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Extensor tendons, interossei and connective tissue form the extensor mechanism.
The entire mechanism coordinates the forces for MCP, PIP and DIP extension.
Dorsal Hood: Fibers run from the palmar plate of the fingers to the EDC tendon, broaden out to form a sling around the dorsum of the proximal end of the proximal phalanx.
Dorsal hood fibers also serve as attachments for lumbricals and interossei (secondary).
Transverse fibers help extend the MCP joint
Oblique fibers help extend PIP and DIP joints
Oblique retinacular ligaments connect the fibrous sheath of the finger (on palmar surface) to the lateral bands of the EDC
Profundus – deep– runs to the base of the distal phalanx after passing through the tendon of the flexor digitorum superficialis, which is then passes over.
Flexor digitorum superficialis splits, then the two parts insert onto the sides of the middle phalanx.
Additional bands of connective tissue, called vincula, attach the flexor tendons to the fingers.
Flexor superficialis & flexor profundus are held against the phalanges by fibrous sheaths that keep the tendons in place. These are called the Annular Pulleys.
They keeps vector of the tendon pull at a good angle to the joint even with a lot of movement of the hand and wrist.
Rupture of an annular pulley can cause bowstringing.
form between the uncinated processes and the adjacent part of the superior vertebra between C3-C7
Wolff’s law: bone gets stronger when stress is put on it
Where the lines of stress cross=dense bone and has the most stress
Fracture of the vertebrae it is generally in the fracture zone-compression fracture, usually stable, often in the thoracic spine (osteoporosis)
Could effect posture if multiple vertebrae are affected
Bone is living tissue that is constantly being broken down and replaced. Osteoporosis occurs when the creation of new bone doesn't keep up with the removal of old bone
Distance of the head from the rest of the spinal column, it is a moment arm for the weight of the head
In the first picture, the muscles in the neck have to work harder because of the longer moment arm
*Note commonality: isometric for trunk!
Smoothly rotates, one ASIS forward and then the other
Rotation of the pelvis contributes to step length
Slight pelvic drop on swing side
Proper pelvic movement is needed for conservation of energy
-same side as step= pelvis moves forward and drops down
Lateral tilt happens during swing
-relation to abduction of the spine
-side bending for the vertebrae
Have to have the spine movement or you do not have the pelvic tilt
You need the rotation in the thoracic region or you cannot rotate the pelvis forward
Erector spinae=burst of activity at initial contact (transferring weight)-does not mean maximum just more contraction..
Red lines=at least 20%=threshold
Very low level contractions
Hip stabilizors=gluteus maximus when the hip is flexed
Gluteus medius=stabilize the dip in the pelvis
The arms provide a counterforce to the movement of the pelvis & legs, helping keep the CoM centered and the gait smooth.
Supraspinatus & upper trap are most active, possible to support the scapula and arm.
The posterior and middle deltoid contract together to extend the shoulder. Forward flexion is mostly passive.
-trunk rotation, counter-rotation, helps to keep the center of mass in the middle, movement back and forward is not equal.. Less extension and more flexion
Variable from person to person and from arm to arm
Nucleus pulposus=90% water
Held in place by hydrophilic proteoglycans
Contains some type 2 and elastin
Condrocytes and fibrocytes and it is avascular and a neural
Chondrocyte: a cell that has secreted the matrix of cartilage
Fibrocyte: inactive mesenchymal cell
Annulus fibrosis=thicker anteriorly and thinner as it goes back to the uncinate processes
Posteriorly the annulus fibrosus consists of only a thin layer of vertical collagen fibers and is like a ligament.. Does not have concentric layers of fiberThey don't bear as much weight and are built to allow more movement
Laminectomy= take off the entire posterior column (did not change the way the disk behaved)
Subject to creep during the day.. Gradually over time with repeated loading they do not return to their normal height.. At the end of the day the person is a little shorter
Anterior pelvic tilt deepens the lumbar lordosis: the facet joints are pushed together, the posterior spinal ligaments are slack, and the anterior longitudinal ligament is pulled tight
The annulus fibrosis bulges slightly posteriorly and the nucleus is under pressure from posterior to anterior but does not move around a lot=because of the annulus fibrosus collagen fibers
Posterior Pelvic Tilt: flattens the lordosis, in flexion the facet joints are pulled apart and the posterior spinal ligaments are taught including posterior longitudinal ligament, intraspinous ligament and the supraspinous ligaments, anterior longitudinal ligament is slack, the annulus fibrosis bulges slightly anteriorly, nucleus is under pressure from anterior to posterior
