Comprehensive Human Musculoskeletal Anatomy: Origins, Insertions, and Actions

Comprehensive practice flashcards detailing origins, insertions, targets, and motion directions for human skeletal muscles across the head, neck, trunk, upper limbs, pelvis, and lower limbs.

Superior rectus

Eye muscle originating from the common tendinous ring (attached to the optic foramen) and inserting into the superior surface of the eyeball; elevates and adducts the eyeball, rotating it from 1 o'clock to 3 o'clock.

Inferior rectus

Eye muscle originating from the common tendinous ring and inserting into the inferior surface of the eyeball; depresses and adducts the eyeball, rotating it from 6 o'clock to 3 o'clock.

Superior oblique

Eye muscle originating on the lesser wing of the sphenoid bone and inserting on the surface of the eyeball between the superior and lateral recti; depresses and abducts the eyeball, moving it down and away from the nose while rotating from 6 o'clock to 9 o'clock.

Inferior oblique

Eye muscle originating from the floor of the orbit (maxilla) and inserting between the inferior and lateral recti; elevates and abducts the eyeball, moving it up and away from the nose while rotating from 12 o'clock to 9 o'clock.

Levator palpebrae superioris

Muscle originating on the roof of the orbit (sphenoid bone) and inserting into the skin of the upper eyelids; elevates the upper eyelid to open the eyes.

Orbicularis oculi

Circular muscle originating from medial bones composing the orbit (Nasal portion of the frontal bone, frontal process of the maxilla, and the medial palpebral ligament) and inserting into the circumference of the orbit; compresses the eyelid along the superior-inferior axis to close the eyelids.

Masseter

Prime mover of the jaw originating on the maxilla arch and zygomatic arch and inserting into the mandible; elevates the mandible to close the mouth and aid in chewing.

Temporalis

Mastication muscle originating on the temporal bone and inserting into the mandible; elevates and retracts the mandible, closing the mouth and pulling the lower jaw in under the upper jaw.

Lateral pterygoid

Jaw muscle originating from the pterygoid process of the sphenoid bone and inserting into the mandible; depresses, protracts, abducts, and adducts the mandible to open the mouth, push the jaw out, and move it side-to-side.

Medial pterygoid

Jaw muscle originating from the sphenoid bone and maxilla and inserting into the mandible and temporomandibular joint; elevates, protracts, abducts, and adducts the mandible to close the mouth, push the jaw out, and move it side-to-side.

Genioglossus

Extrinsic tongue muscle originating from the mandible and inserting into the tongue undersurface and the hyoid bone; depresses and protracts the tongue to move it down and stick it out of the mouth.

Styloglossus

Extrinsic tongue muscle originating from the styloid process of the temporal bone and inserting into the tongue undersurface and sides; elevates and retracts the tongue back into the mouth.

Hyoglossus

Extrinsic tongue muscle originating from the hyoid bone and inserting into the sides of the tongue; depresses and flattens the tongue.

Digastric

Suprahyoid muscle originating from the mandible and temporal bone and inserting into the hyoid bone; elevates the hyoid bone and larynx during deglutition to let the epiglottis cover the glottis, and depresses the mandible to assist mouth opening.

Mylohyoid

Muscle originating from the mandible and inserting into the hyoid bone and median raphe; elevates the hyoid bone to press the tongue against the palate, pushing food into the pharynx during deglutition.

Thyrohyoid

Infrahyoid muscle originating on the thyroid cartilage and inserting on the hyoid bone; depresses the hyoid bone and elevates the thyroid cartilage to decrease their distance, enabling high-pitch vocalizations.

Sternocleidomastoid

Anterior neck muscle originating on the sternum and clavicle and inserting onto the mastoid process of the temporal bone and occipital bone; individually rotates the head to the opposite side and bilaterally flexes the head forward.

