anatomy of the knee(UNFINISHED PG94) Flashcards
patella main functions
by enabling the quads to directly cross the anterior aspect of the knee and by acting as a fulcrum, the patella enhances the leverage that the quadriceps tendon can exert on the femur
protects the anterior aspect of the knee joint from trauma
reduces friction between quadriceps and femoral condyles during extension of the leg
what are the 3 borders of the tibia? any insertions/origins here
anterior border- proximal aspect is marked buy tibial tuberosity which is the insertion site for the patella ligament.
posterior border-marked by a soleal line which is the site of origin for part of the soles muscle. soleal line extends inferomedially eventually blending with the medial edge of the tibia.
lateral border- aka interosseous border. gives attachment to interosseous membrane that binds the tibia and fibula together.
what are the articulations of the fibula
Proximal tibiofibular joint-articulates with lateral condyle of tibia
distal tibiofibular joint-articulates with fibular notch on tibia.
ankle joint-articulates with talus bone of the foot.
what are the two articulation of the knee joint and which one is the weight bearing joint
tibiofemoral
patellofemoral
tibiofemoral is weight bearer
blood supply to knee
through genicular anastomoses around the knee which are supplied by the genicular branches of the femoral and popliteal arteries.
what happens if the popliteal artery his occluded by an atheroma
genicular anastomoses can dilate to maintain the blood supply to the leg
where is the nerve supply to knee from
femoral, tibial and common peroneal nerves
what type of structures are the menisci and what are their functions
fibrocartilaginous
to deepen the articular surface of the tibia increasing stability of the joint
to act as shock absorbers by increasing surface area to further dissipate forces.
which meniscus is more mobile and why
lateral meniscus as its smaller and only attached to intercondylar attatchments whereas medial is also attached to medial collateral ligament and the joint capsule.
how are the menisci connected to each other
transverse ligament of the knee
what are the major ligaments in the knee
intracapsular: cruciate ligaments
ligaments that strengthen the capsule: oblique popliteal ligament
extracapcular ligaments- collateral ligaments , patellar ligament
where does the anterior cruciate ligament attach and what does it do
attaches at the anterior intercondylar region of the tibia where it blends with the medial meniscus. It ascends posteriorly to attach to the femur in the intercondylar fossa. It prevents anterior dislocation of the tibia onto the femur.
where does the posterior cruciate ligament attach and what does it do
attaches proximally to medial border and roof of the intercondylar fossa and passes distally and posterolaterally to attach to the posterior intercondylar area of the tibia.
its the main stabiliser of the weight bearing flexed knee and prevents the femur from sliding off the anterior edge of the tibia.
function of patellar ligament
stabilise hinge movement of knee preventing excessive medial or lateral angulation of the tibia on the femur
role of medial (tibial) collateral ligament
resist valgus (lateral) angulation of the tibia on the femur
role of lateral (fibular) collateral ligament
resists varus (medial) angulation of the tibia on the femur.
what is a bursa and what ism its function
small sac lined by synovial membrane containing a thin layer of synovial fluid
- provides cushion between bones and tendons/muscles surrounding a joint
- reduces friction
- allows free movement
name the 6 bursae at the knee joint
suprapatellar bursa prepatellar bursa superficial(or subcutaneous) infra patellar bursa deep infra patella bursa semimembranosus bursa subsartorial bursa
which muscles allow extension of the knee
quadriceps femoris ( rectus femoris, vastus medialis, vastus intermedius. vastus lateralis) insert into the tibial tuberosity via the patella ligament
which muscles allow knee flexion
hamstrings (biceps femoris , semimembranosus , semitendinosus)
assisted by gracilis, sartorius, popliteus , plantaris and gastrocnemius
what muscle allows lateral (external) rotation of the knee (only possible in a flexed knee)
produced by the biceps femoris
what muscle allows medial (internal) rotation of the knee (only possible in a flexed knee)
semimembranosus semitendinosus gracilis sartorius popliteus
what happens to the knee when fully extended
- knee locks
- 5 degree medial rotation of the femoral condyles on the tibial plateau (screw-home mechanism)
- cruciate ligaments tighten
- lower limb becomes a solid column adapted for weight bearing
- thigh and leg muscles can relax briefly without making the knee joint unstable.
what prevents the patella from displacing laterally during extension of the knee
contraction of fibres of the vastus medialis obliquus
what is the iliopsoas , actions and innervation
- composed of psoas major and iliacus
- psoas major originates from transverse processes of the T12-L5 vertebrae and the lateral margins of the intervertebral discs between them.
- the iliacus originates from the iliac fossa of the pelvis.
- both insert together onto lesser trochanter of the femur
- actions: flexes lower limb at hip joint and assists in lateral rotation of the femur at the hip joint.
innervation: psoas major-anterior rami of L1-L3. iliacus- femoral nerve
vastus lateralis: proximal attachment, action, innervation
Proximal attachment: Originates from the greater trochanter and the lateral lip of linea aspera.
