Muscle Origin, Insertion & Action Quiz
Look up any muscle's origin, insertion, action, and innervation — or switch to quiz mode and test your recall one muscle at a time.
Biceps Brachii
- Origin
- Long head: Supraglenoid tubercle of scapula. Short head: Coracoid process of scapula.
- Insertion
- Radial tuberosity and bicipital aponeurosis into deep fascia of forearm.
- Action
- Flexion of the elbow joint; Supination of the forearm (most powerful supinator when elbow is flexed); Weak flexion of the shoulder joint; Stabilization of the shoulder joint
- Innervation
- Musculocutaneous nerve (C5, C6)
Triceps Brachii
- Origin
- Long head: Infraglenoid tubercle of scapula. Lateral head: Posterior humerus (above radial groove). Medial head: Posterior humerus (below radial groove).
- Insertion
- Olecranon process of ulna
- Action
- Extension of the elbow joint (all three heads); Extension of the shoulder joint (long head only); Adduction of the arm (long head assists)
- Innervation
- Radial nerve (C6, C7, C8)
Deltoid
- Origin
- Anterior fibers: Lateral third of clavicle. Middle fibers: Acromion of scapula. Posterior fibers: Spine of scapula.
- Insertion
- Deltoid tuberosity of humerus
- Action
- Abduction of the arm (middle fibers - main abductor after first 15°); Flexion and medial rotation of the arm (anterior fibers); Extension and lateral rotation of the arm (posterior fibers)
- Innervation
- Axillary nerve (C5, C6)
Pectoralis Major
- Origin
- Clavicular head: Medial half of clavicle. Sternocostal head: Sternum, upper six costal cartilages, and aponeurosis of external oblique.
- Insertion
- Lateral lip of intertubercular (bicipital) groove of humerus
- Action
- Adduction of the arm; Medial rotation of the arm; Flexion of the arm (clavicular head); Extension from flexed position (sternocostal head)
- Innervation
- Medial pectoral nerve (C8, T1) and lateral pectoral nerve (C5, C6, C7)
Latissimus Dorsi
- Origin
- Spinous processes of T7-L5 vertebrae, thoracolumbar fascia, iliac crest, inferior angle of scapula, and lower 3-4 ribs.
- Insertion
- Floor of intertubercular (bicipital) groove of humerus
- Action
- Extension of the arm; Adduction of the arm; Medial rotation of the arm; Depression of the shoulder (pulls shoulder down); Assists with forced expiration
- Innervation
- Thoracodorsal nerve (C6, C7, C8)
Gluteus Maximus
- Origin
- Posterior gluteal line of ilium, sacrum, coccyx, thoracolumbar fascia, and sacrotuberous ligament.
- Insertion
- Iliotibial tract and gluteal tuberosity of femur
- Action
- Extension of the hip (most powerful hip extensor); Lateral rotation of the hip; Abduction of the hip (upper fibers); Adduction of the hip (lower fibers); Stabilization of the hip and knee (via iliotibial tract)
- Innervation
- Inferior gluteal nerve (L5, S1, S2)
Quadriceps Femoris
- Origin
- Rectus femoris: Anterior inferior iliac spine (AIIS) and ilium above acetabulum. Vastus lateralis: Greater trochanter and linea aspera. Vastus medialis: Intertrochanteric line and linea aspera. Vastus intermedius: Anterior and lateral femur.
- Insertion
- All four muscles unite to form the quadriceps tendon, which inserts into the patella and continues as the patellar tendon to the tibial tuberosity.
- Action
- Extension of the knee (all four muscles); Flexion of the hip (rectus femoris only)
- Innervation
- Femoral nerve (L2, L3, L4)
Hamstrings
- Origin
- All three originate from the ischial tuberosity. Biceps femoris long head: Ischial tuberosity. Biceps femoris short head: Linea aspera of femur. Semitendinosus: Ischial tuberosity. Semimembranosus: Ischial tuberosity.
