Muscles Flashcards by Matthew Russell

Pectoralis Minor (A, O, I, Inn)

A: “with serratus anterior” draws scapula laterally and forward - with other muscles rotates scapula and depresses apex of shoulder O: Ribs 3-5 and overlying fascia I: Coracoid process of scapula IN: Medial and lateral pectoral nerve

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Serratus Anterior (A, O, I, Inn)

A: -with pec minor- draw scapula laterally and forward around chest wall, protract scapula aids in rotating scapula to elevate apex of shoulder, fixes scapula during abduction of arm O: All or nearly all ribs I: Medial border of scapula IN: Long thoracic nerve

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Trapezius (A, O, I, Inn)

A: Stabilise scapula and shoulder during arm movements, elevates and depresses apex of shoulder, acts with other muscles to rotate and and retract scapula O: External occipital protuberance; medial one third of superior nuchal line; nuchal ligament; spinous processes of vertebrae C7-T3/4 I: Acromion and spine of scapula, lateral one third clavicle IN: Accessory nerve; anterior rami of C3-C4

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Levator Scapulae (A, O, I, Inn)

A:elevates scapula if cervical vertebrae are fixed; flexes neck laterally is scapula is fixed; retracts scapula and braces shoulder; rotates scapula and depresses apex of shoulder O: transverse process of vertebrae C1-4 I: Superior angle to medial border of scapula IN:Spinal nerve C3-C4 and C5 via posterior scapula nerve

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Rhomboidus Minor (A, O, I, Inn)

A: retracts scapula and braces shoulder; fixes scapula during arm movements O: spinous process of vertebrae C7-T1; nuchal ligament I: Medial border of scapula IN: Posterior scapula nerve

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Rhomboidus Major (A, O, I, Inn)

A:retracts scapula and braces shoulder; fixes scapula during arm movementsO: Spinous processes of T2-T5 I: Medial border of scapula IN: Posterior scapula nerve

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Pectoralis Major (A, O, I, Inn)

A: Flexes, adducts, medially rotates humerus O: Medial half of clavicle; lateral margin of sternum; costal cartilage 1-7; aponeurosis of external oblique I: Lateral lip of intertubercular sulcus of humerus IN: Medial and lateral pectoral nerve

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Latissimus Dorsi (A, O, I, Inn)

A:adducts, medially rotates, extends shoulder O: Vertebrae T7-L5; lower three or four ribs; iliac crest; thoracolumbar fascia I: Floor of intertubercular sulcus of humerus IN: Thoracodorsal nerve

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Deltoid (A, O, I, Inn)

A: anterior fibres flex, medial fibres abduct, posterior fibres extend humerus O: Acromion and spine of scapula; clavicle I: Deltoid tuberosity of humerus IN: Axillary nerve

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Teres Major (A, O, I, Inn)

A: extends and medially rotates humerus O: Inferior angle of scapula I: Medial lip of intertubercular sulcus of humerus IN: Lower subscapular nerve

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Coracobrachialis (A, O, I, Inn)

A: flexes and medially rotates humerus O: coracoid process I: medial aspect of humeral shaft IN: Musculocutaneous nerve

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Supraspinatus (A, O, I, Inn)

A: aids in deltoid abduction, resists downward slippage of humerus when arm is relaxed or carrying weight O:supraspinous fossa of scapula I: greater tubercle of humerus IN: Suprascapular nerve

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Infraspinatus (A, O, I, Inn)

A: modulates action of the deltoid, preventing humeral head from sliding upward as arm is abducted; laterally rotates humerus O:infraspinous fossa of scapula I: greater tubercle of humerus IN: Suprascapular nerve

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Teres Minor (A, O, I, Inn)

A:modulates action of the deltoid, preventing humeral head from sliding upward as arm is abducted; laterally rotates humerus O: lateral border and adjacent posterior surface of scapula I: greater tubercle of humerus; posterior surface of joint capsule IN: Axillary Nerve

