Lower Extremity Anatomy

Question 1

Piriformis

Answer 1

O: Anterior Surface of Sacrum

Ins: Superior Border of Greater Trochanter

Inn: Nerve to piriformis (S1-S2)

Question 2

Levator Ani

Answer 2

O: Inner surface of the side of the lesser pelvis

Ins: Inner surface of coccyx, levator ani of opposite side, and into structures that penetrate it.

Inn:

pubococcygeus and iliococcygeus:

levator ani nerve (S4)

inferior rectal nerve from pudendal nerve (S3, S4)

coccygeal plexus

Question 3

Glute Medius

Answer 3

Origin: Gluteal/Superior Lateral Surface of Ilium

Ins: Greater Trochanter

Inn: Superior Gluteal Nerve (L4-S1)

Question 4

Gluteus Maximus

Answer 4

O: Lateroposterior surface of sacrum and coccyx, gluteal surface of ilium (behind posterior gluteal line), thoracolumbar fascia, Sacrotuberous ligament

Ins: Iliotibial tract, gluteal tuberosity of femur

Inn: Inferior Gluteal Nerve L5-S2

Question 5

Semitendinosus

Answer 5

O: Posteromedial Ischial tuberosity

Ins: Proximal end of tibia below medial condyle (via pes anserinus)

Inn: Tibial division of sciatic nerve (L5-S2)

Question 6

Semimembranosus

Answer 6

Origin: Superolateral impression of ischial tuberosity

Insertion: Medial condyle of tibia

Innervation: Tibial division of sciatic nerve (L5 – S2)

Question 7

Biceps Femoris

Answer 7

Origin

Long head: (inferomedial impression of) ischial tuberosity, sacrotuberous ligament

Short head: linea aspera of femur (lateral lip), lateral supracondylar line of femur

Insertion: (Lateral aspect of) head of fibula

Innervation Long head: tibial division of sciatic nerve (L5-S2)
Short head: common fibular division of sciatic nerve (L5-S2)

Question 8

Gracilis

Answer 8

Origin: Anterior body of pubis, inferior pubic ramus, ischial ramus

Insertion: Medial surface of proximal tibia (via pes anserinus)

Innervation: Obturator nerve (L2-L3)

Question 9

Iliopsoas

Answer 9

Origin: Iliac fossa, Vertebral bodies of T12-L4, intervertebral discs between T12-L4, transverse processes of L1-L5 vertebrae

Insertion: Lesser trochanter of femur,

Lesser trochanter of femur as iliopsoas tendon

Innervation

Iliacus: femoral nerve (L2-L4)
Psoas major: anterior rami of spinal nerves (L1-L3)

Question 10

Quadriceps

Answer 10

OriginsRectus femoris: Anterior inferior iliac spine, supraacetabular groove
Vastus medialis: Intertrochanteric line, pectineal line of femur, linea aspera, medial supracondylar line of femur
Vastus lateralis: Intertrochanteric line, greater trochanter, gluteal tuberosity, linea aspera of femur
Vastus intermedius: Anterior surface of femoral shaft

InsertionsRectus femoris and vastus intermedius: Tibial tuberosity (via patellar ligament), patella
Vastus lateralis: Tibial tuberosity (via patellar ligament), patella, (lateral condyle of tibia)
Vastus medialis: Tibial tuberosity (via patellar ligament), patella, (medial condyle of tibia)

InnervationFemoral nerve (L2-L4)

Question 11

Soleus

Answer 11

Origin: Soleal line, medial border of tibia, head of fibula, posterior border of fibula

Insertion: Posterior surface of calcaneus (via calcaneal tendon)

Innervation: Tibial nerve (S1, S2)

Question 12

Gastrocnemius

Answer 12

Origin

Lateral head: Posterolateral aspect of lateral condyle of the femur
Medial head: Posterior surface of medial femoral condyle, popliteal surface of femoral shaft

Insertion: Posterior surface of the calcaneus via the calcaneal tendon

Innervation: Tibial nerve (S1, S2)

Question 13

Anterior Tibialis

Answer 13

O:

Lateral condyle and upper half or two-thirds of the lateral surface of the body of the tibia

Adjoining part of the interosseous membrane

Deep surface of the fascia

Intermuscular septum between it and the Extensor digitorum longus.

Ins:

Medial and under surface of the first cuneiform bone, and the base of the first metatarsal bone.

Inn:

Deep Pereonal Nerve (L4, L5, S1)

Question 14

Posterior Tibialis

Answer 14

Origin:

Proximal postero-lateral aspect of the tibia.

Proximal postero-medial aspect of the fibula and the interosseous membrane

Mid portion: Situated in the deep posterior compartment of the lower leg and runs proximal to the medial malleoli where it is secured by the flexor retinaculum.

Insertion

The major insertion is onto the navicular and the plantar slip attaches to the medial cuneiform

Nerve

Tibial Nerve (L4-S3)

Question 15

Peroneus Longus

Answer 15

Origin:

Head of fibula, proximal 2/3 of lateral surface of fibula, intermuscular septa

Insertion:

Medial cuneiform bone, metatarsal bone 1

Innervation:

Superficial fibular nerve (L5, S1)

Question 16

Peroneus Tertius

Answer 16

Origin: Medial surface (distal third) of fibula, interosseous membrane (anterior surface), anterior intermuscular septum

Insertion: Dorsal surface of base of metatarsal bone 5

Innervation: Deep fibular nerve (L5, S1)

Question 17

Peroneus Brevus

Answer 17

Origin: Distal 2/3 of the lateral surface of fibula, anterior inermuscular septum

Insertion: Tuberosity of the 5th metatarsal bone

Innervation: Superficial fibular nerve (L5, S1)

Question 18

Flexor Hallucis Longus

Answer 18

Origin: (Distal 2/3 of) Posterior surface of fibula, interosseous membrane, posterior intermuscular septum of leg, fascia of tibialis posterior muscle

Insertion: Base of distal phalanx of great toe

Innervation: Tibial nerve (S2, S3)