Anatomy-->Joints Lower limb

Knee Joint - Intracapsular ligaments *Anterior cruciate ligament

1. anterior cruciate ligament - attaches to the anterior intercondylar area of the tibia - courses superiorly, laterally, and posteriorly to attach to the posterior part of the medial surface of the lateral femoral condyle - LIMITS POSTERIOR SLIPPING OF THE FEMUR ON THE TIBIAL PLATEU- rupture of the ligament allows an ANTERIOR DRAWER TEST to be present which allows the tibia to move anteriorly on the femur.

Knee Joint - Articular surfaces *Femoral surface

1. femoral surface (Netter 476) - medial and lateral femoral condyles, covered in articular cartilage, are convex anteroposteriorly as well as from side to side - curve is tighter posteriorly than anteriorly - two condylar surfaces are not parallel and the medial femoral condyle is longer than the lateral condyle - condyles fuse anteriorly to form the cartilage covered depression, the "patellar surface" (also called "trochlea" by clinicians) - posteriorly, the two condyles are separated by a deep, non-articulating intercondylar fossa into which ligaments such as the cruciate ligaments attach.

Knee Joint - Associated structures *Menisci of knee

1. menisci of knee (Gray's 6.71) - crescent-shaped fibrocartilage discs that attach to the condyles of the tibia, covering more than half of the tibial condylar articular surface - wedge-shaped, being thicker at the periphery of tibia and much thinner interiorly - function to deepen the articular surface of the joint (making it a bit more congruent with the femoral condyles), aid in shock absorption, may assist with joint lubrication and with the various rotatory and gliding movements between the femur and tibia.

Hip Joint - Introduction * Type of Joint

1. type of joint (Gray's 6.29) - ball and socket synovial joint between globular head of femur and cup-shaped acetabulum of os coxae.

Knee Joint - Associated structures *Bursae ~subcutaneous prepatellar burasa

2. bursae (Moore Fig. 5.94, Table 5.17) - are fluid-filled sacs lined by a synovial membrane that are located at areas of potential friction of moving structures such as between tendons and bones or skin and tendons - large number of bursae associated with the knee - only some are detailed below. a. subcutaneous prepatellar bursa - located between skin and anterior surface of patella - prepatellar bursitis (also called "housemaid's knee") can be due to chronic inflammation from excess pressure in the region or as acute trauma from a direct blow to the area and presents as swelling anterior to the patella.

Knee Joint - Collateral ligaments *Fibular collateral ligament

2. fibular collateral ligament (FCL, lateral collateral ligament) - cord-like ligament, further separated from the joint capsule than is the TCL - attaches to the lateral epicondyle of femur and the lateral side of the head of the femur - externally lies the biceps femoris tendon with a bursa intervening - internally lies the tendon of the popliteus which separates the FCL from the lateral meniscus, hence the FCL and lateral meniscus are not attached.

Hip Joint - Fibrous articular capsule * Intrinsic ligaments ~Iliofemoral ligament

2. intrinsic ligaments (Netter 474) - longitudinal, oblique thickenings of the fibrous capsule are important in reinforcing the capsule and limiting various movements of the joint, especially hip extension. Since the joint capsule is most taut when the hip is extended, dislocation occurs almost exclusively when the hip is flexed. a. iliofemoral ligament (Y-ligament or ligament of Bigelow) - strongest ligament in the body - on anterior surface of capsule - shaped like an inverted "Y" with stem attached to anterior inferior iliac spine and acetabular rim and diverging portion attaching to the intertrochanteric line of femur - becomes taut in hip extension and medial rotation, thus major function is to prevent hyperextension and helps support the erect posture.

Ankle - Ligmentous supports *mEDIAL ligament of the ankle

2. medial ligament of the ankle - is commonly called the "DELTOID LIGAMENT" due to its triangular shape with the apex of the triangle being at the attachment sites on the medial malleolus of the tibia and it fans out to attach to the talus, calcaneus, and navicular bones by ANTERIOR AND POSTERIOR TIBIOTALAR LIGAMENTS, THE TIBIOCALCANEAL LIGAMENT, AND THE TIBIONAVICULAR LIGAMENT.

