The Muscular System: Part D 10 The Muscular System: Part D

II. Muscles that Move the leg at the Knee Joint Location: Muscle mass primarily in Thigh Two major Muscle Groups that work in opposition at the knee joint = Quadriceps & Hamstrings © 2013 Pearson Education, Inc.

Muscles of the Thigh that Move the Knee Joint … A. Quadriceps femoris—sole extensor of knee 1. Rectus Femoris-Crosses 2 Joints 2. Vastus Lateralis 3. Vastus Medialis 4. Vastus Intermedius - Deep to Rectus Femoris Common Insertion: Quadriceps Tendon –>Patella- ->Patellar Ligament->Tibia © 2013 Pearson Education, Inc.

Muscles that Move the Knee Joint … PLAY A&P Flix™: Anterior extensors that act on the knee PLAY A&P Flix™: Rectus femoris PLAY A&P Flix™: Vastus lateralis PLAY A&P Flix™: Vastus medialis PLAY A&P Flix™: Vastus intermedius © 2013 Pearson Education, Inc.

VIDEO WORKS A&P Flix™: Movement at the hip joint 12th thoracic Figure 10.20a Anterior and medial muscles promoting movements of the thigh and leg. 12th thoracic vertebra 12th rib Quadratus lumborum Psoas minor Iliac crest Psoas major Iliopsoas Iliacus 5th lumbar vertebra Anterior superior iliac spine Tensor fasciae latae Pectineus Adductor longus Sartorius Gracilis Quadriceps femoris • Rectus femoris Adductor magnus • Vastus lateralis • Vastus medialis Tendon of quadriceps femoris VIDEO WORKS Patella PLAY A&P Flix™: Movement at the hip joint Patellar ligament © 2013 Pearson Education, Inc.

Muscles of the Thigh that Move the Knee Joint … Hamstring muscles—flex knee; antagonists to quadriceps femoris Biceps femoris Semitendinosus– Long Tendon Semimembranosus Cross 2 Joints Other Knee Flexors: Sartorius Gracilis © 2013 Pearson Education, Inc.

Figure 10.21a Posterior muscles of the right hip and thigh. Gluteus medius Gluteus maximus Adductor magnus Gracilis Iliotibial tract Long head Biceps femoris Short head Hamstrings Semitendinosus Semimembranosus VIDEO WORKS PLAY A&P Flix™: Movement at the hip joint © 2013 Pearson Education, Inc.

Muscles of the Thigh that Move the Knee Joint PLAY A&P Flix™: Posterior flexors that act on the knee PLAY A&P Flix™: Biceps femoris PLAY A&P Flix™: Semitendinosus PLAY A&P Flix™: Semimembranosus © 2013 Pearson Education, Inc.

Summary of Movement at the Knee Joint PLAY A&P Flix™: Movement at the knee joint © 2013 Pearson Education, Inc.

III. Muscles That Move The Foot & Toes INTRODUCTION Location = Leg: The Bulk of These Muscles are usually found on the LEG and have long tendons to the foot-toes Movements Include: Ankle—dorsiflexion and plantar flexion Intertarsal joints—inversion and eversion of the foot Toes—flexion and extension Fibularis longus Tibia Gastrocnemius Tibialis anterior Extensor digitorum longus Soleus Extensor hallucis longus Fibularis tertius Superior and inferior extensor retinacula Extensor hallucis brevis Extensor digitorum brevis © 2013 Pearson Education, Inc.

Tips on Locating these Muscles Tibialis Anterior is closest to the Tibia (lateral to the Tibia) on the Anterior Surface. A Digitorum Longus is on either side of T.A. Extensor Digitorum Longus is lateral. It’s long tendons are visible going to the digits from above Flexor Digitorum L. is medial (and more posterior) to T.A. & Tibia. Its tendons go beneath the foot to toes Fibularis longus Tibia Flexor Digitorum Longus Gastrocnemius Tibialis anterior Extensor digitorum longus Soleus Extensor hallucis longus Fibularis tertius Superior and inferior extensor retinacula Extensor hallucis brevis Extensor digitorum brevis

A. Leg Muscles that act on the Ankle Joint 1. Ankle dorsiflexors a) Tibialis anterior lateral to Tibia Tendon crosses diagonally to medial side Also Inverts foot b) Extensor digitorum longus Crosses two joints so acts at ankle and toes Tendon seen on top of foot going to toes Also everts foot © 2013 Pearson Education, Inc.

© 2013 Pearson Education, Inc.

2. Plantar flexors at Ankle a) Gastrocnemius Location: posterior Crosses two joints and acts at knee joint Calcaneal Tendon b) Soleus Location: posterior and anterior to G. c) Flexor digitorum longus Location: medial-posterior Crosses two joints so acts at ankle & toes © 2013 Pearson Education, Inc.

Deep to Soleus and adjacent to Flexor Digitorum Longus d) Fibularis longus Adjacent to Extensor Digitorum Longus Antagonist to Tibialis Anterior e) Tibialis Posterior Deep to Soleus and adjacent to Flexor Digitorum Longus Acts with Tibialis Anterior to Invert Foot Antagonistic to Tibialis Anterior in Plantar Flexing foot Extensor Digitorum Longus Tibialis Anterior Soleus and Gastrocnemius removed © 2013 Pearson Education, Inc.

B. Muscles that act on the Toes 1. Extensor digitorum longus Crosses two joints so acts at ankle and toes Tendon seen on top of foot traveling to superior surface of digits 2. Flexor digitorum longus Crosses two joints so acts at ankle & toes Tendon goes under foot to inferior surface of digits © 2013 Pearson Education, Inc.

© 2013 Pearson Education, Inc.

END © 2013 Pearson Education, Inc.

Figure 10.22a Muscles of the anterior compartment of the right leg. Fibularis longus Tibia Gastrocnemius Tibialis anterior Extensor digitorum longus Soleus Extensor hallucis longus Fibularis tertius Superior and inferior extensor retinacula Extensor hallucis brevis Extensor digitorum brevis © 2013 Pearson Education, Inc.

Figure 10.23a Muscles of the lateral compartment of the right leg. Patella Head of fibula Gastrocnemius Soleus Fibularis longus Extensor digitorum longus Tibialis anterior Extensor hallucis longus Fibularis brevis Fibularis tertius Flexor hallucis longus Superior and inferior extensor retinacula Fibular retinaculum Extensor hallucis brevis Lateral malleolus Extensor digitorum brevis Metatarsal V © 2013 Pearson Education, Inc.

Figure 10.24c Muscles of the posterior compartment of the right leg. Plantaris (cut) Gastrocnemius lateral head (cut) Gastrocnemius medial head (cut) Popliteus Soleus (cut) Tibialis posterior Fibula Fibularis longus Flexor digitorum longus Flexor hallucis longus Tendon of tibialis posterior Fibularis brevis Medial malleolus Calcaneal tendon (cut) Calcaneus The triceps surae has been removed to show the deep muscles of the posterior compartment. © 2013 Pearson Education, Inc.

Figure 10.24a Muscles of the posterior compartment of the right leg. Plantaris Medial head Gastrocnemius Lateral head Tendon of gastrocnemius Calcaneal tendon Medial malleolus Lateral malleolus Calcaneus Superficial view of the posterior leg. © 2013 Pearson Education, Inc.