Ch19: Knee Joint Flashcards
The knee is supported and maintained entirely by…
Muscles and ligaments with no bony stability, and it frequently is exposed to severe stresses and strains. Therefore, it should be no surprise that it is one of the most frequently injured joints in the body.
What is the largest joint in the body?
The knee, and it is classified as a synovial hinge joint
What are the possible motions at the knee?
Flexion and Extension (accessory rotation)
From 0 degrees of extension, there are approximately how many degrees of flexion?
120 to 135
Genu Recurvatum
Beyond 5 degrees of hyperextension (Due to some ligament laxity, the knee may have a few degrees of hyperextension beyond 0)
Unlike the elbow, the knee joint is not a true hinge, because it has…
A rotational component. This rotation is not a free motion but rather an accessory motion that accompanies flexion and extension.
Knee joint (lateral view)
.
Knee motions (lateral view)
.
Flexion vs. Extension End-Feel
- Knee Flexion= Soft End Feel (soft tissue approximation) due to the contact between the muscle bellies of the thigh and leg.
- Knee Extension= Firm End Feel (soft tissue stretch) due to tension of the joint capsule and ligaments.
All three types of arthrokinematic motion occur during…
Knee Flexion and Extension (glide, roll, spin)
The convex femoral condyles move on the concave tibial condyles or vice versa depending on whether its…
An open- or closed-chain activity.
The articular surface is greater on which condyles and longer on which?
- The femoral condyles articular surface is much greater than that of the tibial condyles
- The articular surface of the medial femoral condyle is longer than that of the lateral femoral condyle
How do the femur and tibia move about each other during closed chain extension?
The femur must glide posteriorly on the tibia as it rolls into extension. As extension occurs, the articular surface of the lateral femoral condyle is used up while some articular surface remains on the medial femoral condyle Therefore, the medial condyle of the femur must also glide posteriorly to use its entire articular surface. It is this posterior gliding of the medial femoral condyle during the last few degrees of weight-bearing extension (closed-chain action) that causes the femur to spin (rotate medially) on the tibia.
How do the femur and tibia move about each other during open-chain extension?
With same spin, or rotational, movement during non–weight-bearing extension (open-chain action), the tibia rotates laterally on the femur. These last few degrees of motion lock the knee in extension; aka the screw-home mechanism of the knee. With the knee fully extended, an individual can stand for a long time without using muscles.
How do the femur and tibia move about each other in flexion?
For knee flexion to occur, the knee must be “unlocked” by laterally rotating the femur on the tibia. This small amount of rotation of the femur on the tibia, or vice versa, keeps the knee from being a true hinge joint. Because this rotation is not an independent motion, it will not be considered a knee motion.
Arthrokinematic movements of the knee joint surfaces in a closed-chain activity of knee extension in which the femur moves on the tibia (medial view).
(A) Pure rolling of the femur would cause it to roll off the tibia as the knee extends. (B) Normal motion of the knee demonstrates a combination of rolling, gliding (posteriorly), and spinning (medially) in the last 20 degrees of extension.
The knee has a convex-on-concave relationship in what chain?
Closed Chain
The knee has a concave-on-convex relationship in what chain?
Open Chain where the concave tibial condyles glide posteriorly with flexion, and anteriorly with extension, while the distal end of the tibia moves in the same direction
Open Packed Position of the Knee
25 degrees, that is the position where most joint play is available.
A mobilizing force applied to the proximal tibia in an anterior direction will facilitate…
Knee extension, whereas a posterior glide will promote flexion.
Patellofemoral Joint
The articulation between the femur and patella; The smooth, posterior surface of the patella glides over the patellar surface of the femur.
The Main Functions of the Patella
Involve increasing the mechanical advantage of the quadriceps muscle and protecting the knee joint. An increased mechanical advantage is achieved by lengthening the quadriceps moment arm.
Moment Arm (patella)
The perpendicular distance between the muscle’s line of action and the center of the joint (axis). By placing the patella between the quadriceps, or patellar tendon, and the femur, the action line of the quadriceps muscles is farther away. Hence, the moment arm lengthens, allowing the muscle to have greater angular force. Without the patella, the moment arm would be shorter and much of the muscle’s force would be a stabilizing force directed back into the joint.
Screw-home motion of the left knee.
In the weight-bearing position (closed-chain activity), the femur rotates medially on the tibia as the knee moves into the last few degrees of extension. xxx
Patellofemoral joint (lateral view)
.
