Comprehensive Human Musculoskeletal Anatomy: Origins, Insertions, and Actions
Muscles of the Eyes, Face, and Skull
Extrinsic Eye Muscles and Eyelid Movers:
Superior Rectus:
Movement & Function: Moves the eyes up and toward the nose; rotates the eyes from 1 o'clock to 3 o'clock.
Target: Eyeballs.
Target Motion Direction: Superior (elevates); medial (adducts).
Origin: Common tendinous ring (ring attaches to optic foramen).
Insertion: Superior surface of eyeball.
Inferior Rectus:
Movement & Function: Moves the eyes down and toward the nose; rotates the eyes from 6 o'clock to 3 o'clock.
Target: Eyeballs.
Target Motion Direction: Inferior (depresses); medial (adducts).
Origin: Common tendinous ring (ring attaches to optic foramen).
Insertion: Inferior surface of eyeball.
Lateral Rectus:
Movement & Function: Moves the eyes away from the nose.
Target: Eyeballs.
Target Motion Direction: Lateral (abducts).
Origin: Common tendinous ring (ring attaches to optic foramen).
Insertion: Lateral surface of eyeball.
Medial Rectus:
Movement & Function: Moves the eyes toward the nose.
Target: Eyeballs.
Target Motion Direction: Medial (adducts).
Origin: Common tendinous ring (ring attaches to optic foramen).
Insertion: Medial surface of eyeball.
Inferior Oblique:
Movement & Function: Moves the eyes up and away from the nose; rotates the eyeball from 12 o'clock to 9 o'clock.
Target: Eyeballs.
Target Motion Direction: Superior (elevates); lateral (abducts).
Origin: Floor of orbit (maxilla).
Insertion: Surface of eyeball between inferior rectus and lateral rectus.
Superior Oblique:
Movement & Function: Moves the eyes down and away from the nose; rotates the eyeball from 6 o'clock to 9 o'clock.
Target: Eyeballs.
Target Motion Direction: Inferior (depresses); lateral (abducts).
Origin: Sphenoid bone.
Insertion: Surface of eyeball between superior rectus and lateral rectus.
Levator Palpebrae Superioris (Levator Palpabrae Superioris):
Movement & Function: Opens the eyes.
Target: Upper eyelid.
Target Motion Direction: Superior (elevates).
Origin: Roof of orbit (sphenoid bone).
Insertion: Skin of upper eyelids.
Orbicularis Oculi:
Movement & Function: Closes eyelids.
Target: Eyelid skin.
Target Motion Direction: Compression along superior-inferior axis.
Origin: Medial bones composing the orbit.
Insertion: Circumference of orbit.
Muscles of the Brow and Scalp:
Occipitofrontalis (Frontal Belly):
Movement & Function: Raises eyebrows (e.g., showing surprise).
Target: Skin of scalp.
Target Motion Direction: Anterior.
Origin: Epicranial aponeurosis.
Insertion: Underneath skin of forehead.
Occipitofrontalis (Occipital Belly):
Movement & Function: Tenses and retracts the scalp.
Target: Skin of scalp.
Target Motion Direction: Posterior.
Origin: Occipital bone; mastoid process (temporal bone).
Insertion: Epicranial aponeurosis.
Corrugator Supercilii:
Movement & Function: Lowers eyebrows (e.g., scowling, frowning).
Target: Skin underneath eyebrows.
Target Motion Direction: Inferior.
Origin: Frontal bone.
Insertion: Skin underneath eyebrow.
Muscles of the Nose:
Nasalis:
Movement & Function: Flares nostrils (pushes nostrils open when cartilage is compressed).
Target: Nasal cartilage.
Target Motion Direction: Inferior compression; posterior compression.
Origin: Maxilla.
Insertion: Nasal bone.
Muscles of the Mouth and Cheeks:
Levator Labii Superioris:
Movement & Function: Raises upper lip.
Target: Upper lip.
Target Motion Direction: Elevation.
Origin: Maxilla.
Insertion: Underneath skin at corners of the mouth; orbicularis oris.
Depressor Labii Inferioris:
Movement & Function: Lowers lower lip.
Target: Lower lip.
Target Motion Direction: Depression.
Origin: Mandible.
Insertion: Underneath skin of lower lip.
Depressor Anguli Oris:
Movement & Function: Opens mouth and slides lower jaw left and right.
Target: Lower jaw.
Target Motion Direction: Depression; lateral.
Origin: Mandible.
Insertion: Underneath skin at corners of mouth.
Zygomaticus Major:
Movement & Function: Smiling.
Target: Corners of mouth.
Target Motion Direction: Lateral elevation.
Origin: Zygomatic bone.
Insertion: Underneath skin at corners of mouth (dimple area); orbicularis oris.
Orbicularis Oris:
Movement & Function: Shaping of lips (as during speech).
Target: Lips.
Target Motion Direction: Multiple.
Origin: Tissue surrounding lips.
Insertion: Underneath skin at corners of the mouth.
Buccinator:
Movement & Function: Lateral movement of cheeks (e.g., sucking on a straw; also used to compress air in mouth while blowing).
Target: Cheeks.
Target Motion Direction: Lateral.
Origin: Maxilla; mandible; sphenoid bone (via pterygomandibular raphe).
Insertion: Orbicularis oris.
Risorius:
Movement & Function: Pursing of lips by straightening them laterally.
Target: Corners of mouth.
Target Motion Direction: Lateral.
Origin: Fascia of parotid salivary gland.
Insertion: Underneath skin at corners of the mouth.
Mentalis:
Movement & Function: Protrusion of lower lip and skin of chin (e.g., pouting expression).
Target: Lower lip and skin of chin.
Target Motion Direction: Protraction.
Origin: Mandible.
Insertion: Underneath skin of chin.
Muscles of Mastication, the Tongue, and Neck
Muscles of the Lower Jaw (Mastication):
Masseter:
Movement & Function: Closes mouth; aids chewing.
Target: Mandible.
