Muscle Attachment Flashcards
Obturator Internus
Pelvic surface of ilium and ischium; obturator membrane –> medial surface of greater trochanter
Innervation: nerve to obturator internus
Action: laterally rotates extended hip joint; abducts flexed hip joint; steadies femoral head in acetabulum (stabilizes hip joint)
Piriformis
Pelvic surface of sacral segments 2-4; superior margin of greater sciatic notch and sacrotuberous ligament –> greater trochanter
Innervation: branches of anterior rami of S1, S2
Action: laterally rotates extended hip joint; abducts flexed hip joint; steadies femoral head in acetabulum (stabilizes hip joint)
Psoas major
Transverse processes of lumbar vertebrae; vertebral bodies of T12-S1 vertebrae and intervening IV discs –> by a strong tendon to lesser trochanter
Innervation: anterior rami of lumbar nerves
Action: a postural muscle that helps control deviation of the trunk and is active during standing; acting with iliacus in flexing hip joint and in stabilizing this joint
Iliacus
Superior 2/3 of iliac fossa, ala of sacrum, anterior sacroiliac ligaments –> psoas major tendon, lesser trochanter and shaft inferior to it
Innervation: femoral nerve
Action: acting with psoas major in flexing hip joint and in stabilizing this joint
Quadratus lumborum
Medial half of inferior border of 12th rib and tips of lumbar transverse processes –> iliolumbar ligament and internal lip of iliac crest
Innervation: twelfth thoracic and first through fourth ventral rami of lumbar nerves (T12, L1-L4)
Action: alone (unilateral), lateral flexion of vertebral column; together (bilateral), depression of thoracic rib cage
Pectineus
Superior ramus of pubis –> pectineal line of femur just inferior to lesser trochanter
Innervation: femoral nerve
Action: adducts and flexes hip joint; assists with medial rotation of hip joint
Sartorius
ASIS and superior part of notch inferior to it –> superior part of medial surface of tibia
Innervation: femoral nerve
Action: flexes, abducts and laterally rotates hip joint; flexes knee joint
Rectus femoris
AIIS and ilium superior to acetabulum –> via common tendinous (quadriceps tendon) and independent attachments to base of patella; indirectly via patellar ligament to tibial tuberosity
Innervation: femoral nerve
Action: extend knee joint; stabilizes (helps fix in position) hip joint and helps iliopsoas flex hip joint
Vastus lateralis
Greater trochanter and lateral lip of linea aspera –> patella and tibial tuberosity, and tibia and patella via aponeurosis (lateral patellar retinaculum)
Innervation: femoral nerve
Action: extends knee joint
Vastus medialis
Intertrochanteric line and medial lip of linea aspera –> patella and tibial tuberosity, and tibia and patella via aponeurosis (medial patellar retinaculum)
Innervation: femoral nerve
Action: extends knee joint
Vastus intermedius
Anterior and lateral surfaces of shaft of femur –> patella and tibial tuberosity
Innervation: femoral nerve
Action: extends knee joint
Adductor longus
Body of pubis inferior to pubic crest –> middle third of linea aspera
Innervation: obturator nerve
Action: adducts hip joint
Adductor brevis
Body and inferior ramus of pubis –> pectineal line and proximal part of linea aspera
Innervation: obturator nerve
Action: adducts hip joint and to some extent flexes it
Adductor magnus
Inferior ramus of pubis, ramus of ischium (adductor part); ischial tuberosity (hamstring part) –> gluteal tuberosity, linea aspera, medial supracondylar line (adductor part); adductor tubercle (hamstring part)
Innervation: obturator nerve (adductor part), tibial part of sciatic nerve (hamstring part)
Action: adducts hip joint; its adductor part also flexes hip joint and its hamstring part extends it
Gracilis
Body and inferior ramus of pubis –> superior part of medial surface of tibia
Innervation: obturator nerve
Action: adducts hip joint; flexes knee joint and helps rotate it medially
Obturator externus
Margins of obturator foramen and obturator membrane –> trochanteric fossa of femur
Innervation: obturator nerve
Action: laterally rotates hip joint; pulls head of femur into acetabulum holding pelvis steady
Gluteus maximus
