lower limb

Question 1

2 pelvic bones form pelvic girdle

Transfers weight of the body to lower limb

The hip is of ball and socket synovial variety with spherical articular surfaces. There are 3 axes in the joint: horizontal, vertical, and antero- posterior.

The hip has 3 DOF; flexion/extension (Transverse axis) ; abduction/adduction (ant-post axis) ; and medial/lateral rotation (Vertical axis) Circumduction, the combination of these three movements, occurs in the hip joint.

Answer 1

hip joint

The femoral head forms about 2/3 of a sphere of diameter 4-5 Cm. The head is supported by the neck of femur, the axis of which runs superiorly, medially and anteriorly.

The head in the adult forms an angle of 125 (inclination angle) with the femoral shaft to place the knee under the weight-bearing line of the head of the femur.

Question 2

If the neck-shaft angle is smaller (i.e. 90 degrees), the deviation is called ___ and there is a decrease in leg length.

Answer 2

coxa vara
Both of these structural changes also lead to decreased muscle strength because of changes in torque from alterations in muscle lever arms and length-tension relationships. (coxa valga and coxa vara)

• Valga and Vara cause muscle imbalance.
• If a normal adults has vara and valga the idnv will be more prone to dislocation of the head of the femur

Question 3

An increase in the neck -shaft angle is called ____ and results in an increase of limb length.

Answer 3

coxa valga
Both of these structural changes also lead to decreased muscle strength because of changes in torque from alterations in muscle lever arms and length-tension relationships. (coxa valga and coxa vara)
*Valga and Vara cause muscle imbalance.

*If a normal adults has vara and valga the idnv will be more prone to dislocation of the head of the femur

Question 4

The head in the adult forms an acute angle of 10 -30 with the femoral plane

Answer 4

(angle of anteversion)
The angle of anteversion normally decreases with growth and development of the child, causing orthopedists to be conservative in treatment of children who walk with in -toeing

Question 5

an increase in this angle is called anteverted femur and is one factor that is considered to cause in -toeing, or pigeon toes as well as

Answer 5

genu valgum

Question 6

A decrease in the angle is called retroverted femur, which may lead to out-toeing (lateral rotation) during standing and walking as well as

Answer 6

genu varum during standing.

Question 7

in an umbrella term to encompass both anteversion and retroversion

Answer 7

*torsion angle

Question 8

shows the extent of coaptation between the superior aspect of the head of femur and the acetabulum.
It also indicates the size of the area through which the body weight is transferred to the head of the femur.
This angle is measured between the a vertical line passing through the femoral head and another line joining the center of the femoral head to the superior acetabular rim.

Answer 8

The wiberg angle (angle from the edge of the acetabulum to the awning - process protruding out)

Question 9

is hemispherical and is bounded by the acetabular rim. The central part of the cavity (acetabular fossa) is deeperand is non-articular. The acetabulum is directed laterally, inferiorly, and anteriorly.

Answer 9

Acetabulum
When joint forces are decreased, synovial fluid once again returns to the joint space to provide lubrication and nutrition to the articular cartilages.

Question 10

is lined by a horseshoe-shaped articular cartilage, which is interrupted inferiorly by the deep acetabular notch.

Answer 10

Only the lunate surface of the acetabulum

Question 11

permits movement of the ligamentum teres and importantly serves as a reservoir for synovial fluid when the hip is heavily loaded.

Answer 11

The acetabular fossa

Question 12

Anatomic and Mechanical Axes of the Femur

Answer 12

The anatomic axis of the femur is represented by a line passing through the femoral shaft.

The mechanical axis is represented by a line connecting the centers of the hip and knee joints, which is typically a vertical line in the standing position.

Question 13

is a fibrocartilaginous ring inserted into the acetabular rim. It deepens the acetabulum and fills out the various gaps of the acetabular rim.

Answer 13

The acetabular labrum

Question 14

is attached to either side of the acetabular notch and is also attached to the labrum. The labrum has 3 surfaces: internal, central, and peripheral.

Answer 14

Transverse acetabular lig (TAL)

Question 15

of the head of the femur (ligamentum capitis femoris) (4) is a flattened fibrous band 3 to 3.5 Cm. long which arises from the acetabular notch and runs at the floor of the acetabular fossa before its insertion into the fovea femoris capitis. It is embedded in fibro-adipose tissue within the acetabular fossa and is lined by the synovial membrane.

Answer 15

The ligamentum teres (LT)
This ligament is extremely strong (breaking force equivalent to 45 Kg. weight) and its primary function is to carry the vascular supply to the head of the femur.

Question 16

Tension on the ligamentum teres does not occur until the extreme positions of abduction, flexion, and lateral rotation OR adduction, extension, and medial rotation are achieved.

Answer 16

*the obturator artery is the only artery that supplies the head of the femur. If it gets obstructed it can lead to necrosis of the head of the acetabulum

Question 17

The capsule is like a cylindrical sleeve running from the hip bone to the upper end of the femur. Medially it is inserted into the acetabular rim, and laterally to a line which runs along the intertrochanteric line and at the junction of the lateral and middle thirds of the femoral neck .

Answer 17

hip joint capsule

The capsule of the hip is strengthened by powerful ligaments anteriorly and posteriorly.

Question 18

is a fan shaped ligament that has two thick borders known as superior and inferior bands. It covers the hip joint anteriorly and superiorly. (Y ligament)

Answer 18

The iliofemoral ligament

Question 19

is anterior and inferior to the hip, limiting lateral rotation.

Answer 19

The pubofemoral ligament

Question 20

The ischiofemoral ligament:

Answer 20

is posterior and inferior, limiting medial rotation

Question 21

Role of the Hip Joint Ligaments in Movements

Answer 21

In flexion and hyperextension:
In the erect position , the ligaments are under moderate tension. During hyperextension of the hip all the ligaments become taut as they wind round the femoral neck. Of all these ligaments the inferior band of the iliofemoral ligament is under the greatest tension as it runs nearly vertically and so is responsible for checking the posterior tilt of the pelvis. During flexion of the hip all the ligaments are relaxed.

➢ In lateral and medial rotation:During lateral rotation of the hip the trochanteric line moves away from the acetabular rim with the result that all the anterior
ligaments of the hip become taut , while the ischiofemoral ligament is slackened. During medial rotation of the hip the converse obtains.

➢ In adduction and abduction: During adduction the superior band of iliofemoral ligament becomes taut and the inferior band tenses up only slightly, while
the pubofemoral & ischiofemoral ligaments are slackened.During abduction the iliofemoral ligament is slackened while the pubofemoral and ischiofemoral ligaments tense up

Question 22

There are several factors helping in coaptation of the hip joint.

