Muscular System Origin Insertion Action Muscles of the

Muscular System Origin, Insertion, Action

Muscles of the Scalp • Occipitofrontalis – Frontal Belly – Occipital Belly

Frontalis • O: Galea aponeurotica • I: Skin of eyebrows • A: Raises eyebrows, wrinkles forehead skin

Occipitalis • O: Occipital Bone • I: Galea aponeurotica • A: Pulls scalp posterior

Muscles of Facial Expression

Orbicularis Occuli • O: Frontal and Maxillary bones • I: Tissue of eyelid • A: Blinking, squinting

Orbicularis Oris • O: Maxilla and Mandible • I: Encircles mouth, angles of mouth • A: Closes lips, purses and protrudes lips (kissing and whistling)

Muscles of Mastication

Masseter • O: Zygomatic arch and maxilla • I: Mandible • A: Closes jaw by elevating mandible

Temporalis • O: Temporal fossa • I: Coronoid process of mandible • A: Closes jaw (elevates and retracts mandible)

Buccinator • O: Maxilla and mandible • I: Orbicularis oris • A: Compresses cheek (whistling and sucking), holds food between teeth (during chewing)

Muscles of the Anterior Neck and Throat (Swallowing) • Digastric • All of the muscles that attach to the hyoid

Digastric • O: Mandible and mastoid process • I: Hyoid bone • A: Elevate hyoid during speech and swallowing, • Open mouth and depress mandible

Anterolateral Neck Muscles

Sternocleidomastoid • O: Sternum and Clavicle • I: Mastoid process of temporal bone • A: B/L – head flexion; unilateral – laterally flex towards and rotates away from itself

Scalenes • O: Transverse processes (anterior) of cervical vertebrae • I: 1 st two ribs • A: elevate first two ribs (inspiration), flex and rotate neck

Intrinsic Muscles of the Back

Splenius Capitus • O: Ligamentum nuchae, spinous processes of C 7 – T-6 • I: Occipital bone, mastoid process of temporal bone • A: B/L – extend head; unilateral – lateral flex and rotate towards

Splenius Cervicis • O: Ligamentum nuchae, spinous processes of C 7 – T-6 • I: Transverse Processes of C 2 – C 4 • A: B/L – extend neck; unilateral – lateral flex and rotate towards

Erector Spinae (Sacrospinalis) • Iliocostalis (Most lateral) • Longissimus (Intermediate) • Spinalis (Most medial)

Iliocostalis • O: iliac crest (lumborum); inferior 6 ribs (thoracis); ribs 3 to 6 (cervicis) • I: ribs (lumborum and thoracic); TPs of C 6 -C 4 (cervicis) • A: B/L - Extend spine, posture; unilateral – lateral flex towards

Longissimus • O: TPs of vertebrae • I: Superior TPs and superior ribs; capitis portion inserts on Mastoid process • A: B/L – extend spine; unilateral – laterally flex; capitis portion extends head and rotates towards

Spinalis • O: Spines of upper lumbar and lower thoracic vertebrae • I: Spines of upper thoracic and cervical vertebrae • A: Extends spine, maintains erect posture

Quadratus Lumborum • O: Iliac crest • I: TPs of upper lumbar vetebrae and 12 th rib • A: Unilaterally – laterally flexes spine; b/l – extends L-spine

Muscles of the Thorax (Breathing)

External Intercostals • O: Inferior border of rib above • I: Superior border of rib below • A: Pull ribs toward one another, elevate rib cage; INSPIRATION • Fibers run down and anterior

Internal Intercostals • O: Superior border of rib below • I: inferior border of rib above • A: Draw ribs together and depress rib cage; EXPIRATION • Fibers run down and posterior

Diaphragm • O: Inferior surface of rib cage and sternum, costal cartilages, lumbar vertebrae • I: Central tendon • A: Flattens on contraction; Prime mover of Inspiration

Muscles of the Anterior and Lateral Abdominal Wall

Rectus Abdominus • O: Pubic crest and symphysis • I: Xiphoid process and costal cartilages ribs 5 -7 • A: Flex and rotate lumbar region, stabilize pelvis during walking

External Oblique • O: Outer surfaces of lower eight ribs • I: Linea alba • A: B/L – aid in trunk flexion; unilateral – trunk rotation and lateral flexion

Internal Oblique • O: Lumbar fascia, iliac crest • I: linea alba, pubic crest, costal margin last 3 – 4 ribs • A: B/L – aid in trunk flexion; unilateral – trunk rotation and lateral flexion

Transverse Abdominus • O: Inguinal ligament, lumbar fascia, cartilage of last 6 ribs, iliac crest • I: Linea alba, pubic crest • A: Compresses abdominal contents

