Muscles: Origin, Insertion, and Action

Epicranius

Epicranius

• Origin: Aponeurosis

• Insertion: eyebrow skin

• Action: elevates eyebrows, wrinkles forehead

Orbicularis Oculi

• Origin: frontal & maxilla bone

• Insertion: eyelid tissue

• Action: blinking

Buccinator

• Origin: maxilla & mandible

• Insertion: orbicularis oris

• Action: compresses cheeks inward (whistling/sucking)

Zygomaticus

• Origin: zygomatic bone

• Insertion: skin/muscle at corner of mouth

• Action: raises corners of mouth (smiling)

Orbicularis Oris

• Origin: maxilla & mandible

• Insertion: skin & muscle around mouth

• Action: closes and puckers the lips

Temporalis

• Origin: temporal bone

• Insertion: mandible

• Action: closes jaw

Masseter

• Origin: zygomatic bone

• Insertion: mandible

• Action: closes jaw

Sternocleidomastoid

• Origin: sternum, clavicle

• Insertion: temporal bone

• Action: rotates head to opposite side (one side only)

• flexes head (both sides)

Trapezius

• Origin: occipital bone, thoracic vertebrae

• Insertion: clavicle, scapula

• Action: elevates/adducts scapula, extends neck

Levator Scapulae

• Origin: vertebrae

• Insertion: superior scapula

• Action: adducts scapula

Rhomboid Major & Rhomboid Minor

• Origin: vertebrae

• Insertion: scapula

• Action: adducts scapula

Pectoralis Minor

• Origin: ribs

• Insertion: scapula

• Action: pulls scapula downward/forward (abducts scapula)

Serratus Anterior

• Origin: ribs

• Insertion: scapula

• Action: pulls scapula against chest wall

Supraspinatus

• Origin: scapula

• Insertion: humerus

• Action: stabilizes shoulder joints

Infraspinatus

• Origin: scapula

• Insertion: humerus

• Action: stabilizes shoulder joints

Teres Minor

• Origin: scapula

• Insertion: humerus

• Action: stabilizes shoulder joints

Subscapularis

• Origin: scapula

• Insertion: humerus

• Action: stabilizes shoulder joints

Pectoralis Major

Origin: clavicle, sternum, ribs

Insertion: humerus

Action: adducts/flexes arm

Deltoid

• Origin: clavicle, scapula

• Insertion: humerus

• Action: abducts/flexes arm

Coracobrachialis

• Origin: scapula

• Insertion: humerus

• Action: adducts/flexes arm

Latissimus Dorsi

• Origin: vertebrae, ribs

• Insertion: humerus

• Action: adducts/extends arm

Teres Major

• Origin: scapula

• Insertion: humerus

• Action: adducts/extends arm

Biceps Brachii

• Origin: scapula

• Insertion: radius

• Action: flexes forearm at elbow

Brachialis

• Origin: humerus

• Insertion: ulna

• Action: flexes forearm at elbow

Brachioradialis

• Origin: humerus

• Insertion: radius

• Action: flexes forearm at elbow

Triceps Brachii

• Origin: scapula

• Insertion: ulna

• Action: extends forearm at elbow

Flexor Carpi

• Action: flex hand at wrist

Flexor Digitorum

• Action: flex the fingers

Extensor Carpi

• Action: extend hand at wrist

Extensor Digitorum

• Action: extends hands & fingers

Rectus Abdominis

• Origin: pubic bone

• Insertion: sternum, ribs

• Action: stabilizes pelvis

Tendinous Intersection

between rectus abdominus muscles (horizontal white line on stomach) → 6 pack

Linea Alba

xiphoid process to pubis (vertical white line on stomach)

External Oblique

• Origin: ribs

• Insertion: linea alba

• Action: flexes & compresses abdomen

Internal Oblique

• Origin: os coxae

• Insertion: linea alba

• Action: flexes & compresses abdomen

Transverse Oblique

• Origin: ribs

• Insertion: linea alba

• Action: compresses abdomen

External Intercostals

• Action: breathing in

Internal Intercostals

• Action: breathing out

Diaphragm

• Action: breathing in

Sartorius

• Origin: os coxae

• Insertion: tibia

• Action: flexes knee

Tensor Fasciae Latae

• Origin: os coxae

• Insertion: iliotibial tract

• Action: flexes thigh

Iliopsoas

• Origin: os coxae

• Insertion: femur

• Action: flexes thigh

Gluteus Maximus

• Origin: os coxae

• Insertion: femur

• Action: extends thigh

Gluteus Medius

• Origin: os coxae

• Insertion: femur

• Action: abducts thigh

Gluteus Minimus

• Origin: os coxae

• Insertion: femur

• Action: abducts thigh

Adductor Longus

• Origin: os coxae

• Insertion: femur

• Action: adducts/flexes thigh

Adductor Magnus

• Origin: os coxae

• Insertion: femur

• Action: adducts/flexes thigh

Pectineus

• Origin: os coxae

• Insertion: femur

• Action: adducts/flexes thigh

Gracilis

• Origin: os coxae

• Insertion: tibia

• Action: adducts/flexes thigh

Rectus Femoris

• Origin: os coxae

• Insertion: patella/tibia

• Action: extends leg at knee

Vastus Lateralis

• Origin: femur

• Insertion: patella/tibia

• Action: extends leg at knee

Vastus Medialis

• Origin: femur

• Insertion: patella/tibia

• Action: extends leg at knee

Vastus Intermedius

• Origin: femur

• Insertion: patella/tibia

• Action: extends leg at knee

Biceps Femoris

• Origin: os coxae

• Insertion: tibia

• Action: extends thigh

Semitendinosus

• Origin: os coxae

• Insertion: tibia

• Action: extends thigh

Semimembranosus

• Origin: os coxae

• Insertion: tibia

• Action: extends thigh

Tibialis Anterior

• Action: dorsiflexes foot at ankle

Extensor Digitorum Longus

• Action: dorsiflexes foot at ankle

Fibularis Longus

• Action: plantar flexes foot at ankle

Gastrocnemius

• Origin: femur

• Insertion: calcaneus via calcaneal tendon

• Action: plantar flexes foot at ankle

Soleus

• Action: plantar flexes foot at ankle

Flexor Digitorum Longus

• Action: plantar flexes foot at ankle