Muscles of the Lower Extremity Flashcards
Quadriceps Femoris Group
All: extend the knee
Rectus femoris: flexes the hip
O:
- Rectus femoris: AIIS
- Vastus medialis: medial lip of linea aspera
- Vastus lateralis: lateral lip of linea aspera, gluteal tuberosity and greater trochanter
- Vastus Intermedius: anterior and lateral shaft of the femur
I: tibial tuberosity (via patellar ligament)
Femoral nerve- L2-4
**vastus medialis extends farther distally than the laterals- concerns the tracking/movement of the patella- the angle of the femur, combined with the pull of the quads, causes the patella to track laterally. This is prevented in 2 ways: 1- the edge of the lateral condyle of the femur is elevated, forming a lateral wall; 2nd-the distal fibers of vastus medialis are set at an angle, pulling the patella medially
Hamstrings
located along posterior thigh between vastus laterals and adductor magnus
All 3 hamstrings have a common O at the tibial tuberosity
lateral hamstring: biceps femoris (2 heads- superficial long head and a deeper short head)
Medial hamstrings: semitendinosus lies superficial to the wider and deeper semimembranosis
biceps femoris
flexes the knee, ER the flexed knee
posteriorly tilts the pelvis
long head: extends the hip and assists to ER the hip
O:
- long head: ischial tuberosity
- short head: lateral lip of linea aspera
I: head of the fibula
N:
- long head: sciatic N (tibial branch) L5-S3
- short head: sciatic N (peroneal branch) L5-S2
Semitendinosus
Flexes the knee, IR the flexed knee
Extends and assists to IR the hip
Posteriorly tilts the pelvis
O: ischial tuberosity
I: proximal, medial shaft of the tibia at pes anserinus tendon
N: sciatic (tibial branch) L4-S2
Semimembranosus
Flexes and IR the knee
Extends and IR the hip
Posteriorly tilts the pelvis
O: ischial tuberosity
I: posterior aspect of the medal condyle of the tibia
N: sciatic (tibial branch) L4-S2
Gluteus maximus
All fibers: extend, ER and abd the hip
Lower fibers: Adduct the hip
O: coccyx, edge of sacrum, posterior iliac crest, and SI ligaments
I: ITB (upper fibers) and gluteal tuberosity (lower fibers)
N: inferior gluteal L5-S2
Gluteal medius
All fibers: abduct the hip
Anterior fibers: flex and IR the hip
Posterior fibers: extend and ER the hip
O: gluteal surface of ilium, between post and anterior gluteal lines, just below iliac crest
I: lateral aspect of greater trochanter
N: superior gluteal L4-S1
Gluteus minimus
abduct, IR and flex the hip
O: gluteal surface of ilium between anterior and inferior gluteal lines
I: anterior aspect of greater trochanter
N: superior gluteal L4-S1
Adductor group
5 adductors located along the medial thigh. together their proximal attachments drape from the superior pubic rams to the ischial tuberosity.
Anterior layer: pectineus and adductor longus
2nd layer: adductor brevis
Posterior layer: adductor magnus (anterior to hamstrings)
* these 4 muscles tuck posteriorly to the quads and insert on the posterior femur. The gracilis lies superficially on the medial thigh- only adductor that crosses the knee.
All: adduct and IR the hip
All except gracilis: assist the flex the hip
Gracilis also flexes and IR the knee
posterior fibers of adductor magnus: extends the hip
Adductor magnus
adduct and IR the hip
posterior fibers: extend the hip
O: inferior pubic ramus, ramus of ischium and ischial tuberosity
I: medial lip of linea aspera and adductor tubercle
N: obturator L2-4 and sciatic L4-S1
Adductor Longus
adduct and IR the hip
O: pubic tubercle
I: medial lip of linea aspera
N: obturator L2-4
Adductor brevis
adduct and IR the hip
O: inferior pubic ramus
I: pectinal line and medial lip of linea aspera
N: obturator L2-4
Pectineus
adduct and IR the hip
O: superior pubic ramus
I: pectinal line of femur
N: femoral and obturator L2-4
Gracilis
adduct and IR the hip
Flex and IR the knee
O: inferior pubic ramus
I: proximal, medial shaft of the tibia at pes anserinus tendon
N: obturator L2-4
TFL
small, superficial muscle on lateral side of upper thigh; easily accessible between upper fibers of rectus femurs and glut med
Flexes, IR and abducts the hip
O: iliac crest, posterior to ASIS
I: ITB
N: superior gluteal L4-S1
ITB
superficial sheet of fascia with vertical fibers that run along the lateral thigh. It emerges from the gluteal fascia, is wide and dense over the vastus laterals muscle and funnels into a strong cable along the side of the knee before inserting at the tibial tubercle. The fibers of of the TFL and some fibers of the glut max inside to the proximal aspect of the ITB. The ITB has a thick, matted texture that makes it a strong stabilizing component of the hip and knee.
Sartorius
- longest muscle in the bodyl stretching from the ASIS, across the thigh and to the medial knee.
Flexes, ER, and abducts the hip (tailor position/figure 4)
Flexes and IR the flexed knee
O: ASIS
I: proximal, medial shaft of the tibia at pes anserinus tendon
N: femoral L2-4
Lateral hip rotators:
The “deep 6”
piriformis & quadratus femoris
obturator internus & externus
gemellus superior & inferior
small muscles located deep to the glut max; all attach to aspects of the greater trochanter and fan medially to attach to the sacrum and pelvis
all are deep to the large sciatic nerve (except for piriformis which lies superficial and if over contracted can compress it)
Piriformis
ER and abduct (when flexed) the hip
O: anterior surface of sacrum
I: superior aspect of greater trochanter
N: sacral plexus L5-S2
*form a “T” between the coccyx, PSIS and greater trochanter (piriformis=base of T)
Quadratus femoris
ER the hip
O: lateral border of ischial tuberosity
I: intertrochanteric crest, between greater and lesser trochanters
N: sacral plexus L4-S2