Q Angle
Aka Patellofemoral angle; Angle between the quadriceps muscle (primarily the rectus femoris muscle) and the patellar tendon. Determined by drawing a line from the ASIS to the midpoint of the patella, and from the tibial tuberosity to the midpoint of the patella. Angle formed by the intersection of these lines represents the Q angle.
What is the normal range of the Q angle in knee extension?
Ranges from 13 to 19 degrees in normal individuals.
-The angle tends to be greater in females because the pelvis is generally wider in women.
What happens when Q angle is greater or smaller than normal range?
Many different knee and patellar problems, such as patellofemoral pain syndrome, are associated with Q angles greater or smaller than this range
What is the knee composed of?
The distal end of the femur articulating with the proximal end of the tibia.
Moment arm of the quadriceps muscles is greater with a patella…
(A), than without a patella (B) (lateral view).
Patellofemoral Compressive Forces During Flexion and Extension
- Open Packed Position for Patellofemoral Joint: When knee is fully extended, patella lies in its uppermost position, in shallowest portion of patellar surface of femur. With knee extended and leg muscles relaxed, it should be easy to manually glide the patella side-to side
- As knee flexes, patella is pulled downward by patellar tendon through its attachment to tibial tuberosity. In this lower position, the patella becomes quite stable as the depth of the patellar surface and amount of bony contact both increase.
- As knee flexion increases, manual glide of patella side-to side is no longer possible.
- In activities like a deep knee bend, the knee is flexing and quadriceps are eccentrically contracting. This compresses patella tightly against femur due to tension in the quadriceps and patellar tendons. Chronic compression can lead to patellofemoral pain.
Patella mobility during knee flexion/extension.
(A) with knee extended, patella can be moved side-to-side. (B) With knee flexed, side-to-side motion of patella is not possible
Q angle of the knee (anterior view)
.
Head of the Femur
The rounded portion articulating with the acetabulum.
Neck of the Femur
The narrower portion located between the head and the trochanters.
Greater Trochanter of the Femur
Large projection located laterally between the neck and the body of the femur, providing attachment for the gluteus medius and minimus and for most deep rotator muscles.
Lesser Trochanter of the Femur
A smaller projection located medially and posteriorly, just distal to the greater trochanter; it provides attachment for the iliopsoas muscle.
Parts of the Femur
(right)
Body of the Femur
The long, cylindrical portion between the bone ends; also called the shaft. It is bowed slightly anteriorly.
Medial Femoral Condyle
Distal Medial End
Lateral Femoral Condyle
Distal Lateral End
Lateral Epicondyle of the Femur
Projection proximal to the lateral condyle
Medial Epicondyle of the Femur
Projection proximal to the medial condyle
Adductor Tubercle of the Femur
Small projection proximal to the medial epicondyle to which a portion of the adductor magnus muscle attaches
Linea Aspera of the Femur
Prominent longitudinal ridge or crest running most of the posterior length
Pectineal Line of the Femur
Runs from below the lesser trochanter diagonally toward the linea aspera. It provides attachment for the adductor brevis.
Patellar Surface of the Femur
Located between the medial and lateral condyle anteriorly. It articulates with the posterior surface of the patella.
Intercondylar Eminence of the Tibia
A double-pointed prominence on the proximal surface at about the midpoint, which extends up into the intercondylar fossa of the femur
Medial Tibial Condyle
Proximal medial end
Lateral Tibial Condyle
Proximal lateral end
Parts of the Tibia
(right)
Tibial Plateau
Enlarged proximal end, including the medial and lateral condyles and the intercondylar eminence
Tibial Tuberosity
Large projection at the proximal end on the anterior surface in the midline
Fibula
Lateral to, and smaller than, the tibia. It is set back from the anterior surface of the tibia, allowing a large space for muscle attachment. This feature gives the lower leg its rounded circumference.
-Not part of the knee joint because it does not articulate with the femur. Although it provides a point of attachment for some of the knee structures, it has a larger role at the ankle.
Patella
A triangular sesamoid bone within the quadriceps muscle tendon. It has a broad, superior border and a somewhat pointed distal portion.
Calcaneus
The most posterior of the tarsal bones and is commonly known as the heel. It is identified here because it provides attachment for the gastrocnemius muscle.
Parts of the Leg
Right Leg (lateral view)
What are the 2 main sets of ligaments that hold the knee together?