Target Motion Direction: Superior (elevates).
Origin: Maxilla arch; zygomatic arch (for masseter).
Insertion: Mandible.
Temporalis:
Movement & Function: Closes mouth; pulls lower jaw in under upper jaw.
Target: Mandible.
Target Motion Direction: Superior (elevates); posterior (retracts).
Origin: Temporal bone.
Insertion: Mandible.
Lateral Pterygoid:
Movement & Function: Opens mouth; pushes lower jaw out under upper jaw; moves lower jaw side-to-side.
Target: Mandible.
Target Motion Direction: Inferior (depresses); posterior (protracts); lateral (abducts); medial (adducts).
Origin: Pterygoid process of sphenoid bone.
Insertion: Mandible.
Medial Pterygoid:
Movement & Function: Closes mouth; pushes lower jaw out under upper jaw; moves lower jaw side-to-side.
Target: Mandible.
Target Motion Direction: Superior (elevates); posterior (protracts); lateral (abducts); medial (adducts).
Origin: Sphenoid bone; maxilla.
Insertion: Mandible; temporomandibular joint.
Extrinsic Muscles of the Tongue:
Genioglossus:
Movement & Function: Moves tongue down; sticks tongue out of mouth.
Target: Tongue.
Target Motion Direction: Inferior (depresses); anterior (protracts).
Origin: Mandible.
Insertion: Tongue undersurface; hyoid bone.
Styloglossus:
Movement & Function: Moves tongue up; retracts tongue back into mouth.
Target: Tongue.
Target Motion Direction: Superior (elevates); posterior (retracts).
Origin: Temporal bone (styloid process).
Insertion: Tongue undersurface and sides.
Hyoglossus:
Movement & Function: Flattens tongue.
Target: Tongue.
Target Motion Direction: Inferior (depresses).
Origin: Hyoid bone.
Insertion: Sides of tongue.
Palatoglossus:
Movement & Function: Bulges tongue; active in swallowing and speaking.
Target: Tongue.
Target Motion Direction: Superior (elevation).
Origin: Soft palate.
Insertion: Side of tongue.
Muscles of the Hyoid, Larynx, and Deglutition:
Digastric:
Movement & Function: Raises the hyoid bone in a way that also raises the larynx, allowing the epiglottis to cover the glottis during deglutition; also assists in opening the mouth by depressing the mandible.
Target: Hyoid bone; larynx.
Target Motion Direction: Superior (elevates).
Origin: Mandible; temporal bone.
Insertion: Hyoid bone.
Stylohyoid:
Movement & Function: Raises and retracts the hyoid bone in a way that elongates the oral cavity during deglutition.
Target: Hyoid bone.
Target Motion Direction: Superior (elevates); posterior (retracts).
Origin: Temporal bone (styloid process).
Insertion: Hyoid bone.
Mylohyoid:
Movement & Function: Raises hyoid bone in a way that presses tongue against the roof of the mouth, pushing food back into the pharynx during deglutition.
Target: Hyoid bone.
Target Motion Direction: Superior (elevates).
Origin: Mandible.
Insertion: Hyoid bone; median raphe.
Geniohyoid:
Movement & Function: Raises and moves hyoid bone forward, widening pharynx during deglutition.
Target: Hyoid bone.
Target Motion Direction: Superior (elevates); anterior (protracts).
Origin: Mandible.
Insertion: Hyoid bone.
Omohyoid:
Movement & Function: Retracts hyoid bone and moves it down during later phases of deglutition.
Target: Hyoid bone.
Target Motion Direction: Inferior (depresses); posterior (retracts).
Origin: Scapula.
Insertion: Hyoid bone.
Sternohyoid:
Movement & Function: Depresses the hyoid bone during swallowing and speaking.
Target: Hyoid bone.
Target Motion Direction: Inferior (depresses).
Origin: Clavicle.
Insertion: Hyoid bone.
Thyrohyoid:
Movement & Function: Shrinks distance between thyroid cartilage and hyoid bone, allowing production of high-pitch vocalizations.
Target: Hyoid bone; thyroid cartilage.
Target Motion Direction: Hyoid bone: inferior (depresses); thyroid cartilage: superior (elevates).
Origin: Thyroid cartilage.
Insertion: Hyoid bone.
Sternothyroid:
Movement & Function: Depresses larynx, thyroid cartilage, and hyoid bone to create different vocal tones.
Target: Larynx; thyroid cartilage.
Target Motion Direction: Inferior (depresses).
Origin: Sternum.
Insertion: Thyroid cartilage; hyoid bone.
Muscles That Move the Head and Cervical Spine:
Sternocleidomastoid:
Movement & Function: Rotates and tilts head to the side; tilts head forward.
Target: Skull; vertebrae (cervical vertebrae).
Target Motion Direction: Individually: rotates head to opposite side (medial rotation; lateral flexion); bilaterally: flexion (anterior flexes).
Origin: Sternum; clavicle.
Insertion: Temporal bone (mastoid process); occipital bone.
Semispinalis Capitis:
Movement & Function: Rotates and tilts head backward.
Target: Skull; vertebrae (cervical vertebrae).
Target Motion Direction: Individually: laterally flexes and rotates head to same side; bilaterally: extension.
Origin: Transverse and articular processes of cervical and thoracic vertebra.
Insertion: Occipital bone.
Splenius Capitis:
Movement & Function: Rotates and tilts head to the side; tilts head backward.
Target: Skull; vertebrae.
Target Motion Direction: Individually: laterally flexes and rotates head to same side (lateral rotation; lateral flexion); bilaterally: extension.
Origin: Spinous processes of cervical and thoracic vertebra.
Insertion: Temporal bone (mastoid process); occipital bone.
Longissimus Capitis:
Movement & Function: Rotates and tilts head to the side; tilts head backward.
Target: Skull; vertebrae.
Target Motion Direction: Individually: laterally flexes and rotates head to same side; bilaterally: extension.
Origin: Transverse and articular processes of cervical and thoracic vertebra.
