Weeks 5 – 9 Muscle Anatomy (Vocabulary Flashcards)

Comprehensive vocabulary flashcards summarizing origins, insertions, innervations, and key actions of lower-limb, shoulder, arm, forearm, and hand muscles covered in Weeks 5-9.

Extensor digitorum brevis

Foot muscle; Origin – calcaneus & related ligaments; Insertion – long‐extensor tendons of toes 2-4; Nerve – deep fibular (L5-S1); Action – aids EDL in extending toes 2-4 at MTP & IP joints.

Extensor hallucis brevis

Foot muscle; Origin – calcaneus & retinaculum; Insertion – dorsal base of proximal phalanx of great toe; Nerve – deep fibular (L5-S1); Action – assists EHL in extending great toe at MTP joint.

Abductor hallucis

Medial plantar foot muscle; Origin – medial calcaneal tubercle; Insertion – medial base of proximal phalanx of 1st digit; Nerve – medial plantar (L5-S1); Action – abducts & flexes great toe.

Flexor digitorum brevis

Superficial sole muscle; Origin – medial calcaneal tubercle & plantar aponeurosis; Insertion – sides of middle phalanges of digits 2-5; Nerve – medial plantar (L5-S1); Action – flexes digits 2-5 at MTP & IP joints.

Abductor digiti minimi (foot)

Lateral sole muscle; Origin – medial & lateral calcaneal tubercles; Insertion – lateral base of proximal phalanx of 5th toe; Nerve – lateral plantar (S1-S3); Action – abducts & flexes little toe.

Quadratus plantae

Deep sole muscle; Origin – medial & lateral plantar calcaneus; Insertion – posterolateral tendon of FDL; Nerve – lateral plantar (S1-S3); Action – straightens FDL pull, assisting flexion of digits 2-5.

Lumbricals (foot)

4 small sole muscles; Origin – tendons of FDL; Insertion – medial extensor expansion of digits 2-5; Nerves – 1st: medial plantar (L5-S1); 2-4: lateral plantar (S1-S3); Action – flex MTP & extend IP of digits 2-5.

Flexor hallucis brevis

Medial sole muscle; Origin – plantar cuboid & lateral cuneiform; Insertion – both sides of base of proximal phalanx 1; Nerve – medial plantar (L5-S1); Action – flexes great-toe proximal phalanx.

Adductor hallucis

Oblique & transverse heads; Origin – MT 2-4 bases & plantar ligaments; Insertion – lateral base of proximal phalanx 1; Nerve – deep branch lateral plantar (S1-S3); Action – adducts great toe, supports transverse arch.

Flexor digiti minimi brevis (foot)

Origin – base of 5th metatarsal; Insertion – base of proximal phalanx 5; Nerve – superficial branch lateral plantar (S1-S3); Action – flexes proximal phalanx of 5th toe.

Plantar interossei (3)

Unipennate foot muscles; Origin – plantar medial shafts MT 3-5; Insertion – medial bases proximal phalanges 3-5; Nerve – lateral plantar (S1-S3); Action – adduct & flex toes 3-5 at MTP joints.

Dorsal interossei (4 – foot)

Bipennate foot muscles; Origin – adjacent sides MT 1-5; Insertion – 1→medial P2, 2-4→lateral P2-4; Nerve – lateral plantar (S1-S3); Action – abduct & flex toes 2-4 at MTP joints.

Deltoid

Shoulder muscle; Origin – lateral clavicle, acromion, spine of scapula; Insertion – deltoid tuberosity; Nerve – axillary (C5-C6); Action – anterior part flexes/medially rotates, middle abducts, posterior extends/laterally rotates arm.

Teres major

Origin – posterior inferior angle of scapula; Insertion – medial lip of intertubercular sulcus; Nerve – lower subscapular (C5-C6); Action – adducts & medially rotates arm.

Supraspinatus

Rotator cuff muscle; Origin – supraspinous fossa; Insertion – superior facet greater tubercle; Nerve – suprascapular (C4-C6); Action – initiates & assists deltoid in abduction of arm.

Infraspinatus

Rotator cuff; Origin – infraspinous fossa; Insertion – middle facet greater tubercle; Nerve – suprascapular (C5-C6); Action – laterally rotates arm.