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Subscapularis (A, O, I, Inn)

A: modulates action of the deltoid, preventing humeral head from sliding upward as arm is abducted; medially rotates humerus O: subscapula fossa of scapula I: lesser tubercle of humerus; anterior surface of joint capsule IN: Upper and Lower subscapular nerve

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Brachialis (A, O, I, Inn)

A: Prime flexor of the elbow O: anterior surface of distal half of humerus I: coronoid process and tuberosity of ulna IN: Musculocutaneous and radial nerves

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Biceps Brachii (A, O, I, Inn)

A: synergist in elbow flexion, main supinator of forearm tendon of long head stabilises shoulder by holding humeral head against glenoid cavity O: long head: superior margin of glenoid cavity short head : coracoid process I: Tuberosity of radius; fascia of forearm IN: Musculocutaneous

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Triceps Brachii (A, O, I, Inn)

A: extends elbow, long head extends and laterally rotates humerus O: long head: inferior margin of glenoid cavity and joint capsule lateral head: posterior surface of proximal end of humerus medial head: posterior surface of proximal end of humeral shaft I: Olecranon; fascia of forearm IN: Radial nerve

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Brachioradialis (A, O, I, Inn)

A: Flexes elbow O: Lateral supracondylar ridge of humerus I: lateral surface of radius near styloid process IN:Radial nerve

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Anconeus (A, O, I, Inn)

A:extends elbow, may help control ulna movements during pronation O: Lateral epicondyle of humerus I: olecranon and posterior surface of ulna IN:Radial nerve

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Pronator Quadratus (A, O, I, Inn)

A:prime mover of forearm pronation, also resists separation of radius and ulna when force is applied to forearm through wrist O: anterior surface of distal ulna I: anterior surface of distal radius IN: Median nerve

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Pronator Teres (A, O, I, Inn)

A: assists pronator quadratus in pronation, but only in rapid forceful action; weakly flexes elbow O: humeral shaft near medial epicondyle; coronoid process of ulna I: lateral surface of radial shaft IN: Median nerve

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Supinator (A, O, I, Inn)

A: supinates forearm O: lateral epicondyle of humerus; supinator crest and fossa of ulna just distal to radial notch: annular and radial collateral ligaments of elbow I: proximal one third of radius IN: Posterior interosseous nerve

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Flexor Carpi Radialis (A, O, I, Inn)

A: Flexes wrist anteriorly ; aids in radial deviation of the wrist O: Medial epicondyle of humerus I: Base of metacarpals II-III IN: Median

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**Flexor Carpi Ulnaris (A, O, I, Inn)**

A: flexes wrist anteriorly; aids in ulnar deviation of the wrist O: medial epicondyle of humerus; medial margin of olecranon; posterior surface of ulna I: Pisiform; hamate; metacarpal V IN: Ulnar

**Flexor Digitorum Superficialis (A, O, I, Inn)**

A: flexes wrist, MCP & interP joint depending on action of other muscles O: Medial epicondyle of humerus; ulnar collateral ligament; coronoid process; superior half of radius I: Middle phalanges II-V IN: Median

**Palmaris Longus (A, O, I, Inn)**

A: anchors skin and fascia of palmar region; resists shearing forces when stress is applied to skin by such actions as climbing and tool use. Weakly developed and sometimes absent O: Medial epicondyle of humerus I: Flexor retinaculum; palmar aponeurosis IN: Median

**Flexor digitorum profundus (A, O, I, Inn)**

A: Flexes wrist, MCP and InterP joints, sole flexor of distal interphalangeal joints O: Proximal three quarters of ulna; coronoid process; interosseous membrane I: Distal phalanges II-V IN: Median + ulnar

**Flexor Pollicis Longus (A, O, I, Inn)**

A: Flexes phalanges at thumb O:Radius; interosseous membrane I: Distal phalanx I IN: Median