Actions: Extends the knee joint and stabilises the patella.
Innervation: Femoral nerve.
vastus intermedius: proximal attachment, action, innervation
Proximal attachment: Anterior and lateral surfaces of the femoral shaft.
Actions: Extends the knee joint and stabilises the patella.
vastus medialis: proximal attachment, action, innervation
Proximal attachment: The intertrochanteric line and medial lip of the linea aspera.
Actions: Extends the knee joint and stabilises the patella, particularly due to its horizontal fibres at the distal end (vastus medialis obliquus)
Innervation: Femoral nerve
rectus femoris: proximal attachment, action, innervation
originates as 2 tendons: the anterior tendon arises from the anterior inferior iliac spine of the pelvis; the posterior tendon arises from a groove above the rim of the acetabulum.
actions- crosses both hip and knee joints. flexes the thigh at the hip joint and extends the leg at the knee joint.
-femoral nerve
sartorius: attachments, actions , innervations
Attachments: Originates from the anterior superior iliac spine, and attaches to the superior, medial surface of the tibia.
Actions: At the hip joint, it is a flexor, abductor and lateral rotator. At the knee joint, it is also a flexor.
Innervation: Femoral nerve.
pectineus: attachments, actions , innervations
- flat muscle that forms the base of the femoral triangle.
- Attachments: It originates from the pectineal line on the anterior surface of the pelvis, and attaches to the pectineal line on the posterior side of the femur, just inferior to the lesser trochanter.
- Actions: Adduction and flexion at the hip joint.
- Innervation: Femoral nerve. May also receive a branch from the obturator nerve. (as it has dual innervation it can be considered a transitional muscle between the anterior and medial thigh)
what are the hip abductors
gracilis octurtaor externes adductor brevis adductor longus adductor Magnus
what is all of the medial thigh innervated by, where in the lumbar plexus does this arise from and the arterial supply
obturator nerve
L2,3 and 4
obturator artery
the adductor Magnus can be divided into two parts: adductor component and the hamstring component. where do both originate and insert into
adductor component originates from inferior ramus of the pubis and ischium onto the linea aspera of the femur.
hamstring component originates from ischial tuberosity and inserts onto the adductor tubercle and medial supracondylar line of the femur.
insertions of the two components are separated by the adductor hiatus - space through which the femoral vessels pass
actions and innervation of adductor Magnus
adduct the thigh
adductor component also flexes the thigh
hamstring component also extends the thigh
adductor component innervated by obturator nerve.
hamstring component innervated by tibia component of the sciatic nerve
Adductor Longus
Attachments: Originates from the pubis, and expands into a fan shape, attaching broadly to the linea aspera of the femur
Actions: Adduction of the thigh.
Innervation: Obturator nerve (L2-L4).
Adductor Brevis
lies in between the anterior and posterior divisions of the obturator nerve
Attachments: Originates from the body of pubis and inferior pubic rami. It attaches to the linea aspera on the posterior surface of the femur, proximal to the adductor longus.
Actions: Adduction of the thigh.
Innervation: Obturator nerve (L2-L4).
gracilis
Attachments: It originates from the inferior rami of the pubis, and the body of the pubis. Descending almost vertically down the leg, it attaches to the medial surface of the tibia, between the tendons of the sartorius (anteriorly) and the semitendinosus (posteriorly).
Actions: Adduction of the thigh at the hip, and flexion of the leg at the knee.
Innervation: Obturator nerve (L2-L4).
what are the borders, roof and floor of the femoral triangle
Roof – fascia lata.
Floor – pectineus, iliopsoas, and adductor longus muscles.
Superior border – inguinal ligament (a ligament that runs from the anterior superior iliac spine to the pubic tubercle).
Lateral border – medial border of the sartorius muscle.
Medial border – medial border of the adductor longus muscle. The rest of this muscle forms part of the floor of the triangle.
content of femoral triangle from to medial
femoral nerve, femoral artery, femoral vein, femoral canal( contains deep lymph nodes and vessels)
*everything except the femoral nerve is in the femoral sheath
femoral canal borders
Medial border – lacunar ligament.
Lateral border – femoral vein.
Anterior border – inguinal ligament.
Posterior border – pectineal ligament, superior ramus of the pubic bone, and the pectineus muscle
contents of femoral canal
lymphatic vessels- draining the deep inguinal lymph nodes
deep lymph nodes- the lacunar node
empty space
loose connective tissue
adductor canal borders
anterior:sartorius
lateral: vastus medialis
posterior: adductor longus and adductor Magnus
apex of the adductor canal is marked by the adductor hiatus
contents of adductor canal
femoral artery (after passing through the adductor canal this becomes the popliteal artery)
femoral vein
nerve to the vastus medialis and the saphenous nerve (the largest cutaneous branch of the femoral nerve)
