Anatomy - Lower Limb

Front 1

gluteus maximus

Back 1

Origin: posterior gluteal line, posterior surface of sacrum and coccyx, sacrotuberous ligament

Insertion: upper fibers: iliotibial tract; lowermost fibers: gluteal tuberosity of the femur

Action: extends the thigh; laterally rotates the femur

*Innervation** inferior gluteal nerve

Artery: superior and inferior gluteal aa.

Note: gluteus maximus is a site of intramuscular injection

Front 2

gluteus medius

Back 2

Origin: external surface of the ilium between the posterior and anterior gluteal lines

Insertion: greater trochanter of the femur

Action: abducts the femur; medially rotates the thigh

**Innervation** superior gluteal nerve

Artery: superior gluteal a.

Note: the angle at which the gluteus medius tendon approaches the greater trochanter of the femur is anterior to the axis of rotation of the thigh, resulting in medial rotation

Front 3

gluteus minimus

Back 3

Origin: external surface of the ilium between the anterior and inferior gluteal lines

Insertion: greater trochanter of the femur

Action: abducts the femur; medially rotates the thigh

**Innervation** superior gluteal nerve

Artery: superior gluteal a.

Note: the angle at which the gluteus minimus tendon approaches the greater trochanter of the femur is anterior to the axis of rotation of the thigh, resulting in medial rotation

Front 4

piriformis

Back 4

Origin: anterior surface of sacrum

Insertion: upper border of greater trochanter of femur Action: laterally rotates and abducts thigh

**Innervation**ventral rami of S1-S2

Note: piriformis leaves the pelvis by passing through the greater sciatic foramen

Front 5

superior gemellus

Back 5

Origin: ischial spine

Insertion: obturator internus tendon

Action: laterally rotates the femur

**Innervation** nerve to the obturator internus m.

Artery: inferior gluteal a.

Note: gemellus is a Latin word that means "little twin"

Front 6

inferior gemellus

Back 6

Origin: ischial tuberosity

Insertion: obturator internus tendon

Action: laterally rotates the femur

**Innervation**nerve to the quadratus femoris m.

Artery: inferior gluteal a.

Note: gemellus is a Latin word that means "little twin"

Front 7

obturator externus

Back 7

Origin: the external surface of the obturator membrane and the superior and inferior pubic rami

Insertion: trochanteric fossa of the femur

Action: laterally rotates the thigh

**Innervation** obturator nerve

Artery: obturator a.

Note: the tendon of the obturator externus m. passes inferior to the neck of the femur to reach its insertion site

Front 8

quadratus femoris

Back 8

Origin: lateral border of the ischial tuberosity

Insertion: quadrate line of the femur below the intertrochanteric crest

Action: laterally rotates the thigh



**Innervation** nerve to the quadratus femoris m.

Artery: inferior gluteal a.

Note: the nerve to the quadratus femoris m. also innervates the inferior gemellus m.

Front 9

biceps femoris long head

Back 9

Origin: ischial tuberosity

Insertion: head of fibula and lateral condyle of the tibia

Action: extends the thigh, flexes the leg

**Innervation** tibial nerve

Artery: perforating branches of the deep femoral a.

Note: one of the "hamstring" muscles

Front 10

biceps femoris short head

Back 10

Origin: ischial tuberosity

Insertion: : lateral lip of the linea aspera

Action: extends the thigh, flexes the leg

**Innervation**common fibular (peroneal) nerve

Artery: Inferior gluteal artery

Note: One of the "hamstring" muscles

Front 11

semitendinosus muscle

Back 11

Origin: lower, medial surface of ischial tuberosity (common tendon with biceps femoris m.)

Insertion: medial surface of tibia (via pes anserinus)

Action: extends the thigh, flexes the leg

**Innervation** tibial nerve

Artery: perforating branches of the deep femoral a.

Note: pes anserinus is the common insertion for the gracilis, sartorius, and semitendinosus mm.

Front 12

semimembranosus muscle

Back 12

Origin: upper, outer surface of the ischial tuberosity

Insertion: medial condyle of the tibia

Action: extends the thigh, flexes the leg

**Innervation** tibial nerve

Artery: perforating branches of the deep femoral a.

Note: one of the "hamstring" muscles

Front 13

adductor magnus

Back 13

Origin: ischiopubic ramus and ischial tuberosity

Insertion: linea aspera of the femur; the ischiocondylar part inserts on the adductor tubercle of the femur

Action: adducts, flexes, and medially rotates the femur; extends the femur (ischiocondylar part)



**Innervation** posterior division of the obturator nerve; tibial nerve (ischiocondylar part)

Artery: obturator a., deep femoral a., medial femoral circumflex a.

