Proximal Neurovasculature - Knee & Leg Flashcards Preview

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Flashcards in Proximal Neurovasculature - Knee & Leg Deck (49)
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1
Q

Where is the lumbar plexus and what does it innervate?

A

Appears from the psoas major and supplies the anterior and medial thigh muscles

2
Q

What are the branches of the lumbar plexus?

A
  1. Subcostal (T12)
  2. Iliohypogastric (L1)
  3. Ilioinguinal (L1)
  4. LFCN (L2-3)
  5. Femoral (L2-4)
  6. Genitofemoral (L1-2)
  7. Obturator (L2-4)
  8. Lumbosacral trunk (L4-5)
3
Q

Where does the lateral femoral cutaneous nerve (LFCN) and what problems can this cause?

A

It enters the anterior thigh close to the ASIS under the inguinal ligament and emerges superficial of the sartorius where it can get compressed by trousers, underwear, or belts causing sensory numbness, tingling or burning sensations called meralgia paresthetica (Calvin Klein syndrome)

4
Q

What is contained within the femoral artery?

A
From lateral to medial:
Nerve 
Artery
Vein
Lymphatics
5
Q

How can you find the femoral artery and vein?

A

Artery: enters midinguinal point (half way point between ASIS and pubic symphysis) and you will feel it pulsate

Vein: ~1cm medial to this

6
Q

Where do the femoral vessels and saphenous nerve go after passing through the femoral triangle?

A

Enter the subsartorial/adductor canal, the adductor hiatus and then pass into the popliteal fossa

7
Q

What is the main blood supply (arteries and veins) to the lower limb?

A
  1. Common illiac splits off into external + internal illiac
  2. Internal illiac supplies pelvic + gluteal region
  3. External illiac splits off into circumflex femoral, deep femoral (profundal femoris) + femoral artery
    - Circumflex femoral supplies to hip + proximal femur
    - Deep femoral supplies hip, thigh + femur
    - Femoral supplies thigh, leg and foot
8
Q

What might a pelvic ring fracture damage?

A

Arteries in this region as they lie in close proximity to bone and sacroiliac joints - if internal illiac got damaged the patient would have little time to live

9
Q

What would happen if the femoral artery is damaged?

A

This vessel is large and superficial and if lacerated, can result in death in minutes

10
Q

At what point does the external illiac artery become the femoral artery?

A

Once it goes underneath the inguinal ligament

11
Q

What is the adductor canal?

A

A canal that contains the superficial femoral artery, femoral vein and saphenous nerve running deep to the sartorius down the middle 1/3rd of the medal thigh to the adductor hiatus:

  • Femoral artery and vein then pass deep and posterior to enter popliteal fossa
  • Saphenous nerve innervates the knee and skin of medial leg + foot
12
Q

What is a fasciotomy incision?

A

An emergency intervention which involves incision of the skin, subcutaneous tissue and fascia of limb compartments to relieve raised pressure and prevent vessel and nerve damage so that there is no limb hypoxia or loss of limbs

13
Q

Where are the superficial inguinal lymph nodes?

A

Horizontal group: run below inguinal ligament

Vertical group: follow proximal part of great saphenous vein

14
Q

Where are the deep inguinal lymph nodes?

A

In femoral canal and medial to femoral vein e.g Cloquet’s node (can get bigger in certain conditions and metastatic cancers of the areas drained by these lymph nodes)

15
Q

What areas do the inguinal lymph nodes drain?

A
Lower limb
Perineal region
Penis
Lower anal canal
Lower vagina
Anterior labia majora/scrotal skin
16
Q

What is a saphena varix?

A

Varicose veins in/around the groin area of the great saphenous cutaneous vein which is noticeable as it is running superficially up to meet the femoral vein

17
Q

What attaches at the tibial tuberosity?

A

The patella tendon which attaches the quadriceps muscle group

18
Q

What can the fibula shaft be used for?

A

A useful ‘spare part’ as it is not needed therefore, if a patient needs reconstruction of the mandible of the face for example, the medial part of this bone can be put there with very little morbidity following

19
Q

Where do the saphenous veins run?

A

Short: posteriorly of lateral malleolus (runs with sural n.)
Long: anteriorly of medial malleolus (runs with saphenous n.)

20
Q

What is the interosseous membrane?

A

Fibrous joint (syndesmosis) between bones and muscle attachment point

21
Q

What can happen to lateral malleolus following excess inversion?

A

Avulsion fracture

22
Q

What are the leg compartments below the knee? What is there function, innervation and blood supply?

A
  1. Anterior: foot and digit dorsiflexors + invertors - TA, EDL + EHL innervated by deep fibular n. (L4-S1) + supplied by anterior tibial artery
  2. Lateral: primary foot evertors + weak plantarflexors - FL + FB innervated by superficial fibular n. (L5-S1) + supplied by fibular artery
  3. Posterior: foot and digit plantarflexors + invertors - TP, FDL, FHL, soleus + gastrocnemius innervated by tibial n. (L4-S2) + supplied by posterior tibial artery
23
Q

What is the difference between plantarflexion and dorsiflexion of the ankle? What muscles allow them to happen?

A

Plantarflexion: allows you to go onto tiptoes - gastrocnemius soleus, fibularis longus + brevis and flexor digitorum + hallucis longus

Dorsiflexion: lifts foot up to ceiling rather - extensor digitorum + hallucis longus

24
Q

If a patients dorsiflexors were damaged, what would you notice?

A

If hips were intact: high stepping gait with toe stepping

If hips were not intact: circumduction gait

25
Q

What are the 3 articulations of the patella (knee)?

