MSK 7 Flashcards
What is the inferior gluteal nerve innervating?
-gluteus maximus
What is the superior gluteal nerve innervating?
- gluteus medius and minimus
- abductors of hip and external rotators under gluteus maximus
How does hip stabilization occur?
- gluteus medius has action on pelvis when standing on one leg to stabilize it
- quadratus lumborum contracts on the same side at iliac crest and pulls pelvis upwards while gluteus medius on opposite side of unsupported leg pulls pelvis downwards
- gluteus medius has the greater stabilizing effect
What occurs to give a positive trendelenberg gait?
- injury to gluteus medius or superior gluteal nerve
- pelvis dips when people try to walk
Describe the pathway of nerves through the greater and lesser sciatic foramen
- sciatic nerve comes out below piriformis muscle and continues down back of leg and comes out above the level of pelvic diaphragm (through greater sciatic foramen)
- pudendal nerve comes out underneath sacrotuberous ligament enters the pelvis to innervate the urogential diaphragm
Where are intramuscular injections being given?
- into gluteus medius
- landmark with thumb pointing towards greater trochanter of femur and give injection between second and third finger to avoid piercing the sciatic nerve
How does abduction of hip occur?
- superficial fascia of the thigh (fascia lata) is insertion point for the muscles called iliotibial tract of superficial fascia
- skin of thigh is recruited into a tendon
- gluteus maximus is also inserted into back edge of iliotibial tract
- tensor fascia lata and gluteus maximus contract and exert force onto iliotibial tract
What are the ligaments of the hip? Where are they located?
- ligamentum teres comes from acetabulum
- round
What occurs to the ligaments of the hips when the femur is put in the flexed versus extended positions?
- in the flexed position, ligaments are relatively straight so good freedom to move
- as you flex femur, ligaments get wound up and tighten up to push the head of the femur more tightly into the acetabulum of femur so limited range of movement
Describe hip dislocation
- ligaments of hip can be torn- most often torn between ilio and ischiofemoral ligaments
- head of femur comes out of socket
- ligamentum teres pops and becomes dislocated
- 90% of hip dislocations when hip is in flexed position (posterior)
- sciatic nerve is immediately behind hip so it becomes injured causing foot drop (inability to dorsiflex the foot)
What muscle group is stretched out with a posterior hip dislocation?
- adductors of hip are stretched
- causes some contraction and pulls the femur into internally rotated position
- head of femur is not in acetabulum so when gluteal and iliopsoas muscles contract you get foreshorteneing of limb and internal rotation
Describe hip fracture
- usually occurs in the elderly because of osteoporosis (trabeculae of head of femur has more resorption and therefore is weaker)
- with a fracture, we can observe a pulling of the iliopsoas on the greater trochanter causing shortening of limb and external rotation
Describe the blood flow to the proximal portion of the femoral head
- arteries pass by ligament attachment then enter bone and go through the marrow to get to the femoral head
- in people under 20, there is an epiphyseal plate so the BV’s are unable to get to the epiphysis
- ligamentum teres artery goes from obturator artery to supply head of femur-may disappear after age of 20
How is blood supply affected with a fracture to the neck of the femur?
- blood vessels “fleeing the knee” will be broken
- if ligamentum teres blood supply is absent, necrosis of the femoral head is possible
What two muscle groups are acting on the knee?
- quadriceps (extensors)
- hamstrings (flexors)
Where is popliteal fossa?
- end of hamstrings group
- diamond shape at back of knee
- can feel popliteal knee and artery
What is the pes anserinus?
- muscles all arising from thigh and insert onto medial aspect of tibia (sartorius, gracilis, and semitendinosus)
- when we want to flex the knee, there is a lot of rubbing of these tendons so they are lubricated by a bursa
- anserine bursa protects the tendons from rubbing on medial surface of tibia
- muscles that contribute to balance when standing up are part of pes anserinus so even standing up, you have opportunity for rubbing of tendons and tibia
Where are the cruciate ligaments located in the knee?
-within the joint capsule but extrasynovially
Where are the medial and lateral meniscus located?
- intracapsular and within synovial membrane
- top of tibia is flat but femur is round
- meniscus has curved top and flat bottom to match the two bones so that femoral condyles don’t roll around on tibial plateau