Insertion: Temporal bone (mastoid process).
Muscles of the Thorax and Abdomen
Muscles of the Thorax (Respiration):
Diaphragm:
Movement & Function: Inhalation; exhalation.
Target: Thoracic cavity.
Target Motion Direction: Compression; expansion.
Origin: Sternum; ribs 6–12; lumbar vertebrae.
Insertion: Central tendon.
External Intercostals:
Movement & Function: Inhalation; exhalation.
Target: Ribs.
Target Motion Direction: Elevation (expands thoracic cavity).
Origin: Rib superior to each intercostal muscle.
Insertion: Rib inferior to each intercostal muscle.
Internal Intercostals:
Movement & Function: Forced exhalation.
Target: Ribs.
Target Motion Direction: Movement along superior/inferior axis to bring ribs closer together.
Origin: Rib inferior to each intercostal muscle.
Insertion: Rib superior to each intercostal muscle.
Muscles of the Abdomen:
External Obliques & Internal Obliques:
Movement & Function: Twisting at waist; also bending to the side.
Target: Vertebral column.
Target Motion Direction: Supination; lateral flexion.
Origin: Ribs 5–12; ilium.
Insertion: Ribs 7–10; linea alba; ilium.
Transversus Abdominis:
Movement & Function: Squeezing abdomen during forceful exhalations, defecation, urination, and childbirth.
Target: Abdominal cavity.
Target Motion Direction: Compression.
Origin: Ilium; ribs 5–10.
Insertion: Sternum; linea alba; pubis.
Rectus Abdominis:
Movement & Function: Sitting up.
Target: Vertebral column.
Target Motion Direction: Flexion.
Origin: Pubis.
Insertion: Sternum; ribs 5 and 7.
Quadratus Lumborum:
Movement & Function: Bending to the side.
Target: Vertebral column.
Target Motion Direction: Lateral flexion.
Origin: Ilium; ribs 5–10.
Insertion: Rib 12; vertebrae L1–L4.
Muscles of the Pelvic Floor and Perineum
Pelvic Diaphragm:
Levator Ani Pubococcygeus & Levator Ani Iliococcygeus:
Movement & Function: Defecation; urination; birth; coughing.
Target: Abdominal cavity.
Target Motion Direction: Superior (resists pressure during abdominal compression).
Origin: Pubis; ischium.
Insertion: Urethra; anal canal; perineal body; coccyx.
Superficial Muscles of the Perineum:
Superficial Transverse Perineal:
Movement & Function: None—supports perineal body, maintaining anus at center of perineum.
Target: Perineal body.
Target Motion Direction: None.
Origin: Ischium.
Insertion: Perineal body.
Bulbospongiosus:
Movement & Function: Involuntary response that compresses urethra when excreting urine in both sexes or while ejaculating in males; also aids in erection of penis in males.
Target: Urethra.
Target Motion Direction: Compression.
Origin: Perineal body.
Insertion: Perineal membrane; corpus spongiosum of penis; deep fascia of penis; clitoris in female.
Ischiocavernosus:
Movement & Function: Compresses veins to maintain erection of penis in males; erection of clitoris in females.
Target: Veins of penis and clitoris.
Target Motion Direction: Compression.
Origin: Ischium; ischial rami; pubic rami.
Insertion: Pubic symphysis; corpus cavernosum of penis in male; clitoris of female.
Deep Muscles of the Perineum:
External Urethral Sphincter:
Movement & Function: Voluntarily compresses urethra during urination.
Target: Urethra.
Target Motion Direction: Compression.
Origin: Ischial rami; pubic rami.
Insertion: Male: median raphe; female: vaginal wall.
External Anal Sphincter:
Movement & Function: Closes anus.
Target: Anus.
Target Motion Direction: Sphincter.
Origin: Anoccoccygeal ligament.
Insertion: Perineal body.
Muscles of the Pectoral Girdle and Upper Limb
Muscles That Position the Pectoral Girdle:
Subclavius (Anterior Thorax):
Movement & Function: Stabilizes clavicle during movement by depressing it.
Target: Clavicle.
Target Motion Direction: Depression.
Origin: First rib.
Insertion: Inferior surface of clavicle.
Pectoralis Minor (Anterior Thorax):
Movement & Function: Rotates shoulder anteriorly (throwing motion); assists with inhalation.
Target: Scapula; ribs.
Target Motion Direction: Scapula: depresses; ribs: elevates.
Origin: Anterior surfaces of certain ribs (2–4 or 3–5).
Insertion: Coracoid process of scapula.
Serratus Anterior (Anterior Thorax):
Movement & Function: Moves arm from side of body to front of body; assists with inhalation.
Target: Scapula; ribs.
Target Motion Direction: Scapula: protracts; ribs: elevates.
Origin: Muscle slips from certain ribs (1–8 or 1–9).
Insertion: Anterior surface of vertebral border of scapula.
Trapezius (Posterior Thorax):
Movement & Function: Elevates shoulders (shrugging); pulls shoulder blades together; tilts head backwards.
Target: Scapula; cervical spine.
Target Motion Direction: Scapula: rotates inferiorly, retracts, elevates, depresses; spine: extends.
Origin: Skull; vertebral column.
Insertion: Acromion and spine of scapula; clavicle.
Rhomboid Major (Posterior Thorax):
Movement & Function: Stabilizes scapula during pectoral girdle movement.
Target: Scapula.
Target Motion Direction: Retracts; rotates inferiorly.
Origin: Thoracic vertebrae (T2–T5).
Insertion: Medial border of scapula.
Rhomboid Minor (Posterior Thorax):
Movement & Function: Stabilizes scapula during pectoral girdle movement.
Target: Scapula.
Target Motion Direction: Retracts; rotates inferiorly.
Origin: Cervical and thoracic vertebrae (C7 and T1).
Insertion: Medial border of scapula.
Axial and Scapular Muscles That Move the Humerus:
Pectoralis Major (Axial):
Movement & Function: Brings elbows together; moves elbow up (as during an uppercut punch).
