Muscles

Occipitofrontalis

Origin: Occipital bone and frontal bone (via epicranial aponeurosis)
Insertion: Skin of forehead and eyebrows
Function: Wrinkles forehead, elevates eyebrows
Quick tip: Think “surprise face” muscle

Orbicularis oculi

Origin: Frontal bone and lacrimal bone

Insertion: Skin around the eye (on itself)

Function: Closes eye tightly (squinting)

Quick tip: “Circle around the eye”

Zygomaticus major

Origin: Zygomatic bone

Insertion: Corner of mouth tissue

Function: Elevates mouth corners (smile)

Quick tip: “Zygo = zippy smile”

Orbicularis oris

Origin: Maxilla and mandible (alveolar process)

Insertion: Skin around lips (on itself)

Function: Puckers lips (kiss)

Quick tip: “Circle around the mouth”

Masseter

Origin: Zygomatic arch

Insertion: Mandible (ramus and angle)

Function: Elevates mandible (closes mouth); lateral deviation

Quick tip: Strongest jaw closer

Temporalis

Origin: Temporal bone (temporal fossa)

Insertion: Mandible (coronoid process and ramus)

Function: Elevates mandible; lateral deviation

Quick tip: Fan-shaped temple muscle

Medial pterygoid

Origin: Sphenoid bone (medial surface of lateral pterygoid plate)

Insertion: Mandible (ramus and angle)

Function: Closes mouth; lateral deviation

Quick tip: Works with masseter for chewing

Lateral pterygoid

Origin: Sphenoid bone (lateral surface of lateral pterygoid plate)
Insertion: Mandible (anterior surface, TMJ capsule)
Function: Opens mouth; lateral deviation
Quick tip: Only jaw opener of the group

Semispinalis capitis

Origin: Cervical and thoracic vertebrae
Insertion: Occipital bone
Function: Extends head
Quick tip: Deep postural extender

Splenius capitis

Origin: Cervical and thoracic vertebrae
Insertion: Occipital and temporal bones
Function: Extends and laterally flexes head
Quick tip: “Bandage muscle” across the back of neck

Trapezius

Origin: Occipital bone and spinous processes C7–T12
Insertion: Clavicle and scapula (acromion, spine)
Function: Elevates, retracts, and rotates scapula
Quick tip: Big kite-shaped back muscle

Latissimus dorsi

Origin: Spinous processes T6–T12, iliac crest, lower ribs, scapula (inferior angle)
Insertion: Humerus (intertubercular groove)
Function: Extends, adducts, and internally rotates arm
Quick tip: “Swimmer’s muscle”

Erector spinae (group)

Origin: Spinous and transverse processes of vertebrae
Insertion: Higher vertebrae (spinous and transverse processes)
Function: Extends spine, lateral flexion, rotation

Quick tip: Keeps spine upright

Levator scapulae

Origin: Transverse processes of C1–C4
Insertion: Superior angle of scapula
Function: Elevates scapula, downward rotation Quick tip: “Shrug” helper

Deltoid

Origin: Clavicle and scapula (acromion, spine)

Insertion: Humerus (deltoid tuberosity)
Function: Abducts arm; anterior fibers flex/medially rotate, posterior fibers extend/laterally rotate
Quick tip: “Shoulder cap” muscle — main arm lifter

Supraspinatus

Origin: Scapula (supraspinous fossa)
Insertion: Greater tubercle of humerus
Function: Initiates abduction of arm; stabilizes shoulder joint
Quick tip: First 15° of arm lift

Infraspinatus

Origin: Scapula (infraspinous fossa)
Insertion: Greater tubercle of humerus
Function: External rotation of shoulder; stabilizes joint
Quick tip: Rotator cuff external rotator

Teres minor

Origin: Lateral border of scapula
Insertion: Greater tubercle of humerus
Function: External rotation and stabilization of shoulder
Quick tip: Small but key rotator cuff helper

Teres major

Origin: Inferior angle of scapula
Insertion: Lesser tubercle of humerus
Function: Internal rotation, adduction, extension of arm
Quick tip: “Lat’s little helper”

Rhomboids

Origin: Spinous processes C6–T4
Insertion: Medial border of scapula
Function: Retracts and downwardly rotates scapula Quick tip: Pinches shoulder blades together

Coracobrachialis

Origin: Coracoid process of scapula
Insertion: Medial surface of humerus
Function: Flexes arm at shoulder
Quick tip: Small flexor tucked near biceps

Subscapularis

Origin: Ventral surface of scapula (subscapular fossa)
Insertion: Lesser tubercle of humerus
Function: Internal rotation and adduction of arm Quick tip: Rotator cuff internal rotator

Pectoralis minor

Origin: Ribs (3–5)
Insertion: Coracoid process of scapula
Function: Protracts and downwardly rotates scapula
Quick tip: Deep chest stabilizer

Pectoralis major

Origin: Clavicle, sternum, costal cartilages Insertion: Greater tubercle of humerus
Function: Flexes, adducts, and internally rotates arm
Quick tip: Big chest muscle — “hugging” motion

