Anatomy of joints: Joints of the lower extremity week 4

Question 1

femoroacetabular impingement (FAI)

Answer 1

condition where bony abnormalities of the femur, acetabulum, or both result in pain and altered mechanics at the hip joint. The bony abnormalities can result in impingements of and subsequent damage to acetabular cartilage or labrum

Question 2

What are meniscus tears? Who do they affect?

Answer 2

tear of menisci in knee. most common type of knee injury. atheletes particularly susceptible but can affect anyone and can occur due to degnerative changes with age

Question 3

What is the most commonly injured knee ligaments? Who is most susceptible? What other knee injury is most commonly associated with it?

Answer 3

1. ACL (anterior cruciate ligament)
2. higher in athletes, particularly females
3. about 50% of ACL injuriees occur in conjunction with an injury to the meniscus

Question 4

What are the cause of ankle sprains? What is the most common type of ankle sprain?

Answer 4

occurs when excessive motion at the ankle reults in varying degrees of stretching or tearing of ligaments in this area. ligaments on the lateral side of the ankle tend to be affected more often due to inversion sprains.

Question 5

What type of joint is the hip joint? How many degrees of freedom of motion does it allow? What 2 bones is this articulation formed by?

Answer 5

1. ball and socket
2. allows 3 degrees of freedom of motion
3. formed by articulation of head of femur and acetabulum of hemipelvis

Question 6

What factors affect the limited ROM of the hip joint as compared to the glenohumeral joint?

Answer 6

acetabulum is deeper then glenoid fossa. also, the ligaments and muscles at the hip joint are stronger than at the glenohumeral joint. ppl that are more flexible at the hip joint have more lax ligaments and differences in muscles and bones at the hip joint

Question 7

Where do hip fxs commonly occur?

Answer 7

occur at the neck of the femur. reason why we care about blood supply to the femur.

Question 8

Identify the bony portions of the hip joint.

Answer 8

Question 9

What 3 bones fuse to form the hemipelvis?

Answer 9

ilium, ischium, and pubis (pubic bone) fuse at the acetabulum to form the hemipelvis

Question 10

What is the strongest capsular ligament of the hip? What bones does it span from? When are its fibers maximally taut? What is its fxn thought to be?

Answer 10

ilofemoral ligament. Spans btwn the intertrochanteric line and ilial portion of the acetabular rim and anterior inferior iliac spine. Its fibers are maximally taut in extension and are lax in flexion of the hip. It has been suggested that due to the position of this ligament anterior to the hip joint that it has a special role in maintenance of erect posture by restricting hyperextension of the joint and balancing force of the body’s weight on the femur during standing.

Question 11

From what bones/bony prominences does the pubofemoral ligament span? When is it maximally taut?

Answer 11

the pubofemoral ligament spans from its proximal attachment at the obturator crest and superior pubic ramus to the intertrochanteric fossa. distally at the femoral attachment, its fibers blend with the inferior band of the fibers of the ilofemoral ligament at the attachment site on the lesser trochanter. is maximally taut in abduction. a person that has more than normal ROM of abduction would have a lax pubofemoral ligament

Question 12

From what bones/bony prominences does the ischiofemoral ligament span? When is it maximally taut?

Answer 12

ischiofemoral ligament is attached to the acetabular rim and labrum and the inner surface of the greater trochanter. posteriorly the ischiofemoral ligament reinforces the joint capsule. The thickness of the capsule is decreased posteriorly with thinner and looser fibers except at the distal attachment on the femur. This ligament has been suggested to restric internal rotation due to the length and tautness of its fibers with this motion at the hip joint.

Question 13

Identify these portions of the hip.

Answer 13

Question 14

Identify these portions of the hip.

Answer 14

Question 15

What is the acetabular labrum? What are its connections and function?

Answer 15

the acetabular labrum is a fibrocartilaginous structure attached both along the perimeter of the bony acetabulum and to its articular surface via connecections to the articular cartilage lining the acetabulum. the acetabular labrum plays an important role in increasing congruence btwn the joint surfaces and thus contributing to joint sability

Question 16

What is the ligamentum teres? What does it connect to and what is its possible fxn? What artery is found in the ligamentum teres? What is the fovea capitis?

Answer 16

The ligamentum teres arises from the acetabulum and inserts on the fovea capitis of the femur, a round area on the head of the femur that is devoid of articular cartilage. The ligamentum teres contains a branch of the obturator artery which in some ppl, may contribute some but not all of vascular support to the femoral head. It has been suggested that this ligament may fxn as an intrinsic hip stabilizer of the hip joint and may resist subluxation of the hip joint but this remains to be definitively proven

Question 17

What are the motions at the hip joint?