**Extensor Carpi Radialis Longus (A, O, I, Inn)**

A: extends wrist; aids in RD of wrist O: Lateral supracondylar ridge of humerus I: Base of metacarpal II IN: Radial

**Extensor Carpi Radialis Brevis (A, O, I, Inn)**

A: extends wrist; aids in RD of wrist O: lateral epicondyle of humerus I: Base of metacarpal III IN: Posterior interosseous

**Extensor Digitorum (A, O, I, Inn)**

A: extends wrist; MCP and InterP joints,tends to spread digits apart when extending metacarpophalangeal joints O: lateral epicondyle of humerus I: Dorsal surfaces of phalanges II-V IN: Posterior interosseous

**Extensor Digiti Minimi (A, O, I, Inn)**

A: extends wrist and all joints of little finger O: lateral epicondyle of humerus I: Proximal phalanx V IN: posterior interosseous

**Extensor Carpi Ulnaris (A, O, I, Inn)**

A: extends and fixes wrist when fist is clenched or hand grips an object; aids in ulnar flexion of wrist O: lateral epicondyle of humerus; posterior I: Base of metacarpal V surface of ulnar shaft IN: posterior interosseous

**Abductor Pollicis Longus (A, O, I, Inn)**

A:abducts thumb in frontal plane, extends thumb at carpometacarpal joint O: posterior surface of radius and ulna; interosseous membrane I: Trapezium; base of metacarpal I IN: Posterior interosseous

**Extensor Pollicis Brevis (A, O, I, Inn)**

A: extends metacarpal I and proximal phalanx of thumb O: shaft of radius; interosseous membrane I: Proximal phalanx I IN: Posterior interosseous

**Extensor Pollicis Longus (A, O, I, Inn)**

A: extends distal phalanx I; aids in extending proximal phalanx I and metacarpal I; adducts and laterally rotates thumb O: posterior surface of ulna; interosseous membrane I: Distal phalanx I IN: posterior interosseous

**Extensor Indicis (A, O, I, Inn)**

A: extends wrist and index finger O:posterior surface of ulna; interosseous membrane I: Middle and distal phalanges of index finger IN: posterior interosseous

**Adductor pollicis (A, O, I, Inn)**

A: draws thumb toward palm as in gripping O: capitate; bases of metacarpals II-III; anterior ligaments of wrist; tendon sheath of flexor carpi radialis I: medial surface of proximal phalanx I IN: Ulnar

**Abductor pollicis brevis (A, O, I, Inn)**

A: abducts thumb in sagittal plane O: mainly flexor retinaculum; also scaphoid, trapezium, abductor pollicis longus tendon I: lateral surface of proximal phalanx I IN: median

**Opponens pollicis (A, O, I, Inn)**

A:flexes metacarpal I to oppose thumb to fingertips O: trapezium; flexor retinaculum I: Metacarpal I IN:median

**Abductor Digiti minimi (A, O, I, Inn)**

A:abducts little finger, as in spreading fingers apart O: Pisiform; tendon of flexor carpi ulnaris I: Medial surface of proximal phalanx V IN: ulnar

**Flexor Digiti Minimi Brevis (A, O, I, Inn)**

A:flexes little finger at MCP joint O: hook of hamate; flexor retinaculum I: medial surface of proximal phalanx V IN:ulnar

**Opponens Digiti Minimi (A, O, I, Inn)**

A: flexes metacarpal V CMC joint when little finger is moved into opposition with tip of thumb; deepens palm of hand O: hook of hamate; flexor retinaculum I: Medial surface of metacarpal V IN: ulnar

**Four dorsal interosseous muscles (A, O, I, Inn)**

A: abducts fingers; strongly flex MCP joints but extends interP joints important in grip strength O: each with two heads arising from facing surfaces of adjacent MC I: Proximal phalanges II-IV IN: Ulnar