Muscles of the Anterior Thorax

Pectoralis Minor • O: Anterior surface of ribs 3 -5 • I: Coracoid process of scapula • A: Ribs fixed – draws scapula forward and down; scapula fixed – draws rib cage superior

Muscles of the Posterior Thorax

Trapezius • O: Occipital bone, ligamentum nuchae, spines from C 7 to T 12 • I: Acromion and spine of scapula, lateral 1/3 of clavicle • A: Superior – elevates scapula; middle – retract (adduct) scapula; inferior – depress scapula

Levator Scapulae • O: Transverse processes of C 1 – C 4 • I: Medial border of scapula (superior to spine) • A: Elevates / adducts scapula, laterally flexes neck to same side

Rhomboids • O: Spinous processes of C 7 – T 5 • I: Medial border of scapula • A: Retract (adduct) scapula, stabilize scapula

Muscles Crossing the Shoulder Joint

Pectoralis Major • O: Sternal end of clavicle, sternum, cartilage ribs 1 -6 • I: Intertubercular sulcus of humerus • A: Flexes arm, medially rotates arm, adducts arm (climbing, throwing, pushing)

Latissimus Dorsi • O: Fascial connection to spines of T 7 – L 5, lower 3 -4 ribs, iliac crest • I: Intertubercular sulcus of humerus • A: Arm extension, arm adductor, medially rotates arm (hammering, swimming)

Deltoid • O: Embraces insertion of trapezius; lateral third of clavicle, acromion, spine of scapula • I: Deltoid tuberosity of humerus • A: Abducts arm; anterior fibers – flexion, medial rot. ; posterior fibers – extension, lateral rot.

Rotator Cuff Muscles • • • SITS Supraspinatus Infraspinatus Teres Minor Subscapularis

Supraspinatus • O: Supraspinous fossa of scapula • I: Greater tubercle of humerus • A: Stabilizes shoulder joint. Prevents downward dislocation. Initiates shoulder abduction.

Infraspinatus • O: Infraspinous fossa of scapula • I: Greater tubercle of humerus posterior to supraspinatus insertion • A: Holds head of humerus in glenoid cavity, shoulder stabilization

Teres Minor • O: Lateral border of scapula (dorsal surface) • I: Greater tubercle of humerus inferior to infraspinatus insertion • A: Stabilize shoulder, adducts arm

Subscapularis • O: Subscapular fossa of scapula • I: Lesser tubercle of humerus • A: Medial rotation of humerus, stabilizes shoulder joint

Teres Major • O: Inferior angle of scapula • I: Intertubercular sulcus of humerus • A: Extends, medially rotates, and adducts humerus

Coracobrachialis • O: Coracoid process of scapula • I: Medial humerus • A: Flexion and adduction of humerus

Muscles Crossing the Elbow Joint

Posterior

Triceps Brachii • O: Scapula and humerus • I: Olecranon process of ulna • A: Forearm extensor

Anterior

Biceps Brachii • O: Short head – coracoid process; long head – lip of glenoid cavity • I: Radial tuberosity • A: Flexes elbow joint, supinates forearm

Brachialis • O: Front of distal humerus • I: Styloid process of ulna • A: Forearm flexor

Brachioradialis • O: Distal end of humerus • I: Styloid process of radius • A: Forearm flexion

Muscles of the Forearm

Anterior Superficial

Pronator Teres • O: Medial epicondyle of humerus • I: Lateral radius • A: Pronates forearm

Flexor Carpi Radialis • O: Medial epicondyle of humerus • I: 2 nd and 3 rd metacarpals • A: Flexor of wrist, abducts hand

Palmaris Longus • O: Medial epicondyle of humerus • I: Skin and fascia of palm • A: Wrist flexor

Flexor Carpi Ulnaris • O: Medial epicondyle of humerus, olecranon process and posterior ulna • I: Pisiform, hamate, and 5 th metacarpal • A: Wrist flexion, adducts hand

Flexor Digitorum Superficialis • O: Medial epicondyle of humerus, coronoid process of ulna, shaft of radius • I: Middle phalanges 2 -5. • A: Flexes wrist and middle phalanges

Anterior Deep

Flexor Pollicis Longus • O: Anterior radius, interosseus membrane • I: Distal phalanx of the thumb • A: Flexes distal phalanx of the thumb

Flexor Digitorum Profundus • O: Anteromedial surface of ulna and interosseus membrane • I: Distal phalanges 2 -5 • A: Finger flexion

Posterior Superficial

Extensor Carpi Radialis • O: Lateral epicondyle of humerus • I: 3 rd metacarpal • A: Extends wrist

Extensor Carpi Digitorum • O: Lateral epicondyle of humerus • I: Distal phalanges 2 -5 • A: Finger extension, extends wrist

Extensor Carpi Ulnaris • O: Lateral epicondyle of humerus, posterior ulna • I: 5 th metacarpal • A: Extends wrist, adducts wrist

