Muscle Actions and Attachments

Frontalis Action

Elevates eyebrows

Draws scalp forward

Wrinkles skin of forehead

Occipitalis Action

Retracts scalp

Orbicularis Oculi Action

Closes eye in blinking

Squinting and Sleep

Orbicularis Oris Action

Compresses lips to close mouth

Purses lips

Nasalis Action

Elevates (flares) corners of nostrils

Depressor Anguli Oris Action

Draws corners of mouth laterally and downward (tragedy mask)

Zygomaticus Major Action

Elevates corner of mouth (smile muscle)

Zygomaticus Major Attachments

Zygomatic bone

Skin and muscles of upper lip

Zygomaticus Minor Action

Elevates corner of mouth (smile muscles)

Zygomaticus Minor Attachments

Zygomatic bone

Skin and Muscles of upper lip

Risorius Action

Draws corner of lip laterally

Tenses lips

Buccinator Action

Compresses cheek against teeth and gums during chewing

Masseter Action

Elevation and protraction of the mandible

Masseter Attachments

Zygomatic arch

Mandibular angle and lateral ramus of the mandible

Sternocleidomastoid Action

Unilateral action causes lateral flexion of neck and rotates head to face the opposite side

Bilateral actions flexes the neck

Sternocleidomastoid Attachments

Manubrium of sternum

Medial 1/3 of clavicle

Mastoid process of the temporal bone

Lateral half of superior nuchal line

Scalenes Group Action

Flexes neck forward

Elevates ribs 1 and 2 during inspiration

Scalenes Group Attachments

Transverse processes of C1-C7

Ribs 1-2

Splenius Capitis Action

Unilateral action rotates head to face the same side

Bilateral action extends neck

Trapezius Action

Extension and lateral flexion of neck

Elevation, retraction, lateral (superior) rotation, and depression of the scapula

Trapezius Attachments

External occipital protuberance

Superior nuchal line

Spinous processes of vertebrae C7-T12

Scapula and lateral clavicle

Levator Scapulae Actions

Elevation and medial (inferior) rotation of scapula

Serratus Anterior Action

Lateral (superior) rotation and protraction of scapula

Deltoid Action

Abduction of the arm

Flexion of the arm

Extension of the arm

Medial and Lateral rotation of the arm

Deltoid Attachments

Acromion and spine of scapula

Clavicle

Deltoid tuberosity of humerus

Pectoralis Major Action

Flexion, adduction, and medial rotation of the arm

Pectoralis Major Attachments

Medial clavicle

Sternum

Costal cartilages 1-7

Intertubercular sulcus of humerus

Latissimus Dorsi Action

Extension of arm

Adduction of arm

Medial rotation of the arm

Latissimus Dorsi Attachments

T7-L5

Ribs 9-12

Iliac Crest

Intertubercular sulcus of humerus

Supraspinatus Action

Abduction of the arm

Infraspinatus Action

Lateral rotation of the arm

Teres Minor Action

Lateral rotation and adduction of the arm

Subscapularis Action

Medial rotation of the arm

Teres Major Action

Extension of arm

Adduction of arm

Medial rotation of the arm

Coracobrachialis Action

Flexes arm

Adducts arm

Brachialis Action

Flexion of the forearm at elbow joint

Biceps Brachii Action

Supination of forearm at radioulnar joint

Flexion of the forearm at elbow joint

Flexion of the humerus at the shoulder (Long head only)

Biceps Brachii Attachments

Glenoid Cavity (long head)

Coracoid process of scapula (short head)

Radial tuberosity

Fascia of forearm

Triceps Brachii Action

Extension of the forearm at elbow (whole group)

Extension and adduction of the humerus at the shoulder (long head only)

Triceps Brachii Attachments

Glenoid cavity and joint capsule (long head)

Posterior surface of head of humerus (lateral head)

Posterior surface of humeral shaft (medial head)

Olecranon process of ulna

Fascia of forearm

Anconeus Action

Extends forearm at elbow

Brachioradialis Action

Flexion of the forearm at elbow

Brachioradialis Attachments

Lateral supracondylar ridge of humerus

Lateral surface of radius near styloid process

Pronator Teres Action

Pronation of the forearm at radioulnar joint

Supinator Action

Supination of forearm at radioulnar joint

Flexor Carpi Radialis Action

Anterior flexion of wrist

Radial/lateral flexion (abduction) of wrist

Flexor Carpi Ulnaris Action

Anterior flexion of wrist

Ulnar/medial flexion (adduction) of wrist

Palmaris Longus Action

Anchors skin and fascia of the palm

Weak flexor of hand at wrist

Flexor Digitorum Superficialis Action

Anterior flexion of wrist

Flexion of metacarpophalangeal and middle interphalangeal joints of digits 2-5

Flexor Pollicis Longus Action

Flexion of metacarpophalangeal and interphalangeal joints of the thumb

Weak flexor of hand at wrist

Extensor Carpi Radialis Longus and Brevis Action

Extension of wrist

Radial/lateral flexion (abduction) of wrist

Extensor Digitorum Action

Extension of metacarpophalangeal and interphalangeal joints of digits 2-5

Extension of wrist

Extensor Carpi Ulnaris Action

Extension of wrist ulnar/medial flexion (adduction) of wrist

Extensor Digiti Minimi Action

Extension of metacarpophalangeal joints and the middle of proximal interphalangeal joint of digit 5