Hip Joint - Introduction * Movements

2. movements (Gray's 6.5) - movements allowed in all directions like shoulder joint, but not with as large a range of these movements - flexion greater range than extension and has greater range when knee flexed since less tension in hamstrings inhibiting this flexion - extension to about 30° due to limitation by very strong iliofemoral ligament - abduction wider range than adduction - abduction limited by length of adductor muscles and pubofemoral ligament - adduction limited by contact with other limb, length of abductors, and perhaps ligament of head of femur - lateral rotation is freer and more powerful than medial rotation.

Knee Joint - Introduction *Movements

2. movements - main movements are flexion and extension, with some rotation allowed in the flexed knee - because of the shape of the articular surfaces, just prior to the limit of extension with the foot planted, conjoint medial rotation of the femur occurs to maximally stabilize the joint into its "close-packed" or "locked" position where muscle energy to maintain this position is minimized - conversely, lateral rotation of the femur occurs at the beginning of flexion of the planted foot due to the action of the popliteus - patella moves along patellar surface of femur during flexion and extension movements.

Knee Joint - Intracapsular ligaments *Posterior cruciate ligament

2. posterior cruciate ligament - attaches to the posterior intercondylar area of the tibia - courses superiorly, medially, and anteriorly to attach to the anterior part of the lateral surface of the medial femoral condyle - LIMITS ANTERIOR SLIPPING OF THE FEMUR ON THE TIBIAL PLATEU- rupture of the ligament allows a POSTERIOR DRAWER SIGN to be present which allows the tibia to move posteriorly on the femur.

Knee Joint - Articular surfaces *Tibial surfaces

2. tibial surface (Netter 495, 501) - superior surface of tibia, termed the "tibial plateau", contains two cartilage covered articular surfaces and a non-articular intercondylar region - medial articular facet is slightly concave, oval, and slightly larger than the lateral articular facet which is circular, slightly convex and extends slightly over the posterior condylar margin - roughened, anterior and posterior intercondylar areas exist where cruciate ligaments and horns of menisci attach - in this area centrally is the intercondylar eminence which has a medial and lateral intercondylar tubercle onto the sides of which extends articular cartilage

Knee Joint - Associated structures *Infrapatellar fat pad

3. infrapatellar fat pad (Hoffa's fat pad) (Gray's 6.71) - located between the patellar ligament anteriorly and the synovial membrane covering the anterior part of the synovial cavity - can be the source of anterior knee pain due to traumatic, degenerative, inflammatory, or neoplastic conditions.

Knee Joint - Intrinsic ligaments of capsule *Medial and lateral patellofemoral ligaments

3. medial and lateral patellofemoral ligaments - attach to the sides of the patella and to the epicondylar region of the femur - they are important in stabilizing the patella in the groove on the patellar surface of the femur and preventing medial or lateral dislocation of the patella.

Knee Joint - Articular surfaces *Patella

3. patella (Gray's 6.52) - rounded-edged, triangular sesamoid bone located in the tendon of the quadriceps femoris with base located superiorly and apex pointing inferiorly - posterior surface is articular area with two facets divided by a vertical ridge that lies in the groove on the patellar surface of the femur - lateral patella articular area broader and deeper than medial side - non-articular area at the apex to which the patellar ligament arises.

Knee Joint - Introduction *Stability

3. stability (Moore 5.86) - articulating surfaces are poorly congruent and stress placed through this very mobile joint would suggest that it is very unstable; however the very strong muscles (particularly the quadriceps femoris) and ligaments that support this joint make it a very stable joint, with dislocations being quite rare.

Hip Joint - Introduction * Stability

3. stability (Netter 474, Moore 5.83) - needs to be much greater than the homologous joint in the upper limb (i.e. the shoulder) because the weight of the body passes through this articulation - increased stability by the much greater contact area between articulating surfaces, the very strong ligamentous supports, and the strong muscles closely associated with the joint.

Knee Joint - Intrinsci ligaments of capsule *Oblique popliteal ligament

4. oblique popliteal ligament - strong, broad, ligament that reinforces the posterior fibrous capsule - formed as an expansion from the tendon of insertion of the semimembranosus where it attaches to the posterior margin of the medial tibial condyle - courses superolaterally to attach to the posterior surface of the lateral femoral condyle and intercondylar fossa - this ligament forms part of the floor of the popliteal fossa and is perforated by middle genicular vessels and articular nerve fibers.

