Human Muscular Anatomy: Origins, Insertions, and Actions

Comprehensive vocabulary flashcards covering the origins, insertions, and actions of head, neck, trunk, upper limb, and lower limb muscles.

Deltoid

Origin: Clavicle, acromion, spine of scapula. Insertion: Deltoid tuberosity of humerus. Action: Abducts arm; flexes, extends, medially & laterally rotates humerus.

Biceps brachii

Origin: Long head: superior margin of glenoid cavity; short head: coracoid process of scapula. Insertion: Radial tuberosity. Action: Flexes arm, flexes forearm, supinates forearm.

Brachioradialis

Origin: Lateral supracondylar ridge of humerus. Insertion: Near styloid process of lateral radius. Action: Flexes forearm.

Teres major

Origin: Inferior angle of scapula. Insertion: Crest of lesser tubercle of humerus. Action: Extends & medially rotates humerus.

Triceps brachii

Origin: Infraglenoid tubercle of scapula, lateral & posterior surface of humerus. Insertion: Olecranon & tuberosity of ulna. Action: Extends & adducts arm, extends forearm.

Supraspinatus

Origin: Supraspinous fossa. Insertion: Greater tubercle of humerus. Action: Abducts arm, helps stabilize shoulder joint.

Infraspinatus

Origin: Infraspinous fossa. Insertion: Greater tubercle of humerus. Action: Laterally rotates arm, stabilizes shoulder joint.

Teres minor

Origin: Lateral border of scapula. Insertion: Greater tubercle of humerus. Action: Laterally rotates & adducts humerus, stabilizes shoulder.

Subscapularis

Origin: Subscapular fossa. Insertion: Lesser tubercle of humerus. Action: Medially rotates arm, stabilizes shoulder joint.

Biceps femoris

Origin: Ischial tuberosity of ischium, linea aspera of femur. Insertion: Head of fibula. Action: Extends thigh, flexes knee.

Semitendinosus

Origin: Ischial tuberosity of ischium. Insertion: Proximal, medial tibia. Action: Extends thigh, flexes knee.

Semimembranosus

Origin: Ischial tuberosity of ischium. Insertion: Medial condyle of tibia. Action: Extends thigh, flexes knee.

Iliopsoas (Iliacus & Psoas major)

Origin: $T_{12}$, $L_{1-5}$, sacrum, iliac crest, iliac fossa. Insertion: Lesser trochanter of femur. Action: Flexes thigh & lumbar vertebrae.

Rectus femoris

Origin: Anterior inferior iliac spine, margin of acetabulum. Insertion: Patella, tibial tuberosity, lateral & medial condyles of tibia. Action: Flexes thigh, extends leg.

Vastus intermedius

Origin: Proximal, anterior femur. Insertion: Patella, tibial tuberosity, lateral & medial condyles of tibia. Action: Extends leg.

Vastus lateralis

Origin: Greater trochanter of femur, linea aspera of femur. Insertion: Patella, tibial tuberosity, lateral & medial condyles of tibia. Action: Extends leg.

Vastus medialis

Origin: Linea aspera of femur, medial side. Insertion: Patella, tibial tuberosity, lateral & medial condyles of tibia. Action: Extends leg.

Gluteus maximus

Origin: Outer iliac surface, iliac crest, sacrum, coccyx. Insertion: Gluteal tuberosity of femur, iliotibial tract of fasciae latae. Action: Extends & abducts thigh.

Gastrocnemius

Origin: Condyles of femur. Insertion: Calcaneus. Action: Flexes leg, plantar flexes foot.

Tibialis anterior

Origin: Lateral condyle & proximal tibia. Insertion: First metatarsal & medial cuneiform. Action: Dorsiflexes & inverts foot.

Brachialis

An upper limb muscle whose action is to flex the forearm.

Extensor digitorum

An upper limb muscle whose action is to extend phalanges and extend the hand.

Palmaris longus

An upper limb muscle whose action is to anchor the skin & fascia of the palmar region.

Flexor carpi ulnaris

An upper limb muscle whose action is to flex & adduct the wrist.