Serratus anterior

Origin: Ribs (upper 8–9)
Insertion: Medial border of scapula (ventral surface)
Function: Protracts scapula, upward rotation, stabilizes against ribs
Quick tip: “Boxer’s muscle”

Biceps brachii

Origin: Scapula (coracoid process & supraglenoid tubercle)
Insertion: Radius (radial tuberosity)
Function: Flexes elbow, supinates forearm, assists shoulder flexion
Quick tip: Two heads, two main actions — flex & supinate

Triceps brachii

Origin: Scapula (infraglenoid tubercle), humerus (posterior shaft)
Insertion: Ulna (olecranon process)
Function: Extends elbow, assists shoulder extension
Quick tip: Three heads, one main job — extension

Brachialis

Origin: Humerus (anterior surface)
Insertion: Ulna (coronoid process)
Function: Flexes elbow
Quick tip: Deep to biceps, pure flexor

Brachioradialis

Origin: Humerus (lateral supracondylar ridge) Insertion: Radius (styloid process)
Function: Flexes elbow (especially mid‑pronation) Quick tip: Forearm “beer‑drinking” muscle

Pronator teres

Origin: Humerus (medial epicondyle), ulna (coronoid process)
Insertion: Radius (lateral surface)
Function: Pronates forearm, assists elbow flexion Quick tip: Turns palm down

Supinator

Origin: Humerus (lateral epicondyle)
Insertion: Radius (proximal end)
Function: Supinates forearm
Quick tip: Turns palm up

Flexor carpi radialis

Origin: Humerus (medial epicondyle)
Insertion: 2nd & 3rd metacarpals
Function: Flexes wrist, radial deviation
Quick tip: Flexes toward thumb side

Flexor carpi ulnaris

Origin: Humerus (medial epicondyle)
Insertion: 5th metacarpal, pisiform, hamate Function: Flexes wrist, ulnar deviation
Quick tip: Flexes toward pinky side

Palmaris longus

Origin: Humerus (medial epicondyle)
Insertion: Palmar aponeurosis
Function: Flexes wrist
Quick tip: Absent in ~15% of people

Extensor carpi radialis longus

Origin: Humerus (lateral epicondyle)
Insertion: 2nd metacarpal
Function: Extends wrist, radial deviation
Quick tip: Long extensor on thumb side

Extensor carpi radialis brevis

Origin: Humerus (lateral epicondyle)
Insertion: 3rd metacarpal
Function: Extends wrist
Quick tip: Shorter partner to longus

Extensor carpi ulnaris

Origin: Humerus (lateral epicondyle)
Insertion: 5th metacarpal
Function: Extends wrist, ulnar deviation
Quick tip: Extends toward pinky side

Sartorius

Origin: Pelvis (anterior superior iliac spine) Insertion: Tibia (medial surface, proximal end) Function: Flexes, abducts, and externally rotates hip; flexes knee
Quick tip: Longest muscle — “tailor’s muscle” for crossing legs

Rectus femoris

Origin: Pelvis (anterior inferior iliac spine) Insertion: Tibial tuberosity via patellar tendon Function: Flexes hip, extends knee
Quick tip: Only quad that crosses hip and knee

Vastus lateralis

Origin: Femur (greater trochanter, linea aspera) Insertion: Tibial tuberosity via patellar tendon Function: Extends knee
Quick tip: Big outer quad muscle

Vastus medialis

Origin: Femur (linea aspera)
Insertion: Tibial tuberosity via patellar tendon Function: Extends knee
Quick tip: Inner quad — stabilizes kneecap

Vastus intermedius

Origin: Femur (anterior surface)
Insertion: Tibial tuberosity via patellar tendon
Function: Extends knee
Quick tip: Deep quad under rectus femoris

Iliopsoas

Origin: Vertebrae (T12–L5), iliac fossa of pelvis
Insertion: Femur (lesser trochanter)
Function: Flexes hip, anterior pelvic tilt
Quick tip: Strongest hip flexor

Tensor fascia latae

Origin: Pelvis (ASIS, iliac crest)
Insertion: Tibia via iliotibial band
Function: Abducts, flexes, and internally rotates hip
Quick tip: Tightens IT band

Pectineus

Origin: Pubis (superior ramus)
Insertion: Femur (pectineal line)
Function: Flexes and adducts hip
Quick tip: Small groin muscle

Adductor longus

Origin: Pubis (anterior surface)
Insertion: Femur (linea aspera)
Function: Adducts hip
Quick tip: Long adductor in inner thigh

Adductor brevis

Origin: Pubis (inferior ramus)
Insertion: Femur (linea aspera)
Function: Adducts hip
Quick tip: Shorter adductor under longus

Adductor magnus

Origin: Pubis (inferior ramus), ischial tuberosity
Insertion: Femur (linea aspera)
Function: Adducts and extends hip
Quick tip: Largest adductor — dual action