Target: Humerus.
Target Motion Direction: Flexion; adduction; medial rotation.
Origin: Clavicle; sternum; cartilage of certain ribs (1–6 or 1–7); aponeurosis of external oblique muscle.
Insertion: Greater tubercle of humerus.
Latissimus Dorsi (Axial):
Movement & Function: Moves elbow back (as in elbowing someone standing behind you); spreads elbows apart.
Target: Humerus; scapula.
Target Motion Direction: Humerus: extension, adduction, and medial rotation; scapula: depression.
Origin: Thoracic vertebrae (T7–T12); lumbar vertebrae; lower ribs (9–12); iliac crest.
Insertion: Intertubercular sulcus of humerus.
Deltoid (Scapular):
Movement & Function: Lifts arms at shoulder.
Target: Humerus.
Target Motion Direction: Abduction; flexion; extension; medial and lateral rotation.
Origin: Trapezius; clavicle; acromion; spine of scapula.
Insertion: Deltoid tuberosity of humerus.
Subscapularis (Scapular):
Movement & Function: Assists pectoralis major in bringing elbows together and stabilizes shoulder joint during movement of the pectoral girdle.
Target: Humerus.
Target Motion Direction: Medial rotation.
Origin: Subscapular fossa of scapula.
Insertion: Lesser tubercle of humerus.
Supraspinatus (Scapular):
Movement & Function: Rotates elbow outwards, as during a tennis swing.
Target: Humerus.
Target Motion Direction: Abduction.
Origin: Supraspinous fossa of scapula.
Insertion: Greater tubercle of humerus.
Infraspinatus (Scapular):
Movement & Function: Rotates elbow outwards, as during a tennis swing.
Target: Humerus.
Target Motion Direction: Extension; adduction.
Origin: Infraspinous fossa of scapula.
Insertion: Greater tubercle of humerus.
Teres Major (Scapular):
Movement & Function: Assists with medial rotation at the shoulder.
Target: Humerus.
Target Motion Direction: Extension; adduction.
Origin: Posterior surface of scapula.
Insertion: Intertubercular sulcus of humerus.
Teres Minor (Scapular):
Movement & Function: Assists infraspinatus in rotating elbow outwards.
Target: Humerus.
Target Motion Direction: Extension; adduction.
Origin: Lateral border of dorsal scapular surface.
Insertion: Greater tubercle of humerus.
Coracobrachialis (Scapular):
Movement & Function: Moves elbow up and across body, as when putting hand on chest.
Target: Humerus.
Target Motion Direction: Flexion; adduction.
Origin: Coracoid process of scapula.
Insertion: Medial surface of humerus shaft.
Muscles of the Arm and Forearm Acting on the Elbow and Forearm:
Biceps Brachii (Anterior Flexor):
Movement & Function: Performs a bicep curl; also allows palm of hand to point toward body while flexing.
Target: Forearm.
Target Motion Direction: Flexion; supination.
Origin: Coracoid process; tubercle above glenoid cavity.
Insertion: Radial tuberosity.
Brachialis (Anterior Flexor):
Movement & Function: Flexes forearm.
Target: Forearm.
Target Motion Direction: Flexion.
Origin: Front of distal humerus.
Insertion: Coronoid process of ulna.
Brachioradialis (Anterior Flexor):
Movement & Function: Assists and stabilizes elbow during bicep-curl motion.
Target: Forearm.
Target Motion Direction: Flexion.
Origin: Lateral supracondylar ridge at distal end of humerus.
Insertion: Base of styloid process of radius.
Triceps Brachii (Posterior Extensor):
Movement & Function: Extends forearm, as during a punch.
Target: Forearm.
Target Motion Direction: Extension.
Origin: Infraglenoid tubercle of scapula; posterior shaft of humerus; posterior humeral shaft distal to radial groove.
Insertion: Olecranon process of ulna.
Anconeus (Posterior Extensor):
Movement & Function: Assists in extending forearm; also allows forearm to extend away from body.
Target: Forearm.
Target Motion Direction: Extension; abduction.
Origin: Lateral epicondyle of humerus.
Insertion: Lateral aspect of olecranon process of ulna.
Pronator Teres (Anterior Pronator):
Movement & Function: Turns hand palm-down.
Target: Forearm.
Target Motion Direction: Pronation.
Origin: Medial epicondyle of humerus; coronoid process of ulna.
Insertion: Lateral radius.
Pronator Quadratus (Anterior Pronator):
Movement & Function: Assists in turning hand palm-down.
Target: Forearm.
Target Motion Direction: Pronation.
Origin: Distal portion of anterior ulnar shaft.
Insertion: Distal surface of anterior radius.
Supinator (Posterior Supinator):
Movement & Function: Turns hand palm-up.
Target: Forearm.
Target Motion Direction: Supination.
Origin: Lateral epicondyle of humerus; proximal ulna.
Insertion: Proximal end of radius.
Muscles of the Forearm That Move the Wrist, Hand, and Fingers:
Flexor Carpi Radialis (Superficial Anterior):
Movement & Function: Bends wrist toward body; tilts hand to side away from body.
Target: Wrist; hand.
Target Motion Direction: Flexion; abduction.
Origin: Medial epicondyle of humerus.
Insertion: Base of second and third metacarpals.
Palmaris Longus (Superficial Anterior):
Movement & Function: Assists in bending hand up toward shoulder.
Target: Wrist.
Target Motion Direction: Flexion.
Origin: Medial epicondyle of humerus.
Insertion: Palmar aponeurosis; skin and fascia of palm.
Flexor Carpi Ulnaris (Superficial Anterior):
Movement & Function: Assists in bending hand up toward shoulder; tilts hand to side away from body; stabilizes wrist.
Target: Wrist; hand.
Target Motion Direction: Flexion; adduction.
Origin: Medial epicondyle of humerus; olecranon process; posterior surface of ulna.
Insertion: Pisiform; hamate bones; base of fifth metacarpal.
