Chapter 12, Part 2 Appendicular Muscles Legs and Hips

Fig. 12.15a Psoas minor Iliac crest Psoas major Gluteus medius Iliacus Tensor fasciae latae Sartorius Gluteus maximus Iliopsoas Rectus femoris Pectineus Adductor longus Adductor brevis Vastus lateralis Gracilis Iliotibial tract Biceps femoris, long head Adductor magnus Semimembranosus Patella Biceps femoris, short head Gastrocnemius (a) Right thigh, anterior view (b) Right thigh, lateral view

Fig. 12.15b Iliac crest Sacrum Gluteus medius (cut) Gluteus maximus (cut) Gluteus minimus Piriformis Gluteus medius (cut) Superior gemellus Obturator internus Gluteus maximus (cut) Sacrotuberous ligament Inferior gemellus Ischial tuberosity Quadratus femoris Gracilis Biceps femoris, long head Adductor magnus Semitendinosus Iliotibial tract

Anterior thigh muscles Fig. 12.16 View of cross section Anterior Lateral thigh and some gluteal muscles abduct the thigh. Anterior thigh muscles flex the hip and/or extend the leg/knee. Femur Femur Lateral Medial Posterior thigh muscles extend the thigh and/or flex the leg/knee. Medial thigh muscles adduct the thigh. Posterior

Hip flexors insert on anterior femur and flex thigh Fig. 12.17 (a) Right thigh, anterior view Most muscles that move the thigh originate on the os coxae and insert on the femur Hip flexors insert on anterior femur and flex thigh Psoas major originates on vertebrae, iliacus originates on iliac fossa; both fuse into iliopsoas that inserts on femur Sartorius originates on ASIS, inserts on tibial tuberosity; crosses thigh, assists with hip flexion; medially rotates leg Iliacus Psoas major Iliopsoas Sartorius

Hip adductors are medial on thigh Fig. 12.15a Hip adductors are medial on thigh Adductor longus, adductor brevis, gracilis, and pectineus also flex thigh Adductor magnus also extends and laterally rotates thigh originates on pubis and ischial tuberosity, inserts on medial femur (a) Right thigh, anterior view Adductor longus Pectineus Adductor brevis Gracilis Adductor magnus

(b) Right thigh, lateral view Fig. 12.15a Iliac crest Tensor fasciae latae is small muscle that attaches to lateral thickening of fascia lata called iliotibial tract Tensor fasciae latae Sartorius Gluteus maximus Iliotibial tract

Gluteus muscles extend thigh Iliac crest Fig. 12.15b Gluteus muscles extend thigh Gluteus medius and minimus also abduct and medially rotate thigh Sacrum Gluteus medius (cut) Gluteus maximus (cut) Gluteus minimus Gluteus medius (cut) Gluteus maximus (cut) Iliac crest Gluteus medius Gluteus maximus

Muscles deep to gluteal muscles laterally rotate thigh and hip joint Fig. 12.15b Muscles deep to gluteal muscles laterally rotate thigh and hip joint Piriformis Superior gemellus Obturator internus Inferior gemellus Iliac crest Sacrum Gluteus medius (cut) Gluteus maximus (cut) Gluteus minimus Gluteus medius (cut) Piriformis Superior gemellus Gluteus maximus (cut) Obturator internus Inferior gemellus Quadratus femoris Ischial tuberosity Gracilis Adductor magnus Iliotibial tract

Hamstrings are on back of thigh Extend thigh and flex knee Fig. 12.18 Iliac crest Hamstrings are on back of thigh Extend thigh and flex knee Have common origin on ischial tuberosity; insert separately on leg Biceps femoris inserts on head of fibula Semitendinosus inserts on proximal medial tibia Semimembranosus (deep to biceps femoris) inserts on posterior surface of medial condyle of tibia Gluteus medius Gluteus maximus Adductor magnus Gracilis Iliotibial tract Semitendinosus Biceps femoris, long head Biceps femoris, short head (a) Right thigh, posterior view

Fig. 12.18 (b) Thigh extensors Ischial tuberosity Linea aspera Semitendinosus Adductor magnus Semimembranosus Biceps femoris, long head Biceps femoris, short head Head of fibula

Quadriceps group Located on front of thigh Extends the knee joint

Fig. 12.17 Greater trochanter Rectus femoris Vastus intermedius (deep to rectus femoris) Vastus lateralis Vastus medialis Sartorius Patella Patellar ligament Tibia (b) Anterior thigh muscles

Fig. 12.19 Anterior Anterior leg muscles dorsiflex the foot and/or extend the toes. Posterior leg muscles flex the leg, plantar flex the foot, and/or flex the toes. View of cross section Lateral Lateral leg muscles plantar flex and evert the foot. Posterior