Teres minor

Rotator cuff; Origin – mid lateral border scapula; Insertion – inferior facet greater tubercle; Nerve – axillary (C5-C6); Action – lateral rotation of arm.

Subscapularis

Rotator cuff; Origin – subscapular fossa; Insertion – lesser tubercle; Nerve – upper & lower subscapular (C5-C7); Action – medially rotates arm & stabilizes glenohumeral joint.

Biceps brachii

Two-headed arm flexor; Origin – short: coracoid tip, long: supraglenoid tubercle; Insertion – radial tuberosity & bicipital aponeurosis; Nerve – musculocutaneous (C5-C7); Action – supinates & flexes forearm; resists shoulder dislocation.

Brachialis

Primary elbow flexor; Origin – distal anterior humerus; Insertion – coronoid process & ulnar tuberosity; Nerves – musculocutaneous (C5-C6) & radial (C5-C7); Action – flexes forearm in all positions.

Coracobrachialis

Origin – coracoid process; Insertion – middle medial humerus; Nerve – musculocutaneous (C5-C7); Action – flexes & adducts arm, resists shoulder dislocation.

Brachioradialis

Forearm flexor; Origin – lateral supracondylar ridge; Insertion – lateral distal radius; Nerve – radial (C5-C7); Action – weak flexion, maximal in mid-pronation.

Triceps brachii

Three-headed extensor; Origin – long: infraglenoid tubercle, lateral & medial heads: posterior humerus; Insertion – olecranon; Nerve – radial (C6-C8); Action – chief forearm extensor; long head stabilizes humerus.

Anconeus

Small posterior elbow muscle; Origin – lateral epicondyle humerus; Insertion – lateral olecranon & proximal ulna; Nerve – radial (C7-T1); Action – assists triceps, stabilizes elbow, may abduct ulna in pronation.

Pronator teres

Origin – ulnar coronoid & humeral medial epicondyle; Insertion – lateral mid-radius; Nerve – median (C5-C6); Action – pronates & flexes forearm.

Flexor carpi radialis

Origin – medial epicondyle; Insertion – base 2nd metacarpal; Nerve – median (C5-C6); Action – flexes & abducts wrist.

Palmaris longus

Absent in ~14%; Origin – medial epicondyle; Insertion – flexor retinaculum & palmar aponeurosis; Nerve – median (C7-C8); Action – flexes wrist, tenses palmar aponeurosis.

Flexor carpi ulnaris

Origin – medial epicondyle & olecranon/posterior ulna; Insertion – pisiform, hook of hamate, 5th metacarpal; Nerve – ulnar (C7-C8); Action – flexes & adducts wrist.

Flexor digitorum superficialis

Intermediate flexor; Origin – humeroulnar & radial heads; Insertion – sides of middle phalanges digits 2-5; Nerve – median (C7-T1); Action – flexes PIP, also MCP of digits 2-5.

Flexor digitorum profundus

Deep forearm flexor; Origin – proximal ulna & interosseous membrane; Insertion – distal phalanges 2-5; Nerves – medial part: ulnar; lateral part: anterior interosseous (C8-T1); Action – flexes DIP joints.

Flexor pollicis longus

Origin – anterior radius & interosseous membrane; Insertion – distal phalanx of thumb; Nerve – anterior interosseous (C8-T1); Action – flexes thumb phalanges.

Pronator quadratus

Deep pronator; Origin – distal ulna; Insertion – distal radius; Nerve – anterior interosseous (C8-T1); Action – pronates forearm, binds radius & ulna.

Extensor carpi radialis brevis

Origin – lateral epicondyle; Insertion – base 3rd metacarpal; Nerve – deep branch radial (C7-C8); Action – extends & abducts wrist; active during fist clenching.

Extensor digitorum communis

Origin – lateral epicondyle; Insertion – extensor expansions digits 2-5; Nerve – deep branch radial (C7-C8); Action – extends digits 2-5 primarily at MCP.

Extensor digiti minimi

Origin – lateral epicondyle; Insertion – extensor expansion 5th digit; Nerve – deep branch radial (C7-C8); Action – extends little finger.

