Lecture 9: The thigh and knee Flashcards
What is the lumbosacral plexus?
outflow from lumbar and sacral segments of the spinal cord
The nerve network that innervates the lower limb
Where is the lumbosacral plexus located?
Located in the abdomen and pelvis
How many branches does the lumbosacral plexus give rise to?
3 major branches that provide the motor and sensory innervation of the lower limb
What are the 3 major branches of the lumbosacral plexus?
Femoral
Obturator
Sciatic
Why do femoral fractures occur in young people?
as a result of high energy trauma and blood loss from the femur can be significant.
What is the thigh bone called?
Femur
Where does the distal femur articulate with the tibia?
At the knee joint
How does the femur lie in the body?
Obliquely
Where does the knee joint lie in relation to the hip joint?
Directly below the hip joint
What returns body weight to the midline?
The angulation of the femur
Is the fibula part of the knee joint?
No, But it is an important site for one of the posterior thigh muscles
What is the role of the IOM?
- Transfers force between tibia and fibula so not all resting on tibula.
- Prevents infection spreading from one bone to another
- Helps keep the bones at a reasonable distance from one another
What 3 bones are involved at the knee joint?
distal femur
proximal tibia
patella
What type of joint is the knee joint?
Synovial hinge joint
What movements does the knee joint allow for?
allows flexion and extension
What 3 articulations that occur at the knee joint?
2 femorotibial
1 femoropatellar
Where does the stability of the knee come from? (3)
surrounding muscles
menisci (cartilage)
ligaments inside (intra-articular) and outside (extra-articular) the joint
What is the menisci?
Tibial plateau deepened by 2 plates of fibrocartilage
Where is the menisci usually thicker?
Thicker at external margins
Name 5 functions of the menisci?
1.Increase joint congruency
2. Distribute weight evenly
3.Shock absorption
4. Assist in locking mechanism
5.External edges attach to the fibrous capsule of the joint
When is the knee most stable and congruent?
Extension of the knee
When is the knee least stable and congruent?
Flexion of the knee
What shape is the lateral collateral ligament?
Cord-like band
Is the lateral collateral ligament attached to meniscus?
NOT attached to meniscus
What is the function of the lateral collateral ligament?
Prevents adduction of the leg at the knee
What shape is the medial collateral ligament?
Flat band
Is the medial collateral ligament attached to the meniscus?
Yes
What is the function of the medial collateral ligament?
Prevents abduction of the leg at the knee
What are the two functions of the Anterior cruciate ligaments (ACL)?
Prevents anterior displacement of tibia on femur
Prevents hyperextension
When is the ACL usually injured?
Injury occurs when knee is hyperextended or force is applied anteriorly
What are the 3 functions of the posterior cruciate ligament?
Prevents posterior displacement of tibia on femur
Prevents hyperflexion
Main stabiliser of the flexed knee when weight bearing e.g. walking down hill
When is the PCL usually injured?
Can be injured when landing on the tibial tuberosity with the knee flexed
What is usually injured along with the Medial (tibial) collateral ligament?
The medial meniscus as they are attached
What is the function in the muscles that cross the knee?
move and stabilise the knee
How many compartments do we classify the thigh muscles into?
3
What are the 3 compartments of the thigh muscles?
anterior, posterior, and medial
What are the muscles of the thigh separated by?
fascial septae
What are the muscles of the thigh enclosed by?
fibrous sleeve called the fascia lata
Where do extensors of the knee lie?
Anterior thigh
Where do the flexors of the knee lie?
Posterior thigh
What compartment of the thigh do muscles act on the hip joint?
Medial thigh
What is the anterior thigh mostly innervated by?
Most innervated by the femoral nerve
What does the anterior thigh muscles act upon?
Act on the hip, knee, or both
What are the different muscles in the anterior thigh?
Iliopsoas
Pectineus
Quadriceps femoris
Sartorius
TFL
What does the Iliopsoas muscle do?
flexes the hip
What does the Pectineus muscle do?
flexes & adducts the hip
What does the Quadriceps femoris muscles do?
4 muscles
“the quads”.
Extend the knee;
1 also flexes the hip
What does the satorius muscle do?
ASIS > medial tibia. Flexes hip, laterally rotates hip and flexes the knee
What does the TFL muscle do?
Flexes the hip.
Stabilises the knee
What innervates the Quadriceps femoris?
Femoral nerve: L2-4
How do the quad muscles form?
All 4 muscles converge onto quadriceps tendon > over patella > patella tendon attaches to tibial tuberosity
what are the 4 muscles of the Quadriceps femoris?
Vastus intermedius: anterior femur
Vastus lateralis: G. trochanter & linea aspera
Vastus medialis: intertochanteric line & linea aspera
Rectus femoris: AIIS – so also flexes the hip
Are the quads extensors or flexors?
Powerful extensors of the knee
What is found in the Femoral triangle?
Femoral artery
Femoral Nerve
Femoral Vein
Do the femoral bundle lie deep or superficially?
Superficially
What leaves the femoral artery at the thigh?
Profunda femoris
What major superficial vein drains into the femoral vein?
Great saphenous vein
What is the femoral nerve’s function?
innervates anterior thigh muscles, skin of anterior thigh and a branch called the saphenous n. innervates skin of medial aspect of leg and foot
How many muscles make up the adductor group of the medial thigh?
3
What muscles make up the adductor group of the medial thigh?
Adductor brevis: body of pubis & inf ramus > pectineal line (just inferior to lesser trochanter) & linea aspera
Adductor longus: body of pubis > middle 1/3 linea aspera
Adductor magnus, a deeper muscle
What innervates the medial thigh?
Obturator n. (L2-4)
What makes up the two parts of the Adductor magnus in the medial thigh?
Adductor part: inf pubic ramus > gluteal tuberosity & linea aspera ( = obturator n.)
Hamstring part; ischial tuberosity> adductor tubercle (= tibial n.)
What is the adductor hiatus?
passage way through for femoral artery and vein into popliteal fossa
What is the obturator externus found in the medial thigh?
margins of obturator foramen & obturator membrane > trochanteric fossa
Lateral rotator
What other muscles are found in the medial thigh?
Gracilis (weakly flexes knee too) body & inf. ramus > tibia
Pectineus (femoral n.): sup. pubic ramus > pectineal line
Obturator externus: a deeper muscle (next slide)
Where does the obturator nerve originate?
L2-L4
Where does the obturator nerve innervate?
Nerve of the medial thigh; muscles and skin
Where does the obturator nerve lie?
Exits pelvis through the obturator foramen
Overlies adductor brevis
Location along the lateral wall of pelvis means it can be compressed by pelvic / ovarian masses
Where does the hamstring arise?
ischial tuberosity
What is the function of the hamstring?
extend the hip, flex the knee
What is the hamstring innervated by?
tibialischial tuberosity, n.
What are the 4 muscles of the posterior thigh?
Semimembranosus (medial) > posterior aspect medial tibial condyle
Semitendinosus (medial) > medial aspect of superior tibia
Biceps femoris: long head (lateral) > fibular head
Biceps femoris: short head from linea aspera, flexes knee (doesn’t extend the hip). Common fibular n.
What are the muscles of the posterior thigh supplied by?
Supplied by perforating branches from profunda femoris
What is the function of the hamstring part of the adductor magnus?
extends hip, doesn’t act on the knee. Tibial n.
What shape is the popliteal fossa?
Diamond-shaped fossa
What are the boundaries of the Popliteal fossa?
semimembranosus, semitendinosus, biceps femoris, 2 heads of gastrocnemius (calf muscle)
