Major Skeletal Muscles
The major skeletal muscles are described in following tables and figures.
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TABLE 1
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Muscles of the Head and Neck
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Muscle
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Origin/Insertion
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Action
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Epicranius:frontalis
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O: galea aponeurotica I: skin around eyes
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raises eyebrows; surprised
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Epicranius:occiptalis
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O: occipital bone I : galea aponeurotica
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pulls scalp back; surprised
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Orbicularis oculi
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O: maxillary & frontal bones I: eyelids
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closes eyelids; blinking
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Orbicularis oris
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O: muscle fibers around mouth I: skin around mouth
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closes lips; kissing
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Buccinator
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O: maxilla & mandible I: orbicularis oris
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compresses cheek; whistling
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Platysma
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O: fascia in upper chest I: mandible & corner of mouth
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lowers mandible; opens mouth
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Mentalis
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O: mandible I: skin of chin
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protrudes lower lip; pouting
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Risorius
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O: fascia on masseter muscle I: skin at corner of mouth
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lateral movement of lips; grimacing
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Zygomaticus
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O: zygomatic bone I: skin around mouth
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raises edges of mouth; smiling
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Levator labi superioris
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O: infroarbital margin of maxilla I: skin of upper lip
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raises upper lip; as in disgust
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Depressor labi inferioris
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O: mandible I: skin of lower lip
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lowers lower lip
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Temporalis
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O: parietal bone I: mandible
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raises mandible; closes mouth
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Masseter
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O: zygomatic arch I: mandible
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raises mandible; closes mouth
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Medial pterygoid
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O: sphenoid & maxilla I: mandible
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raises mandible; side-to-side mouth motion
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Lateral pterygoid
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O: sphenoid & maxilla I: mandible
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raises mandible; side-to side mouth motion
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Sternocleidomastoid
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O: ternum & clavicle I: temporal bone
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flexes & rotates head
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Splenius capitis
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O: cervical & thoracic vertebrae I: temporal bone
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rotates, bends, or extends head
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Semispinalis capitis
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O: cervical & thoracic vertebrae I: occipital bone
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rotates or extends head
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Longissimus
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O: cervical & thoracic vertebrae I: temporal bone
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rotates, bends, or extends head
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Omohyoid
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O: scapula I: hyoid bone
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depresses hyoid bone
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Sternohyoid
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O: sternum & clavicle I: hyoid bone
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depresses hyoid bone
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TABLE 2
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Muscles of the Neck, Shoulder, Thorax, and Abdominal Wall
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Muscle
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Origin/Insertion
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Action
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Semispinalis capitis
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O: cervical & thoracic vertebrae I: occipital bone
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extends & rotates head
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Splenius capitis
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O: c & t vertebrae I : occipital & temporal bone
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extends and rotates head
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Deltoid
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O: clavicle & scapula I: humerus
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abducts, flexes, extends, & rotates arm
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Pectoralis major
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O: clavicle, sternum, ribs I: humerus
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flexes, adducts, & rotates arm
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Infraspinatus
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O: scapula I: humerus
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rotates arm
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Teres major
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O: scapula I: humerus
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extends, rotates arm
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Latissimus dorsi
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O: vertebrae, ribs, ilium I : humerus
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extends, adducts, rotates arm
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Levator scapulae
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O: cervical vertebrae I: scapula
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elevates scapula
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Pectoralis minor
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O: ribs I: scapula
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stabilizes scapula, elevates ribs
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Serratus anterior
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O: ribs I: scapula
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stabilizes scapula, elevates ribs
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Trapezius
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O: occipital bone & c & t vertebrae; I : scapula & clavicle
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elevates, adducts, & rotates scapula
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Rhomboideous major/Rhomboideus minor
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O: c & t vertebrae I: scapula
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adducts & rotates scapula
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Rectus abdominis
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O: pubic crest & symphysis I: xiphoid process & ribs
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flexes vertebral column, compresses abdomen
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External oblique
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O: ribs I : linea alba, ilium
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compresses abdomen, rotates trunk
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Transverse abdominis
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O: ilium, ribs I: linea alba, xiphoid process