Cruciate and Collateral Ligaments
Cruciate Ligaments
Located within the joint capsule and are therefore called intracapsular ligaments. Situated between the medial and lateral condyles, the cruciates cross each other obliquely (cruciate means “resembling a cross” in Latin). They are named for their attachment on the tibia
Anterior Cruciate Ligament (ACL)
Attaches to the anterior surface of the tibia in the intercondylar area just medial to the medial meniscus. It spans the knee lateral to the posterior cruciate ligament, and it runs in a superior and posterior direction to attach posteriorly on the lateral condyle of the femur.
Posterior Cruciate Ligament (PCL)
Attaches to the posterior tibia in the intercondylar area, and it runs in a superior and anterior direction on the medial side of the anterior cruciate ligament. It attaches to the anterior femur on the medial condyle.
-Runs from the anterior tibia to the posterior femur, and the posterior cruciate runs from the posterior tibia to the anterior femur.
Parts of the Knee
(right knee in flexion)
Cruciate ligaments are named for their attachment on the tibia
(lateral view)
What plane do cruciate ligaments provide stability in?
Sagittal Plane
What does the ACL do?
The ACL keeps the femur from being displaced posteriorly on the tibia. Conversely, it keeps the tibia from being displaced anteriorly on the femur. It tightens during extension, preventing excessive hyperextension of the knee. When the knee is partly flexed, the ACL keeps the tibia from moving anteriorly.
What does the PCL do?
The PCL keeps the femur from displacing anteriorly on the tibia or the tibia from displacing posteriorly on the femur. It tightens during flexion and is injured much less frequently than the anterior cruciate ligament
What ligaments are located on the sides of the knees?
Medial Collateral Ligament and Lateral Collateral Ligament
Medial Collateral Ligament (MCL)
(aka tibial collateral ligament) Flat, broad ligament attaching to the medial condyles of the femur and tibia. Fibers of the medial meniscus are attached to this ligament, which contributes to frequent tearing of the medial meniscus during excessive stress to the medial collateral ligament.
Lateral COllateral Ligamet (LCL)
(AKA fibular collateral ligament) On the lateral side, this round, cordlike ligament attaches to the lateral condyle of the femur and runs down to the head of the fibula, independent of any attachment to the lateral meniscus. It provides stability to the lateral side of the knee against medial-to-lateral forces (varus force).
What plane do the collateral ligaments supply stability in?
Frontal Plane
What does the Medial Collateral Ligament do?
Provides medial stability and prevents excessive motion if there is a blow to the lateral side of the knee (valgus force)
What does the Lateral Collateral Ligament do?
Provides lateral stability and prevents excessive motion if there is a blow to the medial side of the knee (varus force).
Because their attachments are offset posteriorly and superiorly to the knee joint axis, the collateral ligaments…
Tighten during extension, contributing to the stability of the knee, and slacken during flexion.
Medial and Lateral Menisci
- Located on the superior surface of the tibia
- Two half-moon, wedge-shaped fibrocartilage disks.
- Designed to absorb shock
- Bc they are thicker laterally than medially and bc the proximal surfaces are concave, the menisci deepen the relatively flat joint surface of the tibia. Perhaps bc of its attachment to the medial collateral ligament, the medial meniscus is torn more frequently.
Bursa
Reduce friction, and approximately 13 of them are located at the knee joint.
-Needed because the many tendons located around the knee have a relatively vertical line of pull against bony areas or other tendons.
Popliteal Space
Area behind the knee
-Contains
Important nerves: Tibial and Common Fibular
Blood vessels: Popliteal Artery and Vein
This diamond-shaped fossa is bound superiorly on the medial side by the semitendinosus and semimembranosus muscles and by the biceps femoris muscle on the lateral side
The inferior boundaries are the medial and lateral heads of the gastrocnemius muscle
Pes Anserine Muscle Group
Made up of the sartorius, gracilis, and semitendinosus muscles. Each muscle has a different proximal attachment
-They all cross the knee posteriorly and medially, then join together to attach distally on the anterior medial surface of the proximal tibia.
(Orthopedic surgeons sometimes alter this common attachment to provide medial stability to the knee)
Sartorius Muscle
Arises anteriorly from the iliac spine, the gracilis muscle arises medially from the pubis
Semitendinosus Muscle
Arises posteriorly from the ischial tuberosity
Parts of the Knee (superior view)
.