Semispinalis capitis

Posterior neck muscle originating from transverse and articular processes of cervical and thoracic vertebrae and inserting into the occipital bone; individually laterally flexes and rotates the head to the same side, and bilaterally extends the head backward.

Splenius capitis

Posterior neck muscle originating from spinous processes of cervical and thoracic vertebrae and inserting into the mastoid process and occipital bone; laterally flexes and rotates the head to the same side individually, and extends the head bilaterally.

External and internal obliques

Abdominal wall muscles originating from ribs 5–12 and the ilium and inserting into ribs 7–10, linea alba, and ilium; produce lateral flexion and twisting (supination) at the waist.

Transversus abdominis

Deepest abdominal muscle originating from the ilium and ribs 5–10 and inserting onto the sternum, linea alba, and pubis; compresses the abdominal cavity during forceful exhalations, defecation, urination, and childbirth.

Rectus abdominis

Medial abdominal muscle originating from the pubis and inserting into the sternum and ribs 5 and 7; flexes the vertebral column during movements such as sitting up.

Quadratus lumborum

Posterior abdominal wall muscle originating from the ilium and ribs 5–10 and inserting into rib 12 and vertebrae L1–L4; performs lateral flexion of the vertebral column.

Diaphragm

Primary respiratory muscle originating on the sternum, ribs 6–12, and lumbar vertebrae, and inserting into the central tendon; alters thoracic volume through compression and expansion during inhalation and exhalation.

External intercostals

Thoracic muscles originating from the rib superior to each intercostal space and inserting into the rib inferior; elevate the ribs to expand the thoracic cavity during inhalation.

Internal intercostals

Thoracic muscles originating from the rib inferior to each intercostal space and inserting into the rib superior; move the ribs closer together along the superior/inferior axis during forced exhalation.

Levator ani (pubococcygeus and iliococcygeus)

Pelvic floor muscle group originating from the pubis and ischium and inserting into the urethra, anal canal, perineal body, and coccyx; elevates superiorly to resist intra-abdominal pressure during defecation, urination, birth, and coughing.

Bulbospongiosus

Superficial perineal muscle originating from the perineal body and inserting into erectile tissues/fascia and clitoris; involuntarily compresses the urethra during urination or ejaculation and aids penile erection.

Ischiocavernosus

Perineal muscle originating on the ischium, ischial rami, and pubic rami and inserting into the pubic symphysis, corpus cavernosum, or clitoris; compresses veins to maintain erection of the penis or clitoris.

External anal sphincter

Sphincter muscle originating from the anococcygeal ligament and inserting into the perineal body; constricts to close the anus.

Subclavius

Anterior thoracic muscle originating on the first rib and inserting into the inferior surface of the clavicle; depresses the clavicle to stabilize it during movements.

Pectoralis minor

Anterior thoracic muscle originating from the anterior surfaces of ribs 2–4 or 3–5 and inserting into the coracoid process of the scapula; depresses the scapula in throwing motions and elevates ribs to assist inhalation.

Serratus anterior

Anterior thoracic muscle originating from ribs 1–8 or 1–9 and inserting into the vertebral border of the scapula; protracts the scapula to pull the arm forward and elevates ribs during inhalation.

Trapezius

Large posterior thoracic muscle originating from the external occipital protuberance and vertebral column and inserting into the acromion, spine of scapula, and clavicle; elevates, retracts, depresses, and inferiorly rotates the scapula, and extends the spine.

Rhomboid major

Posterior thoracic muscle originating from thoracic vertebrae T2–T5 and inserting into the medial border of the scapula; retracts and inferiorly rotates the scapula to stabilize the pectoral girdle.

Pectoralis major

Axial muscle originating from the clavicle, sternum, ribs 1–6 (or 1–7) cartilage, and external oblique aponeurosis, inserting into the greater tubercle of the humerus; adducts, flexes, and medially rotates the humerus.

