Anatomy - Lower Limb Lab Questions

Front 1

What do we mean when we use the term "sciatic nerve"? What nerves actually comprise the "sciatic nerve"? What are their root values?

Back 1

Sciatic Nerve – continuation of main part of sacral plexus (L4-S3)
Divides into two main branches in the inferior third of the thigh. . .
- Tibial Nerve:
- Common Fibular Nerve:

Front 2

What is the innervation of the gluteus maximus m? The g. medius and g. minimus mm?

Back 2

Together they are mainly extensors, abductors and medial rotators of the thigh.
Gluteus maximus
Innervation: Inferior gluteal nerve (L5,S1-S2)
Action: extends thigh and assists in its lateral rotation; Steadies thigh and assists in rising from sitting position

Gluteus medius/Gluteus minimus
Innervation: Superior gluteal nerve (L5 and S1)
Action: Abduct and medially rotate thigh; keeps pelvis level when opposite leg is raised

Front 3

What is the importance of the location of the piriformis muscle? What structures emerge superior to it? Inferior to it?

Back 3

The piriformis serves as a landmark muscle in the gluteal region. Superior to it are the superior gluteal artery and nerve. Inferior to it are the inferior gluteal artery and nerve, pudendal artery and nerve.

Front 4

What are the three large thigh compartments? What nerves innervate these compartments? What are their root values?

Back 4

Anterior – hip flexors and knee extensors – Femoral n. (L2-L4)
Medial – adductors – Obturator n. (L2-L4)
Posterior – extensors of thigh and flexors of leg – Tibial and Common Fibular divisions of Sciatic N. (L5-S2)

Front 5

What is the function(s) of the anterior (antero-lateral) compartment of muscles? What muscle largely comprises this group? What is it's innervation?

Back 5

Anterior Compartment – hip flexors and knee extensors
Pectineus Femoral n (L2-L3)
Iliopsoas
Psoas major Ant. Rami of Lumbar nn. (L1-L3)
Iliacus Femoral n. (L2-L3)
Tensor of Fascia Lata Superior Gluteal n. (L4-L5)
Sartorius Femoral n. (L2-L3)
Quadriceps femoris Femoral n. (L2-L4)
Rectus femoris
Vastus femoris
Vastus medialis
Vastus intermedius

Front 6

What is the function(s) of the muscles of the medial compartment? What muscles comprise this group? What are their innervations?

Back 6

Medial Compartment – Adductors of thigh
Adductor longus Obturator n. (L2-L4)
Adductor brevis Obturator n. (L2-L4)
Adductor magnus
Adductor part Obturator n. (L2-L4)
Hamstring part Tibial part of Sciatic n (L4)
Gracilis Obturator n. (L2-L3)
Obturator externus Obturator n. (L3-L4)

Front 7

What is the femoral sheath? Where is it located? What is found in the sheath; what lies outside it?

Back 7

Femoral Sheath
- funnel shaped, fascial tube made of inferior prolongation of transversalis and iliopsoas fascia of the abdomen deep to the inguinal ligament
- allows contents to pass deep to the inguinal ligament during movement of hip joint
- Three compartments
• Lateral – femoral artery
• Intermediate – femoral vein
• Medial – femoral canal (allows for expansion of femoral vein; main pathway for lymphatics from lower limb to abdomen; contains connective tissue, fat and sometimes a deep inguinal lymph node)
- extends from 3-4 cm inferior to inguinal ligament and enclosing proximal parts of femoral vessels and femoral canal
- **does NOT enclose femoral nerve

Front 8

Why is the sciatic "nerve" not a single nerve?

Back 8

The sciatic “nerve” is not a single nerve but rather a continuation of the main part of the sacral plexus. It is the tibial nerve and common peroneal nerve running in a common sheath. However, they are always separate. In the inferior third of the thigh, the sciatic “nerve” “divides” to become the tibial nerve (L4-S3) and the common peroneal nerve (L4-S2).

Front 9

What is the only muscle innervated directly by the common peroneal nerve? What is the function of this muscle?

Back 9

Short head of biceps femoris – knee flexor

Front 10

What is the function of the popliteus muscle? What is its innervation?

Back 10

Popliteus – Tibial nerve (L4-S1) – weakly flexes knee and unlocks it

Front 11

How many crural compartments are there? What muscle groups are in each? What nerves supply these groups?

Back 11

Anterior Compartment (Extensors)
- dorsiflexors of ankle/extensors of toes
- Deep Peroneal n. (L4-S1)

Posterior Compartment (Flexors)
- Superficial: plantarflexors of ankle; flexors of knee)
- Deep: weak knee flexors; flexors of toes; plantarflexors of ankle
- Tibial nerve (L4-S3)

Lateral Compartment
- Evert foot and weakly plantarflex ankle
- Superficial peroneal n. (L5-S2)

Front 12

What nerve carries sensation from the posterior skin of the leg? From the dorsum of the foot? From the plantar surface of the foot?

Back 12

See sensory diagram in study guide
Sural n. (division of Tibial n.): skin of lateral and posterior part of inferior 1/3 of leg
Posterior femoral cutaneous n. (S1-S3): skin of upper part of back of leg
Saphenous nerve: medial and posterior part of leg

See p. 375 for complete cutaneous innervation of foot
Superficial and deep peroneal nn.: dorsum of foot
Medial and lateral plantar nn. (divisions of Tibial n.): sole of foot

Front 13

What is the function of the patella? The medial malleolus? The lateral malleolus?

