TBL7 - Muscles of Anterior and Medial Thigh

Question 1

Where do lower limb muscles derive from?

Answer 1

Like the upper limb, all muscles of the lower limb are derivatives of myoblasts in the parietal layer of lateral plate mesoderm

Question 2

The iliopsoas muscle is formed by the union of which two other muscles? What is its common distal attachment? What is its main function?

Answer 2

1) The iliopsoas muscle is formed by the union of an abdominal muscle (psoas major) and a pelvic muscle (iliacus)
2) The lesser trochanter of the femur is the distal attachment
3) The iliopsoas is the chief flexor of the thigh when lifting the lower limbs for walking

Question 3

Where does the sartorius muscle attach to proximally and distally? What is its function?

Answer 3

1) The sartorius muscle attaches proximally to the ASIS and distally to the superomedial tibia
2) It is mainly a synergist with other stronger muscles during flexion of the hip and knee joints

Question 4

What are the four muscles that constitute the quadriceps femoris? What are their functions collectively?

Answer 4

1) The rectus femoris, vastus lateralis, vastus medialis, & vastus intermedius are the four muscles constituting the quadriceps femoris, the largest muscle of the body
2) It powerfully extends the knee joint mainly when rising from squatting or accelerating during running and jumping i.e. actions that lift or move the entire body weight

Question 5

What does the quadriceps tendon continue as? Where is the patella located? What is the function of the patella?

Answer 5

1) The quadriceps tendon continues as the patellar ligament that attaches to the tibial tuberosity
2) The patella is a sesamoid bone embedded in the ligament
3) The patella provides a bony surface that is able to withstand the compression placed on the quadriceps tendon during kneeling and the friction occurring when the knee is flexed and extended during running
4) The patella also provides additional leverage for the quadriceps in placing the tendon more anteriorly, farther from the joint’s axis, causing it to approach the tibia from a position of greater mechanical advantage
5) The inferiorly directed apex of the patella indicates the level of the joint plane of the knee when the leg is extended and the patellar ligament is taut

Question 6

What is unique about the rectus femoris? How does this contribute to its function?

Answer 6

1) The rectus femoris is the only quadriceps muscle that attaches proximally to the anterior inferior iliac spine
2) Thus, it contributes to flexion of the thigh and extension of the leg when the thigh is extended and the leg is flexed e.g., kicking a soccer ball

Question 7

What are the proximal attachments of the vastus lateralis, vastus medialis, and vastus intermedius? What is their function?

Answer 7

1) Vastus lateralis proximal attachment: Greater trochanter and lateral flex thigh lip of linea aspera of femur
2) Vastus medialis proximal attachment: Intertrochanteric line and medial lip of linea aspera of femur
3) Vastus intermedius proximal attachment: Anterior and lateral surfaces of shaft of femur
4) The three muscles work in unison to extend the leg

Question 8

What is the synovial cavity of the knee joint continuous with?

Answer 8

The synovial cavity of the knee joint is continuous with the suprapatellar bursa positioned between the femur and quadriceps tendon

Question 9

What is the function of the suprapatellar bursa?

Answer 9

The suprapatellar bursa cushions the quadriceps tendon as it pulls lengthwise across the joint during extension of the leg

Question 10

How is suprapatellar bursitis related to popliteal (Baker) cysts?

Answer 10

1) Popliteal (Baker) cysts may be a herniation of the gastrocnemius or semimembranosus bursa through the fibrous layer of the joint capsule into the popliteal fossa, communicating with the synovial cavity of the knee joint by a narrow stalk
2) Synovial fluid may also escape from the knee joint (synovial effusion) or a bursa around the knee and collect in the popliteal fossa. Here it forms a new synovial-lined sac, or popliteal cyst

Question 11

Compare abduction and adduction at the hip joint

Answer 11

1) Abduction: away from midline body

2) Adduction: towards midline of body

Question 12

Where do the adductor longus and adductor portion of the adductor magnus attach to proximally and distally?

Answer 12

1) The adductor longus attaches proximally to the body of the pubis
2) The adductor portion of the adductor magnus attaches proximally to the ischiopubic ramus
3) The adductor longus and adductor portion of the adductor magnus attach distally to the linea aspera

Question 13

What does the medial portion of the adductor magnus contribute to? Where does it attach proximally?

Answer 13

1) The medial part of the adductor magnus constitutes its hamstring portion
2) It attaches proximally to the ischial tuberosity

Question 14

Where does the gracilis muscle attach to? What is the function of the gracilis muscle?

Answer 14

1) The gracilis muscle attaches proximally to the ischiopubic ramus and distally to the superomedial tibia
2) The gracilis is a synergist with stronger muscles during adduction of the thigh and flexion of the leg

Question 15

Where is the gracilis muscle used for transplantation and why is lower limb function not noticeably compromised?

Answer 15

1) Because the gracilis is a relatively weak member of the adductor group of muscles, it can be removed without noticeable loss of its actions on the leg
2) Surgeons often transplant the gracilis, or part of it, with its nerve and blood vessels to replace a damaged muscle in the hand, for example. Once the muscle is transplanted, it soon produces good digital flexion and extension
3) Freed from its distal attachment, the muscle has also been relocated and repositioned to create a replacement for a nonfunctional external anal sphincter

Question 16

What are sports injuries commonly called “hip pointers”, “charley horses”, and “groin pulls”?

Answer 16

1) The term hip pointer may refer to avulsion of bony muscle attachments, for example, of the sartorius or rectus femoris to the anterior superior and inferior iliac spines, respectively, of the hamstrings from the ischium. However, these injuries should be called avulsion fractures
2) Another term commonly used is “charley horse,” which may refer either to the cramping of an individual thigh muscle because of ischemia or to contusion and rupture of blood vessels sufficient enough to form a hematoma. The injury is usually the consequence of tearing of fibers of the rectus femoris; sometimes the quadriceps tendon is also partially torn
3) A “pulled groin” or “groin injury” means that a strain, stretching, and probably some tearing of the proximal attachments of the anteromedial thigh muscles have occurred. The injury usually involves the flexor and adductor thigh muscles. The proximal attachments of these muscles are in the inguinal region (groin), the junction of the thigh and trunk. Groin pulls usually occur in sports that require quick starts (e.g., sprinting and base stealing in baseball), or extreme stretching (e.g., gymnastics)