficial muscle of most medial aspect of thigh; adduction of thigh. |
Adductor muscle group | muscle group located in medial thigh; all in this group insert on femur, adduct thigh, and are used to press thighs together; strain of this group is a “pulled groin;” includes adductor longus and adductor magnus |
Gluteus maximus | largest and most superficial of butt muscles; forms most of buttock mass; overlies sciatic nerve. Insertion-gluteal tuberosity on posterior femur; extends thigh |
Gluteus medius | lateral part of butt; common site for intramuscular injections; insertion-lateral femur (specifically greater trochanter); abducts thigh |
Hamstring muscle group | 3 muscles that form bulk of posterior thigh; strained “pulled” hamstrings-common sports injury in hard-running athletes. Includes biceps femoris, semitendinosus; semimembranosus |
Biceps femoris | most lateral member of hamstring muscle group; origin-ischial tuberosity, insertion-tibia; flexion of leg and extension of thigh; innervation-sciatic nerve |
Semitendinosus | part of hamstring group; lateral to biceps femoris; origin-ischial tuberosity; insertion-tibia; flexion of leg and extension of thigh; innervation-sciatic nerve |
Semimembranosus | part of hamstring group; lies deep to semitendinosus; origin-ishcial tuberosity; insertion-tibia; flexion of leg and extension of thigh; innervation-sciatic nerve |
Muscles that move the foot | most muscles are located in leg; sheets of fascia separate these leg muscles into anterior, lateral, posterior compartments; in ankle, bands of fascia are arranged like ankle bracelets & help hold distal tendons of these muscles in place. |
Tibialis anterior | muscle that moves foot; superficial, anterior leg; immediately lateral to tibia’s anterior crest; insertion-some foot bones; dorsiflexes foot; swelling of tibialis anterior and associated pain=shin splints |
Extensor digitorum longus | muscle that moves foot; lateral to tibialis anterior; extends all toes, except big toe (hallux) |
Gastrocnemius | muscle that moves foot; large superficial muscle of posterior leg (calf); insertion-calcaneus via calcaneal/Achilles tendon; plantar flexes foot |
Soleus | muscle that moves foot; lies deep to gastrocnemius; insertion-calcaneus via calcaneal/Achilles tendon; plantar flexes foot |
Charley horse | common sports injury characterized by tearing of a muscle , bleeding into the surrounding tissues, and severe pain |