Lower Extremity: Muscles

Question 0

Rectus Femoris

Answer 0

O: straight head: AIIS; reflected head: on rim, superior to acetabulum
I: blends into common quadriceps tendon and inserts on tibia tuberosity by way of patellar tendon
A: flexion of the hip, extension of the knee
N: femoral nerve (L2-4)

Question 1

Sartorius

Answer 1

O: ASIS & notch inferior to ASIS
I: Pes anserine (middle & most superior) on the superior medial aspect of the anterior surface of the tibia
A: flexion of the hip, abduction of the hip, external rotation of the hip, flexion of the knee, internal rotation of tibia (when hip/knee are flexed)
N: femoral nerve (L2-4)

Question 2

Vastus Lateralis

Answer 2

O: proximal 1/2 of intertrochanteric line; anterior, inferior border of greater trochanter; lateral lip of gluteal tuberosity; lateral lip of linea aspera; lateral intermuscular septum
I: common quadriceps tendon to tibia tuberosity
A: extension of the knee
N: femoral nerve (L2-4)

Question 3

Vastus Intermedius

Answer 3

O: proximal 2/3 of anterior and lateral shaft of femur; distal 1/2 of linea aspera (as it approaches the lateral lip)
I: quadriceps tendon to tibial tuberosity by way of patellar ligament
A: extension of the knee
N: fermoral nerve (L2-4)

Question 4

Vastus Medialis

Answer 4

O: distal 1/2 of intertrochanteric line; approaches medial lip of linea aspera; proximal 1/2 of medial supracondylar ridge; tendons of adductor longus + magnus; medial intermuscular septum
I: blends into quadriceps tendon to tibial tuberosity by way of patellar ligament
A: extension of knee
N: femoral nerve (L2-4)

Question 5

Psoas Major

Answer 5

O: anterior aspect of vertebral bodies T12-L5; intervertebral disks of T12 thru L4; anterior aspect of the transverse processes of T12-L5
I: lesser trochanter of femur
A: flexion of hip, external rotation of hip, flexion of lumbar spine (bilateral contraction), side bend vertebral column (unilat contraction with foot fixed)
N: anterior rami of L1-4

Question 6

Psoas Minor

Answer 6

O: bodies of T12 and L1
I: arcuate line; iliac fascia
A: flexion of trunk
N: anterior rami of L1-2

Question 7

Iliacus

Answer 7

O: superior 2/3 of iliac fossa; iliolumbar, lumbosacral and anterior sacroiliac ligaments; anterior and lateral aspect of the ala of sacrum
I: lesser trochanter of femur
A: flexion of hip, external rotation of hip, flexion of trunk
N: femoral nerve (L2-4)

Question 8

Piriformis

Answer 8

O: anterior surface of sacrum between pelvic foramina; anterior aspect of sacroiliac joint
I: superior aspect of the greater trochanter
A: external rotation of the hip, abduction of the hip (when hip is flexed), stabilizes femoral head into acetabulum
N: nerve to piriformis (S1-2)

Question 9

Obturator Externus

Answer 9

O: superior & inferior pubic ramus
I: superior aspect of trochanteric fossa
A: external rotation of hip, abduction of hip (when hip is flexed), stabilizes head of femur to acetabulum
N: posterior branch of obturator nerve (L2-4)

Question 10

Obturator Internus

Answer 10

O: obturator membrane & posterior surface of superior and inferior pubic ramus
I: superior greater trochanter (lies inferior to piriformis insertion)
A: external rotation of hip, abduction of hip (when hip is flexed), stabilizes head of femur to acetabulum
N: nerve to obturator internus (L5, S1-2)

Question 11

Gemellus Superior

Answer 11

O: posterior aspect of ischial spine
I: superior aspect of greater trochanter (just inferior to piriformis)
A: external rotation of hip, abduction of hip (when hip flexed), stabilized head of femur to acetabulum
N: nerve to obturator internur (L5, S1-2)

Question 12

Gemellus Inferior

Answer 12

O: superior & posterior aspect of ischial tuberosity
I: superior aspect of greater trochanter (just inferior to piriformis)
A: external rotation of hip, abduction of hip (when hip flexed), stabilizes head of femur to acetabulum
N: nerve to quadratus femoris (L4-5, S1)

Question 13

Quadratus Femoris

Answer 13

O: lateral border of ischial tuberosity
I: quadrate tubercle of femur (in intertrochanteric crest)
A: external rotation of hip, abduction of hip (when hip flexed)
N: nerve to quadratus femoris (L4-5, S1)

