Skeletal Muscle Study Guide

Action: Raises eyebrows, wrinkles forehead

Origin: epicranial aponeurosis

Insertion: skin of eyebrows and forehead

Frontalis

Action: Elevates mandible

Origin: Zygomatic Arch

Insertion: Ramus of Mandible

Masseter

Action: Closes Eyelids

Origin: Medial Orbital Margin

Insertion: Skin around eyelids

Orbicular oculi

Action: Closes/puckers lips

Origin: Maxilla & mandible

Insertion: Lips

Orbicular Oris

Action: Elevates corner of mouth (Smiles)

Origin: Zygomatic bone

Insertion: corner of mouth

Zygomaticus Major

Action: compresses cheek (whistling, chewing)

Origin: Maxilla & Mandible

Insertion: Oribicular Oris

Buccinator

Action: Elevation of Mandible

Origin: Temporal Fossa

Insertion: Coronoid Process of the Mandible

Temporalis

Action: Flexes & rotates neck

Origin: sternum & clavicle

Insertion: Mastoid process

Sternocleidomastoid

Action: Flexes, adducts, medially rotates arm

Origin: clavicle, sternum, costal cartilages

Insertion: intertubercular sulcus of humerus

Pectoralis Major

Action: Protracts scapula

Origin: Ribs 3-5

Insertion: Coracoid process of scapula

Pectoralis Minor

Action: Flexes trunk, compresses abdomen

Origin: Pubic crest & symphysis

Insertion: Xiphoid process, ribs 5-7

Rectus Abdominis

Action: Compresses Abdomen, rotates trunk

Origin: Lower 8 ribs

Insertion: Linea Alba, Iliac Crest

External Oblique

Action: Elevates, retracts, rotates scapula

Origin: Occipital bone, spines of C7-T12

Insertion: Clavicle, acromion, spine of scapula

Trapezius

Action: Extends, adducts, medially rotates arm

Origin: Spinous process of T7-L5, iliac crest

Insertion: Gluteal tuberosity, iliotibial tract

Latissimus Dorsi

Action: Extends thigh

Origin: illium, sacrum, coccyx

Insertion: Gluteal tuberosity, iliotibial tract

Gluteus Maximus

Action: extends vertebral colum and the the head; helps maintain posture

Origin: Posterior iliac creast

Insertion: ribs, spinous process, transverse processes of vertebrae

Errector Spinae

Action: abducts arm

Origin: clavicle, acromion, spine of scapula

Insertion: deltoid tuberosity of humerus

Deltoid

Action: flexes elbow, supinates forearm

Origin: coracoid process & supraglenoid tubercle

Insertion: Radial tuberosity

Biceps Brachii

Action: flexes elbow

Origin: anterior humerus

Insertion: coronoid process of ulna

Brachialis

Action: flexes elbow (especially in neutral grip)

Origin: lateral supracondylar ridge of humerus

Insertion: styloid process of radius

Brachioradialis

Action: extends elbow

Origin: scapula & posterior humerus

Insertion: olecranon of ulna

Triceps Brachii

Action: extends, adducts, medially rotates arm

Origin: inferior angle of scapula

Insertion: intertubercular sulcus of humerus

Teres Major

Action: Laterally rotates arm

Origin: lateral border of arm

Insertion: greater tubercle of humerus

Teres minor

Action: Flexes & abducts wrist

Origin: Medial epicondyle of humerus

Insertion: Base of 2nd or 3rd metacarpal

Flexor Carpi Radialis

Action: extends fingers

Origin: lateral epicondyle of humerus

Insertion: phalanges of digits 2-5

Extensor Digitorum

Action: extend the wrist and abduct the hand

Origin:

- L: lateral supracondylar ridge of humerus

- B: laterial epicondyle of the humerus

Insertion:

- L: base of 2nd MCP

- B: base of 3rd MCP

Extensor Carpi Radialis (Longus & Brevis)

Action: Extends knee, flexes thigh

Origin: Anterior inferior illiac spine

Insertion: tibial tuberosity via patellar ligament

Rectus Femoris

Action: extends knee

Origin: greater trochanter, linea aspera

Insertion: tibial tuberosity

Vastus Lateralis

Action: Extends knee

Origin: greater trochanter, linea aspera

Insertion: tibial tuberosity

Vastus Medialis

Action: Extends knee

Origin: anterior femur

Insertion: tibial tuberosity

Vastus Intermedius

Action: adducts the thigh

Origin: body and inferior ramus of the pubis

Insertion: medial surface of the proximal tibia

Gracilis

Action: Flexes, abducts, laterally rotates thigh; flexes leg

Origin: ASIS

Insertion: Medial tibia

Sartorius

Action: Extends thigh, flexes knee

Origin: Ischial tuberosity, linea aspea

Insertion: head of fibula

Biceps Femoris

Action: Extends thigh, flexes knee

Origin: Ischial tuberosity

Insertion: Medial tibial condyle

Semitendinosus

Action: Dorsiflexes & inverts foot

Origin: Laterial tibia

Insertion: 1st metatarsal & medial cuneiform

Tibialis Anterior

Action: Plantar flexes foot, flexes knee

Origin: Medial & lateral condyles of femur

Insertion: Calcaneus via Achilles tendon

Gastrocnemius

Action: Extends thigh, flexes knee

Origin: Ischial tuberosity

Insertion: Medial Tibial Condyle

Semimembranosus

Action: Plantar flexes foot

Origin: Tibia & fibula

Insertion: Calcaneus via Achilles Tendon

Soleus