Note: the ischiocondylar part of adductor magnus is a hamstring muscle by embryonic origin and action, so it is innervated by the tibial nerve

Front 14

gastrocnemius

Back 14

Origin: femur; medial head: above the medial femoral condyle; lateral head: above the lateral femoral condyle

Insertion: dorsum of the calcaneus via the calcaneal (Achilles') tendon

Action: flexes leg; plantar flexes foot

**Innervation** tibial nerve

Artery: sural aa. (from the popliteal a.), posterior tibial a.

Note: the calcaneal tendon of the gastrocnemius and soleus is the thickest and strongest tendon in the body

Front 15

plantaris

Back 15

Origin: above the lateral femoral condyle (above the lateral head of gastrocnemius)

Insertion: dorsum of the calcaneus medial to the calcaneal tendon

Action: flexes the leg; plantar flexes the foot

**Innervation** tibial nerve

Artery: popliteal a.

Note: plantaris has a long slender tendon that is equivalent to the tendon of the palmaris longus m. of the arm; its tendon is often called the "freshman nerve" because it is often misidentified by the freshman medical student

Front 16

popliteus

Back 16

Origin: lateral condyle of the femur

Insertion: posterior surface of the tibia above soleal line Action: flexes and rotates the leg medially (with the foot planted, it rotates the thigh laterally)

**Innervation** tibial nerve Artery: popliteal a.

Note: has a round tendon of origin; popliteus unlocks the knee joint to initiate flexion of the leg

Front 17

soleus

Back 17

Origin: posterior surface of head and upper shaft of the fibula, soleal line of the tibia

Insertion: dorsum of the calcaneus via the calcaneal (Achilles') tendon

Action: plantar flexes the foot

**Innervation** tibial nerve

Artery: posterior tibial a.

Note: soleus and the 2 heads of gastrocnemius are sometimes called the triceps surae muscle

Front 18

flexor digitorum longus

Back 18

Origin: middle half of the posterior surface of the tibia

Insertion: bases of the distal phalanges of digits 2-5

Action: flexes the metatarsophalangeal, proximal interphalangeal and distal interphalangeal joints of digits 2-5; plantar flexes the foot

**Innervation** tibial nerve

Artery: tibial a.

Note: flexor digitorum longus in the leg is equivalent to the flexor digitorum profundus m. of the arm

Front 19

tibialis posterior

Back 19

Origin: interosseous membrane, posteromedial surface of the fibula, posterolateral surface of the tibia

Insertion: tuberosity of the navicular and medial cuneiform, metatarsals 2-4

Action: plantar flexes the foot; inverts the foot

**Innervation** tibial nerve

Artery: fibular (peroneal) a. and tibial a.

Note: acts as both an antagonist (dorsiflexion/plantar flexion) and a synergist (inversion) of the tibialis anterior m.

Front 20

flexor hallucis longus

Back 20

Origin: lower 2/3 of the posterior surface of the fibula

Insertion: base of the distal phalanx of the great toe

Action: flexes the metatarsophalangeal and proximal interphalangeal joints of the great toe; plantar flexes the foot

**Innervation** tibial nerve

Artery: fibular (peroneal) a. and tibial a.

Note: flexor hallucis longus is very important in the "push off" part of the normal gait

Front 21

tibialis anterior

Back 21

Origin: lateral tibial condyle and the upper lateral surface of the tibia

Insertion: medial surface of the medial cuneiform and the 1st metatarsal

Action: dorsiflexes and inverts the foot

**Innervation**deep fibular (peroneal) nerve

Artery: anterior tibial a.

Note: acts as both an antagonist (dorsiflexion/plantar flexion) and a synergist (inversion) of the tibialis posterior m.

Front 22

extensor hallucis longus

Back 22

Origin: middle half of the anterior surface of the fibula and the interosseous membrane

Insertion: base of the distal phalanx of the great toe

Action: extends the metatarsophalangeal interphalangeal joints of the great toe

**Innervation** deep fibular (peroneal) nerve

Artery: anterior tibial a.