Back 13

Patella – slides along axis of movement during knee flexion/extension; serves as “wheel of pulley”
Lateral malleolus – helps hold talus in socket (i.e. articulates with lateral surface of talus)
Medial malleolus - helps hold talus in socket (i.e. articulates with medial surface of talus)

*Malleoli grip talus tightly as it rocks anteriorly and posteriorly in the mortise (deep socket) during movements of the ankle joint

Front 14

What type of joints are the proximal, middle and distal tibiofibular joints?

Back 14

Proximal tibiofibular joint
- plane type synovial joint b/w fibular head and lateral tibial condyle
Middle tibiofibular joint
- interosseous membrane
Distal tibiofibular joint
- syndesmosis (fibrous joint)

Front 15

Trace the course of the femoral artery as it continues as the popliteal artery and then to its crural and pedal branches.

Back 15

The femoral artery (Figs. 549, 550) begins immediately behind the inguinal ligament, midway between the anterior superior spine of the ilium and the symphysis pubis, and passes down the front and medial side of the thigh. It ends at the junction of the middle with the lower third of the thigh, where it passes through an opening in the Adductor magnus to become the popliteal artery. The vessel, at the upper part of the thigh, lies in front of the hip-joint; in the lower part of its course it lies to the medial side of the body of the femur, and between these two parts, where it crosses the angle between the head and body, the vessel is some distance from the bone. The first 4 cm. of the vessel is enclosed, together with the femoral vein, in a fibrous sheath—the femoral sheath. In the upper third of the thigh the femoral artery is contained in the femoral triangle (Scarpa’s triangle), and in the middle third of the thigh, in the adductor canal (Hunter’s canal).

Front 16

How many tarsal bones are there? What are their names?

Back 16

Seven tarsal bones:

Calcaneous
Talus
Cuboid
Navicular
3 Cuneiform (Lateral, Intermediate, Medial)

Front 17

What is a sesamoid bone? Where in the lower extremity are they found (hint: there is more than one)?

Back 17

Sesamoid Bone: bone encased in a tendon where tendons cross ends of long bones in limbs; protect tendon from excessive wear and change angle from which tendons pass to their attachments

Patella (knee)
Medial and Lateral sesamoids lying beneath first metatarsal head

Front 18

Which side of the knee is more susceptible to injury? Why?

Back 18

The medial side of the knee is more susceptible to injury. Since the lateral side is more exposed to contact, this contact stresses the ligaments on the medial side causing injury

Front 19

What is the function of the popliteus muscle? What innervates it?

Back 19

Popliteus – Tibial nerve (L4-S1) – weakly flexes knee and unlocks it

Front 20

The popliteus tendon serves an important "secondary" function. What is this?

Back 20

Popliteus – Tibial nerve (L4-S1) – weakly flexes knee and unlocks it

Front 21

What is the popliteal fossa? What major artery can be found there? What vessel is it a branch of, and what will it give rise to

Back 21

Popliteal fossa – diamond shaped space posterior to the knee; all important vessels and nerves from thigh to leg pass through here
- Contents:
Small saphenous v.
Popliteal a. and v. (and genicular branches)
Tibial and common fibular nn.
Posterior cutaneous n. of thigh
Popliteal lymph nodes and lymphatic vessels
- Popliteal a. is continuation of femoral a. at adductor hiatus in adductor magnus
- Popliteal a. gives rise to. . .(basically every artery in leg)
- inferior medial (and lateral) genicular a.
- middle genicular a.
- sural aa.
- anterior (and posterior) tibial a.
- Peroneal a.

Front 22

What does the suprapatellar bursa communicate with? Why would inflammation of this bursa be particularly dangerous?

Back 22

Suprapatellar bursa communicates with synovial capsule of knee. Therefore, inflammation of this bursa can create inflammation in joint capsule – BIG PROBLEM!

Front 23

Review what is meant by "Tarsal tunnel" syndrome. What structures run in the tarsal tunnel?

Back 23

Tarsal tunnel syndrome refers to compression of the posterior tibial nerve in the tarsal tunnel.

The flexor retinaculum constitutes the roof of the tarsal tunnel and is formed by the deep fascia of the leg and the deep transverse fascia. The proximal and inferior borders of the tunnel are formed by inferior and superior margins of the flexor retinaculum . The floor of the tunnel is formed by the superior aspect of the calcaneus, the medial wall of the talus, and the distal-medial aspect of the tibia. The remaining fibro-osseus canal is termed the Richet’s or the tibiocalcaneal tunnel. The tendons of the flexor hallucis longus muscle, flexor digitorum longus muscle, tibialis posterior muscle, the posterior tibial nerve and the posterior tibial artery pass through the tarsal tunnel

Front 24

Review the plantar-calcaneo-navicular (a.k.a., "Spring") ligament. If you have not seen it in laboratory, make sure that you are familiar with where it is and what it does.

Back 24

Plantar-Calcaneonavicular “Spring” ligament – extends from talar shelf to the posteroinferior surface of the navicular. Plays an important role in maintaining the longitudinal arch of the foot and in bearing weight transferred from the talar head.

Front 25

Which action - inversion of the foot or eversion of the foot is "easier to lose"? Why?

Back 25

Eversion of foot (Lateral compartment)
• Peroneus longus+brevis
o The tendons of these two muscles run around the lateral malleolus and use it as a pulley.
o The longus is larger, superficial, and its muscle mass more superior

Inversion of Foot
• Tibialis Ant+Posterior
• This motion is harder to lose since these 2 muscles are by 2 separate nerves.