Lower Extremities Summary

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Anterior femoral muscles
1. Articularis genu
  attachments - from anterior distal femoral shaft to proximal synovial membrane of knee
  actions - retracts the suprapatellar bursa during leg extension
  innervation - femoral nerve
2. Iliacus
  attachments - from iliac fossa, iliac crest & sacrum to the lesser trochanter of the femur
  actions - flexes thigh and stabilizes hip joint
  innervation - femoral nerve & lumbar plexus branches
3. Psoas (L. muscle of the loin)
  attachments - from anterior lumbar transverse processes vertebral bodies & discs to the lesser trochanter of the femur
  actions - flexes thigh and stabilizes hip joint
  innervation - ventral rami L1-3
4. Rectus femoris (L2, 3, 4) (L. straight)
  attachments - from anterior inferior iliac spine and groove superior to the acetabulum to the base of the patella
  actions - flexes thigh, and extends leg
  innervation - femoral nerve
5. Sartorius (L. sartor, a tailor)
  attachments - from anterior superior iliac spine to the medial aspect of the proximal tibia
  actions - flexes, abducts & laterally rotates thigh, and flexes leg
  innervation - femoral nerve
6. Tensor fasciae latae
  attachments - from anterior superior iliac spine & adjacent iliac crest to iliotibial tract
  actions - abducts, flexes & medially rotates thigh, and assists in maintaining extended leg
  innervation - superior gluteal nerve
7. Vastus intermedius (L2, 3, 4)
  attachments - from the anterior aspect of the proximal 2/3rds of the femoral shaft to the base of the patella
  actions - extends leg
  innervation - femoral nerve
8. Vastus lateralis (L2, 3, 4)
  attachments - from lateral/posterior femur to the lateral border of the patella
  actions - extends leg
  innervation - femoral nerve
9. Vastus medialis (L2, 3, 4)
  attachments - from medial/posterior femur to the medial border of the patella
  actions - extends leg
  innervation - femoral nerve
Medial Femoral Muscles
1. Adductor brevis
  attachments - from inferior pubic ramus to proximal posterior femur
  actions - adducts thigh
  innervation - obturator nerve
2. Adductor longus
  attachments - from pubic crest to midshaft posterior femur
  actions - adducts & flexes thigh
  innervation - obturator nerve
3. Adductor magnus
  attachments - from ischial tuberosity to posterior femur & adductor tubercle
  actions - adducts (adductor part) & extends (hamstring part) thigh
  innervation - obturator nerve (adductor region) & tibial division (hamstring region) of the sciatic nerve
4. Gracilis (L. scanty)
  attachments - from inferior pubic ramus to the proximal, medial tibia
  actions - flexes & medially rotates the leg, and adducts thigh
  innervation - obturator nerve
5. Pectineus
  attachments - from superior pubic ramus to proximal posterior femoral shaft
  actions - adducts & flexes thigh
  innervation - femoral nerve & accessory obturator nerve when this nerve is present
6. Obturator externus
  attachments - from the external aspect of rim of obturator foramen to the trochanteric fossa
  actions - laterally rotates thigh
  innervation - obturator nerve
Muscles of the Gluteal Region
1. Gemellus inferior (L. twin)
  attachments - from the ischial tuberosity to the obturator internus tendon
  actions - laterally rotates thigh
  innervation - nerve to the quadratus femoris
2. Gemellus superior
  attachments - from the ischial spine to the obturator internus tendon
  actions - laterally rotates thigh
  innervation - nerve to the obturator internus
3. Gluteus maximus
  attachments - from the aponeurosis of the erector spinae, sacrum, sacrotuberous ligament & posterior gluteal line (inominate) to gluteal tuberosity of the femur & the iliotibial tract
  actions - extends & laterally rotates thigh, & tenses fascia lata (iliotibial tract)
  innervation - inferior gluteal nerve
4. Gluteus medius
  attachments - from the external iliac surface to the lateral aspect of the greater trochanter
  actions - abducts & medially rotates thigh; and keeps the pelvis level when opposite leg is raised
  innervation - superior gluteal nerve
5. Gluteus minimis
  attachments - from the external iliac surface to the anterolateral aspect of the greater trochanter
  actions - abducts & medially rotates thigh; and keeps the pelvis level when opposite leg is raised
  innervation - superior gluteal nerve
6. Obturator internus
  attachments - from the anterolateral wall of the pelvis & obturator membrane to the medial surface of the greater trochanter
  actions - laterally rotates thigh
  innervation - nerve to the obturator internus
7. Piriformis
  attachments - from the anterolateral sacrum & posterior inferior iliac spine to the upper border of the greater trochanter
  actions - abducts & laterally rotates thigh
  innervation - branches of the lumbosacral plexus
8. Quadratus femoris
  attachments - from the ischial tuberosity to the quadrate tubercle of the femur
  actions - laterally rotates thigh
  innervation - nerve to the quadratus femoris
Posterior Femoral Muscles
1. Biceps femoris
  attachments - from the ischial tuberosity (long head) & distal posterior/lateral femur (short head) to the fibular head
  actions - flexes leg (both heads) & extends thigh (long head only)
  innervation - tibial (long head) & peroneal (short head) divisions of the sciatic nerve
2. Semimembranosus
  attachments - from ischial tuberosity to posterior aspect of the medial tibial condyle
  actions - extends thigh & flexes leg
  innervation - tibial division of the sciatic nerve
3. Semitendinosus
  attachments - from the ischial tuberosity to the proximal, medial tibia
