Biomech Unit 3 Part 1 Flashcards
(47 cards)
What kind of joints are the knee, hip and ankle - what are they required for?
synovial joints - weight bearing and movement
Describe the hip joint shape
ball (head of femur) and socket (acetabulum of pelvic girdle)
What are the movemetns the hip joint can produce?
flexion/extension, ab/adduction, internal and external rotation, circumduction
Describe a synovial joint
surfaces of bones that form the joint are covered in articular cartilage. A tough fibrous joint capsule encloses the joint and forms the synovial cavity. This is filled with synovial fluid which acts as a lubricant provided nutriets to the AC. The fluid is produced by the synovial membrane on the inner surface of capsule
Why are hip joints rare in adults
It is intrinsically stable as it hada very strong joint capsule and several ligaments. As well as several strong muscles surrounding it
Hip range of movements Flexion Extension Abduction Adduction Ex. Rotation Int. Rotation
F: 0 -140 E:0 - 20 Adb: 0 -30 Add: 0 -25 Ext R 0 - 90 Int R: 0 - 70
functional range of movement
Flex/ext
Add-abd
f/e 120
ad-ab: 20
12 in others
What percent of total body weight is the upper body?
70%
Name the two articulations of the knee joint
tibiofemoral and the patellofemoral
What covers the proximal tibia surface - describe it
The menisci - two crescent shaped pieces of fibrocartilage attached to the tibia by short tough ligaments
What is the function of the menisci
They make the the tibia plateau slightly concave to aid stability, distribute load and absorb shock
Describe the distal end of the femur
Two rounded condyles covered in articular cartilage with trochlear at the front and inter-condylar notch where the cruciate ligaments sit
What kind of the bone is the patella - describe.
sesamoid bone - bone found in a tendon
Which muscle is the patella embedded in
quadriceps femoris
How does the patella move smoothly
it has two depressions that correlate to the femoral condyles - the ridge between guides its movement
What attachs to the fibula
lateral collateral ligament and the biceps femoris muscle
What structures keep the knee stable
The cruciate ligaments from the femur sliding over the tibia and hyperextension, collateral ligaments in ab/duciton, mensici and quadriceps prevent instability esp rotational
Why isnt the knee a hinge joint
It;s centre of rotation moves in circle when considered in the sagittal plane and it has a screw-home mechanism
Describe the screw-home mechanism of the knee
As the knee flexes the tibia rotates internally and ext. when knee extends. This means it moves in a spiral motion when all planes are considered. This is due to the medial condyle being larger than the lateral condyle
ROM of the knee extension flexion abduction* adduction* Internal and external in nex questio n
E: few degrees
F: 140
Ab and Ad depend on knee flexion (optimum is 30) but stil few degrees
Describe internal and external rotation of the knee
Few degrees when flexion 0 due to interlocking tibia and femoral condyles. Rotation is increased at felxions increases to 90 degrees. ER: 0 - 45 and IR 0 - 30
Functional ROM of knee
Full extension and 115 degrees flexion
10 degrees rotation
What is the patellas main function?
To increase the lever arm of the quadriceps muscle (effort) so it can overcome the resistive force - most effect when the knee is full extended
What is the outcome of a patelloectomy
as the lever arm is reduced greatly the quads msut produce a greater force to over come resistance