Ilium posterior to posterior gluteal line; dorsal surface of sacrum and coccyx; and sacrotuberous ligament –> most fibers end in iliotibial tract, which inserts into lateral condyle of tibia; some fibers insert on gluteal tuberosity of femur
Innervation: inferior gluteal nerve
Action: extends hip joint between flexed and standing positions and assists in its lateral rotation; steadies thigh and assists in rising from sitting position
Gluteus medius
External surface of ilium between anterior and posterior gluteal lines –> lateral surface of greater trochanter
Innervation: superior gluteal nerve
Action: abducts and anterior portions medially rotate hip joint, keep pelvis level when opposite limb is elevated; posterior laterally rotates
Gluteus minimus
External surface of ilium between anterior and inferior gluteal lines –> anterior surface of greater trochanter
Innervation: superior gluteal nerve
Action: abduct and anterior portions medially rotate hip joint and posterior portions laterally rotate the hip joint; keep pelvis level when opposite limb is elevated
Tensor fascia latae
ASIS; anterior part of iliac crest –> iliotibial tract, which attaches to lateral condyle of tibia (gerdy tubercle)
Innervation: superior gluteal nerve
Action: flexes hip joint; acts with gluteus maximus to stabilize the extended knee joint
Superior and inferior gemellus
Ischial tuberosity (inferior); ischial spine (superior) –> medial surface of greater trochanter (trochanteric fossa)
Innervation: nerve to obturator internus (superior), nerve to quadratus femoris (inferior)
Action: laterally rotates extended hip joint; abducts flexed hip joint; steadies femoral head in acetabulum (stabilizes hip joint)
Quadratus femoris
Lateral border of ischial tuberosity –> quadrate tubercle on intertrochanteric crest of femur and area inferior to it
Innervation: nerve to quadratus femoris
Action: laterally rotates hip joint; also pulls femoral head into acetabulum to stabilize hip joint/pelvis
Semitendinosus
Ischial tuberosity –> medial surface of superior part of tibia
Innervation: tibial division of sciatic nerve
Action: extend hip joint; flex knee joint and rotate the leg medially when knee is flexed; when hip and knee are flexed, can extend trunk
Semimembranosus
Ischial tuberosity –> posterior part of medial condyle of tibia; reflected attachment forms oblique popliteal ligament (to lateral femoral condyle)
Innervation: tibial division of sciatic nerve
Action: extend hip joint; flex knee joint and rotate the leg medially when knee is flexed; when hip and knee are flexed, can extend trunk
Biceps femoris
Ischial tuberosity (long head); linea aspera and lateral supracondylar line of femur –> lateral side of head of fibula; tendon is split at this site by fibular collateral ligament
Innervation: tibial division of sciatic nerve (long head), common fibular division of sciatic nerve (short head)
Action: flexes knee joint and rotates it laterally when knee is flexed; extends hip joint
Tibialis anterior
Lateral condyle and superior 2/3 of lateral surface of tibia and interosseous membrane –> medial and inferior surfaces of medial cuneiform and base of 1st metatarsal
Innervation: deep fibular nerve
Action: dorsiflexes ankle; inverts foot; supports medial longitudinal arch of foot
Extensor hallucis longus
Middle part of anterior surface of fibula and interosseous membrane –> dorsal aspect of base of distal phalanx of hallux (big toe)
Innervation: deep fibular nerve
Action: extends great toe; dorsiflexes ankle
Extensor digitorum longus
Lateral condyle of tibia and superior 2/3 of anterior surface of fibula and interosseous membrane –> middle and distal phalanges of lateral 4 digits
Innervation: deep fibular nerve
Action: extends lateral four digits; dorsiflexes ankle
Fibularis tertius
Inferior third of anterior surface of fibula and interosseous membrane –> dorsum of base of 5th metatarsal
Innervation: deep fibular nerve
Action: dorsiflexes ankle; aids in eversion of foot
Fibularis longus
Head and superior 2/3 of lateral surface of fibula –> base of 1st metatarsal and medial cuneiform
Innervation: superficial fibular nerve
