Frontal Epicranius Belly .

Origin - Epicranial aponeurosis

Insertion - Skin superior to supraorbital margin.

Action - Draws scalp anteriorly, raises eyebrows, and wrinkles skin of forehead horizontally as in look of surprise.

Occipital Epicranius Belly

Origin: Occipital bone and mastoid process of temporal bone

Insertion: Epicranial aponeurosis.

Action: Draws scalp posteriorly

Orbicularis oris

Origin: Muscle fibers surrounding opening of mouth.

Insertion: Skin at corner of mouth.

Action: Closes and protrudes lips, as in kissing; compresses lips against teeth; and shapes lips during speech.

Orbicularis oculi

Origin: Medial wall of orbit.

Insertion: Circular path around orbit.

Action: Closes eye.

Depressor anguli oris

Origin: Mandible.

Insertion: Angle of mouth.

Action: Draws angle of mouth laterally and inferiorly, as in opening mouth.

Depressor labii inferioris

Origin Mandible.

Insertion Skin of lower lip.

Action Depresses (lowers) lower lip

Mentalis

Origin Mandible.

Insertion Skin of chin.

Action Elevates and protrudes lower lip and pulls skin of chin up, as in pouting.

Buccinators

Origin: Alveolar processes of maxilla and mandible and pterygomandibular raphe (fi brous band extending from pterygoid process of sphenoid bone to mandible).

Insertion: Orbicularis oris.

Action: Presses cheeks against teeth and lips, as in whistling, blowing, and sucking; draws corner of mouth laterally; and assists in mastication (chewing) by keeping food between the teeth (and not between teeth and cheeks).

Masseter

Origin Maxilla and zygomatic arch.

Insertion Angle and ramus of mandible

Action Elevates mandible, as in closing mouth.

Temporalis

Origin Temporal bone.

Insertion Coronoid process and ramus of mandible.

Action Elevates and retracts mandible.

Medial Pterygoid

Origin: Medial surface of lateral portion of pterygoid process of sphenoid bone; maxilla.

Insertion: Angle and ramus of mandible.

Action: Elevates and protracts (protrudes) mandible and moves mandible from side to side.

Lateral Pterygoid

Origin Greater wing and lateral surface of lateral portion of pterygoid process of sphenoid bone.

Insertion Greater wing and lateral surface of lateral portion of pterygoid process of sphenoid bone.

Action Protracts mandible, depresses mandible as in opening mouth, and moves mandible from side to side.

Platysma

ORIGIN
Skin over lower neck and upper lateral chest

INSERTION
Inferior border of mandible and skin over lower face and angle of mouth

ACTION
Depresses and wrinkles skin of lower face and mouth. Aids forced depression of mandible

Sternocleidomastoid

Origin Sternal head: manubrium of sternum; clavicular head: medial third of clavicle.

Insertion Mastoid process of temporal bone and lateral half of superior nuchal line of occipital bone.

Action Mastoid process of temporal bone and lateral half of superior nuchal line of occipital bone.

Digastric

Origin Anterior belly from inner side of inferior border of mandible; posterior belly from temporal bone.

Insertion Body of hyoid bone via an intermediate tendon.

Action Elevates hyoid bone. RMA: Depresses mandible, as in opening mouth

Stylohyoid

Origin Medial end of clavicle and manubrium of sternum.

Insertion Body of hyoid bone.

Action Elevates hyoid bone and draws it posteriorly.

Sternohyoid

Origin Medial end of clavicle and manubrium of sternum.

Insertion Body of hyoid bone.

Action Depresses hyoid bone.

Sternothyroid

Origin Manubrium of sternum.

Insertion Thyroid cartilage of larynx.

Action Depresses thyroid cartilage of larynx.

Biceps brachii

Origin Long head originates from tubercle above glenoid cavity of scapula (supraglenoid tubercle). Short head originates from coracoid process of scapula.

Insertion Radial tuberosity of radius and bicipital aponeurosis.*

Action Flexes forearm at elbow joint, supinates forearm at radioulnar joints, and fl exes arm at shoulder joint.

Triceps brachii

Origin Long head originates from infraglenoid tubercle, a projection inferior to glenoid cavity of scapula. Lateral head originates from lateral and posterior surface of humerus. Medial head originates from entire posterior surface of humerus inferior to a groove for the radial nerve.

Insertion Olecranon of ulna.

Action Extends forearm at elbow joint and extends arm at shoulder joint.

Brachioradialis

Origin Lateral border of distal end of humerus.

