OIAs of Muscles

triceps brachii

O (long head): Infraglenoid tubercle of scapula

O (lateral head): Posterior shaft of humerus

O (medial head): Posterior shaft of humerus

I: Common tendon onto olecranon process of ulna

A: Elbow extension

biceps brachii

O (short head): Coracoid process of scapula

O (long head): Supraglenoid tubercle of scapula

I: Radial tuberosity of radius

A: Elbow flexion/radioulnar supination

deltoid

O: Clavicle/acromion/spine of scapula

I: Deltoid tuberosity of humerus

A: Glenohumeral abduction

The deltoid has three main fiber groups with different isolated functions:

Anterior Deltoid: flexes/medially rotates the GH joint

Middle Deltoid: abducts the GH joint

Posterior Deltoid: extends/laterally rotates the GH joint

When all three parts contract together, they abduct the GH joint

pectoralis major

O: Clavicle/sternum/costal cartilages

I: Greater tubercle of humerus

A: Glenohumeral flexion/medial rotation/adduction

gastrocnemius

O: Medial/lateral femoral condyles

I: Posterior, superior calcaneus

A: Plantarflexion/tibiofemoral flexion

tibialis anterior

O: Lateral condyle, proximal tibial shaft

I: Medial cuneiform/metatarsal I

A: Dorsiflexion/Inversion

biceps femoris - short head

O: Linea aspera

I: Head of fibula/lateral tibial condyle

A: Tibiofemoral flexion

biceps femoris - long head

O: Ischial tuberosity

I: Head of fibula/lateral tibial condyle

A: Femorocoxal extension/tibiofemoral flexion

semimembranosus

O: Ischial tuberosity

I: Medial tibial condyle

A: Femorocoxal extension/tibiofemoral flexion

semitendinsus

O: Ischial tuberosity

I: Medial, proximal shaft of tibia

A: Femorocoxal extension/tibiofemoral flexion

vastus intermedius

O: Anterior shaft of femur

I: Patella/tibial tuberosity

A: Tibiofemoral extension

vastus medialis

O: Linea aspera/medial supracondylar line/intertrochanteric line

I: Patella/tibial tuberosity

A: Tibiofemoral extension

vastus lateralis

O: Linea aspera/greater trochanter/intertrochanteric line

I: Patella/tibial tuberosity

A: Tibiofemoral extension

rectus femoris

O: AIIS/acetabular labrum

I: Patella/tibial tuberosity

A: Tibiofemoral extension/femorocoxal flexion

gracilis

O: Inferior ramus/body of pubis/ ischial ramus

I: Medial tibial condyle

A: Femorocoxal adduction

adductor magnus

O: Ischial ramus/inferior pubic ramus/ ischial tuberosity

I: Linea aspera/adductor tubercle of femur

A: Femorocoxal adduction

gluteus maximus

O: ilium/sacrum/coccyx

I: gluteal tuberosity

A: extends hip

iliacus

O: Iliac fossa/ala of sacrum

I: Lesser trochanter of femur

A: Trunk and femorocoxal flexion

psaos major

O: Lumbar vertebrae

I: Lesser trochanter of femur

A: Trunk and femorocoxal flexion

rectus abdominius

O: Pubic crest/symphysis

I: Xiphoid process/costal cartilages

A: Trunk flexion

sternocleidomastoid (SCM)

O: Manubrium/clavicle

I: Mastoid process of temporal bone

Bilateral action: Cervical flexion

Unilateral action: cervical lateral flexion/rotation