Muscles: Origin, Insertion, and Action

Rectus Femoris

Origin: Anterior inferior iliac spine & superior acetabulum Insertion: Tibial tuberosity & patella Action: Flexes thigh, extends knee

Sartorius

Origin: Anterior superior iliac spine Insertion: Proximal/medial tibia Action: Flexes and laterally rotates thigh, flexes leg

Brachialis

Origin: Anterior, distal surface of humerus Insertion: coronoid process of ulna Action: Flexes forearm

Pectoralis Major

Origin: Clavicle, sternum, cartilages of ribs 1-7 Insertion: Tendon into sulcus of humerus Action: flexes, adducts, and medially rotates arm

Orbicularis oculi

Origin: Frontal and maxillary bones Insertion: tissue of eyelid Action: Closes eyelid

Vastus Lateralis

Origin: Greater trochanter of femur, linea aspera, and interotrochanteric line Insertion: Tibial tuberosity & patella Action: Extends knee

External intercostal

Origin: Inferior border of a rib above Insertion: Superior border of rib below Action: Elevates ribs (increases volume in thorax)

Infraspinatus

Origin: Infraspinous Fossa Insertion: Greater tubercle of humerus Action: Laterally rotates arm, stabilizes shoulder joint

Internal oblique

Origin: Inguinal ligament, iliac crest, lumbar fascia Insertion: Linea alba, ribs 10-12, pubic crest Action: Compresses abdominal wall, laterally rotates trunk

Semitendinosus

Origin: Ischial Tuberosity Insertion: Proximal/medial tibia Action: Extends thigh, flexes knee

External Urethral Sphincter

Origin: Ischial and pubic rami Insertion: To median raphe at base of penis, inner fibers encircle urethra Action: Males: Closes urethra, compresses prostate and bulbo-urethral gland

Semimembranosus

Origin: Ischial tuberosity Insertion: Medial condyle of tibia & lateral condyle of femur Action: Extends thigh, flexes knee

Biceps Femoris

Origin: Ischial tuberosity, Linea aspera Insertion: Head of fibula, lateral condyle of tibia Action: Extends thigh, flexes leg

Extensor digitorum longus

Origin: Lateral Condyle of tibia, proximal fibula, & interosseus membrane Insertion: Middle of distal phalanges Action: Extends toes, dorsiflexes foot

Teres Minor

Origin: Lateral border of scapula Insertion: Greater tubercle of humerus Action: Laterally rotates and adducts arm, stabilizes shoulder joint

Tibialis anterior

Origin: Lateral condyle tibia & interosseus membrane Insertion: First metatarsal and first cuneiform by tendon Action: Dorsiflexes and inverts foot

Brachioradialis

Origin: Lateral supracondylar ridge of humerus Insertion: styloid process of radius Action: Flexes forearm

Rhomboid minor

Origin: Ligamentum nuchae, Spines C7-T1 Insertion: Vertebral border of scapula at scapular spine Action: Adducts scapula (draws scapulae together)

Vastus medialis

Origin: Linea aspera & interotrochanteric line Insertion: Tibial tuberosity & patella Action: Extends knee

Vastus Intermedius

Origin: Proximal, anterior femur Insertion: Tibial tuberosity by patellar tendon Action: extends knee

Adductor Magnus

Origin: Pubis, ischium Insertion: Gluteal tuberosity, linea aspera, adductor tubercle of distal femur Action: Adducts, flexes, extends and laterally rotates thigh

Serratus Anterior

Origin: Ribs 1-8 Insertion: Vertebral border and inferior angle of scapula Action: Abducts scapula (moves scapula away from spinal column)

External oblique

Origin: Ribs 5-12 Insertion: Linea alba, iliac crest, pubis Action: Compresses abdominal wall, laterally rotates trunk

Rhomboid major

Origin: Spines of T2-5 Insertion: Lower one-third of vertebral border of scapula Action: adducts scapula (draws scapulae together)

Sternocleidomastoid

Origin: Sternum, clavicleMastoid process of temporal bone Insertion: Mastoid process of temporal bone Action: Abducts, rotates, and flexes head

Subscapularis

Origin: Subscapular fossa Insertion: Lesser tubercle of humerus Action: Medially rotates arm, stabilizes shoulder joint

Internal intercostals

Origin: Superior border of a rib below Insertion: Inferior border of rib above Action: Depresses ribs (decreases volume in thorax)

Supraspinatus

Origin: Supraspinatus Fossa Insertion: Greater tubercle of humerus Action: Abducts arm, helps stabilize shoulder joint

Temporalis

Origin: Temporal fossa Insertion: coronoid process of mandible Action: Closes mandible

Masseter

Origin: Zygomatic arch Insertion: Angle and ramus of mandible Action: Closes mandible

Pectoralis minor

Origin: anterior surface of ribs 3-5 Insertion: coracoid process of scapula Action: draws scapula forward and inferiorly