Knee Joint - Intrinsci ligaments of capsule *Arcuate popliteal ligament

5. arcuate popliteal ligament - helps to strengthen inferior, lateral aspect of posterior joint capsule - triangular or Y-shaped ligament where stem attaches inferiorly to the head of the fibula - medial part arches over tendon of popliteus and attaches to posterior part of the intercondylar region of the tibia - the superior extension attaches to the lateral femoral epicondyle and is closely associated with the lateral head of the gastrocnemius.

Knee Joint - Introduction *Type of joint

A. Introduction 1. type of joint (Moore 5.84) - synovial, hinge joint consisting of articulations between the condyles of the femur and those of the tibia (femorotibial articulation), as well as an articulation between the patella and femur (femoropatellar articulation).

Hip Joint - Articular surfaces *Acetabulum *Head of the femur

B. Articular surfaces (Netter 473, 474) 1. acetabulum - is a cup-shaped depression located on the lateral aspect of the os coxae - formed by ilium, ischium, and pubis - the articulating portion, covered in hyaline cartilage, is horseshoe-shaped and termed the "lunate surface of the acetabulum" - acetabular rim is the peripheral edge of the articulating surface - to the rim is attached a fibrocartilaginous acetabular labrum which increases the depth of the acetabulum, into which at least half of the femoral head lies - the acetabular notch is present inferior to the lunate surface and is bridged by the transverse acetabular ligament - the acetabular fossa is the deep, non-articular, thinner part of the acetabulum that houses a fat pad. 2. head of femur - smooth, hyaline cartilage-covered structure that forms about 2/3's of a sphere - no cartilage over the medial depression termed the "fovea capitis femoris" for attachment of the ligament of the head of the femur

Ankle - Movements

B. movements - Dorsiflexion and plantarflexion are the two main movements allowed at the ankle joint.

Hip Joint - Fibrous articular capsule *Attachments

C. Fibrous articular capsule (Netter 474, Moore 5.79) - thick and strong - fibers of capsule spiral around inferiorly and anteriorly so that as the hip is extended, the capsule twists and shortens which pulls the femoral head further into the acetabulum. 1. attachments (Moore 5.82, Netter 474, 476) - superior attachments are to the edge of the acetabular rim, just outside of the labrum, and to the transverse acetabular ligament - inferiorly, the fibrous capsule attaches anteriorly to the intertrochanteric line, but lies above the intertrochanteric crest posteriorly where circular "zona orbicularis" fibers encircle the neck of the femur while not actually attaching to the bone of the posterior neck.

Knee Joint - Fibrous articular capsule

C. Fibrous articular capsule (Netter 498, 494) - is extensive, complex, and not entirely complete, but rather partly formed by surrounding ligaments and tendons - posterior fibrous capsule attaches superiorly to the margins of the femoral condyles and the intercondylar fossa of femur, while inferiorly it attaches to posterior edges of tibial condyles - gap in the lateral posterior capsule to allow exit of popliteus tendon - medial and lateral sides of fibrous capsule attach to edges of respective femoral and tibial articular surfaces - discrete anterior aspect of fibrous capsule largely absent, but rather closed mainly by quadriceps tendon, patellar ligament, and medial and lateral patellar retinaculum

Ankle - Ligmentous supports *Lateral ligament of the ankle

C. ligamentous supports - The ankle joint is stabilized significantly by complex lateral and medial collateral ligaments with the MEDIAL LIGAMENT BEING THE STRONGER of these two. 1. lateral ligament of the ankle - is composed of three ligaments which are more dispersed than the medial ligament. These ligaments are the ANTERIOR AND POSTERIOR TALOFIBULAR LIGAMENTS AND THE CALCANEOFIBULAR LIGAMENT. Sprains of the ankle most commonly are due to inversion stresses where the lateral ligaments are damaged with the anterior talofibular ligament Always Torn First.

Hip Joint - Intracapsular ligament

D. Intracapsular ligament (Netter 474) - the ligament of the head of the femur (ligamentum capitis femoris) lies within the joint cavity and is ensheathed by synovial membrane - attaches to edges of acetabular notch and intervening transverse acetabular ligament and then to the fovea capitis femoris - helps to transmit a small artery to the head of the femur - significance of ligament in stabilizing joint is uncertain, but may be more important in fetus than in adults in this regard.