Crural muscles move ankle, foot, and toes (some also help flex leg) Fig. 12.20 (a) Right leg, anterior view Crural muscles move ankle, foot, and toes (some also help flex leg) Gastrocnemius Fibularis longus Tibia Tibialis anterior Fibularis brevis Extensor digitorum longus Extensor hallucis longus Extensor retinaculum Fibularis tertius tendon Extensor hallucis longus tendon Extensor digitorum longus tendons Extensor digitorum brevis Extensor hallucis brevis

Tendons of these muscles pass through extensor retinaculum at ankle Extensor digitorum longus flexes foot and extends toes Fibularis tertius tendon extends from muscle to evert foot Extensor hallucis longus dorsiflexes foot and extends big toe Tibialis anterior is primary dorsiflexor of foot, also inverts foot inserts on medial plantar side of foot Tendons of these muscles pass through extensor retinaculum at ankle (a) Right leg, anterior view Fig. 12.20 Tibia Tibialis anterior Fibularis brevis Extensor digitorum longus Extensor hallucis longus Extensor retinaculum Fibularis tertius tendon Extensor hallucis longus tendon Extensor digitorum longus tendons

Crural muscles move ankle, foot, and toes (some also help flex leg) Fig. 12.20 (a) Right leg, anterior view Crural muscles move ankle, foot, and toes (some also help flex leg) Gastrocnemius Fibularis longus Tibia Tibialis anterior Fibularis brevis Extensor digitorum longus Extensor hallucis longus Extensor retinaculum Fibularis tertius tendon Extensor hallucis longus tendon Extensor digitorum longus tendons Extensor digitorum brevis Extensor hallucis brevis

Fig. 12.20 (b) Anterior leg muscles Tibialis anterior Extensor digitorum longus Extensor hallucis longus Fibularis tertius Fibularis tertius tendon

Fig. 12.21 (b) Lateral leg muscles Gastrocnemius Tibialis anterior Fibularis longus Fibularis longus Fibularis brevis Fibularis brevis Fibularis longus tendon 5th metatarsal

Fig. 12.21 Patella Head of fibula Gastrocnemius Tibialis anterior Soleus Fibularis longus Extensor digitorum longus Fibularis brevis Extensor hallucis longus Extensor retinaculum Fibularis tertius Extensor hallucis brevis Calcaneal tendon Extensor hallucis longus tendon Extensor digitorum brevis Extensor digitorum longus tendons Fibular retinaculum Fibularis tertius tendon 5th metatarsal (a) Right leg, lateral view

Posterior compartment muscles plantar flex foot Fig. 12.22 Posterior compartment muscles plantar flex foot Gastrocnemius has two bellies flexes leg and plantar flexes foot Soleus is deep to gastrocnemius, resembles flat fish plantar flexes foot Gastrocnemius and soleus have common tendon, calcaneal tendon or Achilles tendon Plantaris (absent in some people) is weak leg flexor Plantaris Lateral head Gastrocnemius Medial head Soleus Calcaneal tendon (a) Right leg, superficial posterior view

Popliteus rotates tibia slightly to unlock fully extended knee (b) Deep posterior view Fig. 12.22 Popliteus rotates tibia slightly to unlock fully extended knee Tibialis posterior is deep to soleus plantar flexes and inverts foot Flexor digitorum longus attaches to distal phalanges of toes 2-5 plantar flexes foot, flexes MP, PIP, and DIP joints of toes 2-5 Flexor hallucis longus attaches to distal phalanx of big toe plantar flexes foot and flexes big toe Plantaris (cut) Gastrocnemius (cut) Popliteus Tibialis posterior Fibularis longus Flexor digitorum longus Flexor hallucis longus Fibularis brevis Calcaneal tendon (cut)

Fig. 12.22 (c) Deep posterior leg muscles Distal phalanx of hallux Flexor hallucis longus Fibula Popliteus Tibia Tibialis posterior digitorum Interosseous membrane phalanges of toes 2–5 Tarsal and metatarsal bones Fig. 12.22

Lumbricals flex MP joints and extend DIP and PIP joints Fig. 12.23 Lumbricals flex MP joints and extend DIP and PIP joints Adductor hallucis Lumbricals Flexor hallucis brevis Flexor digiti minimi brevis Tendon of flexor hallucis longus Flexor digitorum brevis Tendons of flexor digitorum longus Abductor hallucis Quadratus plantae Abductor digiti minimi Abductor digiti minimi (cut) Abductor hallucis (cut) Calcaneus (a) Layer 1 (superficial) (b) Layer 2 (deep) (c) Layer 3 (deeper)

Dorsal interossei abduct toes Plantar interossei adduct toes (e) Layer 4 (deepest), dorsal view Fig. 12.23 (d) Layer 4 (deepest), plantar view Plantar interossei Dorsal interossei Dorsal interossei abduct toes Plantar interossei adduct toes