Lower limb muscles

Question 1

Gluteus Maximus (Superficial Muscle)

Answer 1

Attachments:
Originates from the gluteal (posterior) surface of the ilium, sacrum and coccyx. The fibres slope across the buttock at a 45 degree angle and insert onto the iliotibial tract and gluteal tuberosity of the femur.

Actions:
It is the main extensor of the thigh, and assists with lateral rotation. However, it is only used when force is required, such as running or climbing.

Innervation:
Inferior gluteal nerve.

Blood supply:
Inferior gluteal and superior gluteal arteries

Question 2

Gluteus medius (Superficial Muscle)

Answer 2

Attachments:
Originates from the gluteal surface of the ilium and inserts into the lateral surface of the greater trochanter.

Actions:
Abduction and medial rotation of the lower limb. It stabilises the pelvis during locomotion, preventing ‘dropping’ of the pelvis on the contralateral side.

Innervation:
Superior gluteal nerve.

Blood supply:
Deep branch of superior gluteal artery, trochanteric anastomosis

Question 3

Gluteus Minimus (Superficial Muscle)

Answer 3

Attachments:
Originates from the ilium and converges to form a tendon, inserting to the anterior side of the greater trochanter.

Actions:
Abduction and medial rotation of the lower limb. It stabilises the pelvis during locomotion, preventing ‘dropping’ of the pelvis on the contralateral side.

Innervation:
Superior gluteal nerve.

Blood supply:
Superior gluteal artery, trochanteric anastomosis

Question 4

Tensor Fascia Lata (Superficial Muscle)

Answer 4

Attachments:
Originates from the anterior iliac crest, attaching to the anterior superior iliac spine (ASIS). It inserts into the iliotibial tract, which itself attaches to the lateral condyle of the tibia.

Actions:
Assists the gluteus medius and minimus in abduction and medial rotation of the lower limb. It also plays a supportive role in the gait cycle.

Innervation:
Superior gluteal nerve.

Blood supply:
Ascending branch of lateral circumflex femoral artery

Question 5

Piriformis (Deep lateral rotators)

Answer 5

Attachments:
Originates from the anterior surface of the sacrum. The fibres travel inferiorly and laterally through the greater sciatic foramen to insert onto the greater trochanter of the femur.

Actions:
Lateral rotation and abduction.

Innervation:
Nerve to piriformis (S1-S2)

Blood supply:
Superior gluteal artery, inferior gluteal artery, gemellar branches of the internal pudendal

Question 6

Obturator internus (Deep lateral rotators)

Answer 6

Attachments:
Originates from the pubis and ischium at the obturator foramen. It travels through the lesser sciatic foramen, and attaches to the greater trochanter of the femur.

Actions:
Lateral rotation and abduction.

Innervation:
Nerve to obturator internus.

Blood supply:
Obturator artery; internal pudendal artery

Question 7

The Gemelli – Superior and Inferior (Deep lateral rotators)

Answer 7

Attachments:
The superior gemellus muscle originates from the ischial spine, the inferior from the ischial tuberosity. They both attach to the greater trochanter of the femur.

Actions:
Lateral rotation and abduction.

Innervation:
The superior gemellus muscle is innervated by the nerve to obturator internus, the inferior gemellus is innervated by the nerve to quadratus femoris.

Blood supply:
Inf-Medial circumflex femoral artery
Sup-Internal pudendal artery, inferior gluteal artery (and occasionally superior gluteal artery)

Question 8

Quadratus Femoris (Deep lateral rotators)

Answer 8

Attachments:
Originates from the lateral aspect of the ischial tuberosity and attaches to the quadrate tuberosity on the intertrochanteric crest.

Actions:
Lateral rotation.

Innervation:
Nerve to quadratus femoris.

Blood supply:
Inferior gluteal artery

Question 9

Iliopsoas (anterior compartment of the thigh)

Answer 9

Attachments:
The psoas major originates from the lumbar vertebrae, and the iliacus originates from the iliac fossa of the pelvis. They insert together onto the lesser trochanter of the femur.

Actions:
Flexion of the the thigh at the hip joint.

Innervation:
The psoas major is innervated by anterior rami of L1-3, while the iliacus is innervated by the femoral nerve.

Blood supply:
Iliolumbar, obturator, external iliac and femoral arteries

Question 10

Vastus Lateralis (anterior compartment of the thigh)

Answer 10

Proximal attachment:
Originates from the greater trochanter and the lateral lip of linea aspera of the femur –>Inserts onto the patella via the quadriceps tendon

Actions:
Extension of the knee joint. It has a secondary function of stabilising the patella.