Insertion Superior to styloid process of radius.

Action Flexes forearm at elbow joint; supinates and pronates forearm at radioulnar joints to neutral position.

Brachialis

Origin Lateral border of distal end of humerus.

Insertion Superior to styloid process of radius.

Action Flexes forearm at elbow joint; supinates and pronates forearm at radioulnar joints to neutral position.

Brachialis

Origin Distal, anterior surface of humerus.

Insertion Ulnar tuberosity and coronoid process of ulna.

Action Ulnar tuberosity and coronoid process of ulna.

Flexor carpi radialis

Origin Medial epicondyle of humerus.

Insertion Metacarpals II and III.

Action Flexes and abducts hand (radial deviation) at wrist joint.

Flexor carpi ulnaris

Origin Medial epicondyle of humerus and superior posterior border of ulna.

Insertion Pisiform, hamate, and base of metacarpal V.

Action Flexes and adducts hand (ulnar deviation) at wrist joint.

Palmaris longus

Origin Medial epicondyle of humerus

Insertion Flexor retinaculum and palmar aponeurosis (fascia in center of palm).

Action Weakly fl exes hand at wrist joint.

Extensor carpi radialis longus

Origin Lateral supracondylar ridge of humerus.

Insertion Metacarpal II.

Action Extends and abducts hand at wrist joint (ulnar deviation).

Extensor carpi radialis brevus

Origin Lateral epicondyle of humerus.

Insertion Metacarpal III.

Action Extends and abducts hand at wrist joint.

Pectoralis major

Origin Clavicle (clavicular head), sternum, and costal cartilages of ribs 2–6 and sometimes ribs 1–7 (sternocostal head).

Insertion Greater tubercle and lateral lip of intertubercular sulcus of humerus.

Action As a whole, adducts and medially rotates arm at shoulder joint; clavicular head fl exes arm, and sternocostal head extends fl exed arm to side of trunk.

Pectoralis minor

Origin Ribs 2–5, 3–5, or 2–4.

Insertion Coracoid process of scapula.

Action Abducts scapula and rotates it downward. RMA: Elevates ribs 3–5 during forced inhalation when scapula is fi xed.

Deltoid

Origin Acromial extremity of clavicle (anterior fi bers), acromion of scapula (lateral fi bers), and spine of scapula (posterior fibers).

Insertion Deltoid tuberosity of humerus.

Action Lateral fi bers abduct arm at shoulder joint; anterior fi bers fl ex and medially rotate arm at shoulder joint; posterior fi bers extend and laterally rotate arm at shoulder joint.

Serratus anterior

Origin Ribs 1–8 or 1–9.

Insertion Vertebral border and inferior angle of scapula.

Action Abducts scapula and rotates it upward. RMA: Elevates ribs when scapula is stabilized. Known as “boxer’s muscle” because it is important in horizontal arm movements such as punching and pushing.

Internal Intercostals

Origin Superior border of rib below.

Insertion Inferior border of rib above.

Action Contraction draws adjacent ribs together to further decrease anteroposterior and lateral dimensions of thoracic cavity

during forced exhalation.

External Intercostals

Origin Inferior border of rib above.

Insertion Superior border of rib below.

Action Contraction elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity, resulting in inhalation;

relaxation depresses ribs and decreases anteroposterior and lateral dimensions of thoracic cavity, resulting in exhalation.

Diaphragm

Origin Xiphoid process of sternum, costal cartilages and adjacent portions of ribs 7–12, lumbar vertebrae and their

intervertebral discs.

Insertion Central tendon.

Action Contraction of diaphragm causes it to flatten and increases vertical dimension of thoracic cavity, resulting in inhalation; relaxation of diaphragm causes it to move superiorly and decreases vertical dimension of thoracic cavity, resulting in exhalation.

Rectus abdominis

Origin Pubic crest and pubic symphysis.

Insertion Cartilage of ribs 5–7 and xiphoid process.

Action Flexes vertebral column, especially lumbar portion, and compresses abdomen to aid in defecation, urination, forced exhalation, and childbirth. RMA: Flexes pelvis on the vertebral column.

Transverse abdominis

Origin Iliac crest, inguinal ligament, lumbar fascia, and cartilages of ribs 5–10.

Insertion Xiphoid process, linea alba, and pubis.

Action Compresses abdomen.

External Oblique

Origin Ribs 5–12.

Insertion Iliac crest and linea alba.

