Gluteal region, thigh

Question 1

lumbosacral plexus

Answer 1

• The combined lumbar and lumbosacral plexi contain ventral rami from L2 through S3 (L2-L5, S1-S3)
  
  • ​L2 and L3 tend to innervate muscles that act more at the hip
  • S2 and S3 tend to innervate muscles in the foot.
• The lumbosacral plexus exits the pelvic cavity through the greater sciatic foramen
• This puts these nerves into the gluteal region: the sciatic nerve will exit just inferior to the piriformis muscle

Question 2

What is the shoulder joint?

Answer 2

• glenohumeral joint
• “Ball and socket”
• We can move the humerus in all 3 planes: flex/extend, ab/adduct, internally/externally rotate
• Like the hip joint

Question 3

pectoral girdle vs. pelvic girdle

• What bones make them?
• Where is movement possible?

Answer 3

• Comparable structures of upper and lower limbs
• Pectoral girdle = clavicle & scapula
  
  • ​Lots of movement possible
• Pelvic girdle = ilium, ischium, pubis
  
  • No movements possible, fused together at sacroiliac joint

Question 4

What are the nerves of the hip?

Where do they come from?

Answer 4

• Hip nerves are branches of the lumbar plexus
• Because they come out of the top of the plexus, both nerves contain L2, L3, and L4
• Femoral nerve and obturator nerve
  
  • Innervate anterior and medial thigh

Question 5

largest nerve in body?

Answer 5

• Sciatic nerve
• Ventral rami. L4, L5, S1, S2, S3
• Innervates mostly leg and foot
• It’s actually two nerves running together in the same connective tissue sheath
  
  • It’s a tibial nerve + common fibular nerve, as emerge from the pelvis and course down the posterior aspect of the thigh
  • As the the sciatic nerve approaches the popliteal fossa (pit of knee), it splits into its real branches.
    
    • Common fibular nerve sweeps out to lateral and anterior part of leg
    • Tibial nerve continues straight down into posterior leg
  • (So it’s incorrect to say that any lower limb is innervated by sciatic nerve. Innervated by either the tibial or fibular.)

Question 6

What is the hip joint?

Contrast with shoulder joint.

Answer 6

• acetabulofemoral joint
  
  • ​Formed by head of femur and acetabular fossa of pelvic bone
    
    • Acetabular fossa is formed by fusion of 3 joints that make the pelvic girdle (ilium, ischium, pubis)
• Ball and socket joint (like the shoulder joint)
  
  • We can move the femur in all 3 planes: flex/extend (sagittal), AB/ADduct (coronal), internally/externally rotate

Differences from shoulder joint:

• Hip joint is the proximal joint of the lower limb
• Hip joint has limited range of motion (fused)
• Hip joint has an important weight-bearing function.

Question 7

knee joint

• What kind of joint?
• Actions possible?
• What is it similar to?

Answer 7

• Knee joint = modified hinge joint
  
  • ​Can do flexion and extension in sagittal plane, AND there is also some rotation possible
• Similar to the elbow joint, BUT
  
  • Elbow joint is “pure hinge joint” – limited to just flexion and extension, actions that occur in sagittal plane
  • Ankle joint is also a “pure hinge joint”

Question 8

elbow joint

• What kind of joint?
• Actions possible?
• What is it similar to?
• What is it different from?

Answer 8

• Humero-radial-ulnar joint
• The elbow joint is a “pure hinge joint”
  
  • Limited to just flexion and extension, actions that occur in sagittal plane.
• Similar to ankle joint, which is also a pure hinge joint
• Whereas knee joint is a “modified hinge joint” – can do flexion and extension in sagittal plane, and there is also some rotation possible.

Question 9

ankle joint

• Formed by what?
• Type of joint? Actions?

Answer 9

• Formed by distal end of the tibia, fibula, and tarsus
• It’s a pure hinge joint
  
  • ​We move it in the sagittal plane (dorsiflexion, plantar flexion)

Question 10

what are the muscles of gluteal region

and their functions

Answer 10

• Gluteus maximus
  
  • ​Powerful extensor of the thigh at the hip
  • Also laterally rotates the thigh at the hip
• Underneath gluteus maximus are the gluteus medius and gluteus minimus
  
  • ​ABductors of thigh at the hip
  • Major role is to ABduct the trunk, to keep the pelvis level when the opposite lower limb is off the ground
• Deep to gluteus maximus, some small muscles:
  
  • Piriformis
    
    • ​key bc emerges through greater sciatic foramen, and boundary separates superior from inferior gluteal structures
  • 2 gemelli (superior, inferior)
  • obturator internus
  • quadratus femoris
• They’re all just assisting the gluteus maximus, as lateral rotaters of the thigh at the hip.

