MUSCLES OF THE LOWER EXTREMITY

MUSCLES OF THE PELVIC GIRDLE & LOWER EXTREMITY

MUSCLES OF THE HIP

• Gluteus maximus

  • Origin: Ilium, sacrum, coccyx

  • Insertion: Gluteal tuberosity of femur & iliotibial band

  • Action: Extends thigh

• Gluteus medius

  • Action: Abducts & medially rotates thigh

• Iliopsoas

  • Iliacus

  • Action: Flexes thigh

  • Psoas major

  • Action: Flexes thigh

• Piriformis

  • Action: Laterally rotates thigh

• Quadratus femoris

  • Action: Laterally rotates thigh

MUSCLES OF THE THIGH

LATERAL COMPARTMENT

• Tensor fascia latae

  • Origin: Iliac crest & anterior superior iliac spine

  • Insertion: Iliotibial tract

  • Action: Tightens IT band, steadies trunk

ANTERIOR COMPARTMENT (Quadriceps)

• Rectus femoris

  • Origin: Anterior inferior iliac spine & acetabulum

  • Insertion: Patella → tibial tuberosity (via patellar ligament)

  • Action: Extends leg, flexes thigh

• Vastus medialis

  • Origin: Greater trochanter & linea aspera

  • Insertion: Patella → tibial tuberosity

  • Action: Extends leg

• Vastus intermedius

  • Action: Extends leg

• Vastus lateralis

  • Action: Extends leg

• Sartorius

  • Action: Aids knee & hip flexion

MEDIAL COMPARTMENT (Adductors)

• Adductor brevis

  • Action: Adducts thigh

• Adductor longus

  • Action: Adducts thigh

• Adductor magnus

  • Action: Adducts thigh

• Gracilis

  • Action: Adducts thigh

POSTERIOR COMPARTMENT (Hamstrings)

• Biceps femoris

  • Long head:

    • Origin: Ischial tuberosity

  • Short head:

    • Origin: Distal femur

    • Insertion: Head of fibula & lateral condyle of tibia

    • Action: Extends thigh, flexes leg

• Semimembranosus

  • Origin: Ischial tuberosity

  • Insertion: Medial condyle of tibia & lateral condyle of femur

  • Action: Extends thigh, flexes leg

• Semitendinosus

  • Action: Extends thigh, flexes leg

MUSCLES OF THE LOWER LEG

ANTERIOR COMPARTMENT

• Tibialis anterior

  • Origin: Lateral condyle & shaft of tibia

  • Insertion: Medial cuneiform & 1st metatarsal

  • Action: Dorsiflexion

• Extensor digitorum longus

  • Action: Extends toes 2–4

• Extensor hallucis longus

  • Action: Extends hallux

LATERAL COMPARTMENT

• Fibularis (peroneus) brevis

  • Action: Plantar flexes & everts foot

• Fibularis (peroneus) longus

  • Action: Plantar flexes & everts foot

POSTERIOR COMPARTMENT – SUPERFICIAL

• Gastrocnemius

  • Origin: Medial & lateral condyles of femur

  • Insertion: Posterior calcaneus via calcaneal tendon

  • Action: Plantar flexes foot

• Soleus

  • Origin: Tibia & fibula

  • Insertion: Posterior calcaneus via calcaneal tendon

  • Action: Plantar flexes foot

POSTERIOR COMPARTMENT – DEEP

• Flexor digitorum longus

  • Action: Flexes toes 2–4

• Flexor hallucis longus

  • Action: Flexes hallux

• Tibialis posterior

  • Action: Inverts foot

MUSCLES OF THE FOOT

• Extensor digitorum brevis

  • Action: Extends toes 2–4

• Flexor digitorum brevis

  • Action: Flexes toes 2–4

NERVES & OTHER STRUCTURES (ID ONLY)

• Femoral nerve

• Sciatic nerve

• Tibial nerve

• Common fibular nerve

• Achilles (calcaneal) tendon

• Iliotibial band

• Femoral triangle (boundaries & contents)

  • Boundaries:

    • Superior: Inguinal ligament

    • Medial: Lateral border of Adductor longus muscle

    • Lateral: Medial border of Sartorius muscle

  • Contents (Lateral to Medial - NAVL):

    • Femoral nerve

    • Femoral artery

    • Femoral vein

    • Lymphatic vessels (Deep inguinal lymph nodes)

• Popliteal fossa (boundaries)

  • Boundaries:

    • Proximal Medial: Semimembranosus & Semitendinosus

    • Proximal Lateral: Biceps femoris

    • Distal Medial: Medial head of Gastrocnemius

    • Distal Lateral: Lateral head of Gastrocnemius