Answer 22

1. Gravity: to the extent that the roof of the acetabulum covers the femoral head, the latter is pressed against the acetabulum by a force equal and opposite to the weight of the body.
2. Atmospheric pressure: the negative pressure deep in the acetabular fossa prevents the head of the femur from
   dislocation. A force of 45 lbs is required in adult cadavers to laterally distract the joint 3 mm, but when the capsule is punctured, the femur can be distracted about 8 mm without significant traction force.
3. Ligaments: their function varies according to the position of the hip. In the erect position or in extension, the ligament are under tension and are efficient in securing coaptation; in flexion the ligaments are relaxed and the femoral head is not powerfully applied to the acetabulum.
4. Muscles: which play a vital role in maintaining the structural integrity of the joint. Their function is reciprocally balanced Thus anteriorly the muscles are very few and the ligaments powerful while posteriorly the muscles predominate.

➢ Note: the position of flexion (loose packed position) is
therefore a position of instability because of the slackness of the ligaments. When a measure of adduction is added to the flexion, as in sitting position with legs crossed legs a relatively mild force applied along the femoral axis is enough to cause posterior dislocation of the hip joint.

Question 23

Accessory Motions(hip joint)

Answer 23

Normal accessory motions at the hip include distal traction, and lateral, anterior, and posterior gliding
➢ The closed-packed position for the hip is hyperextension, medial rotation, and abduction

Question 24

Axes of Motion and Movements
Although there are an ‘infinite’ number of axes around which hip movement may occur (and all passing through the femoral head), three perpendicular axes are used for descriptive purposes.

Answer 24

1. Flexion – Extension
2. Abduction – Adduction
3. Medial and Lateral Rotation

Question 25

❑ Flexion – Extension(hip joint)
➢ In standing, a horizontal axis running in a side-to-side direction is used for flexion and extension.
➢ The common hip axis represents a line connecting the centers of the two femoral heads, with movement occurring about this axis when, for example, the pelvis rocks forward and backward in standing, or when both
knees are pulled up to the chest from a supine lying position.
➢ Active hip flexion with the knee flexed can be reached to 120. With the knee extended, flexion is limited to 70-90 by the hamstrings.
➢ Passive hip flexion with knee flexed exceeds 145
but with knee extended would be less, due to hamstring stretching.
➢ Hyperextension of the hip is limited to 10-20 by the iliofemoral ligament. (further motion is usually perceived when one attempts this movement, however, it is extension of the lumbar vertebrae which gives a
misleading impression).
➢ Hyperextension of the hip joint is less when knee joint is flexed due to the fact that the hamstrings lose some of their efficiency as extensors of the hip because their contraction has largely been utilised in flexing the knee.

Answer 25

Movement Degrees End Feel
Hip Active Flexion (with knee extended) 70- 90 Firm
Hip Active Flexion (with knee flexed) 120 Firm
Hip Passive Flexion (with knee flexed) 145 Soft
Hip Hyperextension 10- 20 Firm
Hip Passive Hyperextension 30 Firm

Question 26

❑Abduction – Adduction(hip joint)
➢ The axis for abduction and adduction in the standing position is in a front-to-back direction.
➢ Either the limb may move in relation to the pelvis (lifting the limb laterally), or the pelvis may move in relation to the limb (inclining the trunk to the side of the stance leg). In either case, either abduction or adduction of the hip is the correct term to use to describe these movements.
➢ Hip abduction is 45 and is usually accompanied by elevation of the pelvis.
➢ Hip adduction is frequently described as contact between the two thighs, or 0. However, with the legs
crossed 30 - 40 of adduction is possible.

Answer 26

Movement Degrees End Feel
Hip Abduction 45 Firm
Hip Adduction 30 - 40 Firm

Question 27

Medial and Lateral Rotation(hip joint)
➢ The axis for medial and lateral rotation in standing is vertical, and identical to the mechanical
axis of the femur.
➢ Hip rotation is easier to observe when the knee is flexed to 90 and the motion of the tibia from
the neutral position is measured.

Answer 27

Movement Degrees End Feel
Hip Medial Rotation 30 Firm
Hip Lateral Rotation 60 Firm

Question 28

Flexor Muscles of the Hip
➢ These muscles lie anterior to the frontal plane, which
passes through the center of the joint

➢ There are many flexor muscles of the hip joint and
the most important of which are the following

Answer 28

1. Psoas major
2. Iliacus
3. Sartorius
4. Rectus femoris
5. Tensor fascia latae
6. Pectineus
7. Adductor longus
8. Gracilis
9. Anterior fibers of glutei medius and minimus

Question 29

The first group produce flexion,

abduction, and medial rotation

Answer 29

1. Anterior fibers of glutei medius and minimus

2. Tensor fascia latae

Question 30

The second group produce flexion,

adduction, and lateral rotation

Answer 30

1. Psoas major
2. Iliacus
   3 Pectineus
   4 Adductor longus

Question 31

Hip Flexion in the Sitting Position

Answer 31

➢ In the sitting position, the hip is already flexed to about 90, and any additional flexion requires action by the hip flexors in a shortened range of motion.
➢ Iliopsoas is the only hip flexor that can produce enough tension to flex the hip beyond 90 in the sitting position.
➢ In the sitting position, the hip flexors, and especially the Iliopsoas, control the vertebrae and pelvis on the femur as a person leans back and returns to the upright position.
➢ With a bilateral paralysis of the Iliopsoas, a person would fall back as soon as the center of gravity line of the head, arms, and trunk (HAT) falls behind the hip joint axis.

Question 32

The Extensor Muscles of the Hip

➢ These muscles lie behind the frontal plane that passes through the center of the joint (a).
➢ There are two main groups (b): the one group is inserted into the femur and the other in the vicinity of the knee joint.

Answer 32

➢ The first group consists of the following muscles and beside extension they also do the abduction (c):

1. Gluteus maximus
2. Posterior fibers of gluteus medius
3. Posterior fibers of gluteus minimus

➢ The second group consists of the following muscles and beside extension they may also help in adduction (d):

4. Biceps femoris
5. Semitendinosus
6. Semimembranosus
7. Adductor magnus

➢ To produce a pure extension (e) both of these groups should work together.

Question 33

Muscles Crossing Two Joints

The efficiency of a two-joint muscle is substantially influenced by the positions of the two involved joints, in accordance with the principles governing length-tension relationships.

Answer 33

➢ The Rectus Femoris can produce more force as a hip flexor if the knee flexes simultaneously with the hip, because this permits the muscle to contract
within a favorable range.
➢ For the same reason, the Rectus Femoris is a more efficient knee extensor if the hip extends simultaneously.
➢ The hamstrings are more efficient as hip extensors when the knee extends as well; the hamstrings are more efficient as knee flexors when the hip flexes
simultaneously with the knee.