Note: one of the muscles involved in anterior compartment syndrome

Front 23

extensor digitorum longus

Back 23

Origin: lateral condyle of the tibia, anterior surface of the fibula, lateral portion of the interosseous membrane

Insertion: dorsum of the lateral 4 toes via extensor expansions (central slip inserts on base of middle phalanx, lateral slips on base of distal phalanx)

Action: extends the metatarsophalangeal, proximal interphalangeal and distal interphalangeal joints of the lateral 4 toes



**Innervation** deep fibular (peroneal) nerve

Artery: anterior tibial a.

Note: one of the muscles involved in anterior compartment syndrome

Front 24

fibularis (peroneus) tertius

Back 24

Origin: distal part of the anterior surface of the fibula

Insertion: dorsum of the shaft of the 5th metatarsal bone

Action: everts the foot

**Innervation**deep fibular (peroneal) nerve

Artery: anterior tibial a.

Note: fibularis tertius is in the anterior compartment of the leg, not the lateral compartment (which contains fibularis longus and brevis)

Front 25

extensor hallucis brevis

Back 25

Origin: superolateral surface of the calcaneus

Insertion: dorsum of base of proximal phalanx of the great toe

Action: extends the great toe

**Innervation** deep fibular (peroneal) nerve

Artery: dorsalis pedis a.

Note: usually considered to be the medial-most part of the extensor digitorum brevis m.

Front 26

extensor digitorum brevis

Back 26

Origin: superolateral surface of the calcaneus

Insertion: extensor expansion of toes 1-4

Action: extends toes 1-4

**Innervation** deep fibular (peroneal) nerve

Artery: dorsalis pedis a.

Note: the part of the extensor digitorum brevis that goes to the great toe is called the extensor hallucis brevis m.

Front 27

fibularis (peroneus) brevis

Back 27

Origin: lower one third of the lateral surface of the fibula

Insertion: tuberosity of the base of the 5th metatarsal

Action: extends (plantar flexes) and everts the foot

**Innervation** superficial fibular (peroneal) nerve

Artery: fibular (peroneal) a.

Note: stress fracture of the base of the 5th metatarsal bone is a common runner's injury

Front 28

fibularis (peroneus) longus

Back 28

Origin: upper two/thirds of the lateral surface of the fibula

Insertion: after crossing the plantar surface of the foot deep to the intrinsic muscles, it inserts on the medial cuneiform and the base of the 1st metatarsal bone

Action: extends (plantar flexes) and everts the foot

**Innervationsuperficial fibular (peroneal) nerve**

Artery: fibular (peroneal) a.

Note: fibularis longus lies superficial to the fibularis brevis m. in the lateral compartment of the leg

Front 29

abductor hallucis

Back 29

Origin: medial side of the tuberosity of calcaneus

Insertion: medial side of the base of the proximal phalanx of the great toe (hallux)

Action: abducts the great toe; flexes the metatarsophalageal joint

**Innervation** medial plantar nerve

Artery: medial plantar a.

Note: abductor hallucis forms the medial margin of the sole of the foot

Front 30

flexor hallucis brevis

Back 30

Origin: cuboid, lateral cuneiform, medial side of the first metatarsal

Insertion: medial belly: medial side of proximal phalanx of the great toe; lateral belly: lateral side of the proximal phalanx of the great toe flexes the metatarsophalangeal joint of the great toe

**Innervation** medial plantar nerve (lateral belly occasionally receives innervation from the lateral plantar nerve)

Artery: medial plantar a.

Note: each tendon of insertion contains a sesamoid bone

Front 31

abductor digiti minimi (foot)

Back 31

Origin: medial and lateral sides of the tuberosity of the calcaneus

Insertion: lateral side of the base of the proximal phalanx of the 5th digit

Action: abducts the 5th toe; flexes the metatarsophalageal joint

**Innervation** lateral plantar nerve

Artery lateral plantar a.

Note: abductor digiti minimi forms the lateral margin of the sole of the foot

Front 32

flexor digiti minimi brevis (foot)

Back 32

Origin: base of 5th metatarsal bone

Insertion: lateral side of base of proximal phalanx of 5th digit

Action: flexes the metatarsophalangeal joint of the 5th digit

**Innveration** lateral plantar nerve

Artery lateral plantar a.

Front 33

flexor digitorum brevis

Back 33

Origin: tuberosity of the calcaneus, plantar aponeurosis, intermuscular septae

Insertion: base of the middle phalanx of digits 2-5 after splitting to allow passage of the flexor digitorum longus tendons

Action: flexes the metatarsophalangeal & proximal interphalangeal joints of digits 2-5

**Innervation** medial plantar nerve

Artery: medial and lateral plantar aa.