A
  1. Femero-patellar: femoral condyle (medial + lateral parts)
  2. Femero-tibia (x2):
    - Tibial condyle (medial + lateral parts)
    - Intercondylar eminence
26
Q

What supports the knee joint?

A

Muscles
Ligaments
Menisci

27
Q

What are menisci?

A

Crescent-shaped pieces of fibrocartilage sat on the tibial condyles (lateral + medial) that function to:

  • Increase contact area
  • Weight-bear
  • Act as shock absorbers
  • Participate in locking mechanism
28
Q

How can the knee menisci become injured?

A
  • Compression via rotation
  • Medial collateral ligament tears

W/O them patients develop OA within a few years due to excessive wear and tear

29
Q

What is the patella?

A

Sesamoid bone that articulates with the femoral condyles and functions to:

  • Reduce ligament + tendon wear
  • Spread forces passing to femoral condyles
  • Increase movement (mechanical bending force) of quadriceps muscles
30
Q

What are the cruciate (crossing) ligaments?

A

Function to resist translocation and rotation of the knee:

  • PCL: prevent posterior tibial movement on femur
  • ACL: prevent anterior tibial movement on femur
31
Q

How can you examine the cruciate (crossing) ligaments?

A
  1. Drawer test: 90 degree flexion

2. Lachman: 20 degree flexion (most sensitive for ACL damage as it reduces false -ves associated with hamstring tension)

32
Q

What are the medial and lateral collateral ligaments of the knee?

A

Ligaments that resist valgus and varus forces at the knee:

  • MCL (tibial) is attached to medial meniscus (both can be damaged together) and prevents tibial abduction (vagus)
  • LCL (fibula) prevents tibial adduction (varus)
33
Q

Why do tibial or femoral fractures not normally result in avascular bone necrosis?

A

The blood supply to the knee is extensive, bi-directional and anastomotic and also, because the popliteal artery passes posterior to the knee so will probably not be affected by these injuries

34
Q

What types of problems can occur with the knee bursa?

A
  1. Prepatellar bursitis (Housemaid’s knee)
  2. Infrapatellar bursitis (Clergyman’s knee)

Which can come:
3. Suprapatellar bursitis: where inflammation/effusion moves up from knee joint cavity

35
Q

How should you test the knee’s bursa?

A

Patella tap: milk suprapatellar bursa inferiorly and then press the patella posteriorly - ‘tap’ sensation will be felt if excess fluid (effusion) is present where the patella is hitting the femur

36
Q

What does full extension of the knee lead to? How is this reversed?

A

Close packing of the joint when the femur rotates medially on the tibia and ‘locks’ (passive movement) so ligaments are under tension = position of stability (why we can stand-up for long periods of time w/o quads tiring)

Popliteus muscle unlocks this by lateral rotation innervated by the tibial n. (L5-S1)

37
Q

What is the difference between foot inversion and eversion? What muscles allow them to happen?

A

Inversion: outside of foot on ground whilst inside is lifted up - tibialis anterior + posterior allow this and resist excess eversion (more likely to get injury here)

Eversion: inside of foot on ground whilst outside of foot in the air - fibularis longus + brevis allow this and resist excess inversion (rare to get injuries here)

38
Q

What are the functions of the anterior compartment muscles? What regional pain indicate?

A

Foot and digit dorsiflexion and foot inversion so function to:

  • Guide foot placement during gait
  • Support arches of foot

Regional pain can be due to:

  • Compartment syndrome
  • Tibial stress fracture
  • Chronic exertional stress of fascia
39
Q

Where is the common fibular nerve most likely to be damaged or compressed?

A

When it is subcutaneous at the head of the fibula

40
Q

What will loss of function of the tibialis anterior cause?

A

Foot drop during swing phase of walking

41
Q

What are the functions of the lateral compartment muscles?

A

Primary foot evertors and weak plantarflexors so:

  • Resist excess foot inversion
  • Protect lateral collateral ligaments from excess inversion stress
  • Help balance body on foot + foot placement
42
Q

How can the 5th metatarsal tuberosity become damaged?

A

Can be avulsed by fibularis brevis following excess inversion

43
Q

Where is Achilles (calcaneal) tendon? How can it become damaged? How would you test it?

A

It is attached to soleus and gastrocnemius muscles which are so powerful they can rupture the tendon - test with the S1-2 reflex

44
Q

What are the functions of the posterior compartment muscles? What will happen if they lose their function?

A

Foot and digit plantarflexors and foot invertors so support arches of foot

Loss of function = weak/absent push-off when walking

45
Q

Where do neurovascular structures of the posterior leg compartment run?

A

Anterior to the soleal arch so they are deep and protected

46
Q

What is the popliteal fossa?

A

Diamond-shaped fat-filled region sat behind the knee containing the popliteal artery (deep), vein and tibial n. (superficial) with 4 borders:

  1. Semimembranosus + semitendinosus
  2. Biceps femoris
  3. Gastrocnemius medial head
  4. Gastrocnemius lateral head
47
Q

What can a supracondylar fracture of the femur damage?

A

The neurovascular bundle of the popliteal fossa i.e. popliteal artery + vein and tibial n. as they sit close to the femur

48
Q

What different swellings can occur within the popliteal fossa?

A
  1. Neuroma
  2. Popliteal artery aneurysm (pulsatile)
  3. Popliteal cysts from semimembranosus bursa above knee joint line
  4. Synovial (Baker’s) cyst below knee joint line
49
Q

Where does the sciatic nerve divide?

A

Proximal to the knee joint line the sciatic n. becomes the tibial and common fibular nerves - common fibular n. runs superficial and lateral to the tibial n.