ZOOL 3214 1st Edition Lecture 20Lecture 20: The Muscular System VIIV. Appendicular Musculature: Lower LimbA. Hips and Buttocks1. Gluteus maximus muscle• Origin: posterior/lateral ilium, inferior/lateral sacrum, coccyx• Insertion: distal/posterior of femur & proximal tibia via IT band (tract)• Action: thigh abduction, hip extensor (climbing stairs/pushing up-squat)• Iliotibial Tract (band): thick band of CT on lateral thigh which is continuous w/ deeperfascia (fascia latae)• IT Bands: runs from iliac crest to lateral condyle of tibia2. Gluteus medius and Gluteus minimus muscle• Origin: lateral ilium surface (from crest to acetabulum)• Gluteus minimus: deeper• Insertion: greater trochanter of femur• Action: thigh abduction, medial rotation, shifting & maintaining balance as we walk/run on weight bearing leg• Essential to bipedal locomotion: HomosapiensB. Thigh1. Sartorius muscle: Greek = tailor: sitting x legged on floor• Origin: anterior/superior iliac spine• Insertion: proximal medial tibia• Action: thigh abduction & lateral rotation• Lat. = medial thigh2. Gracilis muscle: Gracile = slender, delicate, graceful• Origin: pubic arch• Insertion: proximal medial tibia• Action: thigh & knee adduction & knee flexion3. Quadriceps femoris muscle: 4 Head Femur (anterior thigh)A. Rectus femoris muscle (fill-in)• Origin: • Insertion: • Action:B. Vastuslateralis, Vastusintermedius, and Vastusmedialis• Origin: proximal shaft of femur• Insertion: tibial tuberosity via quadriceps femoris tendon (shaved) – patellar ligament – tibial tuberosity• Action: knee extension (leg) & flexion of hip4. Hamstring group of muscles: posterior thigh• Origin: ischial tuberosity• Insertion: proximal tibia & fibula• Action: leg & knee flexion, hip extension, & thigh rotation• Muscles of the Group1. Biceps femoris: short head & long head (lateral)2. Semitendinosus: (in between)3. Semimembranosus: (medial)C.Leg: Anterior1. Tibialis anterior muscle• Origin: tibia – lateral condyle of tibia & proximal shaft, interosseous membrane• Insertion: a tarsal bone (medial cuneiform) & metatarsal 1: articulated w/proximal phalanges of hallux (big toe)• Action: dorsiflexion – keep toes from scuffing ground when walking (Bipedalism)2. Gastrocnemius muscle: Posterior• 2 heads: Medial & Lateral• Superficial• Origin: femur condyles, popliteal surface3. Soleus muscle• Deep• Origin: mid shaft of tibia, proximal head of fibula, & interosseous membrane• Insertion: calcaneus via calcaneal tendon (Achilles)• Action: plantar flexion of footD.Muscle Compartments• Intermuscular septa: thick CT (deep fascia)• Flexion to separate muscles, form spaces for vessels & nerves• Compartment syndrome: inflammation can “strangle” other more distal tissue• Procedure =