Action: evert foot; weakly plantarflexes ankle; supports transverse arch of foot
Fibularis brevis
Middle part of lateral surface of fibula –> dorsal surface of tuberosity of base of 5th metatarsal
Innervation: superficial fibular nerve
Action: plantarflexes and everts foot
Gastrocnemius
Lateral aspect of lateral condyle of femur (lateral head); popliteal surface of femur, superior to medial condyle –> posterior surface of calcaneus via calcaneal tendon
Innervation: tibial nerve
Action: plantarflexes ankle when knee is extended; raises heel during walking; and flexes knee joint
Soleus
Posterior aspect of head of fibula, superior quarter of posterior surface of fibula, soleal line, and medial border of tibia –> posterior surface of calcaneus via calcaneal tendon
Innervation: tibial nerve
Action: plantarflexes ankle; steadies leg on foot
Plantaris
Inferior end of lateral supracondylar line of femur and oblique popliteal ligament –> posterior surface of calcaneus via calcaneal tendon
Innervation: tibial nerve
Action: weakly assists gastrocnemius in plantarflexing ankle; function is probably mainly proprioceptive
Popliteus
Lateral surface of lateral condyle of femur and lateral meniscus (intra-articular; within cavity of knee joint) –> posterior surface of tibia, superior to soleal line
Innervation: tibial nerve
Action: weakly flexes knee and unlocks it by laterally rotating femur on fixed tibia, may also medially rotate tibia of unplanted limb
Flexor hallucis longus
Inferior 2/3 of posterior surface of fibula and inferior part of interosseous membrane –> base of distal phalanx of hallux
Innervation: tibial nerve
Action: flexes great toe at all joints; weakly plantarflexes ankle; supports medial longitudinal arch of foot
Flexor digitorum longus
Medial part of posterior surface of tibia, inferior to soleal line and by a broad tendon to fibula –> distal phalanges
Innervation: tibial nerve
Action: flexes lateral four digits; plantarflexes ankle; supports longitudinal arches of the foot
Tibialis posterior
Interosseous membrane, posterior surface of tibia inferior to soleal line, and posterior surface of fibula –> primarily to tuberosity of navicular; also cuneiforms, cuboid and bases of 2nd-4th metatarsals
Innervation: tibial nerve
Action: plantarflexes ankle; inverts foot; supports medial longitudinal arch of foot
Abductor hallucis
Medial tubercle of tuberosity of calcaneus, flexor retinaculum, and plantar aponeurosis –> medial side of base of proximal phalanx of 1st digit
Innervation: medial plantar nerve
Action: abducts and flexes 1st digit (great toe, hallux) (at MCP joint)
Flexor digitorum brevis
Medial tubercle of tuberosity of calcaneus, plantar aponeurosis, and intermuscular septa –> both sides of middle phalanges of lateral four digits
Innervation: medial plantar nerve
Action: flexes lateral four digits at PIP and MTP joints
Abductor digiti minimi
Medial and lateral tubercles of tuberosity of calcaneus, plantar aponeurosis, and intermuscular septa –> lateral side of base of proximal phalanx of 5th digit
Innervation: lateral plantar nerve
Action: abducts and flexes 5th digit at MTP joint
Quadratus plantae
Medial surface and lateral margin of plantar surface of calcaneus –> posterolateral margin of tendon of flexor digitorum longus
Innervation: lateral plantar nerve
Action: assists flexor digitorum longus in flexing lateral four digits
Lumbricals (foot)
Tendons of flexor digitorum longus –> medial aspect of expansion over lateral four digits
Innervation: medial plantar nerve (medial one), lateral plantar nerve (lateral three)
Action: flex proximal phalanges; extend middle and distal phalanges of lateral four digits
Flexor hallucis brevis
Plantar surfaces of cuboid and lateral cuneiform –> both sides of base of proximal phalanx of 1st digit
Innervation: medial plantar nerve
Action: flexes proximal phalanx of 1st digit
Adductor hallucis
Bases of metatarsals 2-4 (oblique head); plantar ligaments of 3rd-5th metatarsophalangeal joints (transverse head) –> tendons of both heads attach to lateral side of base of proximal phalanx of 1st digit
Innervation: deep branch of lateral plantar nerve
