Muscles: Lower Limbs

Question 1

What do our gluteus muscles do and what innervates them?

Answer 1

• Gluteus Maximus - Inferior gluteal nerve - Extends the thigh
• Gluteus medius and minimus - Superior gluteal nerve. These guys medially rotate and abduct the thigh

Question 2

What muscles are covered by the gluteus maximus and what do they do?

Answer 2

These guys laterally rotate the thigh

• Piriformis
• Obturator Internus
• Gemelli Superior and Inferior
• Quadratus femoris

Question 3

What are these deep muscles to the gluteus maximis innervated by?

Answer 3

• Piriformis - Ventral rami of S1 and S2
• Obturator Internus - Nerve to Obturator internus (L5/S1)
• Gemelli Superior and Inferior - L5 and S1
• Quadratus femoris - Nerve to quadratus femoris (L5/S1)

Question 4

Discuss the anterior compartment of the thigh in regards to function, innervation, and important vessels

Answer 4

Mostly innervated by the femoral nerve, and the femoral artery courses through here.

These guys flex the hip and extend the knee

Question 5

What 5 muscles make up the anterior compartment of the thigh and what do they do?

Answer 5

• Sartorius - Flexes, abducts, and laterally rotates the thigh. Flexes the knee
• Quads - Flex hip. Extend Knee.
• Illiopsoas - Flexes hip. This guy is innervated by the femoral nerve (illiacus), but also the ventral rami of the lumbar nerves (psoas).
• Pectineus - Flexes, adducts, helps medially rotate the thigh
• Tensor Fascia Lata - Innervated by the superior gluteal nerve. This guy flexes, abducts, medially rotates the thigh. Keep knee extended, and eventually becomes the IT band.

Question 6

What are the four quad muscles

Answer 6

Rectus femoris, vastus lateralis/medialis/intermedius

Question 7

Discuss everything about the medial compartment of the thigh

Answer 7

Innervated by the obturator nerve and fed by the obturator artery (nice)

Everything adducts (nice)

5 muscles:
Adductor Longus
Adductor Brevis
Adductor Magnus
Gracilus
Obturator Externus (which also laterally rotates the thigh)

Question 8

What makes up the posterior compartment of the thigh?

Answer 8

It contains the hamstrings, which are extensors of the thigh and flexors of the leg.

Arteries: Profunda femoral artery, inferior gluteal artery, perforating arteries

Muscles: Semitendinosus, semimembranosus, biceps femoris long and short head

Innervation: Sciatic nerve, except for the biceps femoris short head, which gets innervated by the common peroneal/fibular nerve

Question 9

Discuss the anterior compartment of the leg

Answer 9

This compartment, being right at the front of the leg, is involved with ankle dorsiflexors and toe extensors, and is innervated entirely by the deep peroneal/fibular nerve.

Arteries: Anterior tibial vessels

Muscles: Tibialis anterior, extensor hallucis longus, extensor digitorum longus, peroneus tertius

Question 10

Discuss the lateral compartment of the leg

Answer 10

This guy contains the ankle evertors (Peroneus longus and brevis) both innervated by the superficial peroneal/fibular nerve

Question 11

Discuss how we break down the posterior compartment of the leg

Answer 11

Superficial Posterior

• Gastroc, Soleus, Plantaris
• Innervated by the sural nerve
• Arteries: Posterior tibial artery, small/great saphenous veins

Deep Posterior

• Flexor Hallucis Longus, Flexor Digitorum Longus, Tibialis Posterior, Popliteus
• Artery: Peroneal and posterior tibial artery
• Innervated by the tibial nerve

Question 12

What courses directly in front of an posterior to the medial malleolus?

Answer 12

Tom Dick ANd Harry

• Tibialis Posterior Muscle
• Flexor Digitorum Longus Muscle
• Posterior tibial artery and nerve (AN)
• Flexor Hallucis Longus

The great saphenous vein runs anterior to the medial malleolus.

Question 13

Where does the Dorsalis Pedis come from?

Answer 13

The DP comes from the anterior tibial artery

Question 14

What is piriformis syndrome?