Posterior Deep

Supinator • O: Lateral epicondyle of humerus, proximal ulna • I: Proximal radius • A: Supinates forearm

Extensor Pollicis • O: Dorsal radius and ulna, interosseus membrane • I: Proximal and distal phalanx of thumb • A: Extends thumb

Thenar Muscles

Abductor Pollicis • O: Posterior radius and ulna, interosseus membrane • I: 1 st metacarpal and trapezium • A: Abducts and extends thumb, abducts wrist

Opponens Pollicis • O: Flexor retinaculum and trapezium • I: Anterior 1 st metacarpal • A: Opposition: moves thumb to touch tip of middle finger

Adductor Pollicis • O: Metacarpals 2 -4 • I: Medial side of proximal phalanx of thumb • A: Adducts thumb

Muscles Crossing the Hip and Knee Joints

Anterior and Medial Muscles

Iliopsoas • O: Iliac crest, TPs, bodies, and discs of T 12 – L 5 • I: Lesser trochanter of femur • A: Thigh flexor, trunk flexor, lateral flexion of trunk

Sartorius • O: Anterior Superior Iliac Spine (ASIS) • I: Posterior, medial aspect of proximal Tibia • A: Flexes, abducts, and laterally rotates thigh; flexes knee

Medial Compartment of the Thigh

Gracilis • O: Body of pubis • I: Medial surface of Tibia • A: Adducts thigh; flexes thigh; medially rotates thigh

Anterior Compartment of the Thigh

Quadriceps Femoris • Four Heads – Rectus Femoris – Vastus Lateralis – Vastus Medialis – Vastus Intermedius

Rectus Femoris • O: Anterior Inferior Iliac Spine (AIIS) • I: Patella and tibial tuberosity • A: Extends knee; flexes thigh at hip

Vastus Lateralis • O: Greater trochanter • I: Patella and tibial tuberosity • A: Extends and stabilizes knee

Vastus Medialis • O: Linea aspera, intertrochanteric line • I: Patella and tibial tuberosity • A: Extends knee; inferior fibers stabilize patella

Vastus Intermedius • O: Anterior and lateral surface of proximal femur • I: Patella and tibial tuberosity • A: Extends knee

Tensor Fascia Latae • O: Iliac crest, ASIS • I: Iliotibial tract • A: Flexes and abducts thigh; pulls iliotibial tract taut

Posterior Muscles

Gluteus Maximus • O: Dorsal ilium, sacrum, coccyx • I: Gluteal tuberosity of femur, ITB • A: Extends thigh

Gluteus Medius & Minimus • O: Surface of ilium • I: Greater trochanter of femur • A: Abducts and medially rotates thigh

Lateral Rotators

Piriformis • O: Anterolateral surface of sacrum • I: Greater trochanter of femur (superior border) • A: Laterally rotates thigh

Posterior Compartment of the Thigh

Hamstrings • Biceps femoris (two heads) • Semitendinosus • Semimembranosus

Biceps Femoris • O: Ischial tuberosity • I: Head of fibula and lateral condyle of tibia • A: Extends thigh; flexes knee; laterally rotates leg

Semitendinosus • O: Ischial tuberosity • I: Medial aspect of Tibia • A: Extends thigh; flexes knee; medially rotates leg

Semimembranosus • O: Ischial tuberosity • I: Medial condyle of tibia; lateral condyle of femur • A: Extends thigh; flexes knee; medially rotates leg

Muscles of the Leg

Anterior Compartment

Tibialis Anterior • O: Upper 2/3 of tibia, interosseus membrane • I: Medial cuneiform and 1 st metatarsal bone • A: Dorsiflexion of foot

Extensor Digitorum • O: Proximal ¾ of fibula; interosseous membrane • I: Middle and distal phalanges of toes 2 -5 • A: Toe extension; dorsiflexes foot

Extensor Hallucis • O: Fibula; interosseous membrane • I: Distal phalanx of great toe • A: Extends great toe; dorsiflexes foot

Lateral Compartment

Peroneus (Fibularis) • O: Lateral fibula • I: Long tendon curves under foot to the 1 st metatarsal and medial cuneiform (longus); fifth metatarsal (brevis) • A: Plantar flexes foot; everts foot.

Posterior Compartment

Triceps Surae • Gastrocnemius (Two heads) • Soleus

Gastrocnemius • O: Two heads from medial and lateral condyles of the femur • I: Calcaneus • A: Plantar flexes foot; can flex knee when the foot is dorsiflexed

Soleus • O: Superior tibia and fibula; interoesseous membrane • I: Calcaneus • A: Plantar flexes foot

Flexor Digitorum Longus • O: Posterior Tibia • I: Distal phalanges 2 -5 • A: Plantar flexion of foot and flexion of the toes.