Question 11

gluteus maximus:

What do we use it for?

Innervation

Answer 11

• Largest muscle in the body
• Gluteus maximus = powerful extensor of thigh at the hip
  
  • Use extensor when extending thigh from fully flexed position: rising from sitting position, climbing stairs, running.
    
    • (Not for everyday walking.)
• Also laterally rotates the thigh at the hip
• Innervated by inferior gluteal nerve (whereas superior gluteal nerve innervates the gluteus minimus and medius)

Question 12

gluteus minimus and medius:

What do we use them for?

What happens without them?

Answer 12

• gluteus medius and gluteus minimus = powerful ABductors
  
  • Allow us to move thigh and rest of lower limb in coronal plane. We don’t abduct the thigh a lot, unless we’re dancers.
• Most important function actions of gluteus medius and minimus is to abduct the trunk and keep the pelvis level when the lower limb is off the ground.
  
  • Patient’s foot would otherwise be dragging
  • When lift foot, nerve on opposite side contracts the muscle on opposite side, to level
• They cross the hip joint

Question 13

what are other gluteal muscles

that assist gluteus maximus in lateral rotation of thigh at the hip?

Answer 13

These small muscles are deep to the gluteal maximus:

• Piriformis
  
  • Boundary that separates superior gluteal structures from inferior gluteal structures
• Gemellus superior and gemellus inferior
• Obturator internus
  
  • ​Comes out of the lesser sciatic formane
• Quadratus femoris
• They’re all lateral rotaters of the thigh at the hip, assisting gluteus maximus
• No clinical signficance

Question 14

what is the innervation of gluteal muscles?

Answer 14

• Innervated by gluteal nerves (yay)
  
  • Inferior gluteal nerve innervates 1 muscle: the gluteus maximus
  • Superior gluteal nerve innervates the gluteus medius, gluteus minimus, and tensor fascia latae
• Piriformis, obturator internus, gemilli are all innervated by nerves that have the same name as the muscle.
  
  • Tiny branches off the lumbosacral plexus.
  • No clinical significance. Won’t be tested.

Question 15

tensor fascia latae

Answer 15

• Assists gluteus minimus and medius with ABducting the thigh at the hip
• Also flexes thigh at the hip
• Innervated by superior gluteal nerve
  
  • Which also innervates the gluteus medius and minimus

Question 16

What does the piriformis come through?

What emerges superior to the piriformis?

What emerges inferior to the piriformis?

Answer 16

• piriformis comes through greater sciatic foramen
• Above: Superior gluteal artery and vein
• Below: Inferior gluteal artery and vein, and the sciatic nerve
• Piriformis is the “key” to the gluteal region

Question 17

What comes out of greater sciatic foramen vs lesser foramen?

Answer 17

• Greater has sciatic nerve, piriformis muscle, superior/inferior gluteal neurovascular bundle
• Lesser has pudendal neurovascular bundle and the obturator internus muscle
  
  • Obturator internus muscle acts as lateral rotator

Greater sciatic foramen is more important. All the good stuff.

Question 18

What is the blood supply to entire thigh?

Answer 18

• Deep femoral artery

Question 19

What is the proximal to distal gradient

of the lumbosacral plexus?

• Segments for flexing thigh at hip?
• Segments for extending leg at knee?
• Segments for moving foot at ankle?
• Segments for sole of foot?

Answer 19

• Lumbosacral plexus = L2, L3, L4, L5, S1, S2, S3
  
  • _​_Hip joint and knee joint use branches of lumbar plexus: femoral and obturator nerve
• Similar to the brachial plexus, there is a proximal-to-distal gradient of innervation.
  • L2 and L3 tend to innervate muscles that act more at the hip
  • S2 and S3 tend to innervate muscles in the foot.
• When we flex thigh at the hip, we’re using top spinal cord segments: L2 and L3
• When we extend the leg at the knee, we’re using L3 and L4
• When we move foot at the ankle, we’re using L4 and L5
• Muscles at sole of foot are innervated by S1, S2, S3

Question 20

lumbar plexus:

• What are the 2 terminal nerves?
• What are their spinal cord segments?

