MSK: lower limb

Question 1

At what level does the aorta bifurcate into the left and right common iliac arteries?

Answer 1

L4

Question 2

What are the boundaries of the femoral triangle? What is found within this triangle?

Answer 2

(1. ) Superior = inguinal ligament
(2. ) Medial = adductor longus
(3. ) Lateral = sartorius
(4. ) Floor = iliopsoas + pectineus

• Femoral vessels and nerves are found within the femoral triangle
• Great saphenous v. joins the femoral vein here

Question 3

Where would you feel the femoral pulse?

Answer 3

It can be palpated at the mid-inguinal ligament. This is midway between the ASIS and pubic tubercle

Question 4

Describe how we get the popliteal artery from the abdominal aorta

Answer 4

(1. ) AA bifurcates into the right and left common iliac arteries at L4
(2. ) These divide into external and internal iliac arteries
(3. ) The external iliac a continues to becomes the femoral a
(4. ) The femoral artery passes the hiatus (of the adductor magnus) to become the popliteal artery which goes on to enter the popliteal fossa.

Question 5

What makes up the anterior compartment of the thigh and what innervates it? and their function?

Answer 5

(1. ) Pectineus
(2. ) Iliopsoas = made up of the psoas major and iliacus
(3. ) Sartorius = ASIS (origin) -> tibia (insert)
(4. ) Quadriceps = rectus femorus, vastus lateralis, vastus medialis, vastus intermedius

(5. ) Femoral nerve (except for psoas major)
(6. ) Flex hip and extend knee

Question 6

What makes the medial compartment of the thigh and what innervates these? and their function?

Answer 6

(1. ) Adductor longus
(2. ) Adductor brevis
(3. ) Adductor magnus (adductor component)
(4. ) Gracile
(5. ) Obturator externus

(6. ) Obturator N.
(7. ) Adduct

Question 7

What roots make up femoral and obturator nerve?

Answer 7

L2, 3, 4

Question 8

How is lateral dislocation of the patellar prevented?

Answer 8

1. Contraction of the quadricep causes the patellar to move laterally
2. The lateral movement is counteracted by the following:
   - V.medialis fibres causes medial movement of the patellar
   - Lateral femoral condyl is larger than the medial which limits the movement of the patellar to the lateral side

Question 9

Quadricep: origin (3), insertion (3) and action (2)

Answer 9

(1. ) Origin
- Rectus femoris = AIIS + acetabulum.
- Other quadriceps = femur

(2. ) Insertion
- Tibial tuberosity = via patellar ligament that is a continuation of the quadricep tendon that comprises of all 4 quadriceps tendons
- V.laterallis and v.medialis also attaches to the the patellar independently via aponeurosis (patellar reticular)

(3.) Function = they all extend the knee and the rectus femoris also flexes the hip.

Question 10

Common site of origin for the medial thigh compartment

Answer 10

Inferior ramus of pubis

Question 11

Adductor magnus: innervation, origin, function

Answer 11

It is made up of a ‘hamstring’ and ‘adductor’ part

• Innervated by both obturator and sciatica n.
• Takes origin from the inferior pubic ramus and ischial tuberosity
• Forms the hiatus where the femoral vessels pass through
• powerful adductors, involved in medial rotation of thigh and extends the hip

Question 12

What passes through the greater sciatic foramen?

Answer 12

(1. ) Piriformis
(2. ) Superior and inferior gluteal arteries, veins, nerves
(3. ) Sciatica
(4. ) Pudendal nerve

Question 13

How is the greater + lesser sciatic foramen formed?

Answer 13

(1. ) Greater and lesser sciatic foramina are two openings in the posterior aspect of the pelvis.
(2. ) They are enclosed within the greater sciatic notch and sacrotuberous ligament
(3. ) Greater sciatic foramen is separated from the lesser sciatic foramen by the sacrospinous ligament.

Question 14

Gluteal muscles: muscles, origin, action, innervation?

Answer 14

Muscles + action

• G.Maximus = lateral rotation + hip extension
• G.Medius + G.Minimus = medial rotation + abduct hip

Origin + insertion of G.Maxiumus

• Ilium, sacrum, sacro-tuberous ligament (origin)
• Iliotibial tract (insert)

Innervation

• G.Max = Inferior gluteal n.
• G.Med and Min = superior gluteal n.

Question 15

Why must you give IM injections into the upper outer quadrant of the buttock?

Answer 15

(1. ) The left sciatic is found in the lower inner quadrant so avoid injury to this
(2. ) Gluteus maximus layer here and deep to this are the g.medius and minimus.

Question 16

Posterior thigh/hamstrings: muscles, origin, actions, innervation?