Action: adducts 1st digit; assists in maintaining transverse arch of foot
Flexor digiti minimi brevis (foot)
Base of 5th metatarsal –> base of proximal phalanx of 5th digit
Innervation: superficial branch of lateral plantar nerve
Action: flexes proximal phalanx of 5th digit, thereby assisting with its flexion
Plantar interossei (three muscles)
Bases and medial sides of metatarsals 3-5 –> medial sides of bases of proximal phalanges of 3rd-5th digits
Innervation: lateral plantar nerve
Action: adduct digits (3-5) and flex MTP joints
Dorsal interossei (foot; four muscles)
Adjacent sides of metatarsals 1-5 –> medial side of proximal phalanx of 2nd digit (first); lateral sides of 2nd-4th digits (second to fourth)
Innervation: lateral plantar nerve
Action: abduct digits (2-4) and flex MTP joints
External/internal/innermost intercostals
Inferior border of ribs –> superior border of ribs below
Innervation: intercostal nerve
Action: elevate ribs during forced inspiration (external); during forced inspiration: interosseous part depresses ribs and interchondral part elevates ribs (internal and innermost)
Transversus thoracis
Posterior surface of lower sternum –> internal surface of costal cartilages 2-6
Innervation: intercostal nerve
Action: weakly depresses ribs
Subcostal
Internal surface of lower ribs near their angles –> superior borders of 2nd or 3rd ribs below
Innervation: intercostal nerve
Action: during forced inspiration: interosseous part depresses ribs and interchondral part elevates ribs (same as internal)
Levatores costarum
Transverse processes of C7-T11 –> subadjacent ribs between tubercle and angle
Innervation: posterior rami of C8-T11 nerves
Action: elevate ribs
Serratus posterior superior
Nuchal ligament, spinous processes of C7-T3 vertebrae –> superior borders of 2nd-4th ribs
Innervation: 2nd-5th intercostal nerves
Action: elevate ribs
Serratus posterior inferior
Inferior borders of 8th-12th ribs near their angles –> spinous processes of T11-L2 vertebrae
Innervation: 9th-11th intercostal nerves, subcostal (T12) nerve
Action: depress ribs
External obliques
External surface of ribs 5-12 –> linea alba, pubic tubercle, and anterior half of iliac crest
Innervation: thoraco-abdominal nerves (anterior rami of T7-T11) and subcostal nerve
Action: compress and support abdominal viscera; flex and rotate trunk
Internal obliques
Thoracolumbar fascia, anterior 2/3 of iliac crest, and connective tissue deep to inguinal ligament –> inferior borders of 10th-12th ribs, linea alba, and pubis via conjoint tendon
Innervation: thoraco-abdominal nerves (anterior rami of T7-T11), subcostal nerve and first lumbar nerve
Action: compress and support abdominal viscera; flex and rotate trunk
Transversus abdominus
Internal surfaces of 7th-12th costal cartilages, thoracolumbar fascia, iliac crest, and connective tissue deep to inguinal ligament –> linea alba with aponeurosis of internal oblique, pubic crest, and pubis via conjoint tendon
Innervation: thoraco-abdominal nerves (anterior rami of T7-T11), subcostal nerve and first lumbar nerve
Action: compresses and supports abdominal viscera
Rectus abdominus
Pubic symphisis and pubic crest –> xiphoid process and 5th-7th costal cartilages
Innervation: thoraco-abdominal and subcostal nerves (anterior rami of T7-T12 spinal nerves)
Action: flexes trunk (lumbar vertebrae) and compresses abdominal viscera, stabilizes and controls tilt of pelvis
Splenius capitis
Nuchal ligament, spinous processes of C7-T6 –> superolaterally to mastoid process of temporal bone and lateral 1/3 of superior nuchal line of occipital bone
Innervation: posterior rami of spinal nerves
Action: acting alone: laterally flex neck and rotate head to side of active muscles; acting together: extend head and neck
Splenius cervicis
Nuchal ligament, spinous processes of C7-T6 –> tubercles of transverse processes of C1-C3/C4
Innervation: posterior rami of spinal nerves
Action: acting alone: laterally flex neck and rotate head to side of active muscles; acting together: extend head and neck
Erector spinae
