Muscular System IV/V (Lower Limb)

Question 1

Gluteus Maximus

Answer 1

• gluteus maximus most superficially positioned muscle and has relatively large origin (starts from lateral surface of ilium and has fibers originating from the posterior surface of sacrum - from this origin the muscle fibers are directed laterally and slightly inferiorly and some fibers will attach to a bony elevation just being proximal end of the femur known as gluteal tuberosity and some of the fibers of the muscles as they are invested between the thick layer of dense connective tissue on the lateral side of the thigh - band that stretches from ilium to the tibia called the IT band (can easily palpate it when you are standing and take to your knee to extension or hyperextension) - some of the fibers of gluteus maximus insert to this band and through the band they get inserted to tibia
• function: passing behind the hip joint so it considered the extensor of hip - prime mover for extension of HJ
• crossing the knee but it does not create any specific movement but by tightening IT band it adds to stability of knee on lateral side (so stabilizes knee and extends the hip)
• nerve supply is done by inferior gluteal nerve from the sacral plexus

Question 2

Gluteus Minimus

Answer 2

• deep to gluteus maximus we have another muscle called gluteus medius (little smaller) but significant muscle - deeper to maximus but still superficial - originating from lateral surface of ilium and then passes just lateral to hip joint and inserts to greater trochanter of femur - most of the fibers are running down vertically just lateral to hip - main function of the muscle is abduction of the hip joint (prime mover)
• nerve supply is done by another branch of sacral plexus known as superior gluteal nerve
• this muscle has a reverse function: when the muscle moves it origin rather than insertion (in theory every muscle should be able to do this but in theory only a few do) - regularly does this
  ◦ if the femur is stabilized under my body weight - when the muscle contracts it cannot move the femur anymore but it can work on your pelvis (does lateral tilt of the pelvis) - when you are walking as soon as you take your leg off the ground because of body weight your pelvis tends to drop on that side - gluteus medius prevents that - balances your pelvis as you are walking

Question 3

Deep Layer - Piriformis

Answer 3

• group of small and insignificant muscles except for one known as piriformis
• indicates it shape (pear shaped) - origin: starting from anterior surface or sacrum and exits the pelvics to insert to greater trochanter - needs to pass hip joint from behind to reach that insertion point
• function: lateral rotation is the movement - laterally rotates hip joint - not prime mover but it is considered clinically an important muscle because sciatic nerve is just under that - spasms of that muscle can cause compression of sciatic nerve which can cause pain in numbness in different parts of distribution of that nerve
• nerve supply done by direct branch coming from sacral plexus

Question 4

What are the Three Muscular Compartments of the Thigh

Answer 4

• have 3 muscular compartments - intramuscular septum’s are divided thigh into 3 muscular compartments
• anterior compartment, medial compartment and posterior compartment - classified based on nerve supply
• all muscles in anterior compartment are supplied by femoral nerve
• all muscles in medial compartment are supplied by obturator nerve
• muscles to posterior are supplied by branches of sciatic nerve
  (all from the lumbar plexus)

Question 5

Iliopsoas (need to know) - combination of two separate muscles

Answer 5

◦ psoas major originates from lumbar vertebrae and the other muscle is iliacus starts from medial surface of ilium (iliac fossa) - both of these muscles join together and have common insertion on lesser trochanter
◦ both of these two are crossing hip joint anteriorly so they can flex hip joint - together there are considered prime mover for hip flexion
◦ nerve supply: suppled by branches of lumbar plexus

Question 6

Quadriceps femoris (4 heads)

Answer 6

• one head originates from hip bone and other 3 originate from femur - all 4 heads come together and after embracing the patella they insert to the tibial tuberosity on tibia through a ligament called patellar ligament (considered one muscle not four)
• crossing the both hip joint and knee joint anteriorly it should flex hip joint but prime mover for extension of your knee joint
• all 4 heads are innervated by femoral nerve