Diaphragm Action

Contraction increases volume of thoracic cavity contributing to inspiration

External Intercostals Action

Elevation of ribs increases volume of thoracic cavity for inspiration

Internal Intercostals Action

Depression of the ribs decreases volume of thoracic cavity for forced expiration

External Oblique Action

Compresses abdomen

Flexes/stabilizes vertebral column during lifting

Unilateral contraction causes contralateral rotation

External Oblique Attachments

Ribs 5-12

Iliac crest

Pubic symphysis

Superior ramus of pubis

Internal Oblique Action

Compresses abdomen

Flexes/lateral flexion of vertebral column

Unilateral contraction causes ipsilateral rotation

Transversus Abdominis Action

Compresses abdominal wall

Used in forced expiration

Rectus Abdominis Action

Flexion of vertebral column

Compresses abdominal wall

Used in forced expiration

Rectus Abdominis Attachments

Pubic symphysis

Superior ramus of pubis

Xiphoid process

Costal cartilages 5-7

Iliopsoas Action

Flexion of thigh at hip when trunk is fixed

Flexion of trunk when hip is fixed

Tensor Fasciae Latae Action

Abduction and medial rotation of thigh at hip

Gluteus Maximus Action

Extension and abduction of thigh at hip

Extension of trunk

Gluteus Maximus Attachments

Posterior surface of ilium, coccyx, and sacrum

Gluteal tuberosity of femur

Lateral condyle of tibia via iliotibial tract

Gluteus Medius Action

Abduction and medial rotation of thigh at hip

Adductor Brevis, Adductor Longus, Adductor Magnus Action

Adduction and flexion of thigh at hip

Adductor Brevis and Adductor Longus Attachments

Body and inferior ramus of pubis

Linea aspera of femur

Adductor Magnus Attachments

Inferior ramus of pubis (ischial tuberosity and ramus)

Linea aspera

Gluteal tuberosity

Supracondylar line of femur

Gracilis Action

Adduction of the leg at the hip

Flexion and medial rotation of tibia at knee

Pectineus Action

Flexion and adduction of thigh at hip

Rectus Femoris Action

Extension of knee

Flexion of thigh at hip

Flexion of trunk when thigh is fixed

Rectus Femoris Attachments

Anterior inferior spine of ilium

Superior margin of acetabulum

Capsule of hip joint

Patella

Tibial tuberosity

Lateral and medial condyles of tibia via the patellar tendon

Vastus Lateralis Action

Extension of knee

Vastus Lateralis Attachments

Greater trochanter of femur

Gluteal tuberosity of femur

Linea aspera of femur

Patella

Tibial tuberosity

Lateral and medial condyles of tibia via the patellar tendon

Vastus Medialis Action

Extension of knee

Vastus Medialis Attachments

Intertrochanteric line and supracondylar line of femur

Linea aspera

Patella

Tibial tuberosity

Lateral and medial condyles of tibia via the patellar tendon

Vastus Intermedius Action

Extension of knee

Vastus Intermedius Attachments

Anterior and lateral surfaces of femoral shaft

Patella

Tibial Tuberosity

Lateral and medial condyles of tibia via the patellar tendon

Sartorius Action

Flexion and lateral rotation of thigh at hip

Flexion of knee

Biceps Femoris Action

Extension of thigh at hip

Flexion of knee

Biceps Femoris Attachments

Ischial tuberosity (long head)

Linea aspera (short head)

Head of fibula

Semitendinosus Action

Extension of thigh at hip

Flexion of knee

Medial rotation of tibia at knee when flexed

Semitendinosus Attachments

Ischial Tuberosity

Medial surface of upper tibia

Medial condyle of tibia

Semimembranosus Action

Flexion of knee

Extension of thigh at hip

Medial rotation of tibia at knee when flexed

Semimembranosus Attachments

Ischial tuberosity

Medial condyle of the tibia

Lateral condyle of femur

Popliteal ligament

Popliteus Action

Flexes knee

Medially rotates tibia to “unlock” knee

Gastrocnemius Action

Plantar flexion of foot

Flexion of the knee

Gastrocnemius Attachments

Condyles and popliteal surface of tibia

Calcaneus

Tibialis Anterior Action

Dorsiflexion and inversion of the foot

Soleus Action

Plantar flexion of foot

Fibularis Longus and Brevis Action

Eversion of foot

Maintains concavity of foot during tiptoeing

Extensor Digitorum Longus Action

Extension of interphalangeal joints of digits 2-5

Dorsiflexion of foot

Extensor Digitorum Brevis Action

Extension of interphalangeal joints of digits 2-5

Flexor Digitorum Longus Action

Plantarflexion of foot

Flexion of metacarpophalangeal and proximal/distal interphalangeal joints of digits 2-5

Flexor Hallucis Longus Action

Plantarflexion of foot

Flexion of metacarpophalangeal and interphalangeal joints of digit 1

Flexor Digitorum Brevis Action

Flexion of metacarpophalangeal and interphalangeal joints of digit 1