Flexor Digitorum Superficialis (Superficial Anterior):
Movement & Function: Bends fingers to make a fist.
Target: Wrist; fingers 2–5.
Target Motion Direction: Flexion.
Origin: Medial epicondyle of humerus; coronoid process of ulna; shaft of radius.
Insertion: Middle phalanges of fingers 2–5.
Flexor Pollicis Longus (Deep Anterior):
Movement & Function: Bends tip of thumb.
Target: Thumb.
Target Motion Direction: Flexion.
Origin: Anterior surface of radius; interosseous membrane.
Insertion: Distal phalanx of thumb.
Flexor Digitorum Profundus (Deep Anterior):
Movement & Function: Bends fingers to make a fist; also bends wrist toward body.
Target: Wrist; fingers.
Target Motion Direction: Flexion.
Origin: Coronoid process; anteromedial surface of ulna; interosseous membrane.
Insertion: Distal phalanges of fingers 2–5.
Extensor Carpi Radialis Longus (Extensor Radialis Longus, Superficial Posterior):
Movement & Function: Straightens wrist away from body; tilts hand to side away from body.
Target: Wrist.
Target Motion Direction: Extension; abduction.
Origin: Lateral supracondylar ridge of humerus.
Insertion: Base of second metacarpal.
Extensor Carpi Radialis Brevis (Superficial Posterior):
Movement & Function: Assists extensor radialis longus in extending and abducting wrist; also stabilizes hand during finger flexion.
Target: Wrist.
Target Motion Direction: Extension; abduction.
Origin: Lateral epicondyle of humerus.
Insertion: Base of third metacarpal.
Extensor Digitorum (Superficial Posterior):
Movement & Function: Opens fingers and moves them sideways away from the body.
Target: Wrist; fingers.
Target Motion Direction: Extension; abduction.
Origin: Lateral epicondyle of humerus.
Insertion: Extensor expansions; distal phalanges of fingers.
Extensor Digiti Minimi (Superficial Posterior):
Movement & Function: Extends little finger.
Target: Little finger.
Target Motion Direction: Extension.
Origin: Lateral epicondyle of humerus.
Insertion: Extensor expansion; distal phalanx of finger 5.
Extensor Carpi Ulnaris (Superficial Posterior):
Movement & Function: Straightens wrist away from body; tilts hand to side toward body.
Target: Wrist.
Target Motion Direction: Extension; adduction.
Origin: Lateral epicondyle of humerus; posterior border of ulna.
Insertion: Base of fifth metacarpal.
Abductor Pollicis Longus (Deep Posterior):
Movement & Function: Moves thumb sideways toward body; extends thumb; moves hand sideways toward body.
Target: Wrist; thumb.
Target Motion Direction: Thumb: abduction, extension; wrist: abduction.
Origin: Posterior surface of radius and ulna; interosseous membrane.
Insertion: Base of first metacarpal; trapezium.
Extensor Pollicis Brevis (Deep Posterior):
Movement & Function: Extends thumb.
Target: Thumb.
Target Motion Direction: Extension.
Origin: Dorsal shaft of radius and ulna; interosseous membrane.
Insertion: Base of proximal phalanx of thumb.
Extensor Pollicis Longus (Deep Posterior):
Movement & Function: Extends thumb.
Target: Thumb.
Target Motion Direction: Extension.
Origin: Dorsal shaft of radius and ulna; interosseous membrane.
Insertion: Base of distal phalanx of thumb.
Extensor Indicis (Deep Posterior):
Movement & Function: Extends index finger; straightens wrist away from body.
Target: Wrist; index finger.
Target Motion Direction: Extension.
Origin: Posterior surface of distal ulna; interosseous membrane.
Insertion: Tendon of extensor digitorum of index finger.
Intrinsic Muscles of the Hand:
Intrinsic muscles of the hand originate and insert entirely within the hand, providing fine motor control of the digits by flexing, extending, abducting, and adducting the distal finger and thumb segments.
* **Thenar Muscles:**
* **Abductor Pollicis Brevis:**
* **Movement:** Moves thumb away from body.
* **Target:** Thumb.
* **Target Motion Direction:** Abduction.
* **Origin:** Flexor retinaculum; nearby carpals.
* **Insertion:** Lateral base of proximal phalanx of thumb.
* **Opponens Pollicis:**
* **Movement:** Moves thumb across palm to touch other fingers.
* **Target:** Thumb.
* **Target Motion Direction:** Opposition.
* **Origin:** Flexor retinaculum; trapezium.
* **Insertion:** Anterior of first metacarpal.
* **Flexor Pollicis Brevis:**
* **Movement:** Flexes thumb.
* **Target:** Thumb.
* **Target Motion Direction:** Flexion.
* **Origin:** Flexor retinaculum; trapezium.
* **Insertion:** Lateral base of proximal phalanx of thumb.
* **Adductor Pollicis:**
* **Movement:** Moves thumb toward body.
* **Target:** Thumb.
* **Target Motion Direction:** Adduction.
* **Origin:** Capitate bone; bases of metacarpals 2–4; front of metacarpal 3.
* **Insertion:** Medial base of proximal phalanx of thumb.
* **Hypothenar Muscles:**
* **Abductor Digiti Minimi:**
* **Movement:** Moves little finger away from body.
* **Target:** Little finger.
* **Target Motion Direction:** Abduction.
* **Origin:** Pisiform bone.
* **Insertion:** Medial side of proximal phalanx of little finger.
* **Flexor Digiti Minimi Brevis:**
* **Movement:** Flexes little finger.
* **Target:** Little finger.
* **Target Motion Direction:** Flexion.
* **Origin:** Hamate bone; flexor retinaculum.
* **Insertion:** Medial side of proximal phalanx of little finger.
* **Opponens Digiti Minimi:**
* **Movement:** Moves little finger across palm to touch thumb.
* **Target:** Little finger.
* **Target Motion Direction:** Opposition.
* **Origin:** Hamate bone; flexor retinaculum.