Increased intra-abdominal pressure through use of the Valsalva Maneuver helps to increase trunk stability during lifting works to activate the abdominal muscles while holding one's breath which creates a column of high pressure in the abdominal cavity, activating the transverse abdominis (which attaches into the lumbar fascia) helps pull the fascia tight and creates a stable abdominal brace, contraction of the internal obliques assists with this.. The overall result of holding one's breath and contracting the abdominal muscles=increase in compressive loading of the spine and disks.. The spine does well with compressive loads, the valsalva encourages stabilizing the trunk close to a neutral position
Safer technique=exhale as they lift, contract the abdominal muscles so there is still an abdominal brace.. Helps prevent completely compressing the vena cava
Cantelebra (cantilever) system : forces are different on each side. At the bottom of the femoral head there is a compressive force and at the top of the femoral head it is a tensile force because it wants to bend down and pulls away creating the zone of weakness.. Likely spot for fracture. Tensile leads to fracture.. Compression from the muscle could counteract that force.. Strong hip muscles create joint reaction forces and compression forces
Can help people stay active and build up the muscle and this can build up the bone.. Better stability and less likely to fall
20% of people die within 1 year following hip fraction: frail person anyway, afraid to fall again so they restrict their activity and they are at higher risk of pneumonia, so the cycle continues, depression, poor nutrition..
80% of people over 65 y.o. are female
Risk doubles each decade after 50 years old due to osteoporosis, increased incidence of falls
Falls may be due to balance problems, weakness, low vision, slow reactions, decreased sensation & proprioception, decreased joint range of motion, low blood pressure, polypharmacy.
Blood supply isn’t really very good and can become compromised.
If avascular necrosis occurs, the head of the femur is replaced. THA
Replace the head because there is a high risk of avascular necrosis if the fracture displaces the head
Capsule - strong- surrounds acetabulum and base of the femoral neck
Iliofemoral - Y ligament. anterior. tight in hip extension.
Pubofemoral - Inferior- tight in abduction
Ischiofemoral - posterior-spiral - tight in hip extension and internal rotation
Femoral anteversion is compensated by tibial torsion in the opposite direction
These ligaments can tighten and support you when you lean back
Want to decrease the joint reaction force
Cane=counterclockwise force.. Bigger lever arm=decreased force in the muscles because they don’t have to push as hard
Reduced the joint reaction force.. Helps keep their gate normal and center of mass in the correct location
Tibiofemoral joint and patellofemoral joint. Nearby is the proximal tibiofibular joint --not within the knee joint capsule, it is a synovial joint lateral and inferior to the knee. It is formed between the head of the fibula and the posterior-lateral aspect of the lateral condyle of the tibia. It has its own joint capsule, with anterior and posterior capsular ligaments. The joint surfaces are slightly oval. It doesn’t move much, just has a little gliding motion. The lateral collateral ligament of the knee inserts on the head of the fibula, as does the biceps femoris tendon. The common peroneal nerve winds around under the head of the fibula
The knee capsule surrounds the knee and attaches to the margins of the patella so that the patellar surface is within the knee joint capsule. The patella slides along the intercondylar groove of the femur as the knee flexes and extends.
The articular surface of the tibia is deepened by two crescent shaped menisci made of fibrocartilage. They add to the surface area in contact with the femoral condyles, which spreads out the force over a larger area, reducing pressure on the articular surface. “hoop” stresses. Joint Compression Force at knee = 2.5 to 3 x BW just walking, and 4 X BW going up stairs.
The Medial Meniscus is a little more C, or oval shaped. The Lateral Meniscus is more O shaped.
The medial meniscus is more firmly held in place. Its external border attaches to the medial collateral ligament and to the joint capsule.
Both menisci get small slips of tendon from the quadriceps and from the semimembranosus
The lateral meniscus attaches to the lateral capsule, but not to the lateral collateral ligament. It moves more freely with knee movement.
Both menisci get small slips of tendon from the quadriceps and from the semimembranosus. The lateral meniscus also has an attachment to the popliteus muscle. These muscle help to stabilize the menisci.
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