Ch11 Notes

Pectoralis minor

Origin = anterior surfaces of ribs 3–5.

Insertion = coracoid process of scapula.

Action = draws scapula forward and downward

Serratus anterior

Fan-shaped muscle with serrated or sawtooth origins on the lateral rib cage

Origin = superior anterior ribs 1–8 or 9.

Insertion = anterior surface of vertebral border of scapula.

Action = upwardly rotates and protracts scapula and holds it against chest wall

Subclavius

Origin = costal cartilage of rib 1.

Insertion = inferior surface of clavicle.

Action = helps stabilize and depress pectoral girdle

Trapezius

Upper fibers run inferiorly, middle fibers horizontally, and lower fibers superiorly to the scapula

Origin = occipital bone, ligamentum nuchae, and spinous processes of thoracic.

Insertion = clavicle, acromion, and scapular spine.

Action = stabilizes, raises, retracts, depresses, and rotates scapula

Levator scapulae

Located at back and side of neck deep to trapezius

Origin = transverse processes C1–C4.

Insertion = medial border of scapula near superior boarder.

Action = elevates scapula

Rhomboid minor

Origin = spinous processes C7–T1.

Insertion = medial border of scapula.

Action = stabilizes, adducts, and downwardly rotates scapula

Rhomboid major

Origin = spinous processes of superior thoracic vertebrae.

Insertion = medial border of scapula.

Action = stabilizes, adducts, and downwardly rotates scapula

Rhomboid major and minor location

Both lie deep to trapezius

Pectoralis major

Origin = medial clavicle, body of sternum, ribs 2-6.

Insertion = crest of greater tubercle and lateral hip of intertubercular sulcus of humerus.

Action = primary mover of arm flexion. flexion, adduction, and medial rotation at shoulder

Latissimus dorsi

Origin = inferior thoracic and lumbar vertebrae, ribs 8–12, and thoracolumbar fascia.

Insertion = intertubercular sulcus of humerus.

Action = Prime mover of arm extension and adduction

Deltoid

Origin = clavicle, acromion, and scapular spine.

Insertion = deltoid tuberosity of humerus.

Action = primarily abducts arm

Prime mover of arm abduction when all fibers contract

Note: Deltoid is NOT a rotator cuff muscle

Deltoid fibers are opposites:

• Anterior - Flex and medially rotate shoulder

• posterior - Extend and laterally rotate sjoulder

Teres major

Origin = inferior angle of scapula.

Insertion = medial lip of intertubercular sulcus of humerus.

Action = extension and medially rotates shoulder

Subscapularis

Origin = subscapular fossa of scapula

Insertion = lesser tubercle of humerus

Action = medially rotates shoulder

Chief medial rotator of the humerus

Supraspinatus

Origin = supraspinous fossa of scapula.

Insertion = superior greater tubercle of humerus.

Action = shoulder abduction

Note: Deltoid is the prime mover while supraspinatus initiates abduction

Infraspinatus

Origin = infraspinous fossa of scapula.

Insertion = greater tubercle of humerus.

Action = laterally rotates shoulder

Teres minor

Origin = lateral border of scapula.

Insertion = greater tubercle of humerus.

Action = laterally rotates and adducts shoulder

Rotator cuff muscles

SITS muscles

1. Supraspinatus

2. infraspinatus

3. teres minor

4. subscapularis

Stabilizes the head of the humerus in the glenoid cavity during shoulder movement

Coracobrachialis

Origin = coracoid process of scapula.

Insertion = medial margin of shaft.

Action = flexes and adducts humerus

Note: Synergist of pectoralis major

• A synergist muscle is a muscle that assists the primary moving muscle (the agonist) during a joint action by adding extra force or stabilizing the surrounding area

Elbow flexors location

Primarily found on the anterior aspect of the arm

Elbow extensors location

Primarily found on the posterior aspect of the arm

Triceps brachii

Origins:

• Long head: infraglenoid tubercle of scapula

• Lateral head: superior, lateral margin of humerus

• Medial head: posterior surface of humerus, inferior to radial groove

Insertion: Olecranon process of ulna.

Action: Extends forearm at elbow; long head also extends and adducts arm at shoulder.