Innervation:
Femoral nerve

Blood supply:
Lateral circumflex femoral and deep femoral arteries; artery to quadriceps

Question 11

Vastus Intermedius (anterior compartment of the thigh)

Answer 11

Proximal attachment:
Originates from the anterior and lateral surfaces of the femoral shaft –>Inserts onto the patella via the quadriceps tendon

Actions:
Extension of the knee joint. It has a secondary function of stabilising the patella.

Innervation: Femoral nerve.

Blood supply:
Artery to quadriceps, deep femoral arteries

Question 12

Vastus Medialis (anterior compartment of the thigh)

Answer 12

Proximal attachment:
Originates from the intertrochanteric line and medial lip of the linea aspera of the femur –>Inserts onto the patella via the quadriceps tendon

Actions:
Extension of the knee joint. It has a secondary function of stabilising the patella.

Innervation:
Femoral nerve.

Blood supply:
Femoral, deep femoral, descending genicular artery

Question 13

Rectus Femoris (anterior compartment of the thigh)

Answer 13

Attachments:
Originates from the anterior inferior iliac spine and the ilium of the pelvis. It attaches to the patella via the quadriceps femoris tendon.

Actions:
Extension of the knee joint and flexion of the hip joint (it is the only muscle of the quadriceps group to cross both the hip and knee joints).

Innervation:
Femoral nerve.

Blood supply:
Femoral, lateral femoral circumflex, superficial circumflex iliac arteries

Question 14

Sartorius (anterior compartment of the thigh)

Answer 14

Attachments:
Originates from the anterior superior iliac spine, and attaches to the superior, medial surface of the tibia.

Actions:
At the hip joint, it is a flexor, abductor and lateral rotator. At the knee joint, it is also a flexor.

Innervation:
Femoral nerve.

Blood supply:
Proximal third: branches of femoral artery, deep femoral artery, artery of quadriceps, lateral circumflex femoral artery
Middle third: branches of femoral artery
Distal third: branches of femoral and descending genicular arteries

Question 15

Pectineus (anterior compartment of the thigh)

Answer 15

Attachments:
Originates from the pectineal line of the pubis bone. It inserts onto the pectineal line on the posterior aspect of the femur, immediately inferior to the lesser trochanter.

Actions:
Adduction and flexion at the hip joint.

Innervation:
Femoral nerve. May also receive a branch from the obturator nerve.

Blood supply:
Medial femoral circumflex artery, obturator artery

Question 16

Adductor Magnus (medial compartment of the thigh)

Answer 16

Attachments:
Adductor – Originates from the inferior rami of the pubis and the rami of ischium, attaches to the linea aspera of the femur.
Hamstring part – Originates from the ischial tuberosity, attaches to the adductor tubercle and medial supracondylar line of the femur.

Actions:
Adductor – Adduction and flexion of the thigh
Hamstring – Adduction and extension of the thigh.

Innervation:

Adductor – Obturator nerve (L2-L4)
Hamstring part – Tibial component of the sciatic nerve (L4-S3)

Blood supply:
Deep femoral artery;
Femoral, popliteal and genicular arteries

Question 17

Adductor Longus (medial compartment of the thigh)

Answer 17

Attachments:
Originates from the pubis bone of the pelvis and expands into a fan shape. It has a broad distal attachment along the linea aspera of the femur.

Actions:
Adduction of the thigh.

Innervation:
Obturator nerve (L2-L4).

Blood supply:
Deep femoral artery, obturator artery

Question 18

Adductor Brevis (medial compartment of the thigh)

Answer 18

Attachments:
Originates from the body of pubis and inferior pubic rami. Attaches to the linea aspera on the posterior surface of the femur (proximal to the adductor longus attachment).

Actions:
Adduction of the thigh.

Innervation:
Obturator nerve (L2-L4).

Blood supply:
Arteria profunda femoris

Question 19

Obturator Externus (medial compartment of the thigh)

Answer 19

Attachments:
Originates from the membrane of the obturator foramen and adjacent bone. It passes under the neck of femur and attaches onto the posterior aspect of the greater trochanter.

Actions:
Adduction and lateral rotation of the thigh.

Innervation:
Obturator nerve (L2-L4).

Blood supply:
Obturator and medial circumflex femoral arteries.

Question 20

Gracilis (medial compartment of the thigh)

Answer 20

Attachments:
Originates from the inferior rami of the pubis and the body of the pubis. It descends down the medial aspect of the thigh and attaches to the medial surface of the tibial shaft.

Actions:
Adduction of the thigh at the hip and flexion of the leg at the knee.

Innervation:
Obturator nerve (L2-L4).