Broad tendon from posterior part of iliac crest, posterior surface of sacrum, sacro-iliac ligaments, sacral and inferior lumbar spinous processes, and supraspinous ligament –> fibers run superiorly to angles of lower ribs and cervical transverse processes (iliocostalis); fibers run superiorly to ribs between tubercles and angles to transverse processes in thoracic and cervical regions and to mastoid process of temporal bone (longissimus); fibers run superiorly to spinous processes in upper thoracic region and to cranium (spinalis)
Action: bilaterally: extend vertebral column and head, as back is flexed, control movement by gradually lengthening fibers; unilaterally: laterally flex vertebral column
Semispinalis
Transverse processes of C4-T10 –> fibers run superomedially to occipital bone and spinous processes in upper thoracic and cervical regions, spanning 4-6 segments
Innervation: posterior rami of spinal nerves
Action: extends head, thoracic, and cervical regions of vertebral column and rotates them contralaterally
Multifidus
Thickest in lumbar region, fibers pass superomedially to entire length of spinous processes of vertebrae 2-4 segments superior to origin
Innervation: posterior rami of spinal nerves
Action: unilateral contraction rotates to contralateral side; stabilizes vertebrae during local movements of vertebral column
Brachioradialis
Proximal 2/3 of lateral supracondylar ridge of humerus –> lateral surface of distal end of radius proximal to styloid process
Innervation: radial nerve
Action: relatively weak flexion of elbow, maximal with midpronated forearm
Extensor carpi radialis longus
Lateral supracondylar ridge of humerus –> dorsal aspect of base of 2nd metacarpal
Innervation: radial nerve
Action: extends and radially deviates wrist
Extensor carpi radialis brevis
Lateral epicondyle of humerus –> dorsal aspect of 3rd metacarpal
Innervation: deep branch of radial nerve
Action: extends and radially deviates wrist; also active during fist clenching
Extensor digitorum
Lateral epicondyle of humerus –> extensor expansions of middle four fingers
Innervation: posterior interosseous nerve from deep branch of radial nerve
Action: extend wrist; extend middle four MCP joints (primarily) and IP joints (secondarily)
Extensor digiti minimi
Lateral epicondyle of humerus –> extensor expansion of 5th finger
Innervation: posterior interosseous nerve from deep branch of radial nerve
Action: extends wrist and 5th finger at MCP joint (primarily) and IP joints (secondarily)
Extensor carpi ulnaris
Lateral epicondyle; posterior border of ulna via a shared aponeurosis –> dorsal aspect of base of 5th metacarpal
Innervation: posterior interosseous nerve from deep branch of radial nerve
Action: ulnar deviation and wrist extension (also active during fist clenching)
Supinator
Lateral epicondyle, radial collateral and anular ligaments, supinator fossa, and crest of ulna –> lateral, posterior, and anterior surfaces of proximal third of radius
Innervation: deep branch of radial nerve
Action: supinates forearm; rotates radius to turn palm anteriorly or superiorly (if elbow is flexed)
Abductor pollicis longus
Posterior surface of proximal halves of ulna, radius, and interosseous membrane –> base of 1st metacarpal
Innervation: posterior interosseous nerve; from deep branch of radial nerve
Action: extends wrist; abducts and extends thumb at CMC joint
Extensor pollicis longus
Posterior surface of middle third of ulna and interosseous membrane –> dorsal aspect of base of distal phalanx of thumb
Innervation: posterior interosseous nerve; from deep branch of radial nerve
Action: extends wrist; extends IP, MCP, and CMC joints
Extensor pollicis brevis
Posterior surface of distal third of radius and interosseous membrane –> dorsal aspect of base of proximal phalanx of thumb
Innervation: posterior interosseous nerve; from deep branch of radial nerve
Action: extends wrist; extends MCP and CMC joints
Extensor indicis
Posterior surface of distal third of ulna and interosseous membrane –> extensor expansion of 2nd finger
Innervation: posterior interosseous nerve; from deep branch of radial nerve
Action: extends wrist; extends 2nd finger (enabling its independent extension)
Pronator teres
Coronoid process of ulna (ulnar head); medial epicondyle (humeral head) –> middle convexity of lateral surface of radius