Flexor carpi radialis

An upper limb muscle whose action is to flex & abduct the wrist.

Pronator teres

An upper limb muscle whose action is to pronate & flex the forearm.

Extensor carpi radialis longus

An upper limb muscle whose action is to extend & abduct the wrist.

Extensor carpi radialis brevis

An upper limb muscle whose action is to extend & abduct the wrist.

Piriformis

A lower limb muscle whose action is to laterally rotate & abduct the thigh.

Sartorius

A lower limb muscle whose action is to flex & laterally rotate the thigh, and flex the knee.

Extensor digitorum longus

A lower limb muscle whose action is to extend digitals and extend the foot.

Gracilis

A lower limb muscle whose action is to flex & medially rotate the leg.

Soleus

A lower limb muscle whose action is to plantar flex the foot.

Iliotibial tract

A non-muscle structure of the lower limb responsible for the stabilization of the hip and knee in extension and in partial flexion.

Calcaneal tendon

A non-muscle structure of the lower limb responsible for plantar flexing the foot.

Buccinator

A facial muscle whose action is to compress the cheek.

Occipitofrontalis / Epicranius (Frontal belly)

The frontal belly of the occipitofrontalis whose action is to raise the eyebrows and draw the scalp anteriorly.

Occipitofrontalis / Epicranius (Occipital belly)

The occipital belly of the occipitofrontalis whose action is to retract the scalp.

Mentalis

A facial muscle whose action is to protrude the lower lip.

Orbicularis oris

A facial muscle whose action is to close the lips.

Orbicularis oculi

A facial muscle whose action is to close the eyelid.

Diaphragm

A major muscle of respiration whose action is inspiration.

External intercostals

Thoracic muscles whose action is to elevate the ribs (increases volume in thorax).

Internal intercostals

Thoracic muscles whose action is to elevate & depress the ribs.

External oblique

An abdominal wall muscle whose action is to compress the abdominal wall and laterally rotate the waist.

Internal oblique

An abdominal wall muscle whose action is to compress the abdominal wall and laterally rotate the waist.

Serratus anterior

A muscle whose action is to abduct the scapula (moves scapula away from spinal column).

Transversus abdominis

An abdominal muscle whose action is to compress the abdominal wall and laterally rotate the waist.

Zygomaticus minor

A facial muscle whose action is to elevate the corners of the mouth (in smiling & laughing).

Masseter

Origin: Zygomatic arch. Insertion: Angle and ramus of mandible. Action: Elevates (closes) mandible.

Sternocleidomastoid

Origin: Manubrium of sternum, clavicle. Insertion: Mastoid process of temporal bone. Action: Abducts, rotates, and flexes head.

Temporalis

Origin: Temporal fossa. Insertion: Coronoid process and ramus of mandible. Action: Elevates (closes) mandible.

Trapezius

Origin: Posterior occipital bone, nuchal ligament, $C_7-T_4$. Insertion: Clavicle, acromion, & spine of scapula. Action: Extends & abducts head, rotates & adducts scapula, fixes scapula.

Latissimus dorsi

Origin: $T_{7-12}$, $L_{1-5}$, crest of ilium, ribs $10-12$. Insertion: Intertubercular sulcus of humerus. Action: Extends, adducts, & medially rotates humerus; draws shoulder inferiorly.

Pectoralis major

Origin: Clavicle, sternum, cartilages of ribs $1-7$. Insertion: Crest of greater tubercle of humerus. Action: Flexes, adducts, & medially rotates humerus.

Pectoralis minor

Origin: Ribs $3-5$. Insertion: Coracoid process of scapula. Action: Depresses glenoid cavity.

Rectus abdominis

Origin: Crest of pubis, pubic symphysis. Insertion: Costal cartilages $5-7$, xiphoid process. Action: Flexes spine, compresses abdominal wall.

Zygomaticus major

Origin: Zygomatic bone. Insertion: Superolateral angle of mouth & muscles of upper lip. Action: Elevates corners of mouth (in smiling & laughing).