Note: flexor digitorum brevis in the foot is equivalent to the flexor digitorum superficialis m. of the arm

Front 34

quadratus plantae

Back 34

Origin: anterior portion of the calcaneus and the long plantar ligament

Insertion: tendons of the flexor digitorum longus m.

Action: assists the flexor digitorum longus in flexing the toes

**Innervation** lateral plantar nerve

Artery: lateral plantar a.

Note: the quadratus plantae m. changes the line of force of the flexor digitorum longus m. to bring it in line with the long axis of the foot

Front 35

lumbricals (foot)

Back 35

Origin: tendons of the flexor digitorum longus

Insertion: medial side of the extensor expansion of digits 2-5

Action: flex the metatarsophalangeal joint, extend the proximal interphalangeal & distal interphalangeal joints of digits 2-5

**Innervation** medial (1st) lumbrical: medial plantar nerve; lateral three lumbricals: lateral plantar nerve

Artery: medial and lateral plantar aa.

Note: the lumbricals of the foot have the same action on the toes that the lumbricals in the hand have on the fingers

Front 36

abductor hallucis

Back 36

Origin: medial side of the tuberosity of calcaneus

Insertion: medial side of the base of the proximal phalanx of the great toe (hallux)

Action: abducts the great toe; flexes the metatarsophalageal joint

**Innervation** medial plantar nerve

Artery: medial plantar a.

Note: abductor hallucis forms the medial margin of the sole of the foot

Front 37

dorsal interosseous (foot)

Back 37

Origin: shafts of adjacent metatarsal bones

Insertion: bases of the proximal phalanges for digit 2 (both sides) & digits 3,4 (lateral side)

Action: abduct digits 2-4 (move these digits away from midline as defined by a plane passing through the 2nd digit); flex the metatarsophalangeal joints and extend the interphalangeal joints of those digits

**Innervation** deep branch of the lateral plantar nerve

Artery: dorsal metatarsal aa.

Note: four in number; remember DAB (Dorsal interossei ABduct) and PAD (Plantar interossei ADduct), then logic can tell you where these muscles insert

Front 38

plantar interosseous

Back 38

Origin: base and medial side of metatarsals 3-5

Insertion: bases of proximal phalanges and extensor expansions of digits 3-5

Action: adduct digits 3-5 (move these digits toward the midline of the foot as defined by the second digit),flex metatarsophalangeal and extend interphalangeal joints of digits 3-5

**Innervation** deep branch of the lateral plantar nerve

Arrtery: plantar metatarsal aa.

Note: remember PAD (Plantar interossei ADduct) and DAB (Dorsal interossei ABduct), and logic will tell you where these muscles must insert

Front 39

tibialis anterior

Back 39

Origin: lateral tibial condyle and the upper lateral surface of the tibia Insertion: medial surface of the medial cuneiform and the 1st metatarsal

Action: dorsiflexes and inverts the foot

**Innervation** deep fibular (peroneal) nerve

Artery: anterior tibial a.

Note: acts as both an antagonist (dorsiflexion/plantar flexion) and a synergist (inversion) of the tibialis posterior m.

Front 40

extensor digitorum longus

Back 40

Origin: lateral condyle of the tibia, anterior surface of the fibula, lateral portion of the interosseous membrane

Insertion: dorsum of the lateral 4 toes via extensor expansions (central slip inserts on base of middle phalanx, lateral slips on base of distal phalanx)

Action: extends the metatarsophalangeal, proximal interphalangeal and distal interphalangeal joints of the lateral 4 toes

**Innervation** deep fibular (peroneal) nerve

Artery: anterior tibial a.

Note: one of the muscles involved in anterior compartment syndrome

Front 41

fibularis (peroneus) tertius

Back 41

Origin: distal part of the anterior surface of the fibula

Insertion: dorsum of the shaft of the 5th metatarsal bone everts the foot

**Innervation** deep fibular (peroneal) nerve

Artery: anterior tibial a.

Note: fibularis tertius is in the anterior compartment of the leg, not the lateral compartment (which contains fibularis longus and brevis)

Front 42

extensor hallucis longus

Back 42

Origin: middle half of the anterior surface of the fibula and the interosseous membrane

Insertion: base of the distal phalanx of the great toe

Action: extends the metatarsophalangeal interphalangeal joints of the great toe

**Innervation** deep fibular (peroneal) nerve

Artery: anterior tibial a.

Note: one of the muscles involved in anterior compartment syndrome