Question 14

Gluteus Maximus

Answer 14

O: on ilium, posterior to posterior gluteal line; upper half of sacrotuberous ligament; posterior part of sacrum & coccyx
I: superficial: iliotibial tract; deep: gluteal tuberosity
A: hip extension and external rotation (all fibers), hip abduction (upper fibers only), hip adduction (lower fibers only)
N: inferior gluteal nerve (L5, S1-2)

Question 15

Tensor Fascia Latae

Answer 15

O: anterior aspect of lateral lip of iliac crest; posterior to ASIS
I: iliotibial tract
A: hip flexion, hip abduction, knee extension
N: superior gluteal nerve (L4-5, S1)

Question 16

Gluteus Minimus

Answer 16

O: superior border: anterior gluteal line; inferior border: inferior gluteal line (below AIIS); posterior border: greater sciatic notch; anterior border: AIIS
I: anterior aspect on greater trochanter; anterior aspect of hip joint capsule
A: Flexion of hip, abduction of hip, interior rotation of hip
N: superior gluteal nerve (L4-5, S1)

Question 17

Gluteus Medius

Answer 17

O: inferior border: anterior gluteal line; posterior border: posterior gluteal line; superior border: iliac crest
I: oblique ridge on lateral surface of greater trochanter
A: abduction of hip (all fibers), flexion & internal rotation of hip (anterior fibers), extension & external rotation of hip (posterior fibers), prevents pelvis from dropping in stance
N: superior gluteal nerve (L4-5, S1)

Question 18

Gracilis

Answer 18

O: inferior 1/2 of symphysis pubis; medial margin of inferior ramus of pubic bone
I: superior part of medial surface of tibial (proximal to insertion of semitend & lateral to insertion of sartorius)
A: adduction of hip, flexion of knee, internal rotation of knee (when knee flexed), stabilize medial aspect of knee (when knee extended)
N: obturator nerve (L2-4)

Question 19

Pectineus

Answer 19

O: superior ramus of pubis; pectin pubis (between pubic tubercle & iliopubic eminence)
I: pectineal line
A: adduction of hip, flexion of hip, internal rotation of hip
N: femoral nerve (L2-4)

Question 20

Adductor Longus

Answer 20

O: anterior surface of pubis at junction of crest and symphysis
I: middle 1/3 of medial lip of linea aspera of femur
A: adduction of hip, flexion of hip
N: obturator nerve (L2-4) - anterior branch

Question 21

Adductor Brevis

Answer 21

O: body and inferior ramus of pubis
I: distal 2/3 of pectineal line; proximal 1/2 of medial lip of linea aspera of the femur (posterior to add. longus)
A: adduction of the hip, flexion of the hip, internal rotation of the hip
N: obturator nerve (L2-4)

Question 22

Adductor Magnus

Answer 22

O: adductor part: inferior ramus of pubis & ramus of ischium; hamstring part: ischial tuberosity
I: adductor part: medial to gluteal tuberosity, middle of linea aspera & medial supracondylar line; hamstring part: adductor tubercle
A: adduction of hip (all); flexion & internal rotation of hip (adductor part); extension & external rotation of hip (hamstring part)
N: adductor part: obturator nerve (L2-4); hamstring part: tibial aspect of sciatic nerve (L4-5, S1)

Question 23

Biceps Femoris

Answer 23

O: long head: distal part of sacrotuberous ligament, posterior inferior part of ischial tuberosity & common tendon to semiteninosus; short head: lateral lip of linea aspera (between add. magnus & vastus lateralis), proximal 2/3 of sypracondylar line & lateral intramuscular septum
I: tendon is split by LCL, lateral side of head of fibula, lateral condyle of tibia & fibular collateral ligament
A: flexion of knee, external rotation of knee, extension of knee (long head only), hip extension (long head only), external rotation of hip (long head only)
N: long head: tibial branch of sciatic nerve (L5, S1-3); short head: peroneal branch of sciatic nerve (L5, S1-2)

Question 24

Semitendinosus

Answer 24

O: distal part of sacrotuberous ligament, posterior inferior part of ischial tuberosity & common tendon I: proximal part of medial surface of body of tibia, pes anserine group & deep fascia of leg A: flexion of knee, internal rotation of knee, extension of hip, internal rotation of hip N: tibial branch of sciatic nerve (L4-5, S1-2)