- Insertion
- Biceps femoris: Head of fibula. Semitendinosus: Upper medial tibia (pes anserinus). Semimembranosus: Posterior medial condyle of tibia.
- Action
- Flexion of the knee (all three muscles); Extension of the hip (all three muscles except biceps short head); Lateral rotation of the flexed knee (biceps femoris); Medial rotation of the flexed knee (semitendinosus and semimembranosus)
- Innervation
- Sciatic nerve - tibial division (L5, S1, S2) for all except biceps femoris short head, which is innervated by the common fibular (peroneal) division.
Gastrocnemius
- Origin
- Medial head: Posterior surface of medial femoral condyle. Lateral head: Posterior surface of lateral femoral condyle.
- Insertion
- Calcaneus via the calcaneal (Achilles) tendon
- Action
- Plantarflexion of the ankle (strongest plantarflexor); Flexion of the knee (weak)
- Innervation
- Tibial nerve (S1, S2)
Rectus Abdominis
- Origin
- Pubic crest and pubic symphysis
- Insertion
- Xiphoid process and costal cartilages of ribs 5-7
- Action
- Flexion of the trunk (against gravity); Compression of abdominal contents; Depression of the ribs (assists forced expiration); Stabilization of the pelvis during walking
- Innervation
- Intercostal nerves (T7-T12)
Trapezius
- Origin
- Superior nuchal line, external occipital protuberance, nuchal ligament, and spinous processes of C7-T12 vertebrae.
- Insertion
- Lateral third of clavicle, acromion, and spine of scapula
- Action
- Elevation of the scapula (upper fibers); Retraction of the scapula (middle fibers); Depression of the scapula (lower fibers); Rotation of the scapula (upper and lower fibers working together)
- Innervation
- Accessory nerve (CN XI) for motor; C3, C4 for proprioception
Rotator Cuff
- Origin
- Supraspinatus: Supraspinous fossa. Infraspinatus: Infraspinous fossa. Teres minor: Lateral border of scapula. Subscapularis: Subscapular fossa (anterior scapula).
- Insertion
- Supraspinatus: Superior facet of greater tubercle. Infraspinatus: Middle facet of greater tubercle. Teres minor: Inferior facet of greater tubercle. Subscapularis: Lesser tubercle of humerus.
- Action
- Supraspinatus: Initiates abduction (first 15°), stabilizes shoulder; Infraspinatus: Lateral rotation of the arm; Teres minor: Lateral rotation of the arm; Subscapularis: Medial rotation of the arm
- Innervation
- Supraspinatus: Suprascapular nerve (C5, C6). Infraspinatus: Suprascapular nerve (C5, C6). Teres minor: Axillary nerve (C5, C6). Subscapularis: Upper and lower subscapular nerves (C5, C6).
Diaphragm
- Origin
- Sternal part: Xiphoid process. Costal part: Inner surfaces of lower 6 ribs. Lumbar part: Upper lumbar vertebrae via crura (right crus L1-L3, left crus L1-L2).
- Insertion
- Central tendon (a flat aponeurosis in the center of the muscle)
- Action
- Primary muscle of inspiration (contraction flattens the dome); Increases thoracic volume, decreases intrathoracic pressure; Assists with abdominal straining (defecation, urination, childbirth); Assists with vomiting and coughing
- Innervation
- Phrenic nerve (C3, C4, C5)
Sternocleidomastoid
- Origin
- Sternal head: Manubrium of sternum. Clavicular head: Medial third of clavicle.
- Insertion
- Mastoid process of temporal bone and lateral superior nuchal line
- Action
- Unilateral contraction: Lateral flexion to same side, rotation to opposite side; Bilateral contraction: Flexion of the neck, extension of the head at atlanto-occipital joint; Accessory muscle of inspiration (when head is fixed)
- Innervation
- Accessory nerve (CN XI) for motor; C2, C3 for proprioception
Iliopsoas
- Origin
- Psoas major: Transverse processes and bodies of T12-L5 vertebrae. Iliacus: Iliac fossa.