Question 34

Abductor Muscles of the Hip

Answer 34

➢ These muscles generally lie lateral to the sagittal plane which traverses the center of the joint. One can
classify these muscles based on their accessory function
into 2 groups

A. The first group includes all the muscles lying anterior to the frontal plane passing through the center of the
joint.
1. Anterior fibers of gluteus medius
2. Gluteus minimus
3. Tensor fascia latae
➢ These muscles produce abduction, flexion, and medial rotation

B. The second group are those muscles which lie posterior to the frontal plane running through the center of the hip joint. This group consists of:

4. Gluteus maximus (upper fibers)
5. Piriformis

➢ These muscles produce abduction, extension, and lateral rotation
➢ To obtain pure abduction these two groups of
muscles must be activated as a balanced couple.
➢ In certain positions, other muscles also contribute to the force of abduction: the Sartorius, Piriformis,
Obturators, Gemelli
.

Question 35

Adductor Muscles of the Hip

➢ These lie generally medial to the sagittal plane, which traverses the center of the joint.

Answer 35

1. Adductor magnus
2. Gracilis
3. Semimembranosus
4. Semitendinosus
5. Biceps femoris
6. Gluteus maximus
7. Quadratus femoris
8. Pectineus
9. Obturator externus
10. Adductor longus
11. Adductor brevis

Question 36

Rotator Muscles of the Hip

Answer 36

➢ The lateral rotators of the hip are:

1. Piriformis
2. Obturator internus
3. Obturator externus
4. Quadratus femoris
5. Gluteus maximus
6. Gluteus medius (Posterior fibers)
7. Gemelli (Not Shown)

➢ The medial rotator group consists of:

1. Tensor fascia latae
2. Gluteus minimus (Anterior fibers)
3. Gluteus medius (Anterior fibers)

Question 37

Change of Action Because of Joint Angle

Answer 37

➢ In some hip positions, the line of action of a muscle may change from a position anterior to one posterior of the axis, and thus the same muscle can perform antagonistic actions at the hip.
➢ The role of hip adductors in flexion or extension depends on whether they are originating from the hip bone posterior or anterior to the frontal plane which runs
through the center of the joint.
➢ The hip adductors can act as hip flexors with the hip in extension. With the hip in full flexion, they can act as extensors.
➢ The Gluteus Medius and Tensor Fasciae
Latae are considered medial rotators of the extended hip, but their leverage for medial rotation increases
further when the hip is flexed to 90

➢ A good example of this is the Piriformis:
when the hip is extended it acts as an lateral rotator, but the same muscle becomes a medial rotator when the hip is flexed.

Question 38

consisting of three bones, 2 DOF, and three articulating surfaces: the medial tibiofemoral, lateral tibiofemoral, and
patellofemoral articulations, all of which are enclosed by a common joint capsule.
➢ The multiple functions of the knee include withstanding large forces, providing great stability, and enabling a large ROM.

➢ Mobility is primarily provided by the knee bony structure, while stability is provided by
the soft tissues including ligaments, muscles, and cartilage.

Answer 38

The knee joint is a complex joint (condylar, synovial)

Question 39

articular surface of knee joint

Answer 39

The articular surfaces of the femur represent a segment of a pulley which recalls the twin undercarriage of an aero plane.
The two femoral condyles, convex in both
planes, form the two lips of the pulley, and they are extended anteriorly by the pulley-shaped patellar surface. The neck of the pulley is represented anteriorly by the central groove on the patellar surface and posteriorly by the intercondylar notch.

➢ The tibial surfaces are reciprocally curved and comprise two curved and concaved parallel gutters which are separated by a blunt eminence running antero-posteriorly. This eminence lodges the two intercondylar tubercles and if we prolong this
eminence, it coincides with the vertical ridge on the deep surface of the patella while the two facets on either side of the patellar ridge correspond to the tibial
condyles. These surfaces have a transverse axis (I) which coincides with the inter condylar axis (II) when the joint is closed. The lateral condyle and the medial condyle lie each in a gutter on the surface (S).

➢ To allow axial rotation, the tibial surface (5) must be so modified as to shorten the
intercondylar eminence. This is achieved by planning the two ends of the eminence
(6), and leaving its middle part to act as a pivot, which, by lodging in the inter
condylar notch, allows the tibia to rotate round (axis R) it.

Question 40

Therefore there are two functional joints that make the knee joint.

Answer 40

1. the femoro-tibial

2. the femoro-patellar joints)

Question 41

Knee Joint Capsule

Answer 41

➢ The knee joint capsule is composed of complex
passive and active connections among the menisci, ligaments, retinacula, bones, muscles, and the capsule itself.

➢ The joint capsule forms a sleeve around the
joints, attaching just above the femoral condyles
and below the tibial condyles.

➢ Retinacula and ligaments reinforce and become
integral parts of the capsule.

➢Some examples of the ‘complexity of the capsule include; the proximal tendon of the popliteus muscle pierces the capsule to attach on the lateral femoral condyle;

the Semimembranosus muscle forms part of
the oblique popliteal ligament and gives off fibres to
the MCL as well as to its large bony attachment.

Question 42

The Collateral Ligaments of the Knee

Answer 42

➢ Collateral ligaments strengthen the articular capsule on its medial and lateral aspects. They are therefore responsible for the transverse stability of the knee during
extension.

➢ The medial collateral ligament runs from the postero-superior aspect of the medial femoral condyle to the upper end of the tibia just posterior to the pes
anserinus tendon. So it runs inferiorly and anteriorly.

➢ The lateral collateral ligament runs from the outer surface of the lateral condyle to the head of the fibula.
➢ The collateral ligaments become taut during extension and slackened during
flexion .

Question 43

The Cruciate Ligaments of the Knee

Answer 43

➢ In the anterior view of the knee joint, the cruciate ligaments are seen in the center of the joint being largely contained within the intercondylar notch and fossa.

➢ These ligaments stabilize the knee in the antero-posterior direction and allow the joint to work as a hinge while keeping the articular surfaces in contact.

Question 44

➢ is attached to the anterior intercondylar area of the tibia. It runs obliquely superiorly, posteriorly and laterally and is attached to the internal aspect of the lateral condyle of the femur.

Answer 44

The anterior cruciate ligament

Question 45

➢ is attached to the posterior part of the posterior intercondylar area of the tibia. The ligament runs obliquely medially, anteriorly, and superiorly to be inserted to the edge of the lateral surface of the medial femoral condyle.