Knee Joint - Intrinsic ligaments of capsule *Patellar ligament *Patellar retinacula

D. Intrinsic ligaments of capsule (Netter 494, 498) - form part of the fibrous capsule, strengthening that portion of the capsule. 1. patellar ligament - strong, flat band attaching superiorly to apex of patella and inferiorly to tibial tuberosity - fibers continuous anterior to patella with quadriceps femoris tendon above patella. 2. patellar retinacula - expansions from the vastus medialis and vastus lateralis that attach to the sides of the patella and then insert onto the front of the tibial condyles, on either side of the patellar ligament - lateral patellar retinaculum augmented by iliotibial tract.

Knee Joint - Collateral ligaments *Tibial collateral ligament

E. Collateral ligaments (Netter 494, 496) - ligaments located on the sides of the knee that are separated wholly or partly from the fibrous joint capsule - located behind the vertical axis of the knee so help prevent hyperextension, as well as lateral or medial angulation between the femur and tibia. 1. tibial collateral ligament (TCL, medial collateral ligament) - strong, flat band that attaches proximally to the medial femoral epicondyle immediately inferior to the adductor tubercle and distally to medial tibial condyle and medial shaft of tibia - externally lies the pes anserinus (common site of attachment for 3 muscles - semitendinosus, gracilis, and sartorius) with a bursa intervening - deep surface of TCL is attached to the medial meniscus.

Hip Joint - Synovial membrane

E. Synovial membrane (Moore 5.82, Netter 476) - attaches to the edge of the articulating surfaces, that is, to the margin of the articular cartilage of the head of the femur and to the acetabular labrum - lines the inside of the articular capsule and reflects over intra-articular structures like much of the neck of the femur and the non-articular part of the acetabulum - synovial membrane raised along femoral neck in longitudinal folds called "retinacula".

Hip Joint - Associated bursa *Bursa for obturator externus tendon *Iliopsoas bursa

F. Associated bursa (Moore 5.81, Netter 483) 1. bursa for obturator externus tendon - extension of the synovial membrane inferior to free border of posterior joint capsule 2. iliopsoas bursa (iliopectineal bursa, subtendinous iliac bursa) - a large synovial lined, fluid-filled sac located between the anterior joint capsule of the hip and the iliopsoas muscle - can be in continuity with hip synovial cavity through a connection passing through defect in capsule between iliofemoral and pubofemoral ligaments - overuse of iliopsoas can lead to inflammation of this bursa (bursitis).

Knee Joint - Intracapsular ligaments

F. Intracapsular ligaments (Netter 495, 496, Gray's 6.74, Moore B5.33) - lie within the fibrous joint capsule, but outside of the synovial cavity - called "cruciate" ligaments because they cross each other - named anterior and posterior with regards to their site of attachment to the tibia - limit medial rotation of tibia on femur more than lateral rotation because they "unwind" in lateral rotation and "wind up" in medial rotation - are taut in all stages of flexion and extension, but are tightest in full extension and full flexion.

Hip Joint - Blood supply

G. Blood Supply (Gray's 6.63, Netter 491) -for blood supply to all components of the hip joint, an anastomotic arrangement of branches from a large number of arteries are involved including the MEDIAL AND LATERAL CIRUCUMFLEX HUMERAL ARETERIES and the FIRST PERFORATING BRANCH which all typically are BRANCHES OF THE PROFUNDA FEMORIS ARETERY, the INFERIOR AND SUPERIOR GLUTEAL ARTERIES, and the OBTURATOR ARTERY- of particular interest is the blood supply to the femoral head which is more limited - the main blood supply for femoral head is via RETINACULAR ARTERIES which course along the femoral neck deep to the retinacular folds of synovial membrane - retinacular arteries arise from the medial (major supplier) and lateral (minor supplier) circumflex femoral arteries - artery in ligament of head of femur is a small vessel that typically arises from the posterior division of the obturator artery - FRACTURE OF THE FEMORAL NECK CAN DISRUPT THESE IMPORTANT RETINACULAR ARTERIES AND LEAD TO AVASCULAR NECROSIS (AVN) OF THE FEMORAL HEAD WHICH RESULTS IN NECROSIS AND COLLAPSE OF THE AFFECTED BONE.