Blood supply:
Deep femoral artery (via artery to the adductors)

Question 21

Biceps Femoris (posterior compartment)

Answer 21

Attachments:
The long head originates from the ischial tuberosity of the pelvis. The short head originates from the linea aspera on posterior surface of the femur. Together, the heads form a tendon, which inserts into the head of the fibula.

Actions:
Main action is flexion at the knee. It also extends the thigh at the hip, and laterally rotates at the hip and knee.

Innervation:
Long head innervated by the tibial part of the sciatic nerve, whereas the short head is innervated by the common fibular part of the sciatic nerve.

Blood supply:
Inferior gluteal artery, perforating arteries, popliteal artery

Question 22

Semitendinosus (posterior compartment)

Answer 22

Attachments:
Originates from the ischial tuberosity of the pelvis and attaches to the medial surface of the tibia.

Actions:
Flexion of the leg at the knee joint. Extension of thigh at the hip. Medially rotates the thigh at the hip joint and the leg at the knee joint.

Innervation:
Tibial part of the sciatic nerve.

Blood supply:
First perforating branch of deep femoral artery, medial femoral circumflex artery, inferior gluteal artery and inferior medial geniculate artery

Question 23

Semimembranosus (posterior compartment)

Answer 23

Attachments:
Originates from the ischial tuberosity (more superiorly than the origin of the semitendinosus and biceps femoris). Attaches to the medial tibial condyle.

Actions:
Flexion of the leg at the knee joint. Extension of thigh at the hip. Medially rotates the thigh at the hip joint and the leg at the knee joint.

Innervation:
Tibial part of the sciatic nerve.

Blood supply:
Perforating branches of femoral and popliteal arteries

Question 24

Tibialis Anterior (anterior compartment of the leg)

Answer 24

Attachments:
Originates from the lateral surface of the tibia and attaches to the medial cuneiform and the base of metatarsal I.

Actions:
Dorsiflexion and inversion of the foot.

Innervation:
Deep fibular nerve.

Blood supply:
Branches of anterior tibial artery: Anterior and medial muscular branches; anterior tibial recurrent, dorsalis pedis and anterior medial malleolar arteries
Branches of posterior tibial artery: Medial malleolar and calcaneal arteries

Question 25

Extensor Digitorum Longus (anterior compartment of the leg)

Answer 25

Attachments:
Originates from the lateral condyle of the tibia and the medial surface of the fibula.
The fibres converge into a tendon, which travels onto the dorsal surface of the foot.
The tendon splits into four and each tendon inserts onto a toe.

Actions:
Extension of the lateral four toes, and dorsiflexion of the foot.

Innervation:
Deep fibular nerve.

Blood supply:
Anterior tibial, fibular, anterior lateral malleolar, lateral tarsal, metatarsal, plantar, and digital arteries

Question 26

Extensor Hallucis Longus (anterior compartment of the leg)

Answer 26

Attachments:
Originates from the medial surface of the fibular shaft. The tendon crosses anterior to the ankle joint and attaches to the base of the distal phalanx of the great toe.

Action:
Extension of the great toe and dorsiflexion of the foot.

Innervation:
Deep fibular nerve.

Blood supply:
Anterior tibial artery

Question 27

Fibularis Tertius (anterior compartment of the leg)

Answer 27

Attachments:
Originates with the extensor digitorum longus from the medial surface of the fibula. Its tendon descends onto the dorsal surface of the foot and attaches to the fifth metatarsal.

Actions:
Eversion and dorsiflexion of the foot.

Innervation:
Deep fibular nerve.

Blood supply:
Anterior lateral malleolar artery, lateral tarsal artery, metatarsal arteries, lateral plantar artery, digital arteries, arcuate artery, fourth dorsal metatarsal artery

Question 28

Fibularis Longus (lateral compartment of the leg)

Answer 28

Attachments:
The fibularis longus originates from the superior and lateral surface of the fibula and the lateral tibial condyle.
The fibres converge into a tendon, which descends into the foot, posterior to the lateral malleolus.
The tendon crosses under the foot, and attaches to the bones on the medial side, namely the medial cuneiform and base of metatarsal I.

Actions:
Eversion and plantarflexion of the foot. Also supports the lateral and transverse arches of the foot.

Innervation:
Superficial fibular (peroneal) nerve. (L5-S1)

Blood supply:
Fibular artery

Question 29

Fibularis Brevis (lateral compartment of the leg)

Answer 29

Attachments:
Originates from the inferolateral surface of the fibular shaft. The muscle belly forms a tendon, which descends with the fibularis longus into the foot.
It travels posteriorly to the lateral malleolus, passing over the calcaneus and the cuboidal bones.
The tendon then attaches to a tubercle on the 5th metatarsal.