Gluteus Maximus

Origin: dorsal ilium, sacrum, & coccyx Insertion: Gluteal tuberosity of femur, iliotibial tract Action: Extends thigh (powerfully)

Platysma

Origin: fascia over pectoralis major and deltoid Insertion: inferior border of the mandible and skin of lower face Actions: draws the corners of the mouth down; it aids in depression of the mandible

Triceps Brachii

Origin: glenoid cavity of scapula, distal and posterior groove of humerus Insertion: Olecranon process of ulna Action: Extends and adducts arm, extends forearm

Tensor fasciae latae

Origin: iliac crest, anterior iliac surface Insertion: iliotibial band of fasciae latae Action: steadies trunk

Erector Spinae

Origin: iliac crest, sacrum, transverse and spinous processes of vertebrae and supraspinal ligament Insertion: angles of the ribs, transverse and spinous processes of vertebrae, posterior aspect of the skull Action: extends and laterally bends the trunk, neck and head

Orbicularis oris

Origin: indirect from maxilla and mandible Insertion: Skin of lips Action: Closes lips

Latissimus Dorsi

Origin: indirect to process of lower 6 vertebrae, lumbar verge, iliac crest Insertion: Intertubercular sulcus of humerus Action: Extends, adducts, and medially raises arm; draws shoulder inferiorly.

Diaphragm

Origin: inferior border of ribs and sternum, costal cartilage of last 6 ribs and lumber vertebrae Insertion: central tendon Action: pushes the abdominal viscera inferiorly, increasing the volume of the thoracic cavity (inspiration)

Gracillis

Origin: inferior ramus and body of pubis Insertion: medial tibia Action: Adducts thigh, flexes leg

Transverse abdominus

Origin: inguinal ligament, iliac crest, cartilage of last 5 ribs Insertion: linea alba & pubic crest Action: compresses abdominal contents

Deltoid

Origin: lateral clavicle, acromion process, spine of scapula Insertion: Deltoid tuberosity of humerus Action: Abducts arm; flexes, extends, medially, and laterally rotates arm

Extensor Carpi Ulnaris

Origin: lateral epicondyle of humerus & posterior border of the ulna Insertion: base of metacarpal 5 Action: extends the wrist; adducts the hand

Extensor Carpi Radialis Longus

Origin: lateral supracondylar ridge of the humerus Insertion: base of metacarpal 2 Action: extends the wrist; abducts the hand

Gastrocnemius

Origin: medial & lateral condyles of femur Insertion: Calcaneus by calcaneal tendon Action: Flexes leg, plantar flexes foot

Flexor Carpi Radialis

Origin: medial epicondyle of humerus Insertion: base of metacarpals 2 & 3 Action: flexes the wrist, abducts the hand

Flexor Carpi Ulnaris

Origin: medial epicondyle of humerus, olecranon process, & posterior surface of ulna Insertion: pisiform, hamate, and base metacarpal 5 Action: flexes wrist, adducts hand

Ischiocavernosus

Origin: medial surface of the ischial tuberosity and the ischiopubic ramus Insertion: corpus cavernosum and crus of the penis/clitoris Action: compresses the corpus cavernosum

Trapezius

Origin: occipital bone, spines of C7-T12 vertebrae Insertion: Acromion and spinous process of scapula Action: elevates and adducts scapula

Bulbospongiosus

Origin: perineal body and fascia of the bulb of the vestibule Insertion: perineal membrane and corpus cavernosum of the clitoris Action: compresses the vestibular bulb and compresses the spongy urethra

Levator Ani

Origin: posterior surface of the body of the pubis, fascia of the obturator internus m. (arcus tendineus levator ani), ischial spine Insertion: anococcygeal raphe and coccyx Action: elevates the pelvic floor

Soleus

Origin: proximal tibia and fibula & interosseus membrane Insertion: Calcaneus by calcaneal tendon Action: Plantar flexes foot

Rectus Abdominis

Origin: pubic crest & pubic symphysis Insertion: Cartilages of ribs 5-7, xiphoid process Action: Flexes vertebral column, compresses abdominal wall

Biceps Brachii

Origin: tendon of sulcus, & capsule of shoulder joint. coracoid process of scapula Insertion: Radial Tuberosity Action: Flexes arm, flexes forearm, supinates hand

Levator Scapulae

Origin: transverse processes of C1-C4 vertebrae Insertion: medial border of the scapula from the superior angle to the spine Action: elevates the scapula

Hyoglossus

Origin: upper border of the greater horn of the hyoid and body of the hyoid bone Insertion: spreads out into the intrinsic muscles of the tongue Action: depresses the sides of the tongue; retracts the tongue

Gluteus Medius

Origin: upper lateral ilium Insertion: Greater trochanter of femur Action: Abducts and medially rotates thigh

Zygomaticus

Origin: upper lateral surface of the zygomatic bone Insertion: skin of the angle of the mouth Action: elevates and draws the corner of the mouth laterally