Hip Joint - Innervation

H. Innervation (Netter 488, 490) - main sensory nerves to the hip are articular branches from the femoral nerve and the obturator nerve - less significant are branches from the superior gluteal nerve and nerve to the quadratus femoris.

Knee Joint -Synovial membrane

H. Synovial membrane (Gray's 6.71, Moore 5.87) - lines the knee joint cavity - largest and most complex synovial cavity in the body - attaches to the edges of the articular surfaces of the patella, femur, and tibia and to the external surfaces of the menisci (thus the MENISCI ARE WITHIN THE SYNOVIAL CAVITY) - synovial membrane extends inward from the posterior joint capsule, ENCIRCLING BOTH THE ANTERIOR AND POSTERIOR CRUCIATE LIGAMENTS, THUS EXCLUDING THEM FROM THE SYNOVIAL CAVITY- lines the fibrous capsule except anteriorly where it is separated from the fibrous tissue by the INFRAPATELLAR FAT PAD- synovial cavity space increased by its extension into the large suprapatellar bursa, as well as the smaller bursae which communicate with it - an INFRAPATELLAR SYNOVIAL FOLD is a vertical fold of synovial membrane passing from the infrapatellar fat pad to the intercondylar fossa of the femur, anterior to the cruciate ligaments

Knee - Blood supply

I. Blood supply (Netter 499) - extensive genicular anastomosis typically with 10 vessels that form an anastomosis anterior and posterior to the joint - two descending branches (1 from lateral circumflex femoral a. and one from femoral artery as descending genicular a.) - 5 branches from popliteal artery - and 3 recurrent branches, usually off of anterior tibial a.(see list in Leg and Popliteal Fossa lecture handout 2/9/15).

Proximal tibiofibular joint

III. Proximal tibiofibular joint (Netter 502) - synovial, plane joint between oval facet on medial side of fibular head and lateral condyle of tibia - articular capsule attached just peripheral to articular facets - strengthened by an anterior and a posterior ligament of fibular head of - slight movement during dorsiflexion and plantarflexion at ankle.

Distal tibiofibular joint

IV. Distal tibiofibular joint- This fibrous joint is formed between the medial surface of the distal fibula and the lateral surface of the distal tibia. These surfaces are connected by the very strong TIBIOFIBULAR INTEROSSEOUS LIGAMENT. It is stabilized further by the ANTERIOR, POSTERIOR, AND TRANSVERS TIBIOFIBULAR LIGAMENTS. Damage to these ligaments, most commonly the anterior tibiofibular ligament, is termed "high ankle sprain". The main function of this joint is to stabilize the superior articular surface forming the ankle joint.

Knee - Innervation

J. Innervation (Moore 5.93) - articular branches from femoral, obturator, tibial, and common fibular nerves.

Ankle - Intro - Articular surfaces

V. Ankle (talocrural) joint (Gray's 6.96→6.98) - is a hinge-type synovial joint. A. articular surfaces - include the distal end of the tibia and fibula superiorly and the superior part of the talus inferiorly in a mortise/tenon type arrangement. The sides of the box-like mortise are formed by the articular cartilage covered distal tibia and the lateral aspect of its medial malleolus, as well as the medial aspect of the fibula's lateral malleolus. Into this fits the trochlea of the talus with its articular cartilage superiorly, as well as medially and laterally.

Knee Joint - Associated structures *Menisci of knee ~Medial meniscus

a. medial meniscus (Netter 495, Moore B5.33) - forms a little more than a semicircle - a bit wider posteriorly than anteriorly - anterior horn attached to tibial intercondylar area anterior to attachment site of anterior cruciate ligament - posterior horn attachment is to intercondylar area anterior to attachment of posterior cruciate ligament - EXTERNAL LATERAL ASPECT IS ATTACHED TO TIBIAL COLLATERAL LIGAMENT- tight connection with tibial collateral ligament leads to medial meniscus tearing as part of "UNHAPPY TRIAD" when lateral side of extended knee hit or due to extreme lateral twisting of flexed knee (torn ACL, TCL, and medial meniscus).

