Advanced Anatomy & Physiology Unit 2 Muscles Lesson 2.4 Muscle of the legs
Step 1 Aims This lesson will enable you to describe the location and function of the muscles in the legs. Step 2 Front of the upper leg We will look at the leg muscles in four parts: upper front, upper back, lower front and lower back. Of the muscles labelled in this diagram, we will look at: The adductor muscles Iliopsoas Quadriceps Step 3 Adductors The adductors are five muscles that work together to adduct and medially rotate the hip. They consist of the: Pectineus Adductor brevis Gracilis Adductor longus Adductor magnus These muscles originate from the pubic bone of the hip, and insert to the side and rear of the femur, except the gracilis which inserts on the tibia. May 2015 Future Fit Training, 2015 Page 1 of 7
Step 4 Iliopsoas The iliopsoas is really two muscles that are regarded as one. The psoas major (large) is a flexor muscle of the hip joint which originates from the lumbar vertebrae. The iliacus is a muscle lying close to the front upper bone of the pelvis (the ilium). They flex the hip joint, assist in flexion of the vertebral column and rotate the hip laterally. Step 5 Quadriceps There are four muscles that go to make up the quads or quadriceps: Rectus femoris (the straight thigh muscle), this is above the vastus intermedius Vastus medialis (vastus means large) Vastus intermedius Vastus lateralis This group of muscles extend the knee. The rectus femoris originates at the front of the hip; the others originate on the upper part of the femur. The insertions are at the upper part of the patella, and the tibia. Because of its origin as explained above, the rectus femoris also assists in hip flexion. May 2015 Future Fit Training, 2015 Page 2 of 7
Step 6 Activity Select the correct answers to complete the diagram. Rectus femoris Vastus lateralis Vastus medialis Step 7 Hamstrings There are three muscles that go to make up the hamstrings: Biceps femoris long head and short head Semimembranosus Semitendinosus This group of muscles flex the knee and assist in hip extension. The hamstrings originate at the back of the ischium and insert into the rear of the tibia. The biceps femoris inserts on the fibula and tibia. Step 8 Front of the lower leg Now let's look at the front of the lower leg, and then the back. May 2015 Future Fit Training, 2015 Page 3 of 7
Step 9 Tibialis anterior The tibialis anterior is the front (anterior) muscle of the tibia or shin bone. It acts to lift up (dorsiflex) and invert the foot. The tibialis anterior originates from the top of the tibia and inserts on the first metatarsal of the foot. Step 10 Back of the lower leg Here is the last muscle diagram in this section: the back of the lower leg. Step 11 Gastrocnemius Gastrocnemius in Latin means the belly of the leg. The gastrocnemius is the main calf muscle. It is used to point the foot (plantar flexion), or to lift the body onto the toes. It also assists in knee flexion. The gastrocnemius originates at the bottom of the femur and inserts on the calcaneous (the heel bone). Step 12 Soleus Soleus is Latin for the sole of the foot. The soleus points the foot (plantar flexion). The soleus originates at the top of the tibia and fibula, and inserts onto the heel bone. Step 13 Activity Correctly select the following muscles on the diagram: Tibialis anterior Gastrocnemius Soleus May 2015 Future Fit Training, 2015 Page 4 of 7
Step 14 Activity Which of these pairs of muscles are used for plantar flexion? Soleus and tibialis anterior Gastrocnemius and soleus Tibialis anterior and gastrocnemius Step 15 Activity Which of these three muscles acts to lift up and invert the foot? Tibialis anterior Gastrocnemius Soleus Step 16 Activity Which other action does the gastrocnemius perform? Inverts foot Flexes the knee Flexes hip Abducts hip Step 17 Summary Now that you have completed this lesson you should have a better understanding of the following: The adductors are five muscles on the inner thigh that work together to adduct and medially rotate the hips. May 2015 Future Fit Training, 2015 Page 5 of 7
The iliopsoas is positioned across the hip area from the lumbar spine and pelvis to the inner thigh. The iliopsoas flexes the hip, assists in flexion of the vertebral column and lateral hip rotation. The quadriceps are made up of four muscles and are located on the front of the thigh. This group extend the knee and the rectus femoris assists in hip flexion. The hamstrings are made up of three muscles and are located on the back of the upper thigh. This group flex the knee and assist in hip extension. The tibialis anterior is positioned on the front of the lower leg and is used in dorsiflexion and inverting the foot. The calf (back of the lower leg) is made up of the gastrocnemius and soleus. These muscles plantar flex the foot and the gastrocnemius also flexes the knee. Use the link below to download a summary table of all the muscles we have learned about in this chapter http://www.futurefittraining.co.uk/elearning/a%20&%20p%20handouts/a&p_summary_of_muscles.pdf May 2015 Future Fit Training, 2015 Page 6 of 7
May 2015 Future Fit Training, 2015 Page 7 of 7