Answer 14

The sciatic nerve enters the greater sciatic foramen very closely to the piriformic muscle. Some people who use their gluteal muscles extensively can overdevelop their piriformis, resulting in a pinched nerve and sciatic like symptoms.

Question 15

What causes and what is the Trendelenburg sign?

Answer 15

Occurs following damage to the superior gluteal nerve which feeds the gluteus minimus and intermedius, like with hip dislocations or fractures in the neck of the femur.

Watch the patient’s back while the patient raises each foot off of the ground while standing. If the right pelvis falls while the right foot is coming up, the left superior gluteal nerve is damaged.

Question 16

What muscles insert on the medial tibia via the pes anserinus?

Answer 16

SGT Pes

• Sartorius
• Gracilus
• SemiTendinosus

Question 17

What happens when we damage the femoral triangle and why

Answer 17

May damage the femoral nerve, leading to a weakened ability to flex the thigh (weak iliacus and sartorius) as well as a loss of extension of the thigh (quadriceps femoris muscle).

Question 18

Although needing quite a deep penetration, as with a knife wound, injury to the tibial nerve can occur at the popliteal region. How will we know this has happened?

Answer 18

Loss of flexion of the leg, loss of plantar flexion of the ankle, loss of flexion of the toes and inversion of the foot. There may also be a loss of sensation on the sole of the foot.

Question 19

What is the most common nerve injured in the lower leg and why?

What does this look like in the clinic?

Answer 19

Common fibular/peroneal nerve because it is very superficial around the fibular neck, a common fracture site.

Damage leads to loss of function of muscles in the lateral and anterior compartment, so no foot dorsiflexion or eversion, and no toe extension (known as footdrop).

The patient will develop a high stepping gait to compensate.

Question 20

What courses behind the lateral maleolus?

Answer 20

Peroneus longus and brevis muscles as well as the small saphenous vein

Question 21

What structures pass through the diaphragm and at what levels?

Answer 21

I 8 10 EGGs AT 12

• IVC at T8
• T10: Esophagus and Vagus
• Aorta/Azygous and Thoracic Duct at T12

Question 22

What makes the phrenic nerve?

Answer 22

C3, C4, C5 keep the diaphragm alive!

So when the diaphragm gets irritated, you’ll feel shoulder irritation.

Question 23

Discuss what the popliteal artery gives off

Answer 23

Popliteal artery splits into the anterior and posterior tibial arteries.

The fibular artery is given off by the posterior tibial artery

The deep branch of the fibular nerve runs with the anterior tibial artery, so if you cut the artery, you may get foot drop due to cutting the nerve as well!

Question 24

Deep branch of the fibular nerve

Answer 24

Innervates the anterior compartment of the lower leg and provides sensation to the first webspace.

Question 25

Superficial branch of the fibular nerve

Answer 25

Innervates the lateral compartment and provides sensation to the lateral leg and dorsum of the foot.

Question 26

These muscles invert the foot

Answer 26

Tibialis Anterior and Posterior

Question 27

These muscles evert the foot

Answer 27

Fibularis longus and brevis

Question 28

Inversion and eversion take place at this joint

Answer 28

Subtalar joint (Talocalcaneal Joint)

Question 29

Femoral nerve covers what?

Answer 29

Sensation of the upper thigh and inner leg as well as the muscles that extend the knee.

Gives off the saphenous nerve which covers sensation of the medial lower leg.

Question 30

Obturator Nerve covers what area?

Answer 30

Medial thigh and the adductors there

Question 31

Sciatic nerve covers what area and becomes what?

Answer 31

Sciatic nerve comes off of L4 - S3 and comes down by the piriformis through the greater sciatic foramen, and down the posterior leg, splitting just before the popliteal fossa into the tibial nerve and common peroneal.

Skin to the sole of the foot is provided by the tibial nerve and the entire lower leg except the medial side is provided by the common, as well as the upper portion of the foot

Question 32

Discuss the tibial nerve

Answer 32

The tibial nerve gives off the sural nerve to innervate the lateral skin of the foot

It gives off the medial and lateral plantar nerves which innervate toes and skin on their sides (lateral is the lateral 1.5 toes like the ulnar nerve for the hand)