Innervation: median nerve
Action: pronates and flexes forearm
Flexor carpi radialis
Medial epicondyle of humerus –> base of 2nd (3rd) metacarpal
Innervation: median nerve
Action: flexes and radially deviates wrist
Palmaris longus
Medial epicondyle –> distal half of flexor retinaculum, palmar aponeurosis
Innervation: median nerve
Action: flexes wrist and tenses palmar aponeurosis
Flexor carpi ulnaris
Olecranon and posterior border of ulna (via aponeurosis) –> base of 5th metacarpal
Innervation: ulnar nerve
Action: wrist flexion and ulnar deviation
Flexor digitorum superficialis
Medial epicondyle and coronoid process of ulna (humeroulnar head); oblique line of radius (radial head) –> shafts (bodies) of middle phalanges of medial four digits
Innervation: median nerve
Action: wrist flexion; flexes middle four PIP joints and MCP joints
Flexor digitorum profundus
Proximal 3/4 of medial and anterior surfaces of ulna and interosseous membrane –> bases of distal phalanges of digits 2-5
Innervation: median nerve; anterior interosseous branch (lateral part), ulnar nerve (medial part)
Action: wrist flexion; flexes middle four DIP, PIP, and MCP joints
Flexor pollicis longus
Anterior surface of radius and adjacent interosseous membrane –> base of distal phalanx of thumb
Innervation: anterior interosseous nerve from median nerve
Action: wrist flexion; flexes IP and MCP joint of thumb
Pronator quadratus
Distal surface of anterior surface of ulna –> distal surface of anterior surface of radius
Innervation: anterior interosseous nerve from median nerve
Action: pronates forearm; deep fibers bind ulna and radius together
Biceps brachii
Tip of coracoid process of scapula (short head); supraglenoid tubercle of scapula (long head) –> tuberosity of radius and fascia of forearm via bicipital aponeurosis
Innervation: musculocutaneous
Action: supinates forearm and flexes elbow when supinated; flexes shoulder; short head resists dislocation
Brachialis
Distal half of anterior surface of humerus –> coronoid process and tuberosity of ulna
Innervation: musculocutaneous
Action: flexes elbow
Coracobrachialis
Tip of coracoid process of scapula –> middle third of medial humerus
Innervation: musculocutaneous
Action: helps flex and adduct the shoulder; resists dislocation
Triceps brachii
Infraglenoid tubercle of scapula (long head); posterior surface of humerus, superior to radial groove (lateral head); posterior surface of humerus, inferior to radial groove (medial head) –> proximal end of olecranon of ulna and fascia of forearm
Innervation: radial nerve
Action: chief extensor of elbow; long head extends shoulder joint and resists dislocation (especially important during abduction)
Anconeus
Lateral epicondyle of humerus –> lateral surface of olecranon and superior part of posterior surface of ulna
Innervation: radial nerve
Action: assists triceps in extending elbow joint; stabilizes elbow joint; abducts ulna during pronation
Deltoid
Lateral third of clavicle (anterior); acromion (middle); spine of scapula (posterior) –> deltoid tuberosity of humerus
Innervation: axillary nerve
Action: clavicular (anterior): flexes and medially rotates shoulder; acromial (middle): abducts shoulder; spinal (posterior): extends and laterally rotates shoulder
Supraspinatus
Supraspinous fossa of scapula –> superior facet of greater tubercle of humerus
Innervation: suprascapular nerve
Action: initiates and assists deltoid in abduction of shoulder joint and acts with other rotator cuff muscles
Infraspinatus
Infraspinous fossa of scapula –> middle facet of greater tubercle of humerus
Innervation: suprascapular nerve
Action: laterally rotates shoulder joint; help hold humeral head in glenoid cavity of scapula
Teres minor
Middle part of lateral border of scapula –> inferior facet of greater tubercle of humerus
Innervation: axillary nerve
Action: laterally rotates shoulder joint; help hold humeral head in glenoid cavity of scapula
Teres major
Inferior part of lateral border of scapula posterior surface of inferior angle of scapula –> medial lip of bicipital groove
Innervation: lower subscapular nerve