* **Insertion:** Medial side of fifth metacarpal.
* **Intermediate Muscles:**
* **Lumbricals:**
* **Movement:** Flexes each finger at metacarpophalangeal joints; extends each finger at interphalangeal joints.
* **Target:** Fingers.
* **Target Motion Direction:** Flexion; extension.
* **Origin:** Palm (lateral sides of tendons in flexor digitorum profundus).
* **Insertion:** Fingers 2–5 (lateral edges of extensional expansions on first phalanges).
* **Palmar Interossei:**
* **Movement:** Adducts and flexes each finger at metacarpophalangeal joints; extends each finger at interphalangeal joints.
* **Target:** Fingers.
* **Target Motion Direction:** Adduction; flexion; extension.
* **Origin:** Side of each metacarpal that faces metacarpal 3 (absent from metacarpal 3).
* **Insertion:** Extensor expansion on first phalanx of each finger (except finger 3) on side facing finger 3.
* **Dorsal Interossei:**
* **Movement:** Abducts and flexes the three middle fingers at metacarpophalangeal joints; extends the three middle fingers at interphalangeal joints.
* **Target:** Fingers.
* **Target Motion Direction:** Abduction; flexion; extension.
* **Origin:** Sides of metacarpals.
* **Insertion:** Both sides of finger 3; for each other finger, extensor expansion over first phalanx on side opposite finger 3.
Muscles of the Pelvic Girdle, Thigh, Leg, and Foot
Iliopsoas and Gluteal Muscle Groups:
Psoas Major (Iliopsoas Group):
Movement & Function: Raises knee at hip, as if performing a knee attack; assists lateral rotators in twisting thigh (and lower leg) outward; assists with bending over, maintaining posture.
Target: Femur.
Target Motion Direction: Thigh: flexion and lateral rotation; torso: flexion.
Origin: Lumbar vertebrae (L1–L5); thoracic vertebra (T12).
Insertion: Lesser trochanter of femur.
Iliacus (Iliopsoas Group):
Movement & Function: Raises knee at hip, as if performing a knee attack; assists lateral rotators in twisting thigh (and lower leg) outward; assists with bending over, maintaining posture.
Target: Femur.
Target Motion Direction: Thigh: flexion and lateral rotation; torso: flexion.
Origin: Iliac fossa; iliac crest; lateral sacrum.
Insertion: Lesser trochanter of femur.
Gluteus Maximus (Gluteal Group):
Movement & Function: Lowers knee and moves thigh back, as when getting ready to kick a ball.
Target: Femur.
Target Motion Direction: Extension.
Origin: Dorsal ilium; sacrum; coccyx.
Insertion: Gluteal tuberosity of femur; iliotibial tract.
Gluteus Medius (Gluteal Group):
Movement & Function: Opens thighs, as when doing a split.
Target: Femur.
Target Motion Direction: Abduction.
Origin: Lateral surface of ilium.
Insertion: Greater trochanter of femur.
Gluteus Minimus (Gluteal Group):
Movement & Function: Brings the thighs back together.
Target: Femur.
Target Motion Direction: Abduction.
Origin: External surface of ilium.
Insertion: Greater trochanter of femur.
Tensor Fasciae Latae (Tensor Fascia Lata, Gluteal Group):
Movement & Function: Assists with raising knee at hip and opening thighs; maintains posture by stabilizing the iliotibial tract, which connects to the knee.
Target: Femur.
Target Motion Direction: Flexion; abduction.
Origin: Anterior aspect of iliac crest; anterior superior iliac spine.
Insertion: Iliotibial tract.
Lateral Rotators of the Hip:
Piriformis:
Movement & Function: Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint.
Target: Femur.
Target Motion Direction: Lateral rotation.
Origin: Anterolateral surface of sacrum.
Insertion: Greater trochanter of femur.
Obturator Internus:
Movement & Function: Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint.
Target: Femur.
Target Motion Direction: Lateral rotation.
Origin: Inner surface of obturator membrane; greater sciatic notch; margins of obturator foramen.
Insertion: Greater trochanter in front of piriformis.
Obturator Externus:
Movement & Function: Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint.
Target: Femur.
Target Motion Direction: Lateral rotation.
Origin: Outer surfaces of obturator membrane, pubis, and ischium; margins of obturator foramen.
Insertion: Trochanteric fossa of posterior femur.
Superior Gemellus:
Movement & Function: Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint.
Target: Femur.
Target Motion Direction: Lateral rotation.
Origin: Ischial spine.
Insertion: Greater trochanter of femur.
Inferior Gemellus:
Movement & Function: Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint.
Target: Femur.
Target Motion Direction: Lateral rotation.
Origin: Ischial tuberosity.
Insertion: Greater trochanter of femur.
Quadratus Femoris:
Movement & Function: Twists thigh (and lower leg) outward; maintains posture by stabilizing hip joint.
Target: Femur.
Target Motion Direction: Lateral rotation.
Origin: Ischial tuberosity.
Insertion: Trochanteric crest of femur.
Adductors of the Thigh:
Adductor Longus:
Movement & Function: Brings the thighs back together; assists with raising the knee.
Target: Femur.
Target Motion Direction: Adduction; flexion.
Origin: Pubis near pubic symphysis.
Insertion: Linea aspera.
Adductor Brevis:
Movement & Function: Brings the thighs back together; assists with raising the knee.
Target: Femur.
Target Motion Direction: Adduction; flexion.
Origin: Body of pubis; inferior ramus of pubis.
Insertion: Linea aspera above adductor longus.
Adductor Magnus:
Movement & Function: Brings the thighs back together; assists with raising the knee and moving the thigh back.
Target: Femur.
Target Motion Direction: Adduction; flexion; extension.
Origin: Ischial rami; pubic rami; ischial tuberosity.
Insertion: Linea aspera; adductor tubercle of femur.
Pectineus:
Movement & Function: Opens thighs; assists with raising the knee and turning the thigh (and lower leg) inward.