**Three palmar interosseous muscles (A, O, I, Inn)**

A: adducts fingers; other actions same as for dorsal interosseous muscles O: MC I, II, IV, V I: proximal phalanges II, IV, V IN:ulnar

**Four lumbrical muscles (A, O, I, Inn)**

A: extend interphalageal joints, contributes to ability to pinch objects between fleshy pulp of thumb and finger, instead of these digits meeting by the edges of their nails. O: tendons of FDP I: proximal phalanges II-V IN: median & ulnar

**Iliacus (A, O, I, Inn)**

A: Flexes thigh at hip when trunk is fixed, flexes trunk at hip when thigh is fixed O: iliac crest and fossa; superolateral region of sacrum; anterior sacroiliac and iliolumbar ligaments I: lesser trochanter and nearby shaft of femur IN: femoral nerve

**Psoas (A, O, I, Inn)**

A: Flexes thigh at hip when trunk is fixed, flexes trunk at hip when thigh is fixed O: Bodies and IV discs of vertebrae T12-L5; transverse process of lumbar vertebrae I: lesser trochanter and nearby shaft of femur IN:anterior rami of lumbar spinal nerves

**TFL (A, O, I, Inn)**

A: extends knee, laterally rotates tibia; aids in abduction and medial rotation of femur; during standing steadies pelvis on femoral head and steadies femoral condyles on tibia O: iliac crest;ASIS; deep surface of fascia lata I: lateral condyle of tibia via ITB IN: superior gluteal nerve

**Gluteus Maximus (A, O, I, Inn)**

A: extends thigh at hip, abducts thigh; elevates trunk O: posterior gluteal line of ilium, on posterior surface from iliac crest to posterior superior spine; coccyx; posterior surface of lower sacrum; aponeurosis of erector spinae I: gluteal tuberosity of femur; lateral condyle of tibia via ITB IN: inf gluteal nerve

**Gluteus Medius and Minimus (A, O, I, Inn)**

A: abducts and medially rotates thigh; O: most of lateral surface of ilium between crest and acetabulum I: greater trochanter of femur IN: superior gluteal nerve

**Gamellus superior (A, O, I, Inn)**

A: laterally rotates extended thigh; abducts flexed thigh ; sometimes absent O: ischial spine I: greater trochanter of femur IN: nerve to obturator internus

**Gemellus Inferior (A, O, I, Inn)**

A: laterally rotates extended thigh; abducts flexed thigh O: ischial tuberosity I: greater trochanter of femur IN: nerve to quadratus femoris

**Obturator Externus (A, O, I, Inn)**

A: thought to laterally rotate thigh O: external surface of obturator membrane; rami of pubis and ischium I: femur between head and greater trochanter IN: obturator nerve

**Obturator internus (A, O, I, Inn)**

A: thought to laterally rotate thigh and abduct flexed thigh O: ramus of ischium; inferior ramus of pubis; anteromedial surface of lesser pelvis I: greater trochanter of femur IN: nerve to obturator internus

**Piriformis (A, O, I, Inn)**

A: Laterally rotates extended thigh; abducts flexed thigh O: anterior surface of sacrum; gluteal surface of ilium; capsule of sacroiliac joint I: greater trochanter of femur IN: spinal nerves L5-S2

**Quadratus Femoris (A, O, I, Inn)**

A: Laterally rotates thigh O: ischial tuberosity I: intertrochanteric crest of femur IN: nerve to quadratus femoris

**Adductor Brevis (A, O, I, Inn)**

A: Adducts thigh O: body and inferior ramus of pubis I: linea aspera and spiral line of femur IN: obturator nerve

**Adductor Longus (A, O, I, Inn)**

A: adducts and medially rotates hip; flexes thigh at hip O: body and inferior ramus of pubis I: linea aspira IN: obturator nerve

**Adductor Magnus (A, O, I, Inn)**

A: adducts and medially rotates thigh; extends thigh at hip O: infferior ramus of pubis; ramus and tuberosity of ischium I: linea aspira; gluteal tuberosity; medial supracondylar line of femur IN: obturator and tibial