Note: Prime mover of forearm extension, especially the medial head

Anconeus

Origin = lateral epicondyle of humerus.

Insertion = lateral olecranon of ulna.

Action = extension at elbow

Biceps brachii

Origin =

• short head: coracoid process

• Long head: supraglenoid tubercle of scapula

Insertion = radial tuberosity.

Action = flexion at elbow and and supinates forearm

Note: There’s a short and long head of biceps brachii, both have different origins

Brachialis

Origin = anterior distal humerus.

Insertion = ulnar tuberosity.

Action = major forearm flexor

Brachialis vs biceps action

Brachialis lifts the ulna while biceps brachii lifts the radius

Brachioradialis

Superficial muscle on lateral forearm

Origin = lateral supracondylar ridge of humerus.

Insertion = base of styloid process of radius.

Action = flexion at elbow

Pronator teres

Origin = medial epicondyle of humerus and coronoid process of ulna.

Insertion = lateral radius.

Action = pronates forearm and weak elbow flexion

Flexor carpi radialis

Origin = medial epicondyle of humerus.

Insertion = bases of 2nd and 3rd metacarpals.

Action = flexes and abducts wrist

Palmaris longus

Origin = medial epicondyle of humerus.

Insertion = palmar aponeurosis and flexor retinaculum.

Action = flexion at wrist

Flexor carpi ulnaris

Origin = medial epicondyle, olecranon, and posterior ulna.

Insertion = pisiform, hamate, and base of 5th metacarpal.

Action = flexes and adducts wrist

Flexor digitorum superficialis

Origin = medial epicondyle of humerus, coronoid process, and radius.

Insertion = middle phalanges of fingers 2–5.

Action = flexes fingers 2–5 and wrist

Flexor digitorum profundus

Origin = medial and posterior surfaces of ulna, coronoid process, and interosseous membrane.

Insertion = distal phalanges of fingers 2–5.

Action = flexes distal interphalangeal joints and assists wrist flexion

Extensor digitorum

Origin = lateral epicondyle of humerus.

Insertion = posterior surfaces of phalanges digits 2–5.

Action = extends fingers and wrist

Extensor carpi ulnaris

Origin = lateral epicondyle of humerus and posterior ulna.

Insertion = base of 5th metacarpal.

Action = extends and adducts wrist

Supinator

Origin = lateral epicondyle of humerus and ridge near radial notch

Insertion = proximal radius.

Action = supinates forearm

Shoulder medial rotators

1. Subscapularis

2. pectoralis major

3. latissimus dorsi

4. teres major

5. anterior deltoid

Shoulder lateral rotators

1. Infraspinatus

2. teres minor

3. posterior deltoid

Arm adductors

1. Pectoralis major

2. latissimus dorsi

3. teres major

4. coracobrachialis

5. teres minor

Arm flexors

1. Pectoralis major

2. anterior deltoid

3. coracobrachialis

4. biceps brachii

Arm extensors

1. Latissimus dorsi

2. posterior deltoid

3. teres major

4. long head of triceps brachii

Forearm pronators

Pronator teres and pronator quadratus

Forearm supinators

Biceps brachii and supinator

Note: Supinator assists biceps brachii during forceful supination and works alone during slow supination

Wrist flexors

1. Flexor carpi radialis

2. flexor carpi ulnaris

3. and palmaris longus

Wrist extensors

1. Extensor carpi radialis longus

2. extensor carpi radialis brevis

3. extensor carpi ulnaris

Wrist abductors

1. Flexor carpi radialis

2. extensor carpi radialis: longus and brevis

Wrist adductors

1. Flexor carpi ulnaris

2. extensor carpi ulnaris

Iliacus

Iliopsoas muscles:

• iliacus

• Psoas major/minor

both insert through a common iliopsoas tendon on the femur

Origin = iliac fossa.

Insertion = lesser trochanter via iliopsoas tendon.

Action = prime mover of thigh flexion and flexes trunk

Psoas major

Iliopsoas muscles:

• iliacus

• Psoas major/minor

both insert through a common iliopsoas tendon on the femur

Origin = transverse processes, bodies, and discs of T12–L5.

Insertion = lesser trochanter via iliopsoas tendon.