Question 25

Semimembranosus

Answer 25

O: distal part of sacrotuberous ligament, posterior inferior part of ischial tuberosity & common tendon I: posterior medial aspect of medial condyle of tibia A: flexion of knee, internal rotation of knee, extension of hip, internal rotation of hip, tilts the pelvis posteriorly N: tibial branch of sciatic nerve (L4-5, S1-2)

Question 26

Tibialis Anterior

Answer 26

O: lateral condyle of tibia, proximal 1/2 of lateral surface of tibia, anterior surface of interosseous membrane, deep fascia of leg I: medial and plantar surfaces of medial cuneiform & 1st metatarsal A: dorsiflexion at talocrural joint, inversion at subtalar joint, helps stabilize medial longitudinal arch of foot N: deep fibular nerve (L4-S2)

Question 27

Extensor Hallucis Longus

Answer 27

O: lower 1/2 of anterior surface of interrosseous membrane; middle 1/2 of anterior surface of fibula I: dorsal surface of base of distsal phalanx of 1st metatarsal A: extends interphalangeal & metaphalangeal joint, dorsiflexion at talocrural joint, inversion at subtalar joint N: deep fibular nerve (L4-S2)

Question 28

Extensor Digitorum Longus

Answer 28

O: anterior intermuscular septum; lateral condyle of tibia; proximal 1/2 of anterior surface of fibula; proximal 1/2 of interosseous membrane I: base of distal phalanx on dorsal surface & into dorsal digital expansion (extensor hoods) of digits 2-5 A: extension of metatarsal phalangeal joint, extension of interphalangeal joint (PIP & DIP), extension of talocrural joint N: deep fibular nerve (L4-S2)

Question 29

Fibularis Tertius

Answer 29

O: longer 1/3 of medial surface of fibula I: dorsal aspect of 5th metatarsal A: dorsiflexion at talocrural joint, eversion of subtalar joint N: deep fibular nerve (L4-S2)

Question 30

Peroneus Longus (Fibularis Longus)

Answer 30

O: upper 2/3 of lateral surface of fibula; lateral surface of the head of the fibular; anterior intermuscular septum I: base of plantar surface of lateral cuneiform; head of distal aspect of plantar surface of medial cuneiform; plantar surface of base of 1st metatarsal A: eversion of subtalar joint, plantar flexion N: superficial fibular nerve (L4-S2)

Question 31

Fibularis Brevis

Answer 31

O: distal 2/3 of lateral surface of fibula I: base (styloid process) of 5th metatarsal A: eversion of subtalar joint, plantar flexion N: superficial fibular nerve (L4-S2)

Question 32

Gastrocnemius

Answer 32

O: posterior aspect of medial & lateral femoral condyles I: calcaneal (Achilles) tendon on posterior surface of calcaneus A: plantar flexion of talocrural, knee flexion N: tibial nerve of sciatic branch (L4-S3)

Question 33

Soleus

Answer 33

O: fibular: posterior aspect of fibular head & proximal 2/3 of posterior surface of fibula; tibia: inferior to soleal line & middle 1/3 of medial border of tibia (inferior to soleal line) I: calcaneal (Achilles) tendon on posterior surface of calcaneus A: plantar flexion of talocrural joint N: tibial nerve of sciatic branch (L4-S3)

Question 34

Plantaris

Answer 34

O: distal 1/2 of lateral supracondylar ridge; popliteal surface of femur I: posterior surface of calcaneus (medial to Achilles tendon insertion) A: plantar flexion of talocrural joint, flexion of knee, inversio of subtalar joint N: tibial nerve of sciatic branch (L4-S3)

Question 35

Popliteus

Answer 35

O: anterior aspect of lateral aspect of femur & lateral meniscus I: posterior surface of proximal tibia (above soleal line) A: internal rotation of tibia (non-weight bearing, foot not fixed), external rotation of femur on tibia (during weight bearing) N: tibial nerve of sciatic branch (L4-S3)

Question 36

Flexor Hallucis Longus

Answer 36

O: distal 2/3 of posterior surface of fibula; inferior aspect of posterior aspect of interosseous membrane; transverse intermuscular septum I: plantar surface of base of distal phalanx of 1st metatarsal A: flexion of interphalangeal & metatarsophalangeal joints of 1st, plantar flexion of talocrural joint, inversion of subtalar joint N: tibial nerve of sciatic branch (L4-S3)