Gracilis

Origin: Pubis (near symphysis)
Insertion: Tibia (medial surface, proximal end)
Function: Adducts hip, flexes knee
Quick tip: Slender strap muscle of inner thigh

Popliteus

Origin: Femur (lateral condyle)
Insertion: Tibia (posterior proximal end)
Function: Unlocks knee, flexes knee, internally rotates tibia
Quick tip: Small but key “unlocker” of the knee

Soleus

Origin: Tibia and fibula (proximal ends)
Insertion: Calcaneus via Achilles tendon
Function: Plantar flexes ankle
Quick tip: Deep calf muscle — endurance plantar flexor

Gastrocnemius

Origin: Femur (medial and lateral condyles)
Insertion: Calcaneus via Achilles tendon
Function: Plantar flexes ankle, flexes knee
Quick tip: Big calf muscle — “jumping power”

Tibialis anterior

Origin: Tibia (lateral condyle)
Insertion: Medial cuneiform and base of 1st metatarsal (dorsal side)
Function: Dorsiflexes and inverts ankle
Quick tip: Shin muscle — lifts toes up

Peroneus longus

Origin: Fibula (head), tibia (lateral condyle)
Insertion: Medial cuneiform and base of 1st metatarsal (plantar side)
Function: Plantar flexes and everts ankle
Quick tip: Wraps under foot — stabilizes arch

Peroneus brevis

Origin: Fibula (shaft)
Insertion: Base of 5th metatarsal
Function: Plantar flexes and everts ankle
Quick tip: Shorter lateral stabilizer

Peroneus tertius

Origin: Fibula (distal end)
Insertion: Base of 5th metatarsal
Function: Dorsiflexes and everts ankle
Quick tip: Small helper for toe lift + eversion

Extensor hallucis longus

Origin: Fibula (shaft)
Insertion: Distal phalanx of great toe (dorsal side)
Function: Extends big toe, dorsiflexes ankle
Quick tip: “Hallucis” = big toe lifter

Extensor digitorum longus

Origin: Tibia (lateral condyle), fibula (proximal end)
Insertion: Phalanges of toes 2–5
Function: Extends toes, dorsiflexes ankle, assists eversion
Quick tip: Toe extensor for digits 2–5

Flexor digitorum brevis

Origin: Calcaneus and plantar fascia
Insertion: Middle phalanges of toes 2–5
Function: Flexes toes (curls under)
Quick tip: Short toe flexor in sole

Rectus abdominis

Origin: Pubic crest of pelvis
Insertion: Sternum (xiphoid process) and costal cartilages of ribs 5–7
Function: Flexes trunk, compresses abdomen
Quick tip: “Six‑pack” muscle — main trunk flexor

External oblique

Origin: Lower 8 ribs
Insertion: Iliac crest and linea alba
Function: Flexes trunk, rotates trunk, compresses abdomen
Quick tip: Hands‑in‑pockets fiber direction

Internal oblique

Origin: Iliac crest, pubis, ribs 9–12
Insertion: Linea alba
Function: Flexes trunk, rotates trunk, compresses abdomen
Quick tip: Fibers run opposite to external oblique

Transverse abdominis

Origin: Lower ribs and iliac crest
Insertion: Linea alba and pubic bone
Function: Compresses abdomen, stabilizes core
Quick tip: Deepest abdominal layer — “corset muscle”

Sternocleidomastoid

Origin: Sternum (manubrium), clavicle
Insertion: Mastoid process of temporal bone
Function: Flexes neck, rotates head
Quick tip: “Look over shoulder” muscle

Scalenes

Origin: Ribs 1–2
Insertion: Transverse processes C2–C8
Function: Neck flexion, lateral flexion
Quick tip: Assist breathing and neck bending

Biceps femoris

Origin: Ischial tuberosity (long head), femur (linea aspera, short head)
Insertion: Fibula (head), tibia (lateral condyle)
Function: Extends hip, flexes knee
Quick tip: Lateral hamstring

Semitendinosus

Origin: Ischial tuberosity
Insertion: Tibia (medial surface, proximal end)
Function: Extends hip, flexes knee
Quick tip: Long tendon hamstring

Semimembranosus

Origin: Ischial tuberosity
Insertion: Tibia (posterior medial condyle)
Function: Extends hip, flexes knee
Quick tip: Broad membrane‑like hamstring

Piriformis

Origin: Sacrum (anterior surface)

Insertion: Femur (greater trochanter)

Function: Externally rotates, abducts hip

Quick tip: Landmark for sciatic nerve

Gluteus maximus

Origin: Ilium, sacrum, coccyx
Insertion: Iliotibial tract, femur
Function: Extends, externally rotates hip; posterior pelvic tilt
Quick tip: Largest glute — powerful hip extender

Gluteus medius

Origin: Iliac crest, posterior ilium
Insertion: Greater trochanter of femur
Function: Abducts hip
Quick tip: Stabilizes pelvis when walking

Gluteus minimus

Origin: Posterior ilium
Insertion: Greater trochanter of femur
Function: Abducts, internally rotates hip
Quick tip: Deepest glute — assists medius