Answer 45

The posterior cruciate ligament

Question 46

➢ The lack of congruency in the articular surfaces, is corrected by the interposition of the menisci or semi lunar fibrocartilages with the following three surfaces:
➢ The superior surface is in contact with the femoral condyles.
➢ The peripheral surface adheres to the deep surface of the capsule.
➢ The inferior surface rests on the edges of the medial and lateral tibial condyles.
➢ These rings are incomplete in the region of the intercondylar tubercles of the tibia so that they are crescent -shaped with an anterior and a posterior horn.

Answer 46

Menisci
The horns of the lateral meniscus come closer to each other so that the meniscus is almost a complete
circle. Whereas the medial meniscus is C-shaped

Question 47

These menisci have important attachments from functional point of view. Each horn is anchored to the tibial condyle in the anterior and posterior intercondylar areas respectively.

Answer 47

The two anterior horns are linked by the transverse ligament of the knee

Question 48

Fibrous bands run from the lateral edges of the patella to the lateral borders of each meniscus forming the .

Answer 48

meniscopatellar ligament

Question 49

is attached by its deep fibers to the peripheral surface of medial meniscus.

Answer 49

The medial collateral ligament of the knee

Question 50

is separate from its corresponding meniscus by the tendon of popliteus which sends a fibrous expansion to the posterior border of the lateral meniscus.

Answer 50

The lateral collateral ligament of the knee

Question 51

also sends a fibrous expansion to the posterior edge of the medial meniscus.

Answer 51

The semimembranosus tendon

Question 52

separate fibers of the posterior cruciate ligament are inserted into the posterior horn of the lateral meniscus forming the

Answer 52

meniscofemoral ligament

Question 53

Movements of the Knee Joint

Answer 53

➢ The knee joint possesses two DOF: flexion-extension and medial & lateral rotations.
➢ Flexion ranges from 120 to 150 depending on the size of the muscle mass in the calf and posterior thigh as they make contact.
➢ Hyperextension of the knee is minimal, and usually will not exceed 15

Question 54

Axes for Flexion and Extension

Answer 54

Clinically, the axis of motion of the knee is located a few cm above the joint line, passing horizontally through the femoral condyles (also known as the geometric center).

➢ There is also the instant center of rotation of Reuleaux. This axis represents the point of zero velocity on the femoral condyles during flexion and extension. This axis coincides with the center of the cruciate ligaments in the sagittal plane.

Question 55

Flexion & Extension of the Knee

Answer 55

If femur just rolled on the tibia without sliding to each point on the tibia, corresponds a single point on the femur so that the distance covered on the tibia is exactly equal to the portion of the circumference of the femur which has rolled over tibia. Then after a certain measure of flexion, the femoral condyle would tip over behind the tibial condyle. The possibility of simple rolling
of femur on the tibia is precluded by the fact that the length of the circumference of the femoral condyle is twice as great as the length of the tibial condyle.

➢ Let ’s assume that the femur slides without rolling Therefore to one point on the tibia corresponds a segment of the circumference of the femur. But it is clear that under this condition flexion would be prematurely checked by the impact of the femur on the posterior border of the tibial condyle.

➢ Various experiments have proven that the femoral condyle rolls and slides simultaneously over the tibial condyle On the other hand the ratio of rolling to sliding varies during flexion and extension. Starting from full extension, the femoral condyle begins to roll without sliding and then the sliding movement becomes progressively more important so that at the end of
flexion the condyle slides without rolling.

➢ Finally, the length over which pure rolling takes place varies with the femoral condyle.

For the medial condyle , pure rolling occurs only during the first 10-15 degrees of flexion.
Butthe lateral condyle continues this rolling up to 20 degrees.
Therefore the lateral condyle rolls far more than the medial and this partly explains why the distance covered by the lateral femoral condyle over the corresponding tibial condyle is greater than that covered by the medial condyle. It is interesting to note that the 15-20 degrees of initial rolling corresponds to the normal range of the movement of flexion and extension during
ordinary walking.

Question 56

Movement Degrees End Feel(knee joint)

Answer 56

1 Knee Flexion 120 - 150 Soft
2 Knee Hyperextension 5 - 15 Firm
3. Knee Active Lateral Rotation 40 Firm
4. Knee Passive Lateral Rotation 45- 50 Firm
5.Knee Active Medial Rotation 30 Firm
6. Knee Passive Medial Rotation 30- 35 Firm

Question 57

Medial & Lateral Rotation

Answer 57

➢ Occurs in the transverse plane when the knee is
flexed.
➢ With the knee fully extended, the collateral ligaments
are tense and contribute to joint stability.
➢ With the knee flexed to 90 the ligaments are
slackened, allowing for a considerable amount of
rotation to occur.
➢ The axis for rotation is longitudinal, and located
medial to the inter-condylar eminence of the tibia.
Hence it can be said that the lateral condyle rotates
around the medial condyle.
➢ Motion is limited by capsular and ligamentous
structures, including the collateral, cruciate, and oblique
popliteal ligaments as well as the retinacula and the
Iliotibial tract

Question 58

There is also a type of axial rotation called ____ because it is inevitably and involuntarily linked to movements of flexion and extension. It occurs especially at the end of extension or the start of flexion.

When the knee is extended the foot is externally (laterally) (EXTernally) rotated hence
the mnemonic EXTension and EXTernal rotation.
Conversely, when the knee is flexed the leg is internally
(medially) rotated

Answer 58

automatic (Screw-Home Mechanism )

Question 59

Rotation of the Knee

Answer 59

Axial rotation of the knee can only take place in flexion.
In the neutral position for axial rotation with the knee
flexed, the posterior part of the femoral condyle is in
contact with the middle part of the tibial condyles. With
flexion of the knee the inter-condylar tibial tubercles
move clear of the inter-condylar notch of the femur,
where they normally lodge during extension.

➢ During lateral rotation of the tibia on the femur the
lateral femoral condyle moves forward over the lateral
tibial condyle while the medial femoral condyle moves
backward over the medial tibial condyle.
➢ During medial rotation, the converse takes place.
➢ The antero-posterior movements of the femoral condyles over their respective tibial condyles vary with the condyle.
➢ The medial condyle, moves relatively little. But the
lateral condyle moves about twice as much.

Question 60

Movement of Menisci During Flex. & Ext.