Target: Femur.
Target Motion Direction: Adduction; flexion; medial rotation.
Origin: Pectineal line of pubis.
Insertion: Lesser trochanter to linea aspera of posterior aspect of femur.
Gracilis (Medial Compartment):
Movement & Function: Moves back of lower legs up toward buttocks, as when kneeling; assists in opening thighs.
Target: Femur; tibia/fibula.
Target Motion Direction: Tibia/fibula: flexion; thigh: adduction.
Origin: Inferior ramus; body of pubis; ischial ramus.
Insertion: Medial surface of tibia.
Anterior and Posterior Compartments of the Thigh:
Rectus Femoris (Quadriceps Group):
Movement & Function: Moves lower leg out in front of body, as when kicking; assists in raising the knee.
Target: Femur; tibia/fibula.
Target Motion Direction: Tibia/fibula: extension; thigh: flexion.
Origin: Anterior inferior iliac spine; superior margin of acetabulum.
Insertion: Patella; tibial tuberosity.
Vastus Lateralis (Quadriceps Group):
Movement & Function: Moves lower leg out in front of body, as when kicking.
Target: Tibia/fibula.
Target Motion Direction: Extension.
Origin: Greater trochanter; intertrochanteric line; linea aspera.
Insertion: Patella; tibial tuberosity.
Vastus Medialis (Quadriceps Group):
Movement & Function: Moves lower leg out in front of body, as when kicking.
Target: Tibia/fibula.
Target Motion Direction: Extension.
Origin: Linea aspera; intertrochanteric line.
Insertion: Patella; tibial tuberosity.
Vastus Intermedius (Quadriceps Group):
Movement & Function: Moves lower leg out in front of body, as when kicking.
Target: Tibia/fibula.
Target Motion Direction: Extension.
Origin: Proximal femur shaft.
Insertion: Patella; tibial tuberosity.
Sartorius (Anterior Thigh):
Movement & Function: Moves back of lower legs up and back toward the buttocks, as when kneeling; assists in moving thigh diagonally upward and outward, as when mounting a bike.
Target: Femur; tibia/fibula.
Target Motion Direction: Tibia: flexion; thigh: flexion, abduction, lateral rotation.
Origin: Anterior superior iliac spine.
Insertion: Medial aspect of proximal tibia.
Biceps Femoris (Hamstring Group):
Movement & Function: Moves back of lower legs up and back toward the buttocks, as when kneeling; moves thigh down and back; twists the thigh (and lower leg) outward.
Target: Femur; tibia/fibula.
Target Motion Direction: Tibia/fibula: flexion; thigh: extension, lateral rotation.
Origin: Ischial tuberosity; linea aspera; distal femur.
Insertion: Head of fibula; lateral condyle of tibia.
Semitendinosus (Hamstring Group):
Movement & Function: Moves back of lower legs up toward buttocks, as when kneeling; moves thigh down and back; twists the thigh (and lower leg) inward.
Target: Femur; tibia/fibula.
Target Motion Direction: Tibia/fibula: flexion; thigh: extension, medial rotation.
Origin: Ischial tuberosity.
Insertion: Upper tibial shaft.
Semimembranosus (Hamstring Group):
Movement & Function: Moves back of lower legs up and back toward the buttocks as when kneeling; moves thigh down and back; twists the thigh (and lower leg) inward.
Target: Femur; tibia/fibula.
Target Motion Direction: Tibia/fibula: flexion; thigh: extension, medial rotation.
Origin: Ischial tuberosity.
Insertion: Medial condyle of tibia; lateral condyle of femur.
Muscles of the Leg (Crural Muscles):
Tibialis Anterior (Anterior Compartment):
Movement & Function: Raises the sole of the foot off the ground, as when preparing to foot-tap; bends the inside of the foot upwards, as when catching balance while falling laterally toward the opposite side as the balancing foot.
Target: Foot.
Target Motion Direction: Dorsiflexion; inversion.
Origin: Lateral condyle and upper tibial shaft; interosseous membrane.
Insertion: Interior surface of medial cuneiform; first metatarsal bone.
Extensor Hallucis Longus (Anterior Compartment):
Movement & Function: Raises the sole of the foot off the ground, as when preparing to foot-tap; extends the big toe.
Target: Foot; big toe.
Target Motion Direction: Foot: dorsiflexion; big toe: extension.
Origin: Anteromedial fibula shaft; interosseous membrane.
Insertion: Distal phalanx of big toe.
Extensor Digitorum Longus (Anterior Compartment):
Movement & Function: Raises the sole of the foot off the ground, as when preparing to foot-tap; extends toes.
Target: Foot; toes 2–5.
Target Motion Direction: Foot: dorsiflexion; toes: extension.
Origin: Lateral condyle of tibia; proximal portion of fibula; interosseous membrane.
Insertion: Middle and distal phalanges of toes 2–5.
Fibularis Longus (Lateral Compartment):
Movement & Function: Lowers the sole of the foot to the ground, as when foot-tapping or jumping; bends the inside of the foot downwards, as when catching balance while falling laterally toward the same side as the balancing foot.
Target: Foot.
Target Motion Direction: Plantar flexion and eversion.
Origin: Upper portion of lateral fibula.
Insertion: First metatarsal; medial cuneiform.
Fibularis (Peroneus) Brevis (Lateral Compartment):
Movement & Function: Lowers the sole of the foot to the ground, as when foot-tapping or jumping; bends the inside of the foot downward, as when catching balance while falling laterally toward the same side as the balancing foot.
Target: Foot.
Target Motion Direction: Plantar flexion and eversion.
Origin: Distal fibula shaft.
Insertion: Proximal end of fifth metatarsal.
Gastrocnemius (Posterior Compartment, Superficial):
Movement & Function: Lowers the sole of the foot to the ground, as when foot-tapping or jumping; assists in moving the back of the lower legs up and back toward the buttocks.
Target: Foot; tibia/fibula.
Target Motion Direction: Foot: plantar flexion; tibia/fibula: flexion.