Actions:
Eversion of the foot.

Innervation:
Superficial fibular (peroneal) nerve.

Blood supply:
Anterior tibial artery

Question 30

Gastrocnemius (posterior compartment of the leg- superficial)

Answer 30

Attachments:
The lateral head originates from the lateral femoral condyle. The medial head originates from the medial femoral condyle.
The two heads combine to form a single muscle belly.
Distally, the muscle belly converges with the soleus muscle to form the calcaneal tendon. This inserts onto the calcaneus.

Actions:
Plantarflexion at the ankle joint and flexion at the knee joint.

Innervation:
Tibial nerve.

Blood supply:
lateral and medial sural arteries, which are direct branches of the popliteal artery.

Question 31

Soleus (posterior compartment of the leg- superficial)

Answer 31

Attachments:
Originates from the soleal line of the tibia and proximal fibula. The muscle converges with the fibres of the gastrocnemius to form the calcaneal tendon, which inserts onto the calcaneus.

Actions:
Plantarflexion of the foot at the ankle joint.

Innervation:
Tibial nerve

Blood supply:
Posterior tibial artery

Question 32

Plantaris (posterior compartment of the leg- superficial)

Answer 32

Attachments:
Originates from the lateral supracondylar line of the femur. The fibres condense into a tendon which travels down the leg, between the gastrocnemius and soleus muscles. It blends with the calcaneal tendon and inserts onto the calcaneus.

Actions:
Contributes to plantarflexion at the ankle joint and flexion at the knee joint.

Innervation:
Tibial nerve.

Blood supply:
Superficially: lateral sural and popliteal arteries
Deeply: superior lateral genicular artery

Question 33

Popliteus (posterior compartment of the leg- deep)

Answer 33

Attachments:
Originates from the lateral condyle of the femur and the lateral meniscus of the knee joint. It inserts onto the proximal tibia, immediately above the origin of the soleus muscle.

Actions:
Lateral rotation of the femur relative to the tibia. This ‘unlocks’ the knee joint so that flexion can occur.

Innervation:
Tibial nerve

Blood supply:
Inferior medial and lateral genicular arteries (popliteal artery), posterior tibial recurrent artery, posterior tibial artery, nutrient artery of tibia

Question 34

Flexor Digitorum Longus (posterior compartment of the leg- deep)

Answer 34

Attachments:
Originates from the medial surface of the tibia and attaches to the plantar surfaces of the lateral four digits.

Actions:
Flexion of the lateral four toes.

Innervation:
Tibial nerve (L5, S1, S2)

Blood supply:
Posterior tibial artery

Question 35

Flexor Hallucis Longus (posterior compartment of the leg- deep)

Answer 35

Attachments:
Originates from the posterior surface of the fibula and attaches to the plantar surface of the phalanx of the great toe.

Actions:
Flexion of the great toe.

Innervation:
Tibial nerve

Blood supply:
Posterior tibial artery, fibular artery

Question 36

Tibialis Posterior (posterior compartment of the leg- deep)

Answer 36

Attachments:
Originates from the posterior surface and interosseous membrane of the tibia and fibula. The tendon enters the foot posterior to the medial malleolus and attaches to the plantar surfaces of the medial tarsal bones.

Actions:
Inversion and plantarflexion of the foot. It also contributes to the medial arch of the foot.

Innervation:
Tibial nerve

Blood supply:
Branches of the posterior tibial artery

Question 37

Extensor Digitorum Brevis (dorsal aspect)

Answer 37

Attachments:

Originates from the calcaneus, the interosseous talocalcaneal ligament and the inferior extensor retinaculum. It attaches to proximal phalanx of the great toe and the long extensor tendons of toes 2-4.

Actions:
Aids the extensor digitorum longus in extending the medial four toes at the metatarsophalangeal and interphalangeal joints.

Innervation:
Deep fibular nerve.

Blood supply:
Fibular artery, anterior tibial artery, dorsalis pedis artery

Question 38

Extensor Hallucis Brevis (dorsal aspect)

Answer 38

Attachments:
Originates from the calcaneus, the interosseous talocalcaneal ligament and the inferior extensor retinaculum. It attaches to the base of the proximal phalanx of the great toe.

Actions:
Aids the extensor hallucis longus in extending the great toe at the metatarsophalangeal joint.

Innervation:
Deep fibular nerve.

Blood supply:
Dorsal artery of foot

Question 39

Abductor Hallucis (Plantar aspect-first layer)

Answer 39

Attachments:
Originates from the medial tubercle of the calcaneus, the flexor retinaculum and the plantar aponeurosis. It attaches to the medial base of the proximal phalanx of the great toe.