Answer 60

In extension the posterior part of the tibial condyle
becomes exposed while in flexion , the menisci come to overlie the posterior part of the tibial condyles, especially the lateral meniscus which reaches as far as the posterior border of the lateral condyle.
➢ When the menisci are viewed from above, starting from the position of extension, the menisci move posteriorly unequally; in flexion the lateral meniscus has receded twice as far as the medial meniscus (12mm & 6mm respectively).
➢ The menisci play an important part as an elastic coupling which transmits any compression forces between the femur and the tibia

➢ Factors involved in the movements of the menisci can be classified into two groups:
➢ There is only one passive element involved in the
displacement of the menisci. The femoral condyles push the menisci anteriorly just as a cherrystone is pushed forward between two fingers.
➢ Active mechanisms are numerous. During extension
the menisci are pulled forward by the meniscopatellar fibers which are stretched by the anterior movement of the patella and this draws the transverse ligament forward. In addition the posterior horn of the lateral meniscus is pulled anteriorly by the tension developed in the meniscofemoral ligament, as the posterior cruciate ligament becomes taut.
During flexion the medial meniscus is drawn
posteriorly by the semimembranosus expansion which is attached to its posterior edge, while the anterior horn is
pulled posteriorly by the fibers of the anterior cruciate
ligament attached to it; the lateral meniscus is drawn
posteriorly by the popliteus expansion.

Question 61

Movement of the Menisci During

Axial Rotation

Answer 61

➢ During the movement of axial rotation, the menisci follow exactly the displacement of femoral condyles. Starting from the neutral position, they can be seen to move on the tibial condyles in the
opposite direction.
➢ During lateral rotation, the lateral meniscus is pulled towards the anterior part of the tibial condyle while the medial meniscus is drawn posteriorly.
➢ During medial rotation , the medial meniscus moves forward while the lateral meniscus recedes.
➢ During movements of the knee the menisci can be injured if they fail to follow the movements of the femoral condyles on the tibial condyles, they will be caught in an abnormal position. This happens for instance during violent extension of the knee especially if it is accompanied with lateral or medial rotation of the tibia. This condition may result in:
6. Longitudinal splitting,
7. Complete detachment,
8. Complex tear,
9. Transverse tear.

Question 62

The patella is a sesamoid bone set within the joint capsule and articulates with the anterior and distal saddle -shaped surfaces of the femoral condyles

Answer 62

Patello -femoral Joint

The quadriceps mechanism stabilizes the patella on all sides and guides its motion. The strong patellar ligament anchors the patella to the tibial tuberosity

Question 63

Purposes of the Patella

Answer 63

1. Increases the leverage or torque of the quadriceps muscles by increasing its distance from the axis of motion
2. Provides bony protection to the distal femoral condyles
   when the knee is flexed
3. Decreases pressure and distribute forces on the femur
4. Prevents damaging compression forces on the quadriceps tendon with full range resisted knee flexion/extension activities (i.e. deep knee bends). The tendons are designed to withstand large tension forces but not compression or frictional forces.
   ➢ As the flexion proceeds the patella is compressed against the patellar groove more forcefully. But in extension the patella actually tends to detach from the femur.
   Because of the obtuse angle between the quadriceps tendon and the patellar ligament, the patella also tends to dislocate laterally, which is prevented by the contraction of vastus medialis at the end of extension range of movement. The other preventive factor is the lateral lip of the patellar groove which is higher than the medial lip.

Question 64

is the angle formed between the longitudinal axis of the femur (or the tendon of the quadriceps) and the patellar ligament (which runs right through the center of the patella), and is about 10 in men and 15 in women
➢ Q angles greater than 20 are said to have a higher incidence of patellofemoral joint abnormalities such as chondromalacia patella and patellofemoral tracking problems.

Answer 64

The ‘Q-angle’

The normal angle between the longitudinal axis of the femur and tibia is approximately 170, with the femur angling medially as one travels distally. This angle
is due to the adducted position of the shaft of the femur and the compensatory direction of the tibia to transmit weight perpendicularly to the foot and ground. If the angle becomes smaller than 170, the condition is referred to as genu valgum, or knock knee.
Conversely, if the angle approaches 180 , the deformity is referred to as genu varum, or
bowleg

Question 65

Transverse Stability of the

Knee

Answer 65

During walking and running the knee is
continually subject to side to side stresses. In certain
postures the body is in a state of imbalance, being
tilted medially relative to the supportive knee
tends to exaggerate the physiological valgus and to
open out the inter -space of the joint medially. If the
stress is too sever the medial collateral ligament is
torn
The reverse thing happens in lateral tilt
relative to the supportive knee . When the knee
is severely sprained, abnormal side to side
movement can be demonstrated in full extension of
the knee.
➢ Normal stresses applied during walking and
running are not opposed just by the collateral
ligaments. In fact they are assisted by the following
muscles.
1. Muscles attached to iliotibial tract
2. Sartorius
3. semitendinosus
4. Gracilis

Question 66

Antero-posterior Stability of

the Knee

Answer 66

The mechanism of stabilization of the joint varies
according to whether it is slightly flexed or hyper
-extended.
When the knee is straight or very slightly
flexed , the force exerted by the body weight acts
behind the flexion and extension axis of the knee and
so the knee tends to flex further unless prevented by
contraction of the quadriceps. Therefore in this
position the quadriceps is essential for the
maintenance of the erect posture.
On the other hand, if the knee is hyper extended (C), the natural tendency to increase this hyper extension is checked by the capsule and the related ligaments posteriorly.
This elements (D,E) consist of:
1. Condylar plate
2. Arcuate ligament intermediate band
3. Arcuate ligament lateral band
4. Arcuate ligament medial band
5. Oblique popliteal ligament
6. Semimembranosus tendon
7. Lateral collateral ligament
8. Medial collateral ligament
9. Posterior cruciate ligament
10. Three medial tibial muscles (Pes anserine tendon;
(Sartorius, Semitendinosus & Gracilis)
11. Biceps femoris
12. Gastrocnemius

Question 67

The Rotational Stability of the

Knee During Extension

Answer 67

Axial rotation can only occur when the knee is flexed. On
the other hand, in full extension axial rotation is
impossible, being prevented by the tension of the
collateral and cruciate ligaments.
➢ When seen from above the cruciate ligaments are
parallel to each other and lateral rotation relaxes them
while medial rotation tightens the cruciates. Therefore in
medial rotation the femur is firmly pressed against the
tibia. That ’s why the cruciates prevent medial rotation
when the knee is extended.
➢ A similar line of reasoning can be developed to explain the role of collateral ligaments
On the contrary to cruciates, the collateral ligaments will relax during medial rotation and will be taut in lateral rotation.
Therefore it follows that the collateral ligaments prevent
lateral rotation of the knee in extension.
➢ The rotational stability of the knee is thus secured by
collateral and cruciate ligaments.