Origin: Medial and lateral condyles of femur.
Insertion: Posterior calcaneus.
Soleus (Posterior Compartment, Superficial):
Movement & Function: Lowers the sole of the foot to the ground, as when foot-tapping or jumping; maintains posture while walking.
Target: Foot.
Target Motion Direction: Plantar flexion.
Origin: Superior tibia; fibula; interosseous membrane.
Insertion: Posterior calcaneus.
Plantaris (Posterior Compartment, Superficial):
Movement & Function: Lowers the sole of the foot to the ground, as when foot-tapping or jumping; assists in moving the back of the lower legs up and back toward the buttocks.
Target: Foot; tibia/fibula.
Target Motion Direction: Foot: plantar flexion; tibia/fibula: flexion.
Origin: Posterior femur above lateral condyle.
Insertion: Calcaneus or calcaneus tendon.
Tibialis Posterior (Posterior Compartment, Superficial):
Movement & Function: Lowers the sole of the foot to the ground, as when foot-tapping or jumping.
Target: Foot.
Target Motion Direction: Plantar flexion.
Origin: Superior tibia and fibula; interosseous membrane.
Insertion: Several tarsals and metatarsals 2–4.
Popliteus (Posterior Compartment, Deep):
Movement & Function: Moves the back of the lower legs up and back toward the buttocks; assists in rotation of the leg at the knee and thigh.
Target: Tibia/fibula.
Target Motion Direction: Tibia/fibula: flexion; thigh and lower leg: medial and lateral rotation.
Origin: Lateral condyle of femur; lateral meniscus.
Insertion: Proximal tibia.
Flexor Digitorum Longus (Posterior Compartment, Deep):
Movement & Function: Lowers the sole of the foot to the ground, as when foot-tapping or jumping; bends the inside of the foot upward and flexes toes.
Target: Foot; toes 2–5.
Target Motion Direction: Foot: plantar flexion and inversion; toes: flexion.
Origin: Posterior tibia.
Insertion: Distal phalanges of toes 2–5.
Flexor Hallucis Longus (Posterior Compartment, Deep):
Movement & Function: Flexes the big toe.
Target: Big toe; foot.
Target Motion Direction: Big toe: flexion; foot: plantar flexion.
Origin: Midshaft of fibula; interosseous membrane.
Insertion: Distal phalanx of big toe.
Intrinsic Muscles of the Foot:
Extensor Digitorum Brevis (Dorsal Group):
Movement & Function: Extends toes 2–5.
Target: Toes 2–5.
Target Motion Direction: Extension.
Origin: Calcaneus; extensor retinaculum.
Insertion: Base of proximal phalanx of big toe; extensor expansions on toes 2–5.
Abductor Hallucis (Plantar Group, Layer 1):
Movement & Function: Abducts and flexes big toe.
Target: Big toe.
Target Motion Direction: Adduction; flexion.
Origin: Calcaneal tuberosity; flexor retinaculum.
Insertion: Proximal phalanx of big toe.
Flexor Digitorum Brevis (Plantar Group, Layer 1):
Movement & Function: Flexes toes 2–4.
Target: Middle toes.
Target Motion Direction: Flexion.
Origin: Calcaneal tuberosity.
Insertion: Middle phalanx of toes 2–4.
Abductor Digiti Minimi (Plantar Group, Layer 1):
Movement & Function: Abducts and flexes small toe.
Target: Toe 5.
Target Motion Direction: Abduction; flexion.
Origin: Calcaneal tuberosity.
Insertion: Proximal phalanx of little toe.
Quadratus Plantae (Plantar Group, Layer 2):
Movement & Function: Assists in flexing toes 2–5.
Target: Toes 2–5.
Target Motion Direction: Flexion.
Origin: Medial and lateral sides of calcaneus.
Insertion: Tendon of flexor digitorum longus.
Lumbricals (Plantar Group, Layer 2):
Movement & Function: Extends toes 2–5 at the interphalangeal joints; flexes the small toes at the metatarsophalangeal joints.
Target: Toes 2–5.
Target Motion Direction: Extension; flexion.
Origin: Tendons of flexor digitorum longus.
Insertion: Medial side of proximal phalanx of toes 2–5.
Flexor Hallucis Brevis (Plantar Group, Layer 3):
Movement & Function: Flexes big toe.
Target: Big toe.
Target Motion Direction: Flexion.
Origin: Lateral cuneiform; cuboid bones.
Insertion: Base of proximal phalanx of big toe.
Adductor Hallucis (Plantar Group, Layer 3):
Movement & Function: Adducts and flexes big toe.
Target: Big toe.
Target Motion Direction: Adduction; flexion.
Origin: Bases of metatarsals 2–4; fibularis longus tendon sheath; ligament across metatarsophalangeal joints.
Insertion: Base of proximal phalanx of big toe.
Flexor Digiti Minimi Brevis (Plantar Group, Layer 3):
Movement & Function: Flexes small toe.
Target: Little toe.
Target Motion Direction: Flexion.
Origin: Base of metatarsal 5; tendon sheath of fibularis longus.
Insertion: Base of proximal phalanx of little toe.
Dorsal Interossei (Plantar Group, Layer 4):
Movement & Function: Abducts and flexes middle toes at metatarsophalangeal joints; extends middle toes at interphalangeal joints.
Target: Middle toes.
Target Motion Direction: Abduction; flexion; extension.
Origin: Sides of metatarsals.
Insertion: Both sides of toe 2; for each other toe, extensor expansion over first phalanx on side opposite toe 2.
Plantar Interossei (Plantar Group, Layer 4):
Movement & Function: Abducts toes 3–5; flexes proximal phalanges and extends distal phalanges.
Target: Small toes.
Target Motion Direction: Abduction; flexion; extension.
Origin: Side of each metatarsal that faces metatarsal 2 (absent from metatarsal 2).
Insertion: Extensor expansion on first phalanx of each toe (except toe 2) on side facing toe 2.