Muscles: Actions, Origins & Insertions

Frontalis

Action: raises eyebrows
Origin: galea aponeurotica
Insertion: eyebrow skin, bridge of nose

Masseter

Action: closes jaw; elevates mandible
Origin: zygomatic arch
Insertion: mandibular ramus

Occipitalis

Action: pulls scalp posteriorly
Origin: galea aponeurotica {thin sheet of connective tissue}
Insertion: galea aponeurotica {thin sheet of connective tissue}

Orbicularis Oculi

Action: closes, blinks and squints eyes
Origin: medial margin of orbit
Insertion: skin around eyelids

Orbicularis Oris

Action: closes mouth; kissing muscle
Origin: maxilla and mandible
Insertion: lips

Sternocleidomastoid

Action: rotates head, head flexion
Origin: clavicle and manubrium of sternum
Insertion: mastoid process of temporal bone

Sternohyoid

Action: depresses larynx and hyoid bone
Origin: clavicle and manubrium of sternum
Insertion: hyoid bone

External Intercostals

Action: elevates ribs
Origin: inferior border of each rib
Insertion: superior border of each rib

Temporalis

Action: closes jaw, elevates mandible
Origin: temporal bone
Insertion: coronoid process of mandible

Zygomaticus

Action: retracts and elevates upper lip
Origin: zygomatic bone
Insertion: skin on lateral sides of the mouth

Pectoralis Major

Action: flexion, adduction, and medial rotation at shoulder
Origin: ribs 2-6, sternum, and clavicle
Insertion: greater tubercle of humerus

Pectoralis Minor

Action: protracts scapula
Origin: ribs 3-5
Insertion: coracoid process of scapula

Rhomboid Major

Action: adducts scapula
Origin: spinous processes of vertebrae
Insertion: vertebral border of scapula

Serratus Anterior

Action: protracts scapula
Origin: ribs 1-8
Insertion: vertebral border of scapula

Trapezius

Action: extends neck; elevate or retract scapula
Origin: occipital bone and spinous processes of cervical and thoracic vertebrae
Insertion: clavicle and scapula

External Intercostals

Action: elevates ribs
Origin: inferior border of each rib
Insertion: superior border of each rib

Internal Intercostals

Action: depresses ribs
Origin: superior border of each rib
Insertion: inferior border of each rib

Deltoid

Action: abduction at shoulder
Origin: clavicle and scapula
Insertion: deltoid tuberosity of humerus

Latissimus Dorsi

Action: extension, adduction, and medial rotation at shoulder
Origin: spinous processes of inferior thoracic and all lumbar vertebrae
Insertion: intertubercular groove of humerus

Infraspinatus

Action: lateral rotation at shoulder
Origin: infraspinous fossa of scapula
Insertion: greater tubercle of humuerus

Supraspinatus

Action: Abduction at shoulder
Origin: supraspinous fossa of scapula
Insertion: greater tubercle of humerus

Teres Major

Action: extension, adduction, and medial rotation at shoulder
Origin: scapula
Insertion: intertubercular groove of humerus

Subscapularis

Action: medial rotation at shoulder
Origin: subscapular fossa of scapula
Insertion: lesser tubercle of humerus

Biceps Brachii

Action: flexion at elbow and shoulder, supination
Origin: coracoid process of scapula, and tubercle above the glenoid cavity of the scapula
Insertion: tuberosity of radius

Triceps Brachii

Action: extension at elbow
Origin: Three heads: scapula (1) and posterior humuerus (2)
Insertion: olecranon of ulna

Brachialis

Action: flexion at elbow
Origin: anterior distal humerus
Insertion: tuberosity of ulna

Brachioradialis

Action: flexion at elbow
Origin: ridge above lateral epicondyle of humerus
Insertion: styloid process of radius

Pronator Teres

Action: pronation
Origin: medial condyle of humerus and coronoid process of ulna
Insertion: radius

Flexor Carpi Radialis

Action: flexion and abduction at wrist
Origin: medial epicondyle of humerus
Insertion: base of 2nd and 3rd metacarpals

Palmaris Longus

Action: flexion at wrist
Origin: medial epicondyle of humerus
Insertion: palmar aponeurosis

