Muscle Actions Flashcards
sternocleidomastoid
acting together: flex cervical portion of vertebral column, flex head at atlanto-occipital joints
acting singly: laterally rotate and flex head to opposite side of contracting muscle
posterior fibers can assist in extension of head
rectus abdominis
flexes vertebral column especially lumbar portion and compresses abdomen to aid in defecation, urination, force exhalation, and child birth
external oblique
bilaterally: compress abdomen and flex vertebral column
unilaterally: laterally flex vertebral column, especially lumbar portion, and rotate vertebral column
internal oblique
bilaterally: compress abdomen and flex vertebral column
unilaterally: laterally flex vertebral column, especially lumbar portion, and rotate vertebral column
transversus abdominis
compresses abdomen
diaphragm
contraction causes it to flatten and increase vertical dimensions of thoracic cavity resulting in inhalation
relaxation causes it to move superiorly and decrease vertical dimension of thoracic cavity resulting in exhalation
external intercostals
contraction elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity resulting in inhalation
relaxation depresses ribs and decreases anteroposterior and lateral dimensions of thoracic cavity resulting in exhalation
internal intercostals
contraction draws adjacent ribs together to further decrease anteroposterior and lateral dimensions of thoracic cavity during forced exhalation
trapezius
elevate clavicle & head and adduct, rotate, elevate, and depress scapula
extends the head
superior fibers upward rotate scapula
middle fibers adduct scapula
inferior fibers depress and upward rotate scapula
superior and inferior fibers together rotate scapula upward
stabilizes scapula
superior fibers can help extend head
rhomboideus major
elevates and adducts scapula and rotates it downward
stabilizes scapula
pectoralis major
flex, medially rotate, and adduct humerus
as whole: adducts and mediall rotates arm at shoulder joint
calvicular head flexes arm
sternocostal head extends the flexed arm to side of trunk
latissiums dorsi
extends, adducts, and medially rotates humerus
extends, adducts, and medially rotates arm at shoulder joint
draws arm inferiorly and posteriorly
RMA: elevates vertebral column and torso
deltoid
abducts, flexes, extends, medially and laterally rotates humerus
lateral fibers abduct arm at shoulder joint
anterior fibers flex and medially rotate arm at shoulder joint
posterior fibers extend and laterally rotate at should joint
supraspinatus
assists deltoid in abducting arm at shoulder joint
teres major
extends arm at shoulder joint and assists in adduction and medial rotation of arm at shoulder joint
teres minor
laterally rotates, extends, and adducts humerus
biceps brachii
flexes forearm
supinates and pronates forearm
flexes arm
brachialis
flexes forearm
brachioradialis
flexes forearm
partially supinates and pronates forearm (to neutral position)
triceps brachii
extends forearm at elbow joint
extends arm at shoulder joint
rotator cuff
strengthen and stabilize shoulder joint
palmaris longus
weakly flexes hand at wrist joint
flexor digitorum superficialis
flexes middle phalanx of each finger
flexor digitorum profundus
flexes distal phalanx of each finger
flexor pollucis longus
flexes distal phalanx of thumb
extensor carpi radialis longus
extends and abducts hand at wrist joint (radial deviation)
extensor digitorum
extends phalanges of each finger
extensor pollucis brevis
extends phalanges of thumb
thenar
act on thumb
hypothenar
act on little finger
midpalmer
act on all fingers
psoas major
flexes vertebra (flexes trunk on hip as in sitting up from supine position) flexes and laterally rotates femur
gluteus maximus
extends, abducts, adducts, and laterally rotates femur
gluteus medius
abducts and medially rotates femur
tensor fasciae latae
flexes and abducts femur
medial compartment (thigh)
adducts femur
adductor longus, adductor magnus, adductor brevis, gracilis
adductor longus
flexes, adducts, and laterally rotates femur
RMA: extends femur
adductor brevis
flexes, adducts, and laterally rotates femur
gracilis
adducts femur
flexes leg
anterior compartment (thigh)
extends leg
quadriceps femoris (rectus femoris, vastus lateralis, vastus medialis, vastus intermedias), sartorius
quadriceps femoris
extends leg
rectus femoris, vastus lateralis, vastus medialis, vastus intermedius
rectus femoris
alone: flexes femur
sartorius
flexes and medially rotates leg
flexes and laterally rotates femur
posterior compartment (thigh)
extends femur and flexes leg
biceps femoris, semitendinososis, semimembranosus
biceps femoris
flexes and laterally rotates leg
extends femur
semitendinosis
flexes and medially rotates leg
extends femur
semimembranosus
flexes and medially rotates leg
extends femur
posterior compartment (leg)
plantar flexion
gastrocnemius, soleus, flexor hallucis longus, flexor digitorum longus
gastrocnemius
plantar flexion and leg flexion
soleus
plantar flexion
flexor hallucis longus
plantar flexion
flexes distal and proximal phalanges of big toe
flexor digitorum longus
plantar flexion
flexes phalanges of toes 2-5
anterior compartment (leg)
dorsiflexion
tibialis anterior, extensor digitorum longus, extensor hallucis longus
tibialis anterior
dorsiflexion inverts (supinates) foot
extensor digitorum longus
dorsiflexion
everts and extends phalanges of toes
extensor hallucis longus
dorsiflexion
inverts and extends proximal phalanges
flexor digitorum brevis
flexes toes 2-5 (lateral 4)
flexor hallucis brevis
flexes big toe
splenius
splenius capitis
splenius cervicis
extend head and laterally flex and rotate head
erector spinae
iliocastilis -cervicis, thoracis, lumborum
longissimus - capitis, cervicis, thoracis
spinalis - capitis, cervicis, thoracis
chief extensor of vertebral column
important in controlling flexion, lateral flexion, and rotation of vertebral column and in maintaining lumbar curve
transversospinales
semispinalis (capitis, cervicis, thoracis) - extend vertebral column and rotate head
multifidus (C7-sacrum) - extends and laterally flexes vertebral column; important in maintaining lumbar curve
rotatores (cervicis, thoracis, lumborum) - contribute little to vertebral movement but play important role in monitoring position of vertebral column and providing propioceptive feedback to stronger vertebral muscles