Question 37

Flexor Digitorum Longus

Answer 37

O: posterior surface of tibia in between soleal line and vertical ridge I: base of distal phalanx on plantar surface of 2-5th A: flexion of DIP, PIP & MP; plantar flexion of talocrural; inversion of subtalar joint N: tibial nerve of sciatic branch (L4-S3)

Question 38

Tibialis Posterior

Answer 38

O: posterior surface of tibia (lateral to vertical ridge, inferior to soleal line); posterior aspect of interosseous membrane; proximal 2/3 of medial surface of tibula; transverse intermuscular septum) I: plantar surface of navicular tiberosity; plantar surface of all cuneiforms; medial aspect of plantar surface of cuboid; plantar surface of bases of 2-4 A: inversion of subtalar joint, plantar flexio of talocrural joint, assists with medial longitudinal arch of foot N: tibial nerve of sciatic branch (L4-S3)

Question 39

Extensor Digitorum Brevis

Answer 39

O: dorsal lateral aspect of calcaneus (just infront of sinus tarsi); lateral talocrural ligament I: 1st: head of proximal phalanx of big toe (EXTENSOR HALLUCIS BREVIS); 2nd-5th: head of proximal phalanx A: extension of MP, DIP & PIP N: deep fibular nerve (L4-S2)

Question 40

Abductor Hallucis

Answer 40

O: medial process of calcaneus, flexor retinaculum I: medial side of medial sesamoid bone; medial side of proximal phalanx A: abduction of big toe, flexion of MP joint, adduction of forefoot N: medial plantar nerve (S2-3)

Question 41

Flexor Digitorum Brevis

Answer 41

O: medial process on calcaneal tuberosity; plantar aponeurosis (plantar fascia) I: either side of plantar surface of middle phalanx A: flexion of MP & PIP N: medial plantar nerve (S2-3)

Question 42

Abductor Digiti Minimi

Answer 42

O: medial and lateral processes of calcaneal tuberosity I: lateral aspect of base of proximal phalanx of 5th A: abduction of 5th toe, flexion of MP joint of 5th N: lateral plantar nerve (S2-3)

Question 43

Flexor Digitorum Accessories (Quadratus Plantae)

Answer 43

O: medial: medial surface of calcaneus & medial border of long plantar ligament; lateral: lateral surface of calcaneus & lateral border of long plantar ligament I: lateral side of flexor digitorum longus tendon (before it divides) A: flexion of DIP, PIP & MP N: lateral plantar nerve (S2-3)

Question 44

Lumbricals

Answer 44

O: flexor digitorum longus tendons (1st: medial aspect; 2nd-4th: lateral and medial aspect) I: dorsal digitorum expansion (extensor hoods) A: extension of DIP, PIP & MP; flexion of MP N: 2nd-3rd: medial plantar nerve (S2-3); 4th-5th: lateral plantar nerve (S2-3)

Question 45

Flexor Hallucis Brevis

Answer 45

O: lateral: plantar surface of cuboid just proximal to ridge; medial: tendon of tibialis posterior I: plantar surface of base of proximal phalanx & lateral/medial sesamoid bones A: flexion of MP joint N: medial plantar nerve (S2-3)

Question 46

Adductor Hallucis

Answer 46

O: transverse: plantar plates of 3-5 of MP joints; oblique: bases of metatarsals 2-4 I: common tendon attaches to lateral sesamoid bone & lateral surface of proximal phalanx of big toe A: adduction of 1st toe, flexion of MP of 1st toe N: lateral plantar nerve (S2-3)

Question 47

Flexor Digitorum Minimi

Answer 47

O: plantar base of 5th metatarsal I: lateral side of base of proximal phalanx A: flexion of MP of 5th toe N: lateral plantar nerve (S2-30

Question 48

Dorsal Interossei

Answer 48

O: adjacent parts on our metatarsals I: 1st: medial aspect of base of proximal phalanx; 2nd-3rd: lateral side of base of proximal phalanx; 4th: lateral side of base of proximal phalanx & medial side of 5th A: abduction of toes (2-4) N: lateral plantar nerve (S2-3)

Question 49

Plantar Interossei

Answer 49

O: bases of 3rd to 5th metatarsals I: medial surface of base of proximal phalanx & dorsal digital expansion A: adduction of toes (3-5), extension of toes (3-5) N: lateral plantar nerve (S2-3)