Forces on the Knee Joint with Varus and Valgus Angles
- When the lower limb is aligned neutrally (Fig. B), the weight-bearing force passes through the midline of the knee joints.
- With genu varus (Fig. A), the weight-bearing line shifts medial to the knee, which compresses the articular surfaces on the medial side of the knee joint.
- With genu valgus (Fig. C), the compressive force moves to the lateral knee joint.
- Once the weight-bearing force shifts medially or laterally, the constant sideward force causes the varus or valgus angle to worsen over time. Greater angles lead to greater compressive forces, which can damage the articular cartilage. Abnormal stresses to the knees will also alter the stresses placed upon the ankle and hip joints.
All of the knee muscles, except the popliteus cross the joint in a…
Relatively vertical fashion.
Anterior muscles produce what knee motion?
Extension
Posterior muscles produce what knee motion?
Flexion
Muscles crossing the medial and lateral sides help produce provide what?
Medial and Lateral Stability.
Muscles that cross the Knee
Bursae around the knee joint (medial view).
Anterior Muscles of the Knee
The quadriceps muscles are comprised of four muscles that cross the anterior surface of the knee
What is the only anterior knee muscle that crosses the hip?
Rectus Femoris Muscle
Quadriceps Tendon
(akapatellar tendon).
- Encases the patella, crosses the knee joint, and attaches to the tibial tuberosity.
- Some sources refer to the quadriceps tendon as that tendinous portion above the patella and the patellar tendon as that portion between the patella and the tibial tuberosity. There is not universal agreement, and that distinction will not be made here
Rectus Femoris Muscle
Proximal attachment is on the AIIS and it runs almost straight down the thigh, where it is joined by the three vasti muscles and blends into the quadriceps tendon)
It is a prime mover in hip flexion and knee extension.
Prepatellar (Anterior Bursae of the Knee)
Between patella and skin
Deep Infrapatellar (Anterior Bursae of the Knee)
Between proximal tibia and patellar ligament
Superficial Infrapatellar (Anterior Bursae of the Knee)
Between tibial tuberosirt and skin
Suprapatellar (Anterior Bursae of the Knee)
Between distal femur and quadriceps tendon
Gastrocnemius (Posterior Bursae of the Knee)
- Between lateral head of gastrocnemius muscle and capsule
- Between medial head of gastrocnemius muscle and capsule
Biceps (Posterior Bursae of the Knee)
Between fibular collateral ligament and biceps tendon
Politeal (Posterior Bursae of the Knee)
Between popliteus tendon and lateral femoral condyle.
Semimembranosus (Posterior Bursae of the Knee)
Between tendon of semimembranosus muscle and tibia
Iliotibial (Lateral Bursae of the Knee)
Deep to iliotibial band at its distal attachment
Fibular Collateral Ligament (Lateral Bursae of the Knee)
Deep to fibular collateral ligament, next to the bone
Anserine (Medial Bursae of the Knee)
Deep to sartorius, gracilis, and semitendinosus tendons (communicates with knee joint
3 Vasti Muscles
One-joint muscles, which come together with the rectus femoris in the lower part of the thigh to form a single, very strong, quadriceps tendon before crossing the knee to attach to the tibial tuberosity.
Vastus Lateralis Muscle
Located lateral to the rectus femoris muscle. It originates from the linea aspera of the femur and spans the thigh laterally to join the other quadriceps muscles at the patella.
Vastus Medialis Muscle
Comes from the linea aspera, but it spans the thigh medially. Both the vastus lateralis and medialis “wrap around” the femur on their respective sides.
Vastus Intermedialis Muscle
Located deep to the rectus femoris muscle. It arises from the anterior surface of the femur and spans the thigh anteriorly in a very vertical direction. It blends together with the other vasti muscles along its length.
Where do all four quadricep muscles attach attach and span?
All four quadriceps muscles attach to the base of the patella and the tibial tuberosity via the patellar tendon. All four muscles span the knee anteriorly, and all extend the knee. Because the rectus femoris muscle also spans the hip anteriorly, it also flexes the hip.
Muscular boundaries of the right popliteal space (posterior view).
.
Three muscle attachments of pes anserine (medial view).
.
