Appendicular Muscles- Lower Extremities Flashcards
What is the fascia lata?
- The deep fascia of the thigh
- Encircles thigh muscles like a supportive stocking and tightly binds them together
- The fascia lata along with the intermuscular septa partition the thigh muscles into compartments, each with its own blood and nerve supply
- Most muscles of the thigh attach proximally to the os coxae and distally to the femur
- They work together to stabilize the highly mobile hip joint and support the body during standing and walking
What do the anterior compartment muscles do? (thigh)
- Either extend the knee or flex the thigh
What do the medial compartment muscles do? (thigh)
- Act as adductors of the thigh
What do the posterior compartment muscles do? (thigh)
- Act as both flexors of the knee and extensors of the thigh
- Some also may abduct the thigh
What are the psoas major and iliacus muscles? (anterior compartment)
- Attach to the anterior femur and flex the thigh at the hip
- Have different proximal attachments but share the same distal attachment to the lesser trochanter of the femur
- Together these muscles merge and attach to the femur as the iliopsoas
- They work synergistically to flex the thigh
What is the sartorius? (anterior compartment)
- A long, thin muscle that crosses over the anterior thigh and helps flex the thigh
- The rectus femoris also does this
What are the medial compartment muscles?
- Adductor longus, adductor brevis, gracilis and pectineus (primary adductors/ thigh flexors)
- Adductor magnus extends laterally and rotates the thigh as well as flexing it
- The obturator externus does not adduct the thigh but laterally rotates it
What is the lateral compartment muscle?
- Single muscle called the tensor fasciae latae
- Attaches to a lateral thickening of the fascia lata, called the iliotibial tract
- Abducts and medially rotates the thigh
- The iliotibial tract extends from the iliac crest to the lateral condyle of the tibia
What are the posterior compartment muscles?
- Includes 3 gluteal muscles and the hamstring muscle group
What is the gluteus maximus?
- The largest of the 3 gluteal muscles and one of the largest muscles in the whole body
- The chief extensor of the thigh
- Laterally rotates the thigh
What is the gluteus medius?
- Deep and lateral to the gluteus maximus
- Powerful abductor of the thigh
- Also medially rotates the thigh
- Intramuscular injections are often given in this muscle
What is the gluteus minimus?
- The smallest of the gluteal muscles
- Lies deep to the gluteus medius
- Abducts and medially rotates the thigh
What posterior compartment muscles are deep to the gluteal muscles?
- Piriformis, superior gemellus, obturator internus, inferior gemellus and quadratus femoris
- Organized from superior to inferior within the posterior thigh
- All laterally rotate the thigh and the hip joint, as when the legs are crossed with one ankle resting on the knee
What are the hamstrings? (posterior compartment)
- Biceps femoris, semimembranosus, and semitendinosus
- Share a common proximal attachment to the ischial tuberosity of the os coxae and distally attach to the leg
- These muscles move the thigh and the knee (primary thigh movement is extension)
What is the anterior (extensor) compartment of the thigh?
- Composed of the large quadriceps femoris
- Agonist of knee extension and the most powerful muscle in the body
- Has 4 heads: rectus femoris, vastus lateralis, vastus medialis and vastus intermedius which all converge into the single tendon
- Extends to the patella and then continues inferiorly as the patellar ligament and attaches to the tibial tuberosity
- Acts with the iliopsoas to flex the hip while the leg is kicking off the ground
What is the rectus femoris? (quadriceps femoris)
- On the anterior surface of the thigh
- Proximally attaches to the os coxae
- Also flexes the thigh
What is the vastus lateralis? (quadriceps femoris)
- Forms the anterolateral surface of the thigh
What is the vastus medialis?
- Forms the anteromedial surface of the thigh
What is the vastus intermedius?
- Positioned deep to the rectus femoris and sandwiched between the other 2 vastus muscles
What is the sartorius? (anterior compartment)
- Projects obliquely across the anterior surface of the thigh from the superolateral to the inferomedial side
- Acts on both the hip and knee joints, flexing and laterally rotating the thigh while flexing the leg
- Longest muscle in the body (used when crossing our legs)
What is the gracilis? (medial compartment)
- Adducts the thigh
- Also flexes the leg, as it spans the knee joint
What is the biceps femoris? (posterior compartment)
- 2 headed muscle that attaches to the lateral side of the leg
- Can laterally rotate the leg while it’s being flexed
- The long head proximally attaches to the ischial tuberosity with the semimembranosus and semitendinosus
- The short head attaches proximally to the linea aspera of the femur (cannot move the thigh but assists in flexing the leg)