Muscle Origins, Insertions & Actions – Vocabulary Flashcards

45 vocabulary flashcards summarizing the origin, insertion, and primary action of major skeletal muscles.

Orbicularis oculi

Origin: frontal bone & maxilla; Insertion: tissue around eyelid; Action: closes the eye for blinking.

Masseter

Origin: zygomatic arch; Insertion: angle & ramus of mandible; Action: elevates mandible to close the jaw while chewing.

Buccinator

Origin: alveolar processes of maxilla & mandible; Insertion: orbicularis oris; Action: compresses cheek for blowing, sucking, whistling.

Sternocleidomastoid

Origin: sternum & clavicle; Insertion: mastoid process of temporal bone; Action: flexes and rotates the head.

Trapezius

Origin: occipital bone & C7–T12 vertebrae; Insertion: clavicle & scapula; Action: moves and elevates scapula (shoulder shrug).

Splenius muscles

Origin: C7–T6 vertebrae & ligamentum nuchae; Insertion: temporal & occipital bones; Action: extend or hyper-extend the head.

Platysma

Origin: fascia of deltoid & pectoralis major; Insertion: mandible; Action: depresses mandible, opens mouth.

Rectus abdominis

Origin: pubic crest & symphysis; Insertion: xiphoid process & costal cartilages 5-7; Action: flexes vertebral column (sit-ups).

Transversus abdominis

Origin: iliac crest & inferior 6 ribs; Insertion: linea alba & pubic crest; Action: compresses abdominal contents.

Erector spinae

Origin: iliac crest, ribs, vertebrae; Insertion: ribs, vertebrae, mastoid process; Action: extends spine to keep trunk erect.

External oblique

Origin: lower 8 ribs; Insertion: linea alba & iliac crest; Action: rotates and flexes spine – trunk twisting.

Internal oblique

Origin: iliac crest; Insertion: linea alba & pubic crest; Action: rotates and flexes spine – internal trunk twist.

Diaphragm

Origin: ribs, xiphoid process, lumbar vertebrae; Insertion: central tendon; Action: flattens for inspiration (main breathing muscle).

External intercostals

Origin: inferior border of rib above; Insertion: superior border of rib below; Action: elevate ribs during quiet inhalation.

Internal intercostals

Origin: superior border of rib below; Insertion: inferior border of rib above; Action: depress ribs for forced exhalation.

Scalene muscles

Origin: transverse processes of cervical vertebrae; Insertion: 1st & 2nd ribs; Action: elevate ribs 1-2 in forced inspiration.

Pectoralis major

Origin: clavicle, sternum, ribs 1-6; Insertion: intertubercular sulcus of humerus; Action: flexes, adducts, and medially rotates arm (push/hug).

Pectoralis minor

Origin: ribs 3-5; Insertion: coracoid process of scapula; Action: depresses and protracts scapula (shoulder forward).

Deltoid

Origin: clavicle & scapula; Insertion: deltoid tuberosity of humerus; Action: abducts, flexes, and extends the arm.

Latissimus dorsi

Origin: T7–L5 vertebrae, iliac crest, ribs; Insertion: intertubercular sulcus of humerus; Action: extends and adducts arm (pull-down).

Subscapularis

Origin: subscapular fossa of scapula; Insertion: lesser tubercle of humerus; Action: medially rotates arm.

Supraspinatus

Origin: supraspinous fossa of scapula; Insertion: greater tubercle of humerus; Action: initiates arm abduction.

Infraspinatus

Origin: infraspinous fossa of scapula; Insertion: greater tubercle of humerus; Action: laterally rotates arm.

Teres minor

Origin: lateral border of scapula; Insertion: greater tubercle of humerus; Action: laterally rotates arm.

Biceps brachii

Origin: coracoid process & supraglenoid tubercle of scapula; Insertion: radial tuberosity; Action: flexes elbow and supinates forearm.

Brachialis

Origin: distal anterior humerus; Insertion: coronoid process of ulna; Action: primary forearm flexor at elbow.

Triceps brachii

Origin: scapula & posterior humerus; Insertion: olecranon of ulna; Action: extends elbow (straightens arm).

Flexor carpi ulnaris

Origin: medial epicondyle of humerus; Insertion: 5th metacarpal; Action: flexes and adducts wrist.

Extensor carpi ulnaris

Origin: lateral epicondyle of humerus; Insertion: 5th metacarpal; Action: extends and adducts wrist.

Gluteus maximus

Origin: ilium, sacrum, coccyx; Insertion: gluteal tuberosity & IT band; Action: extends thigh for climbing stairs.

Gluteus medius

Origin: ilium; Insertion: greater trochanter of femur; Action: abducts thigh, steadies pelvis when walking.

Adductor longus

Origin: pubis; Insertion: linea aspera of femur; Action: adducts and flexes thigh.

Iliopsoas

Origin: iliac fossa & T12-L vertebrae; Insertion: lesser trochanter of femur; Action: primary hip flexor (lifts thigh).

Gracilis

Origin: pubis; Insertion: medial tibia; Action: flexes and adducts leg, assists in crossing legs.

Sartorius

Origin: anterior superior iliac spine (ASIS); Insertion: medial condyle of tibia; Action: flexes, abducts, and laterally rotates thigh; aids tailor-style leg crossing.

Rectus femoris

Origin: ilium; Insertion: tibial tuberosity via patella; Action: extends knee and flexes thigh (kicking).

Vastus lateralis

Origin: femur; Insertion: tibial tuberosity; Action: extends knee (outer quad).

Vastus medialis

Origin: femur; Insertion: tibial tuberosity; Action: extends knee (inner quad).

Vastus intermedius

Origin: femur; Insertion: tibial tuberosity; Action: extends knee (deep to rectus femoris).

Biceps femoris

Origin: ischial tuberosity & femur; Insertion: head of fibula & tibia; Action: flexes knee and extends thigh (hamstring).

Semitendinosus

Origin: ischial tuberosity; Insertion: medial tibia; Action: flexes knee and extends thigh (long, narrow hamstring).

Semimembranosus

Origin: ischial tuberosity; Insertion: medial tibia; Action: flexes knee and extends thigh (broad hamstring).

Tibialis anterior

Origin: tibia; Insertion: 1st metatarsal & medial cuneiform; Action: dorsiflexes foot (lifts toes).

Gastrocnemius

Origin: femur condyles; Insertion: calcaneus via Achilles tendon; Action: plantar flexes foot (tiptoe, gas pedal).

Soleus

Origin: tibia & fibula; Insertion: calcaneus; Action: plantar flexes foot, maintains posture while standing.