Answer 16

Muscles

• Long and short head of bicep femoris
• Semi-tendinous
• Semi-membranous
• Adductor Magnus

Origin
- Ischial tuberosity

Action
- extend hip + flex knee

Innervation

• Sciatic (tibial branch) except for short head of bicep femoris
• Peroneal N innervates the short head of bicep femoris

Question 17

How do you feel for the popliteal artery pulse?

Answer 17

(1. ) Place person in prone position with knee flexed

(2. ) Pulse can be felt in inferior aspect of the popliteal fossa.

Question 18

What would we see with superior gluteal nerve injury?

Answer 18

(1. ) Superior gluteal nerve supplies the G.Medius and minimus which are important for abduction and medial rotation of hip. These muscles are important for keeping the pelvis in an horizontal position when raising the contralateral leg
(2. ) Injury to this nerve may arise after hip surgery + can be detected with trendelenburg test
(3. ) This is where ‘waddling’ or ‘gluteal gait’ would be seen as the pelvis is not stable and walking is difficult due to impaired abductors

Question 19

Anterior compartment of the leg: 4 muscles? Function? artery? nerve?

Answer 19

(1. ) Tibialis Anterior
(2. ) Extensor hallucis longus
(3. ) Extensor digitorium longus
(4. ) Extensor digitorium brevis

(5. ) Function = dorsiflexion + extensors of hallux and digits. T.anterior inverts foot.
(6. ) Innervation = deep peroneal nerve
(7. ) Blood = Anterior tibial artery

Question 20

Lateral compartment of the leg: 2 muscles? Function? artery? nerve?

Answer 20

(1. ) Peroneus longus
(2. ) Peroneus brevis

(3. ) Function = Evert foot
(4. ) Innervation = Superficial peroneal nerve
(5. ) Blood = Perineal A.

Question 21

Posterior compartment of the leg: superficial (3) and deep (4) muscles? Function? artery? nerve?

Answer 21

Superficial

(1. ) Gastrocmieus
(2. ) Soleus
(3. ) Plantaris

Deep

(1. ) Popliteus
(2. ) Flexor hallucis longus
(3. ) Flexor digitorium longus
(4. ) Tibialis posterior

Function

(1. ) Superficial muscles = plantarflexion (+flex knee by gastrocmieus)
(2. ) Flexors = flex the hallux and digits
(3. ) Tibialis posterior = invert the foot

Blood supply = posterior tibial artery
Innervation = Tibial nerve

Question 22

Describe the nerve supply in the leg

Answer 22

(1. ) Anterior compartment = Deep peroneal n
(2. ) Lateral compartment = Superficial peroneal n
(3. ) Posterior compartment = Tibial N.

Question 23

What are the invertors and evertors of the foot?

Answer 23

(1. ) Invertors = Tibilalis posterior and anterior

(2. ) Evertors = Peroneus brevis and longus

Question 24

What causes dorsiflexion and plantar flexion of the ankle joint

Answer 24

(1. ) Dorsiflexion = Anterior compartment

(2. ) Plantarflexion = Gastrocmieus, soleus

Question 25

Where could the common peroneal nerve be damaged?

Answer 25

(1. ) Fracture to fibular can damage/compress the common peroneal nerve, this can cause a foot drop (i.e. can’t dorsiflex or evort)
(2. ) Superfical peroneal n –> lateral leg –> responsible for evorting foot
(3. ) Deep peroneal nerve –> anterior leg –> responsible for dorsiflexion

Question 26

Where can you feel for pulses in the leg?

Answer 26

(1. ) Popliteal artery = popliteal fossa when knee is flexed
(2. ) Anterior tibial A. aka dorsal pedi = between 1st and 2nd metatarsal
(3. ) Posterior tibial A. = Posterior to medial malleolus

Question 27

Where do bones get their blood supply? Why are compound fractures more common in tibia + why may tibial fractures take a long time to heal?

Answer 27

(1. ) Bone recive the blood from muscles overlying it
(2. ) There are more muscles attactched to the fibula than the tibia and therefore the tibia has poor blood supply so will take a long time to heal
(3. ) Compound fractures are more common in tibia due to the bone being superficial and in contact with the skin as there is no soft tissue overlying it.

Question 28

What is makes up the popliteal fossa? Content?

Answer 28

Diamond shape fossa posterior to the knee joint. Boundaries:

• Superior laterally = bicep femoris
• Medial = semitendinous and semimembranosus
• Inferior = gastrocnemius

Content

• Popliteal vessels
• tibial nerves
• lymphatics
• termination of small saphenous vein

Question 29

Nerve roots and branches of the sciatica? what does it innervate?

Answer 29

(1. ) L5, S1-4
(2. ) Sciatica runs through the medial and lateral groups of the hamstring
(3. ) Divides into the tibial and common peroneal nerve
(4. ) Tibial N runs into the popliteal fossa
(5. ) Common peroneal N runs lateral to popliteal fossa with the bicep femoris

(6.) It innervates the posterior thigh and below knee (anterior and posterior leg).