Action = thigh flexion and flexes trunk

Sartorius

Longest muscle in the body

Sartorius joints cross both the hip and knee joints

helps you sit cross legged!

Origin = anterior superior iliac spine.

Insertion = medial surface of proximal tibia.

Action = flexes, abducts, and laterally rotates thigh and flexes knee.

Medial thigh muscles

Primarily adduct the thigh

Include:
Adductor longus, adductor brevis, and adductor magnus

Adductor longus

Origin = inferior ramus of pubis, near pubic symphysis.

Insertion = linea aspera of femur.

Action = adduction and flexion of hip

Pectineus

shortest of adductors

Origin = pectineal line and superior ramus of pubis. Insertion = line from lesser trochanter to linea aspera. Action = adducts, flexes, and medially rotates thigh

Gracilis

Origin = inferior ramus and body of pubis and adjacent ischial ramus. Insertion = medial tibia just inferior to medial condyle. Action = adducts and medially rotates thigh and flexes and medially rotates leg

Anterior thigh muscles

Flex the femur at the hip and extend the leg at the knee

Quadriceps femoris

Four-headed muscle group on front and sides of thigh
powerful knee extensors and prime movers in knee extension

includes: Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius

Rectus femoris

Origin = anterior inferior iliac spine and superior acetabular rim.

Insertion = tibial tuberosity via quadriceps tendon, patella, and patellar ligament.

Action = extends knee and flexes hip

Vastus lateralis

Largest head of the quadriceps femoris

Origin = greater trochanter, intertrochanteric line, and linea aspera.

Insertion = same as rectus femoris, tibial tuberosity via quadriceps tendon, patella, and patellar ligament.

Action = extends and stabilizes knee

Vastus medialis

Origin = entire length of linea aspera.

Insertion = same as rectus femoris. tibial tuberosity via quadriceps tendon, patella, and patellar ligament.

Action = extends knee and stabilizes patella

Vastus intermedius

Deep to and obscured by rectus femoris

Origin = anterior and lateral surfaces of proximal femoral shaft.

Insertion = same as rectus femoris. tibial tuberosity via quadriceps tendon, patella, and patellar ligament.

Action = extends knee

Tensor fasciae latae

Origin = anterior iliac crest and anterior superior iliac spine.

Insertion = iliotibial tract.

Action = flexes and abducts thigh, and medially rotates hip.

Steadies trunk on thigh by making iliotibial tract taut

Iliotibial tract (IT band)

Thickened lateral portion of the Tensor fasciae latae

Posterior thigh muscles

Mostly extend the thigh and flex the leg during the backswing phase of walking

Gluteus medius

Important site for intramuscular injections at the ventral gluteal site

Origin = lateral ilium between anterior and posterior gluteal lines.

Insertion = lateral greater trochanter of femur.

Action = abducts and medially rotates hip

Gluteus minimus

Smallest and deepest of the gluteal muscles

Origin = lateral ilium between inferior and anterior gluteal lines.

Insertion = anterior border of greater trochanter.

Action = abducts and medially rotates thigh

Piriformis

Origin = anterolateral surface of sacrum.

Insertion = superior border of greater trochanter.

Action = laterally rotates extended thigh, abducts hip, and stabilizes hip

Obturator internus

Origin = margins of obturator foramen.

Insertion = medial surface of greater trochanter.

Action = laterally rotates extended thigh, abducts hip, and stabilizes hip

Superior gemellus

Gemelli:

• Superior gemellus

• Inferior gemellus

small lateral rotators associated with obturator internus

Origin = ischial spine.

Insertion = greater trochanter.

Action = laterally rotates extended thigh, abducts hip, and stabilizes hip

Inferior gemellus

Gemelli:

• Superior gemellus

• Inferior gemellus

small lateral rotators associated with obturator internus

Origin = ischial tuberosity.

Insertion = greater trochanter.

Action = laterally rotates extended thigh, abducts hip, and stabilizes hip

Hamstrings

Posterior compartment of the thigh
Prime movers of knee flexion and thigh extension

Includes:

Biceps femoris, semitendinosus, and semimembranosus

Biceps femoris

Most lateral muscle of the hamstring group

Includes Long head and short head

Origin =

• long head: ischial tuberosity

• short head: linea aspera/lateral supracondylar line

Insertion = head of fibula and lateral condyle of tibia.