Action: adducts and medially shoulder
Subscapularis
Subscapular fossa (most of anterior surface of scapula) –> lesser tubercle of humerus
Innervation: upper and lower subscapular nerves
Action: medially rotates and adducts shoulder joint; helps hold humeral head in glenoid cavity
Trapezius
Medial third of superior nuchal line, external occipital protuberance, nuchal ligament, spinous processes of C7-T12 –> lateral third of clavicle (upper); acromion (middle); spine of scapula (lower)
Innervation: spinal accessory nerve (CNXI: motor fibers) and C3, C4 spinal nerves (pain and proprioceptive fibers)
Action: descending (superior): elevates scapula; ascending (inferior): depresses scapula; middle: retracts scapula; descending and ascending parts act together to rotate glenoid cavity superiorly
Latissimus dorsi
Spinous processes of inferior six thoracic vertebrae, thoracolumbar fascia, iliac crest, and inferior three or four ribs –> floor of bicipital groove
Innervation: thoracodorsal
Action: extends, adducts, and medially rotates shoulder joint; raises body toward arms during climbing
Levator scapulae
Posterior tubercle of transverse processes of C1-C4 vertebrae –> medial border of scapula, superior to root of spine
Innervation: dorsal scapular and cervical (C3, C4) spinal nerves
Action: elevates scapula and tilts its glenoid cavity inferiorly by rotating scapula
Rhomboid minor
Nuchal ligament, spinous processes of C7 and T1 –> triangular area at medial end of spine of scapula
Innervation: dorsal scapular nerve
Action: retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall
Rhomboid major
Spinous processes of T2-T5 vertebrae –> medial border of scapula from level of spine to inferior angle
Innervation: dorsal scapular nerve
Action: retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall
Rectus capitis posterior minor
Posterior tubercle of posterior arch of atlas –> medial inferior nuchal line
Innervation: suboccipital nerve
Action: extends skull on C1; stabilizes skull
Rectus capitis posterior major
Spinous process of axis –> inferior nuchal line (just lateral to minor)
Innervation: suboccipital nerve
Action: head extension (bilaterally); ipsilateral rotation (unilaterally)
Obliquus capitis inferior
Spinous process of axis –> lateral mass/transverse process of atlas
Innervation: suboccipital nerve
Action: ipsilateral neck rotation
Obliquus capitis superior
Lateral mass/transverse process of atlas –> lateral half of inferior nuchal line
Innervation: suboccipital nerve
Action: extend skull on C1 (bilaterally); contralateral rotation (unilaterally)
Opponens pollicis
Flexor retinaculum and tubercles of scaphoid and trapezium –> lateral side of 1st metacarpal
Innervation: recurrent branch of median nerve
Action: oppose thumb; draws 1st metacarpal medially to center of palm and rotates it medially
Abductor pollicis brevis
Flexor retinaculum and tubercles of scaphoid and trapezium –> lateral side of base of proximal phalanx of thumb
Innervation: recurrent branch of median nerve
Action: abducts thumb; helps oppose it
Flexor pollicis brevis
Flexor retinaculum and tubercles of scaphoid and trapezium –> lateral side of base of proximal phalanx of thumb
Innervation: recurrent branch of median nerve (superficial head), deep branch of ulnar nerve (deep head)
Action: flexes thumb at MCP joint
Adductor pollicis
Bases of 2nd and 3rd metacarpals, capitate, adjacent carpals (oblique head); anterior surface of shaft of 3rd metacarpal (transverse head) –> medial side of base of proximal phalanx of thumb
Innervation: deep branch of ulnar nerve
Action: adducts thumb toward lateral border of palm
Abductor digiti minimi (hand)
Pisiform –> medial side of base of proximal phalanx of 5th finger
Innervation: deep branch of ulnar nerve
Action: abducts 5th finger; assists in flexion of MCP joint
Flexor digiti minimi brevis (hand)
Hook of hamate and flexor retinaculum –> medial side of base of proximal phalanx of 5th finger
Innervation: deep branch of ulnar nerve
Action: flexes 5th MCP joint
Opponens digiti minimi
Hook of hamate and flexor retinaculum –> medial border of 5th metacarpal
Innervation: deep branch of ulnar nerve