- Insertion
- Lesser trochanter of femur (combined tendon)
- Action
- Flexion of the hip (strongest hip flexor); Lateral rotation of the hip (weak); Flexion of the trunk on the lower limb (when limb is fixed)
- Innervation
- Psoas major: Lumbar plexus (L1, L2, L3). Iliacus: Femoral nerve (L2, L3, L4).
Soleus
- Origin
- Soleal line and medial border of tibia, posterior head and upper shaft of fibula.
- Insertion
- Calcaneus via the calcaneal (Achilles) tendon (shared with gastrocnemius)
- Action
- Plantarflexion of the ankle; Postural muscle for standing (prevents forward sway)
- Innervation
- Tibial nerve (S1, S2)
Tibialis Anterior
- Origin
- Lateral condyle and upper two-thirds of lateral surface of tibia, interosseous membrane
- Insertion
- Medial cuneiform bone and base of first metatarsal
- Action
- Dorsiflexion of the ankle; Inversion of the foot
- Innervation
- Deep fibular (peroneal) nerve (L4, L5)
External Obliques
- Origin
- External surfaces of ribs 5-12
- Insertion
- Linea alba, pubic tubercle, iliac crest (anterior half)
- Action
- Flexion of the trunk (bilateral contraction); Rotation of the trunk to opposite side (unilateral contraction); Lateral flexion of the trunk (unilateral contraction); Compression of abdominal contents
- Innervation
- Intercostal nerves (T7-T11) and subcostal nerve (T12)
Erector Spinae
- Origin
- Sacrum, iliac crest, spinous and transverse processes of vertebrae
- Insertion
- Ribs, transverse and spinous processes of vertebrae, mastoid process (longissimus capitis)
- Action
- Extension of the vertebral column (bilateral contraction); Lateral flexion of the vertebral column (unilateral contraction); Maintenance of upright posture; Control of trunk flexion (eccentric contraction)
- Innervation
- Posterior rami of spinal nerves
Masseter
- Origin
- Zygomatic arch (superficial part) and zygomatic bone (deep part)
- Insertion
- Lateral surface of mandibular ramus and angle of mandible
- Action
- Elevation of the mandible (closing the jaw); Protraction of the mandible (superficial fibers)
- Innervation
- Mandibular nerve (V3, trigeminal nerve)
Rhomboids
- Origin
- Rhomboid minor: Nuchal ligament and spinous processes of C7-T1. Rhomboid major: Spinous processes of T2-T5.
- Insertion
- Medial border of scapula (rhomboid minor: at root of scapular spine; rhomboid major: below the spine of scapula)
- Action
- Retraction of the scapula (pulling shoulder blades together); Elevation of the scapula; Downward rotation of the scapula
- Innervation
- Dorsal scapular nerve (C4, C5)
Sartorius
- Origin
- Anterior superior iliac spine (ASIS)
- Insertion
- Upper medial surface of tibia (pes anserinus)
- Action
- Flexion of the hip; Abduction of the hip; Lateral rotation of the hip; Flexion of the knee; Medial rotation of the flexed knee
- Innervation
- Femoral nerve (L2, L3)
Adductor Group
- Origin
- Pubic bone (body and rami) and ischium (adductor magnus also from ischial tuberosity)
- Insertion
- Linea aspera of femur (most adductors), medial tibia (gracilis), adductor tubercle (adductor magnus hamstring part)
- Action
- Adduction of the hip (all muscles); Flexion of the hip (anterior fibers); Extension of the hip (adductor magnus hamstring part); Medial rotation of the hip (most adductors)
- Innervation
- Obturator nerve (L2, L3, L4) primarily; adductor magnus also by sciatic nerve (tibial division)
Studying origins & insertions
The fastest way to remember a muscle is to reason from its attachments to its action: a muscle pulls its insertion toward its origin. Drill the pairs, then connect each to its innervation. Browse every muscle in depth on the muscle reference.