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compresses abdomen
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External intercostals
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O: lower border of rib above I: upper border of rib below
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elevates ribs, aids inspiration
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Internal intercostals
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O: upper border of rib below I: lower border of rib above
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pulls ribs together, aids expiration
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Diaphragm
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O: lower ribs, sternum I: central tendon
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aids inspiration
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Spinalis
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O: lumbar & thoracic vertebrae I: thoracic & cervical vertebrae
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extends vertebral column
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Longissimus
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O: lumbar & cervical vertebrae I : temporal bone, vertebrae
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extends vertebral column
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Iliocostalis
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O: ilium, ribs I: ribs
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extends vertebral column
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TABLE 3
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Muscles of the Arm and Forearm
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Muscle
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Origin/Insertion
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Action
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Coracobrachiolis
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O: scapula I: humerus
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flexes & adducts arm
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Biceps brachii
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O: scapula, glenoid cavity I: radius
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flexes arm, flexes forearm, & rotates hand
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Brachialis
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O: humerus I: ulna
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flexes forearm
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Brachioradialis
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O: humerus I: radius
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flexes forearm
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Triceps brachii
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O: humerus I: ulna
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extends forearm
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Anconeus
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O: humerus I: ulna
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extends forearm
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Pronator teres
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O: humerus, ulna I: radius
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rotatesforearm
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Pronator quadratus
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O: ulna I: radius
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rotates forearm
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Supinator
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O: ulna I: radius
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rotates forearm
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Flexor carpi radialis
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O: humerus I : metacarpals
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flexes & abducts wrist
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Flexor carpi ulnaris
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O : humerus, ulna I : carpals, metacarpals
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flexes & abducts wrist
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Flexor digitorum superficialis
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O: humerus, ulna, radius I: phalanges
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flexes finger 2–5
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Flexor digitorum profundus
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O: ulna I: phalanges
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flexes distal fingers 2–5
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Palmaris longus
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O: humerus I : flexor retinaculum
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flexes wrist
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Extensor carpi radialis longus
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O : humerus I : second metacarpal
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extends & abducts wrist
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Extensor carpi ulnaris
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O: humerus, ulna I: fifth metacarpal
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extends & adducts wrist
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Extensor digitorum
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O: humerus I: distal phalanges
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extends fingers 2–5
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Extensor pollicis brevis
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O: radius I: phalanx of thumb thumb
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extends
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Extensor pollicis longus
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O: radius I: phalanx of thumb
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extends thumb
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Extensor indicis
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O: ulna I: index finger
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extends index finger
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Abductor pollicis longus
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O: radius & thumb I: first metacarpal
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abducts & extends thumb
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TABLE 4
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Muscles of the Thigh and Leg
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Muscle
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Origin/Insertion
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Action
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Gluteus maximus
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O: ilium, sacrum, coccyx I: femur
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extends & rotates thigh
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Gluteus medius
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O: ilium I: femur
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abducts & rotates thigh
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Pectineus
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O: pubis I: femur
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adducts & flexes thigh
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Adductor longus
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O: pubis I: femur
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adducts, flexes, & rotates thigh
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Adductor brevis
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O: pubis I: femur
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adducts, flexes, & rotates thigh
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Adductor magnus
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O: pubis, ischium I: femur
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adducts, flexes, & rotates thigh
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Gracilis
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O: pubis I: tibia
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adducts thigh & flexes leg
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Sartorius
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O: ilium I: tibia
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flexes & rotates thigh, flexes leg
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Quadriceps femoris: rectus femoris
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O: ilium, femur I: patella, tibia
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extends leg, flexes thigh
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Quadriceps femoris: vastus lateralis
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O: ilium, femur I: patella, tibia
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extends leg
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Quadriceps femoris: vastus medialis
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Anatomy and Chemistry Basics
The Muscular System