Flexor Carpi Ulnaris

Action: flexion and adduction at wrist
Origin: medial epicondyle of humerus
Insertion: 5th metacarpal

Extensor Digitorum

Action: extension at finger joints and wrist
Origin: lateral epicondyle of humerus
Insertion: fingers 2-5

Extensor Carpi Ulnaris

Action: extension and adduction at wrist
Origin: lateral epicondyle of humerus
Insertion: base of 5th metacarpal

Extensor Carpi Radialis Longus

Action: extension and abduction at wrist
Origin: lateral supracondylar ridge of humerus
Insertion: base of 2nd metacarpal

diaphragm

Action: inspiration

Rectus Abdominis

Action: depresses ribs, flexes vertebral column, compresses abdomen
Origin: superior surface of pubis around symphysis
Insertion: xiphoid process of sternum

External Oblique

Action: compresses abdomen, depresses ribs, flexes or bends spine
Origin: ribs 5-12
Insertion: linea alba and pubis

Internal Oblique

Action: compresses abdomen, depresses ribs, flexes or bends spine
Origin: iliac crest
Insertion: inferior ribs, xiphoid process, linea alba

Transversus Abdominis

Action: compresses abdomen
Origin: cartilage of ribs 6-12, iliac crest
Insertion: linea alba and pubis

Gluteus Maximus

Action: extension and lateral rotation at hip
Origin: ilium, sacrum, coccyx
Insertion: iliotibial tract and gluteal tuberosity of femur

Gluteus Medius

Action: abduction and medial rotation at hip
Origin: iliac crest of ilium
Insertion: greater trochanter of femur

Sartorius

Action: flexion at knee, flexion and lateral rotation at hip
Origin: iliac spine of ilium
Insertion: medial surface of tibia near tibial tuberosity

Adductor Magnus/Longus/Brevis

Action: adduction, flexion, and medial rotation at hip
Origin: inferior ramus of pubis
Insertion: linea aspera of femur

Gracilis

Action: flexion at knee
Origin: inferior ramus of pubis
Insertion: medial surface of tibia

Iliopsoas (Iliacus)

Action: flexion at hip
Origin: iliac fossa of ilium
Insertion: lesser trochanter of femur

Iliopsoas (Psoas Major)

Action: flexion at hip
Origin: transverse processes of vertebra (T12-L5)
Insertion: lesser trochanter of femur

Biceps Femoris

Action: flexion at knee; extension and lateral rotation at hip
Origin: ischial tuberosity and linea aspera of femur
Insertion: head of fibula, lateral condyle of tibia

Semitendonosus

Action: flexion at knee; extension and medial rotation at hip
Origin: ischial tuberosity
Insertion: medial surface of tibia

Semimembranosus

Action: flexion at knee; extension and medial rotation at hip
Origin: ischial tuberosity
Insertion: medial condyle of tibia

Rectus Femoris

Action: extension ar knee; flexion at hip
Origin: iliac spine and acetabulum
Insertion: tibial tuberosity via patellar ligament

Vastus Lateralis

Action: extension at knee
Origin: greater trochanter of femur
Insertion: tibial tuberosity via patellar ligament

Vastus Medialis

Action: extension at knee
Origin: linea aspera of the femur
Insertion: tibial tuberosity via patellar ligament

Tibialis Anterior

Action: flexion (dorsiflexion) at ankle, inversion of foot
Origin: lateral condyle of tibia
Insertion: base of first metatarsal

Gastrocnemius

Action: extension (plantar flexion) at ankle, inversion of foot, flexion at knee
Origin: femoral condyles
Insertion: calcaneus bone

Soleus

Action: extension (plantar flexion) at ankle
Origin: head of fibula and shaft of tibia
Insertion: calcaneus bone

Fibularis Longus

Action: eversion of foot and extension (plantar flexion) at ankle
Origin: lateral condyle of tibia, head and shaft of fibula
Insertion: First metatarsal

Extensor Digitorum Longus

Action: Extension at joints of toes 2-5
Origin: lateral condyle of tibia, anterior surface of fibula
Insertion: toes 2-5