  actions - extends thigh & flexes leg
  innervation - tibial division of the sciatic nerve
Anterior Crural Muscles
1. Extensor digitorum longus
  attachments - from the lateral tibial condyle, proximal fibula and interosseous membrane to the dorsal digital expansions of toes 2-5
  actions - dorsiflexes ankle, and extends digits 2-5 (IP & MP)
  innervation - deep peroneal nerve
2. Extensor hallucis longus (L. hallex, great toe)
  attachments - from the mid-fibula & interosseous membrane to the distal phalangeal base of the 1st toe
  actions - dorsiflexes ankle, and extends great toe (MP & IP)
  innervation - deep peroneal nerve
3. Peroneus tertius
  attachments - from the distal fibula and interosseous membrane to the base of the 5th metatarsal
  actions - dorsiflexes ankle, and everts foot
  innervation - deep peroneal nerve
4. Tibialis anterior
  attachments - from the lateral condyle and proximal lateral tibia & interosseous membrane to the medial cuneiform & adjacent 1st metatarsal
  actions - dorsiflexes ankle, and inverts foot
  innervation - deep peroneal nerve
Lateral Crural Muscles
1. Peroneus longus
  attachments - from the head & proximal fibula to the lateral aspects of the 1st metatarsal & adjacent medial cuneiform
  actions - plantar flexes ankle, and everts foot
  innervation - superficial peroneal nerve
2. Peroneus brevis
  attachments - from the distal fibula to the lateral base of the 5th metatarsal
  actions - plantar flexes ankle, and everts foot
  innervation - superficial peroneal nerve
Posterior Crural Muscles
1. Flexor digitorum longus
  attachments - from the posterior tibia distal to the soleal line to the plantar surfaces of the distal phalangeal bases
  actions - plantar flexes ankle, and flexes digits 2-5 (MP & IP)
  innervation - tibial nerve
2. Flexor hallucis longus
  attachments - from the distal posterior fibular surface & interosseous membrane to the plantar aspect of the distal phalangeal base of the 1st toe
  actions - plantar flexes ankle, and flexes great toe (MP & IP)
  innervation - tibial nerve
3. Gastrocnemius (S1,2) (G. gaster, belly + kneme, leg)
  attachments - from the posterior aspect of the femoral condyles to the calcaneal tuberosity
  actions - flexes leg, and plantar flexes ankle
  innervation - tibial nerve
4. Plantaris (L. planta, sole)
  attachments - from the lateral supracondylar line to the calcaneal tuberosity
  actions - flexes leg, and plantar flexes ankle
  innervation - tibial nerve
5. Popliteus
  attachments - from the lateral femoral condyle to the soleal line of the tibia
  actions - unlocks knee during (initial) flexion
  innervation - tibial nerve
6. Soleus (S1,2)
  attachments - from the posterior proximal fibula & tibial soleal line to the calcaneal tuberosity
  actions - plantar flexes ankle
  innervation - tibial nerve
7. Tibialis posterior
  attachments - from the interosseous membrane, lateral tibia & medial fibula to the medial tarsals & metatarsals
  actions - plantar flexes ankle, and inverts foot
  innervation - tibial nerve
Muscles of the foot
1. Abductor digiti minimi
  attachments - from calcaneal tuberosity to lateral side of proximal phalangeal base of 5th digit
  actions - abducts & flexes 5th digit
  innervation - lateral plantar nerve
2. Abductor hallucis
  attachments - from medial calcaneal tuberosity to medial side of proximal phalangeal base of great toe
  actions - flexes & abducts great toe
  innervation - medial plantar nerve
3. Adductor hallucis
  attachments - from 2-4th metatarsal bases (oblique head) & distal ends of 3-5 metatarsal (transverse head) to lateral base of proximal phalanx of great toe
  actions - adducts great toe
  innervation - lateral plantar nerve
4. Extensor digitorum brevis
  attachments - from anterolateral calcaneus to the lateral sides of tendons of extensor digitorum longus (2-4)
  actions - extension of digits 2-5 (MP & IP)
  innervation - deep peroneal nerve
5. Extensor hallucis brevis
  attachments - from anterolateral calcaneus to dorsal aspect of base of proximal phalanx of the hallux
  actions - extension of great toe (MP & IP)
  innervation - deep peroneal nerve
6. Flexor digitorum accessorius
  attachments - from medial surface of calcaneus & lateral process of calcaneal tuberosity to long flexor tendons
  actions - assists flexor digitorum longus
  innervation - lateral plantar nerve
7. Flexor digitorum brevis
  attachments - from medial process of calcaneal tuberosity to sides of intermediate phalanges of digits 2-5
  actions - flexes toes (proximal IP)
  innervation - medial plantar nerve
8. Flexor digiti minimi
  attachments - from 5th metatarsal base to proximal phalangeal base
  actions - flexion of 5th digit (MP)
  innervation - lateral plantar nerve
9. Flexor hallucis brevis
  attachments - from cuboid & tendon of tibialis posterior to base of proximal phalanx of great toe
  actions - flexion of great toe (MP)
  innervation - medial plantar nerve
10. Interossei-dorsal
  attachments - from metatarsal shafts to proximal phalangeal bases & dorsal digital expansions of digits 2-4
  actions - abducts (MP) & flexes (MP) & extends (IP) digits 2-4
  innervation - lateral plantar nerve
11. Interossei-plantar
  attachments - from plantar surface of shaft of metatarsals to dorsal digital expansions of digits 3-5
  actions - adducts & flexes (MP) & extends (IP) digits 3-5
  innervation - lateral plantar nerve
12. Lumbricals
  attachments - from tendons of flexor digitorum longus to medial sides of dorsal expansions of digits 2-5
  actions - flexes proximal phalanges (MP), and extend IP joints
  innervation - 1st- medial plantar nerve & 2-4- lateral plantar nerve

Overview