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
Obturator internus
ER the hip
O: obturator membrane and inferior surface of of obturator foramen
I: medial surface of greater trochanter
N: sacral plexus L5-S2
Obturator externus
ER the hip
O: remi of pubis and ischium, obturator membrane
I: trochanteric fossa of femur
N: obturator L3-4
Gemellus superior
ER the hip
O: ischial spine
I: medial surface of greater trochanter
N: sacral plexus L5-S2
Gemellus inferior
ER the hip
O: ischial tuberosity
I: medial surface of the greater trochanter
N: sacral plexus L4-S2
Psoas major
with the origin fixed: flexes and ER the hip
with the insertion fixed: flexes the trunk and anteriorly tilts the pelvis
unilaterally: assists to laterally flex the lumbar spine
O: bodies and TP of lumbar vertebrae
I: lesser trochanter
N: lumbar plexus L1-4
- only 40% of ppl have a poses minor- assists to create lordotic posture and posteriorly tilt the pelvis
Iliacus
with origin fixed: flex and ER the hip
with insertion fixed: flex the trunk and ant tilt the pelvis
O: iliac fossa
I: lesser trochanter
N: femoral L1-4
Triceps surae
formed by the gastroc and soleus and attaches to the strong calcaneal (achilles) tendon
Gastrocnemius
flexes the knee
PF the ankle
O: medial and lateral heads to posterior surfaces of femoral condyles
I: calcaneus via calcaneal (achilles) tendon
N: tibial S1-2
Soleus
PF the ankle
O: solid line; proximal, posterior surface of tibia and posterior aspect of fibula
I: calcaneus via achilles tendon
N: tibial L5-S2
sometimes called the “2nd heart” because of the important role its strong contractions play in returning blood from the leg to the heart
Plantaris
short belly but longest tendon in the body
weak PF of the ankle
weak knee flexion
O: lateral supracondylar line of femur
I: calcaneus via achilles tendon
N: tibial L4-S2
Popliteus
deepest muscle of the posterior knee
although a weak knee flexor, it is vital in “unlocking” the joint from an extended position
(aka “the key which unlocks the knee”)
flexes and IR the flexed knee
O: lateral femoral condyle
I: proximal, posterior aspect of the tibia
N: tibial T4-S1
Peroneus longus
evert the foot
assists to PF the ankle
O: head of fibula and proximal 2/3 of lateral fibula
I: base of the 1st MT and medial cuneiform
N: superficial peroneal
Peroneus brevis
everts the foot
assists to PF the ankle
O: distal 2/3 of lateral fibula
I: tuberosity of the 5th MT
N: superficial peroneal L4-S2
Tibialis anterior
inverts the foot
DF the ankle
O: lateral condyle of tibia; proximal, lateral surface of tibia and interosseous membrane
I: medial cuneiform and base of the 1st MT
N: deep peroneal L4-S1
Extensor digitorum longus
extends toes 2-5 (MTP & IP)
DF the ankle
evert the foot
O: lateral condyle of tibia; proximal, anterior shaft of fibula and interosseous membrane
I: middle and distal phalanges of toes 2-5
N: peroneal L4-S1
Extensor hallucis longus
extends the 1st toe (MTP and IP)
DF the ankle
invert the foot
O: middle, anterior surface of fibula and interosseous membrane
I: distal phalanx of 1st toe
N: deep peroneal L4-S1
Tibialis posterior
invert the foot
PF the ankle
O: proximal, posterior shafts of tibia and fibula; and interosseous membrane
I: all 5 tarsal bones and bases of MTs 2-4
N: tibial L4-S1
Flexor digitorum longus
flexes toes 2-5 (MTP and IP)
weak PF
inverts the foot
O: middle, posterior surface of tibia
I: distal phalanges of toes 2-5
N: tibial L5-S2
Flexor hallucis longus
flexes the 1st toe (MTP and IP)
weak ankle PF
inverts the foot
O: middle half of posterior fibula
I: distal phalanx of 1st toe
N: tibial L5-S2
Extensor digitorum brevis
extends toes 2-4 (MTP and IP)
O: dorsal surface of calcaneus
I: toes 2-4 via extensor digitorum longus tendons
N: deep peroneal L4-S1
Flexor digitorum brevis
flex middle phalanges of toes 2-5 (PIPs)
O: medial process of calcaneus and plantar aponeurosis
I: middle phalanges of toes 2-5
N: tibial L4-S1
Abductor hallucis
abducts 1st toe (MTP)
assists to flex 1st toe (MTP)
O: medial process of calcaneus and plantar aponeurosis
I: proximal phalanx of 1st toe (medial surface) and medial sesamoid bone
N: tibial L4-S1
Abductor digiti minimi
flexes the 5th toe
assists to abduct 5th toe (MTP)
O: lateral process of calcaneus and plantar aponeurosis
I: proximal phalanx of 5th toe (lateral surface
N: tibial S1-2
Extensor hallucis brevis
extends the 1st toe (MTP)
O: dorsal surface of calcaneus
I: proximal phalanx of 1st toe
N: deep peroneal L4-S1
Flexor hallucis brevis
flex the 1st toe (MTP)
O: plantar surfaces of cuboid and lateral cuneiform
I: medial and lateral surfaces of base of proximal phalanx of 1st toe
N: tibial L4-S1
Adductor hallucis
adducts the 1st toe
assists to maintain transverse arch of the foot
assist to flex the 1st toe
O:
- oblique head: bases of 2nd-4th MT
- transverse head: plantar ligament of 3rd-5th MTP joints
I: lateral surface of base of proximal phalanx of 1st toe
N: tibial S1-2
Flexor digiti minimi brevis
flex the 5th toe (MTP)
O: base of 5th MT
I: base of proximal phalanx of 5th toe
N: tibial S1-2
Quadratus plantae
assist flexor digitorum longus to flex toes 2-5
O: medial and lateral sides of plantar surface of calcaneus
I: posterior, lateral aspect of flexor digitorum longus tendon
N: tibial S1-2
Plantar interossei of the foot
adducts and flexes toes 3-5 (MTP)
O: medial surfaces of 3-5 MTs
I: medial surfaces of proximal phalanges of toes 3-5
N: tibial S1-2
Dorsal interssei of the foot
abducts and flexes toes 2-4 (MTP)
O: adjacent surfaces of all MT
I:
- 1st: medial surface of proximal phalanx of 2nd toe
- 2-4: lateral surfaces of proximal phalanges of toes 2-4
N: tibial S1-2
Lumbricals of the foot
flex the proximal phalanges of toes 2-5 (MTP)
extend middle and distal phalanges of toes 2-5 (IP)
O: tendons of flexor digitorum longus
I: bases of proximal phalanges of toes 2-5 and extensor digitorum longs tendons (on dorsal surface of toes)
N:
- 1st- tibial L4-S1
- 2-4: tibial L4-2
