Week 2: Lower Limbs and Glutes

Question 1

Where is the gluteal region and what is it’s significance?

Answer 1

The gluteal region is between the iliac crest and the bottom border of the buttock

Important nerves pass from the pelvis to the gluteal region and lower extremity

Question 2

What are the main muscles (superficial and deep) of the gluteal region?

Answer 2

Superficial: gluteus maximus, gluteus medius, gluteus minimus

Deep: piriformis, which performs lateral rotation of the thigh

Question 3

What are the functions of the superficial gluteal region muscles?

Answer 3

Gluteus maximus - extensor of thigh from the seated position

Gluteus medius and minimus - deep to gluteus maximus, abduction of hip, secure position of the pelvis when walking

Question 4

What is the main deep muscle of the gluteal region, and what does it do?

Answer 4

The piriformis is a part of the pelvic wall, and divides the greater sciatic foramen where important vessels pass above and below

It is also the lateral rotator of the thigh

Question 5

What are the main nerves of the gluteal region?

Answer 5

The sciatic nerve, a VERY LARGE nerve that passes below the piriformis deep to the gluteus maximus, traveling to the posterior thigh

and

Pudendal nerve, which passes below the piriformis in the greater sciatic foramen and enters the perineum (innervates external genetalia elements)

Question 6

What are the principal nerves of the lumbosacral plexus?

Answer 6

Sciatic

Pudendal

Femoral

Obturator

Question 7

What are the functions of the nerves of the lumbosacral plexus?

Answer 7

Sciatic - innervates posterior leg, thigh and foot, feeds into tibial nerve (posterior leg/foot) and common fibular nerve (anterior/lateral leg/foot)

Pudendal - innervates the perineum and external genitalia (somatic)

Obturator - innervates the medial thigh

Femoral - innervates the anterior thigh

Question 8

What are the three compartments of the thigh, and what are their common actions?

Answer 8

Anterior - extend knee

Medial - abduct thigh

Posterior - flex the knee

Question 9

What are the main regions of the thigh, what muscles are within them, and what nerves are they innervated by?

Answer 9

The anterior compartment contains the sartorius, rectus femoris, and vastus lateralis, intermedius, and medialis (femoral nerve)

The medial compartment contains the gracilis, pectineus, and adductor group of the adductor longus, brevis, and magnus (obturator nerve)

The posterior compartment contains the hamstrings - biceps femoris, semitendinosus, and semimembranosus (sciatic nerve)

Question 10

What are the muscles of the anterior compartment of the thigh and what do they do?

Answer 10

The sartorius flexes the knee and hip, allows for external rotation and abduction (“is there gum on my shoe?” muscle)

The quadriceps contain the rectus femoris, the vastus lateralis, intermedius and medialis. They all insert on the patellar tendon via the quadriceps femoris tendon.

Vastus group extends the knee

Rectus femoris extends knee AND flexes at the hip

Question 11

Which two thigh muscles can act on the hip?

Answer 11

The rectus femoris and sartorius (both go “across” the thigh)

Question 12

What muscles are in the medial compartment of the thigh and what is their function?

Answer 12

The gracilis and adductors (longus, brevis, and magnus) all function to adduct the femur/thigh and help stabilize you when standing. The adductor longus also participates in lateral rotation and flexion of the thigh. The pectineus muscle flexes and adducts the thigh.

Question 13

What is the femoral triangle and what does it contain? How do we remember the organization of these elements from lateral to medial?

Answer 13

It is a bundle of nerves (femoral nerve), vessels (femoral artery and vein), and lymphatics

Lat - NAVeL - Med

Nerve Artery Vein Lymphatics

These structures are continuous inferiorly with the adductor canal, supply the lower limb, and allow passage of the femoral A/V down the medial side of the thigh and to the popliteal fossa

Question 14

What are the major muscles of the hamstring and what is their collective action?

Answer 14

The hamstring contains the:

biceps femoris

semitendinosus

semimembranosus

They all work to flex the knee and extend the hip from the standing position.

Question 15

What muscles insert on the medial side of the knee? What compartment do they come from? What is this structure ultimately called?

Answer 15

The gracilis (medial)

semitendinosus (posterior)

sartorius (anterior) muscles all insert medially

This is called the pes anserinus (literally the “goose’s foot”) and

Question 16

What is the popliteal fossa and what does it contain?

Answer 16

It is the space on the posterior aspect of the knee, and contains the popliteal A/V (continuation of femoral A/V), tibial and common fibular nerves, as well as branches of the sciatic nerve

Question 17

What are the three compartments of the leg and what is the general action of each?

Answer 17

Posterior (plantar flexion, flex toes, invert foot)

Lateral (eversion of foot)

Anterior (dorsiflexion, invert foot, extend toes)

Question 18

What are the superficial and deep muscles of the posterior leg compartment? What are they innervated by?

Answer 18

Superficial: gastrocnemius, soleus

Deep: flexor hallucis longus, flexor digitorum longus, tibialis posterior

All of these are innervated by the tibial nerve

Question 19

What are the muscles of the lateral leg compartment? What are they innervated by?

Answer 19

Fibularis longus and brevis, which are innervated by the common fibular nerve

Question 20

What are the muscles of the anterior leg compartment? What are they innervated by?

Answer 20

The tibialis anterior, extensor hallucis longus, and extensor digitorum longus are all innervated by the common fibular nerve

Question 21

What are the superficial muscles of the posterior leg compartment and where do they insert?

Answer 21

The gastrocnemius and soleus muscles enact plantarflexion (both) of the foot, and flex the knee (gastrocnem.)

They both insert via the calcaneal tendon onto the calcaneus bone (heel)

Question 22

What are the deep muscles of the posterior compartment of the leg? What actions are they involved in?

Answer 22

The tibialis posterior is involved in inversion and plantarflexion (weak, acts on ankle)

and the flexor digitorum longus and hallucis longus allow for flexion of toes (tendons extend through plantar surface to the phalanges)

Question 23

What are the muscles of the anterior compartment of the leg, and what actions are they involved in?

Answer 23

The tiabilis anterior attaches to the medial food and is involved in dorsiflexion and inversion of the foot

The extensor digitorum longus and hallucis longus are involved in dorsiflexion and extension of the toes

Question 24

What are the muscles of the lateral leg compartment and what movement are they involved in?

Answer 24

The fibularis longus and brevis are involved in eversion of the ankle

Question 25

How does damage to the common fibular nerve affect one's walking gait?

Answer 25

**Damage to the common fibular nerve** can **prevent** the **anterior compartment muscles** **from acting correctly (dorsiflexion)**. This means you can't "pick your toes up" when walking (foot drop), and need to compensate in one of several depicted ways.

Question 26

What are the main characteristics of the foot?

Answer 26

**Intrinsic** (bellies of muscles within foot) and **extrinsic** muscle control Innervation from **tibial (mostly)** and **common fibular nerve** **(lesser)** branches Supplied with blood from the **arterial arch** and **posterior tibial artery** Contains the **tarsal tunnel,** an area formed by the **tarsal bone** and a piece of CT called the **flexor retinaculum,** through which the **posterior tibial artery** and **tibial nerve** pass