Anterior Muscles of the Knee (one/two joint)
One-Joint Muscle: Vastus Lateralis, Vastus Medialis, Vastus Intermedialis
Two-Joint Muscle: Rectus Femoris
Posterior Muscles of the Knee (one/two joint)
One-Joint Muscle: Biceps Femoris (short), Popliteus
Two-Joint Muscle: Biceps Femoris (long), Semimembranosus, Semitendinosus, Sartorius, Gracilis, Gastrocnemius
Lateral Muscles of the Knee (one/two joint)
One-Joint Muscle: N/A
Two-Joint Muscle: Tensor Fascia Lata
Quadriceps muscle group (anterior view).
The three vasti muscles lie deep to the rectus femoris. The vastus medialis and lateralis attach proximally on the posterior femur but join the other two muscles to cross the knee anteriorly.
Rectus Femoris Muscle (OIAN)
O: AIIS
I: Tibial tuberosity via patellar tendon
A: Hip flexion and knee extension
N: Femoral nerve (L2, L3, L4)
Vastus Lateralis Muscle (OIAN)
O: Linea aspera
I: Tibial tuberosity via patellar tendon
A: Knee extension
N: Femoral nerve (L2, L3, L4)
Vastus Medialis Muscle (OIAN)
O: Linea aspera
I: Tibial tuberosity via patellar tendon
A: Knee extension
N: Femoral nerve (L2, L3, L4)
Vastus Intermedialis Muscle (OIAN)
O: Anterior femur
I: Tibial tuberosity via patellar tendon
A: Knee extension
N: Femoral nerve (L2, L3, L4
Hamstring Muscles
- Three muscles that cover the posterior thigh.
- Consist of the semimembranosus, the semitendinosus, and the biceps femoris muscles
- They have a common site of origin on the ischial tuberosity.
Semimembranosus Muscle (hamstring)
Runs down the medial side of the thigh deep to the semitendinosus muscle and inserts on the posterior surface of the medial condyle of the tibia.
Semitendinosus Muscle (hamstring)
Has a much longer and narrower distal tendon that moves anteriorly after spanning the knee joint posteriorly. It attaches to the anteromedial surface of the tibia with the gracilis and sartorius muscles.
Biceps Femoris Muscle (hamstring)
Has two heads and runs laterally down the thigh on the posterior side.
- Long head arises with the other two hamstring muscles on the ischial tuberosity
- Short head arises from the lateral lip of the linea aspera (only part of the hamstring muscle group that has a function only at the knee, other parts have a function at both the hip and the knee)
- Both heads join together, spanning the knee posteriorly to attach laterally on the head of the fibula and, by a small slip, to the lateral condyle of the tibia.
Hamstring muscle group (posterior view).
.
Semimembranosus Muscle (OIAN)
O: Ischial tuberosity
I: Posterior surface of medial condyle of tibia
A: Hip extension and knee flexion
N: Sciatic nerve (L5, S1, S2)
Semitendinosus Muscle (OIAN)
O: Ischial tuberosity
I: Anteromedial surface of proximal tibia
A: Extend hip and flex knee
N: Sciatic nerve (L5, S1, S2)
Biceps Femoris Muscle (OIAN)
O: Long head: ischial tuberosity
Short head: lateral lip of linea aspera
I: Fibular head
A: Long head: hip extension and knee flexion
Short head: knee flexion
N: Long head: sciatic nerve (S1, S2, S3)
Short head: common fibular nerve (L5, S1, S2)
Popliteus Muscle
A one-joint muscle located posteriorly at the knee in the popliteal space, deep to the two heads of the gastrocnemius muscle. It originates on the lateral side of the lateral condyle of the femur and crosses the knee posteriorly at an oblique angle to insert medially on the posterior proximal tibia. Because it spans the knee posteriorly, it flexes the knee. Because it has an oblique line of pull, it creates the rotational pull needed to “unlock” the knee as it initiates knee flexion.
Popliteus Muscle (OIAN)
O: Lateral condyle of femur
I: Posterior medial condyle of tibia
A: Initiates knee flexion
N: Tibial nerve (L4, L5, S1)
Popliteus muscle (posterior view).
.
Gastrocnemius Muscle
A two-joint muscle that crosses the knee and the ankle.Extremely strong ankle plantar flexor but also has a significant role at the knee. It attaches by two heads to the posterior surface of the medial and lateral condyles of the femur. After descending the posterior leg superficially, it forms a common Achilles tendon with the soleus muscle and attaches to the posterior surface of the calcaneus.
-Major function is at the ankle, spans the knee posteriorly, has a good angle of pull, and is a large muscle. Its contribution as a knee flexor cannot be overlooked.