Question 68

➢ The quadriceps (A) femoris is the extensor muscle of
the knee. It is composed of four heads known as:

➢ The patella which is embedded in the tendon of this
muscle increases the efficiency of the muscle up to
33%.

Answer 68

1. Vastus intermedius
2. Vastus lateralis
3. Vastus medialis
4. Rectus femoris

Question 69

The flexor muscles (B) of the knee are the hamstrings
and some other muscles which consist of:

The efficiency of hamstring muscles largely depends
on the position of the hip. The more the hip is flexed
the higher the efficiency of these muscles. The flexor
muscles are also rotators of the knee. If they are
attached to the fibula and lateral tibial condyle then
they rotate the knee laterally otherwise they will be
medial rotators of the knee.

Answer 69

1. Biceps femoris
2. Semitendinosus
3. Semimembranosus
4. Gracilis
5. Sartorius
6. Gastrocnemius

Question 70

❑ Muscle Movement Summary Muscles

Answer 70

PM = Prime Mover
X = Synergist

Biceps Femoris PM-flexion PM-lateral rotation
Semimembranosus X flexion PM-medial rotation
Semitendinosus X- flexion
Gastrocnemius X-flexion
Plantaris X-flexion

Popliteus X-flexion X-medial rotation
Sartorius X -flexion X-medial rotation
Gracilis X-flexion X-medial rotation
Rectus Femoris X-extension
Vastus Lateralis PM-extension
Vastus Medialis X-extension
Vastus Intermedius X-extension
Tensor Fascia Latae X-lateral rotation

Question 71

Functions of Muscles of the Knee
1.Knee Extensors
➢ The Rectus Femoris produces its highest torques for extension of the leg when the hip is in an extended position. With the hip flexed, it cannot generate as much force, as the muscle is in a shorter position, and therefore lower on the tension-length relationship curve.
➢ It is believed that the vastus medialis plays an important role in keeping the patella on track in gliding on the femoral condyles by counteracting the laterally directed forces of the vastus lateralis, and thus preventing lateral displacement of the patella in the trochlear groove of the femur.

2. Knee Flexors
   ➢ Open-chain motions of knee flexion and rotation are important for placement and movement of the foot but require little muscle force to execute (except deceleration of the leg in walking or running).
   ➢ The hamstrings are primarily hip extensors and contract strongly to stabilize the pelvis during trunk extension, and to control the pelvis on the femur as a subject leans forward to touch the feet and then returns to the upright position.
3. Knee Rotators
   ➢ The hamstrings, sartorius, and gracilis muscles have rotary actions at the hip and knee, and the popliteus on the knee only.
   ➢ These rotator muscles control hip and knee rotation in walking after the foot is planted during the stance phase as the hip and knee must rotate for forward motion of the body to occur.

Answer 71

4. One-Joint and Two-Joint Muscles Acting at the Knee
   ➢ Only 5 of the muscles acting on the knee are one-joint muscles: the three vasti, the popliteus, and the short head of the biceps femoris.
   ➢ Muscles that cross both the hip and knee include: rectus femoris, sartorius, gracilis, semitendinosus, semimembranosus, long head of the biceps femoris, and the TFL.
   ➢ The gastrocnemius and plantaris are the only muscles that cross both the ankle and knee.
   ➢ Under ordinary conditions, two-joint muscles are seldom used to move both joints simultaneously, such as combining knee flexion with hip extension, or knee extension with hip flexion.
   ➢ Typically the action of two-joint muscles is prevented at one joint by resistance from gravity or the contraction of other muscles.
5. Squatting
   ➢ When performing a squatting motion such as squatting itself, rising from a sitting position or climbing stairs, the hamstrings act as hip extensors while the quadriceps act as knee extensors, and by doing so, elongate the hamstrings over the knee.
   ➢ When a person rises from a squat position, the quadriceps performs a concentric contraction to extend the knee, and the hamstrings perform a concentric contraction to extend the hip.
   ➢ When and individual lowers him/herself back into the squatted position, eccentric contractions of both muscle groups control the rate of knee flexion (quadriceps) and hip flexion (hamstrings).
6. Knee Flexion combined with Plantar Flexion
   ➢ The gastrocnemius is capable of performing these two motions simultaneously.
   ➢ However, if this movement is attempted, the gastrocnemius quickly will become actively insufficient as it shortens.
   ➢ This movement is not one which typically occurs under natural conditions.
7. Knee Extension combined with Plantar Flexion
   ➢ In this movement, the quadriceps extend the knee while the gastrocnemius (and soleus) plantar flex the ankle.
   ➢ The extension of the knee elongates the gastrocnemius over the knee joint, providing optimal contractile conditions for plantar
   flexion.
   ➢ This functional combination is frequently seen in such activities as rising on tiptoes, running, and jumping.

Question 72

A person with paralyzed quadriceps cannot extend the leg against resistance, and will usually press on the distal end of the thigh with their hand during walking to prevent inadvertent knee flexion.

➢ The gluteus maximus can also be used as a strong extensor of the hip and to maintain the knee in
the extended position during walking.

Answer 72

Paralysis of the Quadriceps (Genu recurvatum)

Question 73

Otherwise known as “runner’s knee”. A soreness and aching around or deep to the patella results from a muscular imbalance of the quadriceps, typically a weakness of the vastus medialis allowing the patella to track abnormally towards the lateral side of the knee.

➢ Strengthening of the vastus medialis may help to relieve these symptoms and correct the abnormally
tracking patella.

Answer 73

Chondromalacia Patellae

Question 74

Almost always involves a dislocation of the patella to
the lateral side, and happens more frequently
in women.
➢ Lateral movement of the patella is counterbalanced
by the vastus medialis, and the lateral femoral condyle
has a more anterior projection and a deeper
slope for the larger lateral patellar facet, providing a
further mechanical deterrent to lateral
dislocation.

Answer 74

Patellar Dislocation

Question 75

A direct blow to the patella or a sudden contraction of the quadriceps (such as when one slips and attempts to prevent a backward fall) may fracture the patella into two or more pieces.

Answer 75

Patellar Fractures

Question 76

If it is fracture into two pieces from a powerful quadriceps contraction,in which the proximal patellar fragment is pulled superiorly with the quadriceps tendon and the distal fragment remains with the patellar ligament.

Answer 76

it is called a transverse patellar fracture

Question 77

The patella may have to be removed due to such injuries as a comminuted fracture.
➢ This results in the quadriceps having to exert about 30% more force to extend the leg.

Answer 77

Patellectomy

Question 78

➢ Articular Surfaces
o lateral condyle of tibia and the head of the fibula
o Surfaces are flat, oval facets covered by cartilage and
connected by capsule and ligaments.