Answer 17

abduction/adduction

flexion/extension. note that when standing upright, the hip is already in extension. when move leg further back, this is hyperextension

medial rotation/lateral rotation. in medial rotation, the head of the femur moves posteriorly. in lateral rotation, the head of the femur moves anteriorly

Question 18

What motions are allowed at the knee joint? What are the articulating surfaces of the knee joint?

Answer 18

1. the knee joint is a hinge joint that allows flexion and extension but rotation of the tibia on the femur also occurs
2. the knee joint is composed of articulations btwn the femoral and tibial condyles and the patello-femoral articulation. note that the tibia does not articulate with the patella.

Question 19

Identify the bones of the knee joint.

Answer 19

Question 20

What determines the stability of the knee joint? What muscle is the most important for stability of the knee joint?

Answer 20

The knee joint is weak mechanically (like the shoulder due to incongruence of its articulating surfaces). Stability of the knee joint depends on muscles that cross the joint and ligaments that connect the articulating surfaces. The quadriceps femoris is the most important muscle for stability at the knee joint.

Question 21

What are the cruciate ligaments and where are they located? What are their fxns? Which is stronger and why?

Answer 21

There are the anterior and posterior cruciate ligaments. They are intrinsic to the knee joint and connect the femur and tibia at the intercondylar region.

The ACL is the main static stabilizer against anterior translation of the tibia at the knee and is reported to resist 86% of the total force of anterior draw. Its action is enhanced by muscles. Has a suggested proprioceptive fxn and it has been shown that in injured knees the threshold for passive motion dectection is decreased.

The PCL is the main static stabilizer agains posterior translation of the tibia at the knee. Research suggests it contributes 90% of the resitance to posterior draw in the knee in flexion but less in extension. The PCL is stronger than the ACL due to its broad femoral attachment. Suggested susceptibility of this ligament to injury in hyperflexion due to course of this ligament through the intracondylar eminence of the femur.

Question 22

What are the collateral ligaments? What are their fxs? Where are they attached?

Answer 22

There are the medial and lateral collateral ligaments. They are taut in extension and resist hyperextension in addition to their roles in restricting frontal plane motions.

Valgus stress: picture knock kneed. decreases joint space laterally so the medial collateral ligament resists valgus stress

Varus stress: picture bow legged (varus is Paris). reduces joint space medially so is resisted by the lateral collateral ligament

The medial collateral ligament is attached to the medial meniscus and the joint capsule while the lateral collateral ligament has no meniscal or capsular attachments

Question 23

What are the menisci? What is their fxn? What is their shape and how does this affect fxn? Which more commonly injured and why? How are the menisci commonly injured?

Answer 23

Medial and lateral menisci are plates of fibrocartilage on the articular surface of the tibia that improve congruency btwn the femoral and tibial condyles and play a role in shock absroption and motion at the tibiofemoral joint. Both are thick peripherally and thinner centrally thus deepening the articular surface of the tibia. The open ends are called horns and attach to the intercodylar eminences (see pg 406 of atlas of anatomy). The medial meniscus is more firmly attached (attaches to joint capsule and medial collateral ligament) and is less movable than the lateral (but both move during flexion and extension of knee, called extrusion). The medial meniscus is thus more susceptible to injury. trauma generally results from sudden extension or rotation or rotation of the flexed knee while the leg is fixed.

Question 24

Identify the parts of the anterior knee.

Answer 24

Question 25

Identify the parts of the posterior knee.

Answer 25

Question 26

Identify the parts of the dorsal foot.

Answer 26

Question 27

Identify the parts of the lateral foot.

Answer 27

Question 28

What is the talocrural joint? What bones participate in this joint? What movements are available at this joint?

Answer 28

The talocrural joint is the ankle. It is an articulation btwn the talus of the foot and the tibia and fibula (crural portion). dorsiflexion and plantar flexion are actions of the ankle joint. dorsiflexion-dorsal surface of foot moves up. picuture standing on heels. plantarflexion: plantar surface of foot moves down. picture walking on toes.

Question 29

What is the subtalar joint? What bones participate? What movements occur at this joint?

Answer 29

the subtalar joint is the articulation btwn the talus and calcaneus. inversion and eversion occurs at subtalar joint.

Question 30

Identify the ligaments of the ankle joint. What type of ankle sprains are more common (inversion vs eversion) and why? Which ligaments are most commonly involved in this type of ankle sprain?

Answer 30

inversion bc lateral ligaments are not as strong as medial ligaments. the anterior talofibular and the calcaneofibular ligaments are most often implicated in ankle sprains.

Question 31

What are the functions of the arches of the foot and ligaments of the plantar surface (sole) of the the foot? Identify these parts in the picture.

Answer 31

Arches: serve to absorb shock and distribute forces during standing and walking

Ligaments of sole: serve to support the arches