**Gracillis (A, O, I, Inn)**

A: flexes and medially rotates tibia at knee O: body and inferior ramus of pubis ; ramus of ischium I: medial surface of tibia just below condyle IN: obturator

**Pectineus (A, O, I, Inn)**

A: flexes and adducts thigh O: superior ramus of pubis I: spiral line of femur IN: femoral

**Rectus Femoris (A, O, I, Inn)**

A: extends knee; flexes thigh at hip; flexes trunk on hip if thigh is fixed O: ilium at anterior inferior spine and superior margin of acetabulum; capsule of hip joint I: patella; tibial tuberosity; lateral and medial condyles of tibia IN: femoral

**Vastus Lateralis (A, O, I, Inn)**

A: extends knee; retains patella groove on femur during knee movements O: femur at greater trochanter and intertrochanteric line, gluteal tuberosity, linea aspira I: patella; tibial tuberosity; lateral and medial condyles of tibia IN: femoral

**Vastus Medialis (A, O, I, Inn)**

A: extends knee; retains patella groove on femur during knee movements O: femur at intertrochanteric line; spiral line; linea aspera, medial supracondylar line I: patella; tibial tuberosity; lateral and medial condyles of tibia IN: femoral

**Vastus Intermedius (A, O, I, Inn)**

A: extends knee O: anterior and lateral surfaces of femoral shaft I: patella; tibial tuberosity; lateral and medial condyles of tibia IN: femoral

**Sartorius (A, O, I, Inn)**

A: aids in knee and hip flexion abducts and laterally rotates thigh O: on and near anterior superior spine of ilium I: medial surface of proximal end of tibia IN: femoral

**Biceps Femoris (A, O, I, Inn)**

A: Flexes knee; extends hip; elevates ; laterally rotates tibia on femur when knee is flexed, laterally rotates femur when hip is extended O: long head - ischial tuberosity short head- linea aspera and lateral supracondylar line of femur I: Head of fibula IN: Tibial; common fibula

**Semitendinosus (A, O, I, Inn)**

A: Flexes knee; medially rotates tibia on femur when knee is flexed; medially rotates femur when hip is extended: counteracts forward bending at hips O: ischial tuberosity I: medial surface of upper tibia IN: tibial

**Semimembranosus (A, O, I, Inn)**

**Popliteus (A, O, I, Inn)**

A: Rotates tibia medially on femur if femur is fixed O: lateral condyle of femur; lateral meniscus and joint capsule I: posterior surface of upper tibia IN: tibial

**Fibularis Tertius (A, O, I, Inn)**

A: DF and everts foot during walking; helps toes clear the ground during forward swing of leg O: Medial surface of lower 1/3 fibula; interosseous membrane I: Metatarsal V IN: Deep peroneal

**Extensor Digitorum Longus (A, O, I, Inn)**

A: extends toes; dorsiflexes foot; tautens plantar aponeurosis O: lateral condyle of tibia; shaft of fibula; interosseous membrane I: Middle and distal phalanges II-V IN: deep peroneal

**Extensor Hallucis Longus (A, O, I, Inn)**

A:Extends great toe, DF foot O: anterior surface of middle of fibula; interosseous membrane I: Distal phalanx I IN: deep peroneal

**Tibialis Anterior (A, O, I, Inn)**

A:DF and inverts foot; O: lateral condyle and lateral margin of proximal half of tibia; interosseous membrane I: Medial cuneiform, metatarsal I IN: deep peroneal

**Gastrocnemius (A, O, I, Inn)**

A: PF foot; flexes knee O: condyles; popliteal surface and lateral supracondylar line of femur; capsule of knee joint I: Calcaneus IN: tibial