➢ Classification – Synovial (diarthrodial) planar (gliding)
o This joint has a synovial membrane that lines the
fibrous capsule.
o The popliteus tendon runs close & sometimes
communicates with the synovial cavity.
➢ Ligaments
o Anterior tibiofibular ligament of the head of the fibula
o Posterior tibiofibular ligament of the head of the fibula
o Interosseous membrane – firm connection with syndesmosis superiorly & inferiorly
➢ Motion
o This joint is more active in dorsiflexion and plantar flexion. There is small superior gliding movement of this joint with
dorsiflexion and small inferior gliding movement with plantar flexion

Answer 78

❑ Superior (Proximal) Tibiofibular joint

➢ Motion at the superior tibiofibular joint is impossible without motion first at the inferior tibiofibular joint.

Question 79

➢ Articular Surfaces
o Formed by a rough convex surface on the medial side of the distal fibula and the rough concave surface on the lateral side of the distal tibia.
o A strong interosseous ligament continues with the interosseous membrane and forms the strong connection between distal ends of tibia & fibula.

➢ Classification
o Syndesmosis (fibrous)

➢ Closed Packed position = Max dorsiflexion

➢ Ligaments
o Posterior tibiofibular ligament
o Anterior tibiofibular ligament
– Both strengthen the joint anteriorly & posteriorly
– They extend from the fibular notch of the tibia to the Ant. & Post. surface of the lateral malleolus.
o Interosseous Membrane

Answer 79

❑ Inferior (Distal) Tibiofibular Joint
➢ Motion
o A few degrees of “gliding” motion inferiorly & superiorly in both plantar & dorsiflexion.
o Maleoli are held firmly together by anterior & posterior ligaments.
o This joint is more active on plantar flexion.
o This articulation forms a strong union between the distal ends of the tibia & fibula and contributes to much of the strength of the ankle joint itself.

Question 80

Between the talus and the crus (lower leg-tibia & fibula) ➢ Classification: synovial hinge joint
➢ DOF: one or uniaxial

Answer 80

❑ Talocrural joint (Ankle Joint, Mortise Joint)

plantar flexion-30-45 degrees firm
Dorsiflexion-30 degrees firm

Question 81

The Articular Surfaces of the Ankle Joint

Answer 81

The superior or trochlear surface of talus, convex antero-posteriorly, is depressed centrally by a longitudinal groove bounded by the medial and lateral lip of the pulley.
This groove runs anteriorly and laterally . This surface is
broader anteriorly than posteriorly. The trochlear surface of the talus corresponds to a reciprocally shaped surface on the inferior aspect of the tibia which is concave antero
-posteriorly and has a blunt sagittal ridge to fit into the trochlear groove. One either side of this ridge, a medial and a lateral gutter, respectively receive the corresponding lips of the trochlear surface.

➢ The medial surface of the body of the talus is nearly
plane. It articulates with the facet on the lateral surface of medial malleolus which is lined by cartilage continuous with that lining the inferior surface of the tibia.

➢ The lateral surface is in contact with the articular facet
of the medial surface of the lateral malleous

➢ The articular surfaces are covered by cartilage and are within a fibrous capsule which is thin anteriorly & posteriorly, but is supported by strong collateral ligaments both laterally & medially.

➢ The tibia and fibula are bound together by the anterior & posterior tibiofibular ligaments thus forming a strong mortise for the trochlea.

Question 82

is made up of four different bands that can be considered as different ligaments including : Posterior Tibiotalar ligament Tibiocalcaneal ligament Tibionavicular ligament and anterior tibiotalar ligament (

Answer 82

Medial collateral (deltoid) ligament (MCL), 
The deltoid ligament is stronger than the lateral collateral ligament

Question 83

: In general it attaches the lateral malleolus to the talus & calcaneus and is made up of three separate bands that can be considered as different ligaments including : Posterior talofibular ligament Calcaneofibular ligament and Anterior talofibular ligament

Answer 83

Lateral collateral ligament (LCL)

Question 84

ankle joint- Axis of Motion
– Draw a line connecting the distal tips of the maleoli-this is the axis of motion for plantarflexion / dorsiflexion at the ankle joint.

Answer 84

The medial maleolus is anterior & superior to the lateral
maleolus, therefore the axis is an oblique line. Rotated 30 degrees in the transverse plane, therefore with
dorsiflexion you toe OUT and with plantar flexion you
toe IN
➢ Closed Packed position
– Max Dorsiflexion

Question 85

is the forcible wrenching or twisting of a joint that

stretches or tears its ligaments but does not dislocate the bones.

Answer 85

sprain

Question 86

is a stretched or partially torn muscle or muscle and

tendon

Answer 86

strain

Question 87

o 1st Degree • Tear one ligament – Anterior Talofibular Ligament

o 2nd Degree • Tear of two ligaments – Talofibular Ligament (anterior or posterior) – Calcaneofibular Ligament

o 3rd Degree • Tear all 3 lateral ligaments – Anterior Talofibular Ligament – Posterior Talofibular Ligament – Calcaneofibular Ligament

– MOST COMMON Sprained Ankle • Includes the anterior Talofibular ligament

Answer 87

Inversion Sprain

Question 88

– Most commonly associated with fracture

Answer 88

Eversion Sprains

Question 89

– Talus shoved between tibia and fibula
– Tear of interosseous membrane
– Very difficult recovery time

Answer 89

High ankle sprain or syndesmotic ankle sprain

Question 90

Complex series of interconnected joints
➢ Can be divided into 3 functional areas:
o Hindfoot – Talus and calcaneus
o Midfoot – Navicular, Cuboid, 3 Cuneiforms
o Forefoot – Metatarsals and Phalanges

Answer 90

The Foot

Question 91

A synovial joint between the inferior surface of the body of the talus & the superior surface of the calcaneus surrounded by an articular capsule.

Articular Surfaces:
Talus: Inferior surface has 3 articular facets (anterior, middle and posterior).
Calcaneus: Superior surface has 3 facets (anterior, middle and posterior).