Latissimus dorsi

Broad axial back muscle originating from T7–T12 vertebrae, lumbar vertebrae, lower ribs 9–12, and iliac crest, inserting into the intertubercular sulcus of the humerus; extends, adducts, and medially rotates the humerus, and depresses the scapula.

Deltoid

Scapular muscle originating on the clavicle, acromion, spine of scapula, and trapezius, and inserting on the deltoid tuberosity; abducts, flexes, extends, and medially and laterally rotates the humerus.

Subscapularis

Rotator cuff muscle originating in the subscapular fossa of the scapula and inserting into the lesser tubercle of the humerus; medially rotates the humerus and stabilizes the shoulder joint.

Supraspinatus

Rotator cuff muscle originating in the supraspinous fossa of the scapula and inserting into the greater tubercle of the humerus; abducts the humerus, rotating the elbow outward as in a tennis swing.

Infraspinatus

Rotator cuff muscle originating in the infraspinous fossa of the scapula and inserting into the greater tubercle of the humerus; extends and adducts the humerus, rotating the elbow outward.

Coracobrachialis

Scapular muscle originating from the coracoid process of the scapula and inserting onto the medial humerus shaft; flexes and adducts the humerus, pulling the elbow up and across the chest.

Biceps brachii

Anterior arm muscle originating from the coracoid process and the supraglenoid tubercle and inserting into the radial tuberosity; flexes and supinates the forearm.

Brachialis

Deep anterior arm muscle originating on the front of the distal humerus and inserting into the coronoid process of the ulna; acts as a powerful flexor of the forearm.

Triceps brachii

Posterior arm muscle originating from the infraglenoid tubercle and posterior humeral shaft, and inserting into the olecranon process of the ulna; extends the forearm, as during a punch.

Pronator teres

Anterior forearm muscle originating from the medial epicondyle of the humerus and coronoid process of the ulna, inserting on the lateral radius; pronates the forearm to turn the hand palm-down.

Supinator

Posterior forearm muscle originating from the lateral epicondyle of the humerus and proximal ulna, inserting into the proximal radius; supinates the forearm to turn the hand palm-up.

Flexor digitorum superficialis

Anterior forearm muscle originating from the medial epicondyle, coronoid process, and radius shaft, inserting onto the middle phalanges of fingers 2–5; flexes the wrist and digits to make a fist.

Flexor digitorum profundus

Deep anterior forearm muscle originating from the coronoid process, anteromedial ulna, and interosseous membrane, inserting onto the distal phalanges of fingers 2–5; flexes digits 2–5 and the wrist.

Extensor digitorum

Superficial posterior forearm muscle originating from the lateral epicondyle of the humerus and inserting into extensor expansions and distal phalanges; extends and abducts the fingers and wrist.

Abductor pollicis longus

Deep posterior forearm muscle originating from the posterior radius, ulna, and interosseous membrane, inserting onto the first metacarpal and trapezium; abducts and extends the thumb, and abducts the wrist.

Intrinsic Muscles of the Hand

Hand muscles originating and inserting entirely within the hand (thenar, hypothenar, and intermediate groups) that provide fine motor control of digits through flexion, extension, abduction, and adduction.

Thenar muscles

Group of intrinsic thumb muscles (abductor pollicis brevis, opponens pollicis, flexor pollicis brevis, adductor pollicis) that control fine movements including abduction, opposition, flexion, and adduction.

Lumbricals (Hand)

Intermediate hand muscles originating from tendons of flexor digitorum profundus and inserting into extensor expansions of digits 2–5; flex each finger at metacarpophalangeal joints and extend interphalangeal joints.

Palmar interossei

Intermediate intrinsic hand muscles originating from metacarpals facing metacarpal 3 (absent on 3); adduct and flex fingers at metacarpophalangeal joints and extend interphalangeal joints.

Occipitofrontalis

Bipartite muscle connected by the epicranial aponeurosis: the frontal belly raises the eyebrows in surprise, while the occipital belly tenses and retracts the scalp posteriorly.