Extensor carpi ulnaris

Origin – lateral epicondyle & posterior ulna; Insertion – base 5th metacarpal; Nerve – deep branch radial (C7-C8); Action – extends & adducts wrist.

Extensor carpi radialis longus

Origin – lateral supracondylar ridge; Insertion – base 2nd metacarpal; Nerve – radial (C6-C7); Action – extends & abducts wrist; active in fist clench.

Abductor pollicis longus

Origin – posterior ulna, radius & interosseous membrane; Insertion – base 1st metacarpal; Nerve – posterior interosseous (C7-C8); Action – abducts thumb & extends CMC joint.

Extensor pollicis longus

Origin – posterior mid-ulna & interosseous membrane; Insertion – base distal phalanx thumb; Nerve – posterior interosseous (C7-C8); Action – extends IP, MCP, CMC of thumb.

Extensor pollicis brevis

Origin – posterior distal radius & membrane; Insertion – base proximal phalanx thumb; Nerve – posterior interosseous (C7-C8); Action – extends MCP & CMC of thumb.

Supinator

Origin – lateral epicondyle, ligaments, supinator fossa, crest of ulna; Insertion – proximal lateral, posterior, anterior radius; Nerve – deep branch radial (C7-C8); Action – supinates forearm.

Extensor indicis

Origin – posterior distal ulna & membrane; Insertion – extensor expansion 2nd digit; Nerve – posterior interosseous (C7-C8); Action – extends index finger & helps extend wrist.

Palmaris brevis

Subcutaneous hypothenar muscle; Origin – palmar aponeurosis & flexor retinaculum; Insertion – skin of medial palm; Nerve – superficial branch ulnar (C8-T1); Action – wrinkles skin, deepens grip.

Abductor pollicis brevis

Thenar muscle; Origin – flexor retinaculum, scaphoid, trapezium; Insertion – lateral base proximal phalanx thumb; Nerve – recurrent median (C8-T1); Action – abducts thumb, aids opposition.

Flexor pollicis brevis

Thenar; Origin – flexor retinaculum, scaphoid, trapezium; Insertion – lateral base proximal phalanx thumb; Nerves – superficial head median, deep head ulnar (C8-T1); Action – flexes thumb.

Opponens pollicis

Thenar; Origin – flexor retinaculum, scaphoid, trapezium; Insertion – lateral 1st metacarpal; Nerve – recurrent median (C8-T1); Action – opposes thumb (medial rotation & flexion of 1st metacarpal).

Abductor digiti minimi (hand)

Hypothenar; Origin – pisiform; Insertion – medial base proximal phalanx 5; Nerve – deep branch ulnar (C8-T1); Action – abducts little finger, aids flexion.

Flexor digiti minimi brevis (hand)

Origin – hook of hamate & flexor retinaculum; Insertion – medial base proximal phalanx 5; Nerve – deep ulnar (C8-T1); Action – flexes proximal phalanx of 5th digit.

Opponens digiti minimi

Hypothenar; Origin – hook of hamate & flexor retinaculum; Insertion – medial border 5th metacarpal; Nerve – deep ulnar (C8-T1); Action – draws 5th metacarpal anterior & rotates for opposition.

Adductor pollicis

Thenar adductor; Origin – oblique: bases 2-3 MT & capitate; transverse: anterior 3rd MT; Insertion – medial base proximal phalanx thumb; Nerve – deep ulnar (C8-T1); Action – adducts thumb toward palm.

Lumbricals (hand)

4 muscles; Origin – FDP tendons; Insertion – lateral extensor expansions digits 2-5; Nerves – 1-2 median, 3-4 deep ulnar (C8-T1); Action – flex MCP & extend IP joints.

Palmar interossei (hand – 3)

Unipennate; Origin – palmar surfaces of MT 2,4,5; Insertion – bases proximal phalanges & extensor expansions 2,4,5; Nerve – deep ulnar (C8-T1); Action – adduct digits toward axial line, assist lumbricals.

Dorsal interossei (hand – 4)

Bipennate; Origin – adjacent sides of two MT; Insertion – bases proximal phalanges & extensor expansions digits 2-4; Nerve – deep ulnar (C8-T1); Action – abduct digits 2-4, assist lumbricals.