Actions:
Abducts and flexes the great toe.

Innervation:
Medial plantar nerve.

Blood supply:
Medial plantar and first plantar metatarsal arteries

Question 40

Flexor Digitorum Brevis (Plantar aspect-first layer)

Answer 40

Attachments:
Originates from the medial tubercle of the calcaneus and the plantar aponeurosis. It attaches to the middle phalanges of the lateral four digits.

Actions:
Flexes the lateral four digits at the proximal interphalangeal joints.

Innervation:
Medial plantar nerve (S1-S3)

Blood supply:
Medial and lateral plantar arteries and plantar arch, plantar metatarsal and plantar digital arteries

Question 41

Abductor Digiti Minimi (Plantar aspect-first layer)

Answer 41

Attachments:
Originates from the medial and lateral tubercles of the calcaneus and the plantar aponeurosis. It attaches to the lateral base of the proximal phalanx of the 5th digit.

Actions:
Abducts and flexes the 5th digit.

Innervation:
Lateral plantar nerve.

Blood supply:
Lateral plantar artery

Question 42

Quadratus Plantae (Plantar aspect-second layer)

Answer 42

Attachments:
Originates from the medial and lateral plantar surface of the calcaneus. It attaches to the tendons of flexor digitorum longus.

Actions:
Assists flexor digitorum longus in flexing the lateral four digits.

Innervation:
Lateral plantar nerve.

Blood supply:
Medial plantar artery, lateral plantar artery, deep plantar arterial arch

Question 43

Lumbricals (Plantar aspect-second layer)

Answer 43

Attachments:
Originates from the tendons of flexor digitorum longus. Attaches to the extensor hoods of the lateral four digits.

Actions:
Flexes at the metatarsophalangeal joints, while extending the interphalangeal joints.

Innervation:
The most medial lumbrical is innervated by the medial plantar nerve. The remaining three are innervated by the lateral plantar nerve.

Blood supply:
Lateral plantar artery, plantar metatarsal arteries, dorsal metatarsal arteries, dorsal digital arteries

Question 44

Flexor Hallucis Brevis (Plantar aspect-third layer)

Answer 44

Attachments:
Originates from the plantar surfaces of the cuboid and lateral cuneiforms, and from the tendon of the posterior tibialis tendon. Attaches to the base of the proximal phalanx of the great toe.

Actions:
Flexes the proximal phalanx of the great toe at the metatarsophalangeal joint.

Innervation:
Medial plantar nerve

Blood supply:
First metatarsal artery (plantar arch); superficial branch of the medial plantar artery (posterior tibial artery)

Question 45

Adductor Hallucis (Plantar aspect-third layer)

Answer 45

Attachments:
The oblique head originates from the bases of the 2nd, 3rd and 4th metatarsals. The transverse head originates from the plantar ligaments of the metatarsophalangeal joints. Both heads attach to the lateral base of the proximal phalanx of the great toe.

Actions:
Adduct the great toe. Assists in forming the transverse arch of the foot.

Innervation:
Deep branch of lateral plantar nerve.

Blood supply:
Medial plantar artery, lateral plantar artery, plantar arch, plantar metatarsal arteries

Question 46

Flexor Digiti Minimi Brevis (Plantar aspect-third layer)

Answer 46

Attachments:
Originates from the base of the fifth metatarsal. Attaches to the base of the proximal phalanx of the fifth digit.

Actions:
Flexes the proximal phalanx of the fifth digit.

Innervation:
Superficial branch of lateral plantar nerve (S2-S3)

Blood supply:
Arcuate, lateral tarsal and lateral plantar arteries

Question 47

Plantar Interossei (Plantar aspect-fourth layer)

Answer 47

Attachments:
Originates from the medial side of metatarsals three to five. Attaches to the medial sides of the phalanges of digits three to five.

Actions:
Adduct digits three to five and flex the metatarsophalangeal joints.

Innervation:
Lateral plantar nerve.

Blood supply:
Lateral plantar artery

Question 48

Dorsal Interossei (Plantar aspect-fourth layer)

Answer 48

Attachments:
Originates from the sides of metatarsals one to five. The first muscle attaches to the medial side of the proximal phalanx of the second digit. The second to fourth interossei attach to the lateral sides of the proximal phalanxes of digits two to four.

Actions:
Abduct digits two to four and flex the metatarsophalangeal joints.

Innervation:
Lateral plantar nerve.

Blood supply:
Arcuate artery, dorsal and plantar metatarsal arteries