Action Acting together (bilaterally), compress abdomen and fl ex vertebral column; acting singly (unilaterally), laterally fl ex vertebral column, especially lumbar portion, and rotate vertebral column.

Internal Oblique

Origin Iliac crest, inguinal ligament, and thoracolumbar fascia.

Insertion Cartilage of ribs 7–10 and linea alba.

Action Acting together, compress abdomen and fl ex vertebral column; acting singly, laterally fl ex vertebral column, especially

lumbar portion, and rotate vertebral column.

Trapezius

Origin Superior nuchal line of occipital bone, ligamentum nuchae, and spines of C7–T12

Insertion Clavicle and acromion and spine of scapula.

Action Superior fi bers upward rotate scapula; middle fi bers adduct scapula; inferior fi bers depress and upward rotate scapula; superior and inferior fi bers together rotate scapula upward; stabilizes scapula. RMA: Superior fi bers can help extend head.

Latissimus dorsi

Origin Spines of T7–L5, lumbar vertebrae, crests of sacrum and ilium, ribs 9–12 via thoracolumbar fascia.

Insertion Intertubercular sulcus of humerus.

Action Extends, adducts, and medially rotates arm at shoulder joint; draws arm inferiorly and posteriorly. RMA: Elevates vertebral column and torso.

Infraspinatus

Origin Infraspinous fossa of scapula.

Insertion Greater tubercle of humerus.

Action Laterally rotates arm at shoulder joint.

Popliteus

Origin Lateral condyle of femur.

Insertion Proximal tibia.

Action Flexes leg at knee joint and medially rotates tibia to unlock the extended knee.

Gastrocnemius

Origin Lateral and medial condyles of femur and capsule of knee.

Insertion Calcaneus by way of calcaneal (Achilles) tendon.

Action Plantar fl exes foot at ankle joint and fl exes leg at knee joint.

Tibalis Anterior

Origin Lateral condyle and body of tibia and interosseous membrane (sheet of fi brous tissue that holds shafts of

tibia and fi bula together).

Insertion Metatarsal I and fi rst (medial) cuneiform.

Action Dorsifl exes foot at ankle joint and inverts (supinates) foot at intertarsal joints.

Fibularis Longus

Origin Head and body of fi bula.

Insertion Metatarsal I and fi rst cuneiform.

Action Plantar fl exes foot at ankle joint and everts (pronates) foot at intertarsal joints.

Fibularis Longus

Origin Head and body of fi bula.

Insertion Metatarsal I and fi rst cuneiform.

Action Plantar fl exes foot at ankle joint and everts (pronates) foot at intertarsal joints.

Fibularis Brevis

Origin Distal half of body of fibula.

Insertion Base of metatarsal V.

Action Plantar fl exes foot at ankle joint and everts (pronates) foot at intertarsal joints.

Rectus femoris

Origin Anterior inferior iliac spine.

Insertion Patella via quadriceps tendon and then tibial tuberosity via patellar ligament.

Action All four heads extend leg at knee joint; rectus femoris muscle acting alone also fl exes thigh at hip joint.

Gluteus Maximus

Origin Iliac crest, sacrum, coccyx, and aponeurosis of sacrospinalis.

Insertion Iliotibial tract of fascia lata and superior lateral part of linea aspera (gluteal tuberosity) under greater trochanter of femur.

Action Extends thigh at hip joint and laterally rotates thigh; helps lock knee in extension. RMA: Extends torso.

Gluteus Medius

Origin Ilium

Insertion Greater trochanter of femur.

Action Abducts thigh at hip joint and medially rotates thigh.

Biceps femoris

Origin Long head arises from ischial tuberosity; short head arises from linea aspera of femur.

Insertion Head of fi bula and lateral condyle of tibia.

Action Flexes leg at knee joint and extends thigh at hip joint.

Sartorius

Origin Anterior superior iliac spine.

Insertion Medial surface of body of tibia.

Action Weakly fl exes leg at knee joint; weakly fl exes, abducts, and laterally rotates thigh at hip joint.

Gracilis

Origin Body and inferior ramus of pubis.

Insertion Medial surface of body of tibia.

Action Adducts thigh at hip joint, medially rotates thigh, and fl exes leg at knee joint.

• Psoas Major

Origin: Transverse processes of T12-L5 & the lateral aspects of the intervertebral discs

Insertion: Lesser trochanter of the femur

• Psoas Minor

Origin: Side of T12+L1 & IV intervertebral disc between

Insertion: Pectineal line & iliopectineal eminence (lesser trochanter of the femur)

• Iliacus