Question 7

Adductor Magnus

Answer 7

• adductor magnus implies that it is joint to do adduction and it is largest muscle in this area - prime mover for adduction of hip joint
• muscle has two different sets of fibers and each set of fibers are innervated by a different nerve - have their own origin and insertion
• the muscle is originating mostly from ischial tuberosity and ischiopubic ramus - some fibers of the muscle will insert to linea aspera (rough line on femur) and some other fibers are inserted to medial epicondyle to a bony elevation called adductor tubercle (two insertions)
• if the muscle is coming from ischial tuberosity which is behind hip joint so some fivers are passing behind the joint so they can extend the hip joint- can help in extensor as well as adduct
• some fibers extend the hip but most fibers adduct the hip
• it has dual nerve supply so those fibers that extend dare innervated by sciatic nerve whereas those fibers that are adducting the hip are innervated by obturator nerve

Question 8

Biceps Femoris

Answer 8

• one muscle is called biceps femoris two heads - long and short heads
• long head starts from ischial tuberosity and short head is mostly covered by long head is originating from shaft of femur
• merge and join and then together they insert to head of fibula
• function: crossing behind the hip and knee meaning can extend the hip and flex your knee in which it is prime mover (knee flexion)
• nerve supply is sciatic nerve

Question 9

Tibialis Anterior

Answer 9

• within anterior compartment there is tibialis anterior (testable) originates from shaft of tibia and inserts to medial cuneiform - crossing the ankle - dorsiflexion (extension of ankle)
• common fibular nerve

Question 10

Extensor Digitorum Longus

Answer 10

• extensor digitorum longus - should extend your digits - originates mainly from fibula and partly from tibia and cross the ankle anteriorly and divides into 4 branches which end to middle and distal phalanges of toes number 2-5
• prime mover for extension of the ankle and your toes

Question 11

Gastrocnemius

Answer 11

• most superficial muscle is gastrocnemius with two heads that are starting from femoral epicondyles and insert to calcaneus (posterior surface) - the tendon that attaches to the muscle is called calcaneal or achillis tendon
• tendon is passing behind ankle so it should do plantarflexion - not prime mover
• tibial nerve

Question 12

Soleus

Answer 12

• soleus (bigger muscle that causes that bulge) deep to gastrocnemius - attaches to both tibia and fibula and its tendon joints to calcaneal tendon - same insertion as gastrocnemius - prime mover for plantarflexion
  ◦ thickness is almost 3 times that of gastrocnemius
• tibial nerve

Question 13

Tibialis Posterior

Answer 13

tibialis posterior - deep groove or deep layer of posterior compartment of leg - origin is both tibia and fibula insertion to all tarsal bones except talus - has a significant role in maintaining your foot arches- collapse of foot arch could be through losing this muscle or weakness of this muscle (important muscle)

Question 14

Fibularis (peroneus) longus

Answer 14

• fibularis (peroneus) longus originates only from fibula and passing begind lateral malleolus and wraps around lateral border of foot
• crosses plantar aspect of foot towards medial border specifically to the medial cuneiform - obliquely crossing plantar aspect of foot from lateral to medial to insert to medial cuneiform
• bringing the plant or aspect of my foot facing laterally: eversion of the foot - prime mover
• nerve supply is superificial fibular nerve

Question 15

Foot - Plantar Aspect

Answer 15

• divide them into 4 layers (do not need to know origin and insertion - just function)
• first layer is most superficial and layer 4 is most deep
• muscles in first layer can abduct toes 1 and 5 and flex toes 2-5
• second layer only do flexion of toes 2-5
• third layer we have muscles that are involved in adduction of the big toe and flexion of toes 1 and 5
• fourth layer - plantar interossei and dorsal interossei because they are sitting between the metatarsal bones
• axis of adduction and abduction is second toe not the third - plantar can do adduction (innervated by branches of tibial nerve) dorsal does abduction
• they are crucial to maintain the foot arches

Question 16

What is a transitional area?

Answer 16

area in upper or lower limb which is passage for MAJOR blood vessels and nerves from one region to the other

Question 17

Femoral Triangle

Answer 17

femoral triangle has major blood vessels and nerves that are coming from pelvic region to thigh

Question 18

Popliteal Fossa & Tarsal Tunnel

Answer 18

just behind you knee there is a diamond shaped space where major blood vessels are passing from your thigh to your leg
- tarsal tunnel - just behind medial malleolus there is a tunnel that provides passages from leg into the foot