Action = extends thigh, flexes knee, and laterally rotates leg

Semitendinosus

Origin = ischial tuberosity.

Insertion = medial upper tibial shaft.

Action = extends thigh, flexes knee, and medially rotates leg

Semimembranosus

Deep to semitendinosus

Origin = ischial tuberosity.

Insertion = medial condyle of tibia.

Action = extends thigh, flexes knee, and medially rotates leg

Anterior compartment of leg

Contains extensor muscles that extend toes and dorsiflex the foot

Lower leg compartment arrangement

Anterior lower-leg muscles are extensors

posterior lower-leg muscles are flexors

Tibialis anterior

prime mover in dorsiflexion

Origin = lateral condyle and upper two-thirds of tibial shaft.

Insertion = inferior medial cuneiform and first metatarsal.

Action = dorsiflexes and inverts foot

Extensor digitorum longus

Origin = lateral condyle of tibia and anterior surface of fibula.

Insertion = middle and distal phalanges of toes 2–5.

Action = extends toes 2–5 and dorsiflexes foot

Extensor hallucis longus

Origin = anteromedial fibular shaft.

Insertion = distal phalanx of great toe.

Action = extends great toe and dorsiflexes foot

Lateral compartment of leg function

Plantar flexes and everts foot and helps stabilize lateral ankle and foot arches

Fibularis longus

Origin = head and upper lateral fibula.

Insertion = first metatarsal and medial cuneiform.

Action = plantar flexes and everts foot and supports foot arches

Posterior compartment of leg function

Primarily produces plantar flexion of the ankle

Triceps surae

Triceps surae muscles:

• Gastrocnemius

• soleus

form the posterior calf and insert through the calcaneal tendon

Prime movers of plantar flexion

Gastrocnemius

Superficial muscle of triceps surae with two prominent bellies forming proximal calf

Origin = medial and lateral condyles of femur.

Insertion = posterior calcaneus via calcaneal tendon.

Action = plantar flexes foot when knee is extended and flexes knee

Soleus

Broad, flat muscle deep to gastrocnemius

Acts as a postural muscle when standing

Origin = superior tibia, fibula, and interosseous membrane.

Insertion = posterior calcaneus via calcaneal tendon.

Action = plantar flexes foot

Plantaris

Origin = posterior femur above lateral condyle.

Insertion = via calcaneal tendon.

Action = assists knee flexion and plantar flexion

Tibialis posterior

Prime mover of foot inversion

Origin = interosseous membrane and adjacent tibia and fibula.

Insertion = navicular, cuneiforms, cuboid, and metatarsals 2–4.

Action = inverts and plantar flexes foot

Reference axis for toe abduction and adduction

Second toe is the reference axis for the foot

Hip flexors

1. Iliacus

2. psoas major

3. sartorius

4. rectus femoris

5. pectineus,

6. tensor fasciae latae

Hip abductors

1. Gluteus medius

2. gluteus minimus

3. tensor fasciae latae

4. superior fibers of gluteus maximus

Hip adductors

1. Adductor longus

2. adductor brevis

3. adductor magnus

4. pectineus

5. gracilis

Medial rotators of thigh

1. Gluteus medius

2. gluteus minimus

3. tensor fasciae latae

4. adductor longus

5. adductor brevis

6. pectineus

7. gracilis

Lateral rotators of thigh

1. Gluteus maximus

2. piriformis

3. obturator internus

4. obturator externus

5. gemelli

6. quadratus femoris

Knee flexors

1. Hamstrings

2. sartorius

3. gracilis

4. gastrocnemius

5. plantaris

6. popliteus

Foot dorsiflexors

1. Tibialis anterior

2. extensor digitorum longus

3. extensor hallucis longus

4. fibularis tertius

Foot plantar flexors

1. Gastrocnemius

2. soleus

3. fibularis longus

4. fibularis brevis

5. flexor digitorum longus

6. flexor hallucis longus

7. tibialis posterior

Foot invertors

1. Tibialis anterior

2. tibialis posterior

3. flexor digitorum longus

4. flexor hallucis longus

Foot evertors

1. Fibularis longus

2. fibularis brevis

3. fibularis tertius