Its unusual contribution to knee extension has been demonstrated in individuals with no quadriceps muscle function.
In a closed kinetic chain action with the foot planted on the ground so that the distal segment (leg) is stationary, the proximal segment (thigh) becomes the movable part. This is also a reversal of muscle action in which the femur is pulled posteriorly, or into knee extension. This feature of the gastrocnemius muscle makes it possible for a person to stand upright without the use of the quadriceps muscles.
Achilles Tendon
(often called the heel cord by laypersons)
Gastrocnemius muscle (posterior view)
.
Lateral view of Muscle Action
(A) With a paralyzed quadriceps unable to pull the knee into extension, the body weight line falls behind the knee, causing flexion. However, a combined reverse muscle action of the gluteus maximus and gastrocnemius muscles makes knee extension possible during stance. (B) In the closed-chain position, they pull the knee into extension. The soleus assists by plantar flexing the dorsiflexed ankle into a neutral ankle position. This puts the body weight line in front of the knee and ankle axes and allows the knee to remain extended.
Gastrocnemius Muscle (OIAN)
O: Medial and lateral condyles of femur
I: Posterior calcaneus
A: Knee flexion and ankle plantar flexion
N: Tibial nerve (S1, S2)
The Gracilis, Sartorius, and Tensor Fascia Lata Muscles
Span the knee joint posteriorly, but because of their angle of pull, their size in relation to other muscles, and other factors, they do not have a prime mover function. However, they do provide stability to the joint
Tensor Fascia Lata Muscle
Spans the knee laterally, essentially in the middle of the joint axis for flexion and extension. It contributes greatly to lateral stability.
Gracilis and Sartorius Muscles
Span the knee medially, contributing greatly to medial stability. The gastrocnemius and hamstring muscles provide posterior stability both medially and laterally, and the quadriceps muscles provide anterior stability.
What muscle is the most superficial of the anterior group?
Rectus Femoris
At the mid- and lower thigh, which muscles are superficial on either side of the rectus femoris?
Vastus Lateralis and the Vastus Medialis
Deep to the rectus femoris and between the two vasti muscles lies what muscle?
Vastus Intermedialis
The hamstring muscles are where on the thigh?
On the posterior thigh.
Superficially, on the posterior side of the thigh, which muscle is on the lateral side? Which is on the medial side?
The biceps femoris (long head) is on the lateral side, and the semitendinosus is on the medial side.
Deep to long head of the biceps femoris and the semitendinosis muscles is the…
Short head of the biceps femoris (laterally) and the semimembranosus (medially).
The deepest muscle at the distal end of the thigh is the…
Popliteus. It lies deep to the proximal heads of the gastrocnemius.
Sartorius Anatomical Relationships
Crosses the knee on the medial side, anterior to the gracilis, followed more posteriorly by the semitendinosus (pes anserine).
Tensor Fascia Lata Anatomical Relationships
Crosses the knee joint laterally by way of the iliotibial band.
What nerves play a major part in the innervation of the knee joint?
Femoral and Sciatic Nerves (The femoral nerve innervates the quadriceps muscle group, and the sciatic nerve innervates the hamstring muscle group)
Biomechanical Analysis of Wall Slide Exercise
From a starting position (Fig. A) sliding down a wall moves the knee axis further away from the line of gravity for the body (Fig. B). This increases the resistance arm created by the weight of the body, requiring the quadriceps to produce more force to prevent excessive knee flexion. To meet this demand, the rectus femoris maintains a constant length-tension relationship by shortening at the hip and lengthening at the knee while the one-joint vasti muscles are lengthened over the knee. This brings the entire quadriceps group to optimal length where they can create a large amount of force.
The other two knee flexors, the popliteus and gastrocnemius muscles, receive innervation from the…
Tibial Nerve
The knee extensors receive innervation from the…
Femoral nerve, which comes off the spinal cord at a higher level than does innervation of the knee flexors. This is significant when dealing with individuals with spinal cord injuries
Anterior knee muscles (superficial view).
.
Anterior knee muscles (deep view).
.
