Gross Lecture 6

Question 1

Define Pes Anserine and list its component muscles/tendons; indicate where they insert and their collective function

Answer 1

“goose’s foot”: formed by tendons of insertion of the sartorius, gracilis, and semitendinosus msucles - insert on the anteromedial portion of the tibia and collectively FLEX the knee

Question 2

List the posterior thigh compartment muscles, their innervation and functions

Answer 2

hamstring muscles: biceps femoris, semitendinosus and semimembranousus muscles. they all originate on the ischial tuberosity and are innervated by sciatic nerve. they insert on the tibia, therefore act on 2 joints (hip and knee) - extend the hip joint and flex the knee joint

Question 3

Name 2 muscles in the anterior thigh compartment that act at more than one joint. Specify their actions

Answer 3

sartorius: flexes hip and knee
rectus femoris (one of the quad muscles): flexes hip and EXTENDS knee

Question 4

List the ligaments that stabilize the knee joint. In what position is this joint most table?

Answer 4

laterally by iliotibial band; medially by pes anserine (gracilis, sartorius, semitendinosus); medial and lateral collateral ligaments resist valgus and varus forces
joint is most stable in extended position

Question 5

Injuries to what other structures often accompany traumatic damage to the medial collateral ligament of the knee? What is this condition known as?

Answer 5

Anterior cruciate ligament and medial meniscus. Damage to all 3 = “unhappy triad”

Question 6

Describe the function of the menisci. Which one is more often injured? Why?

Answer 6

pieces of fibrocartilage that add depth and cushioning to the articular surfaces of the tibial plateau; facilitate weight transfer and distribution from femur to tibia. medial meniscus most often injured bc it is attached to the medial collateral ligament

Question 7

Describe the function of the cruciate ligaments. Which one is more often injured? Why?

Answer 7

ACL resists anterior movement of the tibia on the femur; PCL resists posterior movement of the tibia on the femur. ACL more injured bc it is stressed whenever a forward movement is stopped abruptly

Question 8

How is locking of the knee joint accomplished? Why is this mechanism important? How is it unlocked?

Answer 8

as the knee comes into the extended position, the lateral femoral condyle comes into congruency with the lateral meniscus on the tibial plateau; in order for the medial femoral condyle to achieve congruency with the medial meniscus, the femur must rotate medially on the tibia to be locked. this is important for achieving full knee extension (which means long periods of time, little energy); unlocked by action of the popliteus msucle

Question 9

What are the actions of the muscles in the anterior thigh compartment? How can the same muscle act as a knee extensor and a hip flexor?

Answer 9

Muscles in this compartment flex the hip (iliopsoas m, fectus femoris, sartorius) or extend the knee (rectus femoris and vasti medius); some muscles act on both the hip and knee joints - sartorius muscle flexes both hip and knee joints; rectus femoris flexes the hip and extends the knee (based on points of attachment)