Knee Joint - Associated structures *Menisci of knee ~Lateral meniscus

b. lateral meniscus (Netter 495) - smaller than the medial meniscus - nearly circular in form and covers a greater proportion of the associated tibial articular surface than does the medial meniscus - anterior and posterior horn attachments are to the intercondylar area of tibia close to one another and between the more widely spaced medial meniscus attachment sites - the LATERAL MENISCUS IS SEPARATED FROM THE FIBULAR COLLATERAL LIGAMENT BY THE POPLITEUS TENDON and thus doesn't directly attach to the collateral ligament.

Hip Joint - Fibrous articular capsule * Intrinsic ligaments ~Pubofemoral ligament ~ Ischiofemoral ligament

b. pubofemoral ligament - triangular ligament reinforcing inferior medial aspect of capsule - attaches superiorly and medially to the part of the acetabular rim formed by the pubic bone and attaches inferior and laterally to the femoral neck and inferior part of the intertrochanteric line merging with the iliofemoral ligament here - weakening in area between the iliofemoral and pubofemoral ligaments near the femoral head is REINFORCED BY THE TENDON OF THE ILIOPSOAS crossing this area - pubofemoral ligament becomes taut in hip extension and abduction and thus helps to limit these two movements. c. ischiofemoral ligament - triangular ligament reinforcing the posterior aspect of capsule - attaches medially to the ischial rim of the acetabulum - spirals superiolaterally to attach to the superior part of the neck of the femur, just medial to the base of the greater trochanter - becomes taut in hip extension and medial rotation, thus helping to limit those movements.

Knee Joint - Associated structures *Bursae ~subcutaneous infrapatellar bursa ~Deep infrapatellar bursa

b. subcutaneous infrapatellar bursa - located between skin and tibial tuberosity - subcutaneous infrapatellar bursitis (also called "clergyman's knee) caused by excessive friction in this area presents as swelling over the proximal part of the tibia. c. deep infrapatellar bursa - located between the patellar ligament and the anterior surface of the tibial condyles - deep infrapatellar bursitis presents as a swelling that rounds out the normal depression on the sides of the patellar ligament

Knee Joint - Associated structures *Menisci of knee ~Associated Ligaments - Coronary ligametn of knee - Transverse ligament of knee

c. associated ligaments i. coronary ligament of knee (meniscotibial ligament) (Moore 5.89) - connection of the inferior peripheral edges of the menisci, to the joint capsule and through that to the periphery of the tibial condyles.

Knee Joint - Associated structures *Bursae ~suprapatellar bursa ~popliteal bursa ~medial and lateral gastrocneumius bursae ~Anserine bursa

d. suprapatellar bursa - large synovial membrane-lined structure that initially develops as a bursa located between the tendon of the quadriceps femoris and the distal femur, but the separation between the bursa and the synovial cavity typically is lost so that the suprapatellar bursa in reality is a superior extension of the synovial cavity - the articularis genu inserts into this. e. popliteal bursa - located between the tendon of the popliteus and the lateral meniscus and communicates with the synovial cavity. f. medial and lateral gastrocnemius bursae - deep to the two heads of the gastrocnemius - both bursae frequently communicate with the synovial joint cavity. g. anserine bursa - lies between the 3 tendons forming the pes anserinus and the tibial collateral ligament

Knee Joint - Associated structures *Menisci of knee ~Associated Ligaments -Transverse ligament of knee

ii. transverse ligament of knee (Netter 496) - connects the anterior edges of the two menisci to each other.

Knee Joint - Associated structures *Menisci of knee ~Associated Ligaments - Posterior meniscofemoral ligament

iii. posterior meniscofemoral ligament (Netter 496) - connecting posteromedial aspect of lateral meniscus to lateral surface of medial femoral condyle, passing posterior to the posterior cruciate ligament.

Knee Joint - Associated structures *Menisci of knee ~Associated Ligaments - Attachment of menisci to posteriorly lying muscles

iv. attachment of menisci to posteriorly lying muscles - there is an attachment between the popliteus muscle and the posterior horn of the lateral meniscus which results in the meniscus being pulled slightly posteriorly during knee flexion - the semimembranosus has a similar association and action with the medial meniscus.