Extension (Prime Movers of the knee)
- Quadriceps group
- Rectus femoris
- Vastus medialis
- Vastus intermedialis
- Vastus lateralis
Flexion (Prime Movers of the Knee)
- Hamstring group
- Semimembranosus
- Semitendinosus
- Biceps femoris
- -Popliteus and Gastrocnemius
Genu Valgum
Aka “knock knees,” is a malalignment of the lower extremity in which the distal segments (ankles) are positioned more laterally than normal. The knees tend to touch while the ankles are apart. Therefore, coxa varus is seen in conjunction with genu valgus,
Genu Varum
(bowlegs) is the opposite malalignment problem in which the distal segments are positioned more medially than normal. The ankles tend to touch while the knees are apart. Malalignment at one joint often affects alignment at an adjacent joint. Therefore, coxa valgus may be seen in conjunction with genu varus.
Genu Recurvatum
Aka “back knees,” is the positioning of the tibiofemoral joint in which range of motion goes beyond 0 degrees of extension.
Quadriceps (Innervation of the Muscles of the Knee)
- Rectus femoris: Femoral (L2, L3, L4)
- Vastus lateralis: Femoral (L2, L3, L4)
- Vastus intermedialis: Femoral (L2, L3, L4)
- Vastus medialis: Femoral (L2, L3, L4)
Hamstrings (Innervation of the Muscles of the Knee)
- Semimembranosus: Sciatic, tibial division (L5, S1, S2)
- Semitendinosus: Sciatic, tibial division (L5, S1, S2)
- Biceps femoris: long head Sciatic, tibial division (S1, S2, S3)
- Biceps femoris: short head Sciatic, common fibular division (L5, S1, S2)
Others (Innervation of the Muscles of the Knee)
- Popliteus: Tibial (L4, L5, S1)
- Gastrocnemius: Tibial (S1, S2)
Patellar Tendonitis
aka Jumper’s knee, is characterized by tenderness at the patellar tendon and results from the overuse stress or sudden impact overloading associated with jumping. It is commonly seen in basketball players, high jumpers, and hurdlers.
Osgood-Schlatter Disease
A common overuse injury among growing adolescents. It is an inflammation involving the traction-type epiphysis (growth plate) on the tibial tuberosity of growing bone where the tendon of the quadriceps muscle attaches
Popliteal Cyst
aka Baker’s cyst, is actually misnamed as a “cyst.” This general term refers to any synovial hernia or bursitis involving the posterior aspect of the knee.
Patellofemoral Pain Syndrome
Although there is no universal agreement on terminology and causation, generally refers to a common problem causing diffuse anterior knee pain. It is generally considered the result of a variety of alignment factors, such as increased Q angle, patella alta (high-riding patella), quadriceps weakness or tightness, weakness of hip lateral rotators, and excessive foot pronation.
Chondromalacia Patella
The softening and degeneration of the cartilage on the posterior aspect of the patella, causing anterior knee pain. Abnormal tracking of the patella within the patellofemoral groove causes the patellar articular cartilage to become inflamed, leading to its degeneration.
Prepatellar Bursitis
(housemaid’s knee) Occurs when there is constant pressure between the skin and the patella. It is commonly seen in carpet layers and is the result of repeated direct blows or sheering stresses on the knee.
Terrible Triad
A knee injury caused by a single blow to the knee and involves tears to the anterior cruciate ligament, the medial collateral ligament, and the medial meniscus.
Miserable Malalignment Syndrome
An alignment problem of the lower extremity involving increased anteversion of the femoral head and is associated with genu valgus, increased tibial torsion, and a pronated flat foot.
The body commonly experiences forces such as…
Traction, approximation, shear, bending, and rotation. These forces also have other names.
The muscle’s point of attachment to the bone is used to determine…
Leverage. With a second-class lever, resistance occurs between the axis and the force. With a third-class lever, force is in the middle.
The longer the force arm…
The easier it is to move the part. Conversely, the longer the resistance arm, the harder it is to move the part.
End Feel
The quality of the feel when slight pressure is applied at the end of the joint’s passive range.
An open kinetic chain requires…
That the distal segment is free to move and the proximal segment(s) remains stationary.
To stretch a one-joint muscle, it is necessary to…
Put any two-joint muscles on slack over the joint not crossed by the one-joint muscle.
To contract a two-joint muscle most effectively, start with…
It being stretched over both joints.
A muscle becomes actively insufficient when it…
Contracts over all its joints as the same time.
When determining whether a concentric or eccentric contraction is occurring, decide…
- If the activity is accelerating against gravity or slowing down gravity, or
- If a weight greater than the pull of gravity is affecting the activity.
Reversal of muscle action occurs when…
The origin moves toward the insertion.