Corrugator supercilii

Facial muscle originating from the frontal bone and inserting into skin beneath the eyebrow; draws eyebrows downward and medially during scowling or frowning.

Zygomaticus major

Facial muscle originating from the zygomatic arch and inserting into skin and orbicularis oris at the mouth corners; elevates the mouth corners laterally when smiling.

Buccinator

Principal muscle of the cheek originating from the maxilla, mandible, and sphenoid bone, inserting into orbicularis oris; compresses cheeks for whistling, blowing, or sucking through a straw.

Mentalis

Facial muscle originating from the incisive fossa of the mandible and inserting into the skin of the chin; elevates, protracts, and wrinkles the lower lip and chin during a pout.

Psoas major

Iliopsoas group muscle originating from T12 and L1–L5 vertebrae and inserting into the lesser trochanter of the femur; flexes and laterally rotates the thigh, and flexes the torso.

Gluteus maximus

Largest gluteal muscle originating from the dorsal ilium, sacrum, and coccyx, inserting into the gluteal tuberosity and iliotibial tract; extends the femur to lower the knee and move the thigh back.

Tensor fascia lata

Hip muscle originating from the iliac crest and anterior superior iliac spine, inserting into the iliotibial tract; flexes and abducts the thigh and stabilizes the knee through the iliotibial tract.

Piriformis

Lateral rotator of the hip originating from the anterolateral sacrum and inserting into the greater trochanter of the femur; laterally rotates the thigh and stabilizes the hip joint.

Adductor magnus

Large medial thigh muscle originating from ischial and pubic rami and ischial tuberosity, inserting on the linea aspera and adductor tubercle; adducts, flexes, and extends the femur.

Tibialis anterior

Anterior leg muscle originating on the lateral shaft and condyle of the tibia, and interosseous membrane, inserting onto the medial cuneiform and first metatarsal; dorsiflexes and inverts the foot.

Fibularis longus

Lateral leg muscle originating on the upper lateral fibula and inserting into the first metatarsal and medial cuneiform; plantar flexes and everts the foot.

Gastrocnemius

Superficial calf muscle originating from the medial and lateral condyles of the femur and inserting into the posterior calcaneus; plantar flexes the foot and flexes the knee.

Soleus

Superficial posterior leg muscle originating from the superior tibia, fibula, and interosseous membrane, inserting into the posterior calcaneus; plantar flexes the foot to maintain posture while walking.

Popliteus

Deep posterior knee muscle originating from the lateral condyle of the femur and lateral meniscus, inserting into the proximal tibia; flexes the leg and rotates the thigh/lower leg to unlock the knee joint.

Extensor digitorum brevis

Dorsal intrinsic foot muscle originating from the calcaneus and extensor retinaculum, inserting onto proximal phalanx of the hallux and extensor expansions of toes 2–5; extends toes 2–5.

Quadratus plantae

Plantar layer 2 intrinsic foot muscle originating from both sides of the calcaneus and inserting into the flexor digitorum longus tendon; assists in flexing toes 2–5.

Gracilis

Medial compartment thigh muscle originating on the body and inferior ramus of the pubis and ischial ramus, inserting on the medial proximal tibia; flexes the leg at the knee and adducts the thigh.

Rectus femoris

Quadriceps femoris group muscle originating from the anterior inferior iliac spine and superior margin of the acetabulum, inserting on the patella and tibial tuberosity; extends the lower leg and flexes the thigh.

Sartorius

Longest strap muscle of the anterior thigh originating on the anterior superior iliac spine and inserting onto the medial proximal tibia; flexes, abducts, and laterally rotates the thigh, and flexes the leg.

Biceps femoris

Lateral hamstring muscle originating from the ischial tuberosity, linea aspera, and distal femur, inserting onto the fibular head and lateral tibial condyle; flexes the leg, extends the thigh, and laterally rotates the leg.