Anatomy of Skeletal Muscle on Lower Extremity Seung

Anatomy of Skeletal Muscle on Lower Extremity Seung Yeol Lee, M. D. Department of Orthopaedic Surgery, Seoul National University Bundang Hospital

Anterior Muscles of Pelvis

Psoas Major Origin : T 12 -L 5 vertebra Insertion : lesser trochanter Action : powerful hip flexion

Psoas Minor Origin : T 12 & L 1 vertebra Insertion : pectineal line Action : weak flexion of trunk

Iliacus Origin : iliac fossa Insertion : lesser trochanter Action : powerful hip flexion

Gluteal Muscles

Gluteal Maximus Origin : ilium & dorsal sacrum Insertion 1. gluteal tuberosity 2. iliotibial band Action 1. powerful extension 2. ER of hip

Gluteal Medius Origin: ilium between anterior & posterior gluteal lines Insertion: greater trochanter Action: 1. powerful abduction 2. IR of hip 3. Balancing during walking

Gluteal Minimus Origin: ilium between anterior & inferior gluteal lines Insertion: anterior greater trochanter Action: 1. abduction & IR of hip 2. Assist gluteus medius during walking

Trendelenburg sign

Piriformis Origin: anterior sacrum Insertion: superior greater trochanter Action: 1. hip ER 2. hip abduction during flexion

Obturator internus Origin 1. ischiopubic rami 2. obturator membrane Insertion: medial greater trochanter Action: 1. hip ER 2. hip abduction during flexion

Sup. & Inf. gemellus Origin: ischial spine(sup. ) ischial tuberosity(inf. ) Insertion: medial greater trochanter Action: 1. hip ER 2. hip abduction during flexion

Quadratus femoris Origin: ischial tuberosity Insertion: intertrochanteric crest Action: hip ER

Posterior Femoral Muscle (Hamstrings)

Biceps Femoris (long head) Origin: ischial tuberosity Insertion: head of fibula Action: 1. hip extension 2. knee flexion & ER

Biceps Femoris (short head) Origin: 1. linea aspera, 2. supracondylar line Insertion: fibula, lateral tibia Action: knee flexion & ER

Semitendinosus Origin: ischial tuberosity Insertion: proximal medial tibia Action: 1. hip extension 2. knee flexion & IR

Semimembranosus Origin: ischial tuberosity Insertion: posterior medial tibial condyle Action: 1. hip extension 2. knee flexion & IR

Rectus Femoris muscle

Origin : 1. AIIS 2. superior rim of acetabulum Insertion : patella, tibial tubercle Action : 1. hip flexion 2. knee extension

Triceps surae

Gastrocnemius Origin : Lateral and medial femoral condyle Insertion : Calcaneus ( via Achilles tendon) Action : Knee flexion, ankle plantar flexion

Soleus Origin : 1. Posterior fibula head 2. Soleal line of tibia Insertion : Calcaneus( via Achilles tendon) Action : ankle plantar flexion

Soleus Origin : 1. Posterior fibula head 2. Soleal line of tibia Insertion : Calcaneus( via Achilles tendon) Action : ankle plantar flexion

The Anterior and Lat Compartment (Extensor and Fibularis Groups)

Anterior Tibialis Origin : 1. Upper 2/3 of lat. Surface of tibia 2. Crural interosseous membrane 3. Highest part of Superficial crural fascia Insertion : 1. Medial and plantar surface of medial cuneiform 2. Medial base of metatarsal Action : Ankle dorsiflexion Inversion

Fibularis longus Origin : 1. Head of fibula 2. Proximal 2/3 of lateral surface of fibula Insertion : 1. Plantar side of medial cuneiform 2. Base of first metatarsal Action : Ankle plantar flexion Eversion

The Posterior Compartment (Deep Flexor Groups)

Posterior Tibialis Origin : 1. Crural interosseous membrane and adjacent borders of tibia and fibula Insertion : 1. Tuberosity of navicular, cuneiforms, base of second fourth metatarsals Action : Ankle plantar flexion Inversion

Flexor Hallucis longus Origin : 1. Distal 2/3 of posterior surface of fibula Insertion : 1. Base of distal phalanx of big toe Action : Plantar flexion Inversion

Flexor Digitorum longus Origin : 1. Middle third of posterior surface of tibia Insertion : 1. Base of second through fifth distal phalanges Action : Plantar flexion Inversion

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