**Soleus (A, O, I, Inn)**

A: PF foot; steadies leg on ankle during standing O: posterior surface of head and proximal 1/4 of fibula; middle 1/3 of tibial; interosseous membrane I: Calcaneus IN: tibial

**Flexor Digitorum Longus (A, O, I, Inn)**

A: Flexes phalanges of digits II-V as foot is raised from ground O: posterior surface of tibial shaft I: Distal phalanges II-V IN: tibial

**Flexor Hallucis Longus (A, O, I, Inn)**

A: flexes phalanx I O: distal 2/3 of fibula and interosseous membrane I: Distal phalanx I IN: tibial

**Tibialis Posterior (A, O, I, Inn)**

A:Inverts foot; may assist in strong plantar flexion or control pronation of foot during walking O: posterior surface of proximal half of tibia, fibula and interosseous membrane I: Navicular, medial cuneiform, metatarsal V IN: tibial

**Peroneus Brevis (A, O, I, Inn)**

A: Maintains concavity of sole during toe off and tiptoeing, may evert foot and limit inversion O: lateral surface of distal two thirds of fibula I: Base of V metatarsal IN: superficial peroneal

**Peroneus Longus (A, O, I, Inn)**

A: maintains concavity of sole during tiptoeing and toe off; everts and PF foot O: head and lateral surface of proximal 2/3 of fibula I: Medial cuneiform, metatarsal I IN: superficial peroneal

**Extensor Digitorum Brevis (A, O, I, Inn)**

A: extends proximal phalanx I and all of digits II-V O: calcaneus; inferior extensor retinaculum of ankle I: Proximal phalanx I, tendons of extensor digitorum IN: Deep peroneal

**Flexor Digitorum Brevis (A, O, I, Inn)**

A: flexes digits II-IV; supports the arch of the foot O: calcaneus; plantar aponeurosis I: middle phalanges II-V IN: medial plantar

**Abductor Digiti Minimi (A, O, I, Inn)**

A: abducts and flexes little toe; supports arch of foot O: calcaneus; plantar aponeurosis I: proximal phalanx V IN: lateral plantar

**Abductor Hallucis (A, O, I, Inn)**

A: abducts great toe; supports arch of foot O: calcaneus; plantar aponeurosis; flexor retinaculum I: proximal phalanx I IN: medial plantar

**Quadratus Plantae (A, O, I, Inn)**

A:flexion of digits II-V and associated locomotor function O: two heads on the medial and lateral sides of calcaneus I: Distal phalanges II-V via flexor digitorum longus IN: Lateral plantar

**Flexor Digiti Minimi Brevis (A, O, I, Inn)**

A: flexes little toe O: metatarsal V, sheath of fibularis longus I: proximal phalanx V IN: Lateral plantar

**Adductor Hallucis (A, O, I, Inn)**

A: adducts great toe O: metatarsals II-IV; fibularis longus tendon; ligaments at bases of digits III-V I: proximal phalanx I IN: Medial plantar

**SCM (A, O, I, Inn)**

A:unilateral action tilts head slightly upward and toward opposite side; rotating head, bilateral action moves head straight forward and down, aids in deep breathing when head is fixed O: manubirum of sternum; medial one third of clavicle I: mastoid process; lateral half of superior nuchal line IN: Accessory nerve, spinal nerves C2-C3

**Scalenes (A, O, I, Inn)**

A: unilateral contraction causes ipsilateral flexion or contralateral rotation bilateral contraction flexes neck elevates ribs in breathing O: transverse process of all cervical vertebrae I: Ribs 1-2 IN: anterior rami of spinal nerves C3-8

**Splenius Capitis and Splenius Cervicis (A, O, I, Inn)**

A:acting unilaterally, produce ipsilateral flexion and slight rotation of head; extend head when acting bilaterally O: inferior half of nuchal ligament; spinous processes of vertebrae C7-T6 I: Mastoid process and occipital bone just inferior to superior nuchal line; cervical vertebrae C1-2 or 3 IN: posterior rami of middle cervical nerves