Action: draws 5th metacarpal anterior and rotates it, bringing 5th finger into opposition with thumb
Lumbricals (hand)
Lateral two tendons of flexor digitorum profundus (as unipennate muscles) (1 and 2); medial three tendons of flexor digitorum profundus (as bipennate muscles) (3 and 4) –> lateral sides of extensor expansion of 2nd-5th fingers
Innervation: median nerve (1 and 2), deep branch of ulnar nerve (3 and 4)
Action: flex MCP joints; extend IP joints of 2nd-5th fingers
Dorsal interossei (1-4) (hand)
Adjacent sides of two metacarpals (as bipennate muscles) –> bases of proximal phalanges; extensor expansions of 2nd-4th fingers
Innervation: deep branch of ulnar nerve
Action: abduct 2nd-4th fingers from axial line; act with lumbricals in flexing MCP joints and extending IP joints
Palmar interossei (1-3)
Palmar surfaces of 2nd, 4th, and 5th metacarpals (as unipennate muscles) –> bases of proximal phalanges; extensor expansions of 2nd, 4th, and 5th fingers
Innervation: deep branch of ulnar nerve
Action: adduct 2nd, 4th, and 5th fingers towards axial line; assists lumbricals in flexing MCP joints and extending IP joints
Pectoralis major
Anterior surface of medial half of clavicle (clavicular head); anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle (sternal head) –> lateral lip of intertubercular groove
Innervation: lateral and medial pectoral nerve
Action: flex shoulder (clavicular head); adduction, horizontal adduction, extension and medial rotation of shoulder (sternal head)
Pectoralis minor
3rd-5th ribs near their costal cartilages –> medial border and superior surface of coracoid process of scapula
Innervation: medial pectoral nerve (and lateral)
Action: stabilizes scapula (pulling inferiorly and anteriorly against thoracic wall) and elevates ribs during inspiration
Subclavius
Junction of 1st rib and its costal cartilage –> inferior surface of middle third of clavicle
Innervation: subclavian nerve
Action: depression of clavicle, elevation of 1st rib
Serratus anterior
External surfaces of lateral parts of ribs 1-8 –> anterior surface of medial border of scapula
Innervation: long thoracic nerve
Temporalis
Temporal lines on the parietal bone of the skull and the superior temporal surface of the sphenoid bone –> coronoid process of the mandible and retromolar fossa
Innervation: anterior trunk of mandibular nerve (CNV)
Action: elevates mandible (closing jaw); posterior fibers retract mandible
Masseter
Zygomatic arch and maxillary process of zygomatic bone –> angle and lateral surface of ramus of mandible, coronoid process
Innervation: anterior trunk of mandibular nerve (CNV)
Action: elevates mandible
Medial Pterygoid
Medial side of lateral pterygoid plate behind the upper teeth (deep head); pyramidal process of palatine bone and maxillary tuberosity (superficial head) –> medial angle of the mandible
Innervation: anterior trunk of mandibular nerve (CNV)
Action: acts synergistically with masseter to elevate mandible; contributes to protrusion; alternate unilateral activity produces smaller grinding movements
Lateral Pterygoid
Infratemporal surface of sphenoid bone (superior head); lateral pterygoid plate (inferior head) –> anterior side of the condyle (superior head); pterygoid fovea (inferior head)
Innervation: anterior trunk of mandibular nerve (CNV)
Action: bilaterally: protracts mandible and depresses chin; unilaterally, swings jaw toward contralateral side; alternate unilateral contraction produces larger lateral chewing movements
Sternocleidomastoid
Manubrium and medial portion of the clavicle –> mastoid process of the temporal bone, superior nuchal line
Innervation: spinal accessory nerve (CNXI; motor), C2 and C3 nerves (pain and proprioception)
Action: unilateral: same side lateral flexion and rotation so face is turned superiorly to opposite side; bilateral: extends neck at atlanto-occipital joints, flexes cervical vertebrae so chin approaches manubrium, or extends superior cervical vertebrae while flexing inferior cervical vertebrae so chin is thrust forward while head is level; may assist pump-handle action by elevating manubrium and medial end of clavicles with cervical vertebrae fixed