❖ This joint has two capsules
1) Encloses the posterior articular facets of the inferior talus & the superior calcaneus.
2) Encloses the middle & anterior articular facets of the subtalar joint as well as the
talonavicular joint.
➢ Classification – planar synovial joint
➢ Closed Packed Position: Supination

➢ Motions – also described as rotation with a screw-like motion around the triplanar axis
1) Inversion/Eversion (terms often used in open chain motions) are the frontal plane
motions at the ankle joint.
– Inversion occurs at the hindfoot (heel) as the calcaneus/heel moves in the direction
that the bottom of your foot faces inward.
– Eversion also occurs at the hindfoot, but instead of the heel facing inwards, it faces outward.
• 40 degrees total motion (from max inversion to max eversion)
2) Supination/Pronation (terms often used in closed chain motions) are the triplanar motions of the ankle/foot complex.
– Supination is made up of inversion of the hindfoot, abduction of the forefoot, and dorsiflexion of the ankle regions.
– Pronation is made up of eversion of the hindfoot, adduction of the forefoot, and plantarflexion of the ankle regions.
3) Abduction/Adduction: actually it is rotation movements in knee joint!
• In foot & ankle this motion occurs around a vertical axis
• Small movements throughout the leg, ankle & foot

Answer 91

Subtalar (Talocalcaneal) Joint

Question 92

– anteriorly
o A thick strong band that binds the talus & calcaneus runs through the sinus tarsi (a canal between these articulations).

Answer 92

Interosseous Talocalcaneal ligament

Question 93

Connects medial tubercle of talus to sustentaculum tali on medial surface of calcaneus.

Answer 93

Medial Talocalcaneal ligament

Question 94

Connects lateral talus to lateral calcaneus

Answer 94

Lateral Talocalcaneal ligament

Question 95

Connects lateral tubercle of talus to upper medial calcaneus

Answer 95

Posterior Talocalcaneal ligament

Question 96

Connects the neck of the talus to the front & lateral surfaces of the superior calcaneus

Answer 96

Anterior Talocalcaneal ligament (also called the anterior interosseous ligament)

Question 97

Made up of 2 joints that work together; they do not create motion independently.
o Talonavicular jointo Calcaneocuboid joint-has a capsule and is reinforced by ligaments.

➢ Motion: Complex
o Motion is generally inversion/eversion.
o Participate in movement of the forefoot on the hindfoot to lower the longitudinal arch in pronation and to elevate it in supination.
o In inversion the navicular & cuboid move medially & turn around & under a fixed talus.
o Positions forefoot for contact with ground during gait.

➢ Closed packed position: Supination

Answer 97

❑ Transverse Tarsal Joint (Midtarsal or Chopart’s Joint)

Question 98

Plantar calcaneonavicular ligament (Spring ligament ) • A triangular band from sustentaculum tali to the navicular
bone and then blends with the deltoid ligament.
• Very important for maintaining the longitudinal arch of the foot.

o Dorsal talonavicular ligament o Bifurcate ( Y-shaped) Ligament: (made of calcaneonavicular and calcaneocuboid ligaments).

o Long Plantar ligament: (from calcaneus to cuboid and four lateral metatarsal bones).

o Plantar calcaneocuboid (Short Plantar ) ligament

Answer 98

Transverse Tarsal Joint Ligaments

Question 99

Any separation or fracture at this site is called a
Lisfranc fracture.
➢ Articular Surfaces
o 1st metatarsal with medial cuneiform
o 2nd metatarsal with medial and intermediate cuneiforms
• More rigid
o 3rd metatarsal with lateral cuneiform
o 4th and 5th metatarsals with cuboid

• Most mobile
➢ Classification: Synovial planar
➢ Motions
– Gliding of bones upon each other with plantar
flexion and dorsiflexion

Answer 99

Tarsometatarsal (Lisfranc) Joints

Question 100

Tarsometatarsal (Lisfranc) Joints Ligaments
➢ Function
o To maintain contact with ground at all time

Answer 100

o Plantar metatarsal ligaments
o Dorsal metatarsal ligaments
o Dorsal Tarsometatarsal
o Plantar Tarsometatarsal

Question 101

➢ Articular Surfaces o MTPs: Between the head of the metatarsals and the base of the proximal phalanges of toes # 1to 5
➢ Classification: Synovial condylar joints
➢ Motions – Flexion – Extension – Abduction – Adduction
➢ Ligaments : Collateral and plantar ligaments as well
as the deep transverse metatarsal ligaments
➢ Closed packed position: Hyperextension

Answer 101

Metatarsophalangeal (MTP) Joints
Movement Degrees End Feel
1 MTP Flexion 30- 45 firm
2 MTP Hyperextension 90 Firm

Question 102

➢ Articular Surfaces o PIP: Between the head of the proximal phalange and base of the middle phalange of
toes #2 to 5

o DIPs: Between the head of the middle phalange
and base of the distal phalange of toes # 2 to 5
o In big toe there is only one IP joint.
➢ Classification: Synovial hinge joints
➢ Motions – Flexion – Extension
➢ Ligaments : Collateral and plantar ligaments

➢ Closed packed position: Hyperextension

Answer 102

Interphalangeal (IP)Joints

Question 103

The ability of the foot to change from a flexible to a rigid
structure within a single step is dependent upon:
1. The bony structure of the three arches of the foot
2. Static ligament, fascial support
3. Dynamic muscle contraction

The body weight is transferred to the ground mainly
through three points via three arches:
o The medial longitudinal arch is the longest and
the highest. It is composed of the calcaneus, the
talus, the navicular, the medial cuneiform, and
the first metatarsal bones.
o The lateral longitudinal arch is lower and
composed of the calcaneus, the cuboid, and the
fifth metatarsal.
o The transverse arch is concave from medial to
lateral in the midtarsal and tarsometatarsal areas.

Answer 103

Arches of the Foot

➢ Ligaments connect the tarsal and metatarsal bones on the dorsal and plantar surfaces to bind the bones of the arches into
a structure with properties of the solid
curved beam.
When loaded, the curved beam bends, and compression forces occur on the top (convex side) and tension forces
occur on the plantar surface (concave side).

As the amount of load, increases, the beam
eventually collapses. Larger forces can be supported by the beam if a tie-rod is placed across the base of the beam to prevent the two ends from moving apart. In the foot, the tie-rod is represented by the plantar
aponeurosis as well as by contraction of
intrinsic and extrinsic muscles of the foot.

Question 104

All the extrinsic and most of the intrinsic muscles on the plantar surface of the foot cross under the arches. When the muscles contract in closed-chain motion, the forces that are produced tighten the arches. The tibialis posterior and the peroneus (fibularis) longus with their extensive plantar attachments have major effects on the transverse arch but also tighten the longitudinal arches.

The flexor hallucis longus and the abductor hallucis span the medial arch, and the abductor digiti minimi runs the length of the lateral arch. The flexor digitorum brevis, quadratus plantae, and flexor digitorum longus run the midplantar length and tighten the longitudinal arches. The adductor hallucis affects the transverse arch. Thus, the muscles of the toes, which, compared to the
fingers, have limited function and use in open chain motion, have great importance in closed-chain motions of walking and running.

Answer 104

Dynamic Muscle Forces