**Semispinalis Capitis and Semispinalis Cervicis (A, O, I, Inn)**

A: Extend and contralaterally rotate head O:articular processes of vertebrae C4-7, Transverse process of T1-T6 I: Occipital bone between nuchal lines; spinous processes of vertebrae C2-C5 IN: posterior rami of cervical and thoracic nerves

**Diaphragm (A, O, I, Inn)**

A:prime mover of inspiration O: Xiphoid process of sternum; ribs and costal cartilages 7-12; lumbar vertebrae I: central tendons of diaphragm IN: phrenic

**External Intercostals (A, O, I, Inn)**

A: When scalenes fix rib 1, external intercostals elevate and protract rib 2-12, expanding the thoracic cavity O: inferior margin of ribs 1-11 I: superior margin of next lower rib IN: intercostal nerve

**Internal Intercostals (A, O, I, Inn)**

A: in inspiration, intercartilagenous part aids in elevating the ribs and expanding the thoracic cavity; in expiration, the interosseous part depresses and retracts the ribs O:Superior margins and costal cartilages of ribs 2-12; margin of sternum I: inferior margin of next higher rib IN: intercostal nerve

**External Abdominal Obliques (A, O, I, Inn)**

A:supports the abdominal viscera against pull of gravity stabilises vertebral column during heavy lifting, unilateral contraction causes contralateral rotation of waist O:ribs 5-12 I: anterior half of iliac crest; symphysis and superior margin of pubis IN: Anterior rami of spinal nerves T7-12

I**nternal Abdominal Oblique (A, O, I, Inn)**

A: same as external but causes ipsilateral rotation of waist O: inguinal ligament; iliac crest; thoracolumbar fascia I: ribs 10-12; costal cartilages 7-10; pubis IN: anterior rami of spinal nerves T7-L1

**Transverse Abdominals (A, O, I, Inn)**

A: compresses abdominal contents with same effects as external obliques but does not contribute to movements of vertebral column O: inguinal ligament; iliac crest; thoracolumbar fascia; costal cartilage 7-12 I: linea alba; pubis; aponeurosis of internal oblique IN: Anterior rami of spinal nerves T7-L1

**Rectus Abdominis (A, O, I, Inn)**

A: flexes lumbar region of vertebral column, producing forward bending at the waist O:pubic symphysis and superior margin of pubis I: xiphoid process; costal cartilages 5-7 IN: Anterior rami of spinal nerves T6-T12

**Erector Spinae (A, O, I, Inn)**

A:extension and lateral flexion of vertebral column, the longissimus capitis also produces ipsilateral rotation of the head O: nuchal ligament; ribs 3-12; thoracic and lumbar vertebrae; median and lateral sacral crests; thoracolumbar fascia I: Mastoid process; cervical and thoracic vertebrae; all ribs IN: posterior rami of cerical to lumbar spinal nerves

**Semispinalis Thoracic (A, O, I, Inn)**

A: extension and contralateral rotation of vertebral column O: vertebrae T6-T10 I: vertebrae C6-T4 IN: posterior rami of cervical and thoracic spinal nerves

**Quadratus Lumborum (A, O, I, Inn)**

A: aids in respiration by fixing rib 12 and stabilising inferior attachments of diaphragm. unilateral contraction causes ipsilateral flexion of lumbar vertebral column; bilateral contraction extends lumbar vertebral column O: Iliac crest; iliolumbar ligament I: Rib 12; Vertebrae L1-4 IN: Anterior rami of spinal nerves T12-L4

**Multifidus (A, O, I, Inn)**

A: stabilisation of adjacent vertebrae, maintenance of posture, control of vertebral movement when erector spinae acts on vertebral column O: Vertebra C4-L4, PSIS, sacrum, aponeurosis of erector spinae I: Laminae and spinous processes of vertebrae superior to origins IN: Posterior rami of cervical to lumbar spinal nerves