Answer 20

• Femoral nerve
  
  • Major source of innervation to anterior thigh
• Obturator nerve
  
  • Major source of innervation to medial thigh
• Both contain L2, L3, L4 spinal segments (top of the lumbosacral plexus)

Question 21

Where does the sciatic nerve emerge?

Answer 21

• Just inferior to the piriformis
• Does not innervate any muscle in the gluteal region. Starts innervation in the posterior thigh.

Question 22

anterior compartment of thigh

• Function?
• Innervation?
• Muscles?

Answer 22

Function: anterior thigh = hip flexors

• Rectus femoris, iliopsoas = the best flexors of the thigh at the hip
• weak flexors = pectineus muscle, and adductor longus

Innervation

• The muscles of the anterior compartment of the thigh are innervated by the femoral nerve
• No exceptions.
• Muscles
  
  • sartorius - the longest muscle in the body
  • iliopsoas
  • quadriceps femoris group - the rectus femoris muscle and the three vasti muscles: the vastus lateralis, vastus intermedius, and the vastus medialis
    
    • Best flexors = rectus femoris, iliopsoas
  • pectineus, adductor longus

Question 23

flex thigh at the hip -

which muscles are the best for this?

Answer 23

• The best flexors of thigh at the hip are in the anterior thigh:
  
  • iliopsoas, rectus femoris, sartorius
  • The very best = the iliopsoas!
    
    • ​Combination of the psoas + iliacus muscles
• Innervated by femoral nerve

Question 24

extend thigh at hip

Answer 24

• posterior thigh muscles (hamstrings) extend thigh at the hip
• Mostly tibial nerve
  
  • ​(exception for short head of biceps femoris)

Question 25

What innervates the muscles of the medial compartment of the thigh?

Answer 25

• The muscles of the medial compartment of the thigh are innervated by the obturator nerve
  
  • ​with the exception of a part of the adductor magnus (tibial nerve innervates the hamstring portion)

Question 26

medial thigh

• Function?
• Muscles?
• Antagonist to what?
• Innervation?

Answer 26

• Function = ADduct thigh at hip
• Muscles = pectineus, gracilis, adductor longus, adductor brevis, adductor magnus
• Antagonist to gluteus medius and gludeus minimus, which ABduct the thigh at the hip
• Innervated by obturator nerve
  
  • ​(except for part of the adductor magnus, the hamstring portion of it has tibial nerve)

straightforward, adductors

Question 27

posterior thigh:

• Muscles?
• Action?
• Innervation?

Answer 27

• Posterior thigh contains hamstring muscles (3)
  
  • Biceps femoris
    
    • Biceps means 2 heads, short and long.
    • Positioned laterally
  • Semimembranosus and semitendinosus on medial side
  • True hamstrings cross hip joint and knee joint
    
    • At hip: extensors of thigh at hip
    • At knee: flex leg at the knee, and contribute to medial or lateral rotation
• True are innervated by branches of the tibial nerve (half of the sciatic)
• Exception: short head of the biceps is NOT true. Only crosses the knee joint. Can only flex at the knee, doesn’t act at the hip.
  
  • Innervated by branches of the common fibular nerve

Question 28

What are the hamstrings,

and when do we use them?

Answer 28

• We use our hamstrings when we’re walking in everyday life, and extending a partially flexed hip
• 3 hamstring muscles, in posterior thigh:
  
  • Biceps femoris, semimembranosus, and semitendinosus
  • Arise from ischial tuberosity
• True hamstrings cross at hip and knee joints
  
  • Extend the thigh at the hip
    
    • Gluteus maximus does this too, but only from fully flexed position
  • Flex and rotate the leg at the knee
• True hamstrings are innervated by branches of the tibial nerve (half of the sciatic)
• Exception: short head of the biceps is NOT true. Only crosses the knee joint. Innervated by common fibular nerve.

Question 29

What’s special about the SHORT head of the biceps femoris?

Answer 29

• Part of the biceps femoris of the hamstrings, but it’s the exception: NOT a true hamstring
  
  • Because it doesn’t cross at the hip joint. Only crosses the knee joint, because it’s short.
• Innervated by common fibular nerve (while the others are all innervated by the tibial nerve)

Question 30

quadriceps:

• Where are they?
• Muscles?
• Function of all 4? Function of 1 of them?
• Innervation?

Answer 30

• anterior thigh
• 4 muscles:
  
  • Rectus femoris
  • Vastus medialis, vastus lateralis, vastus intermedius
• All 4 converge to form quadriceps tendon at patella, which attaches to tibia –> can act to extend the leg at the knee.
• Rectus femoris is ALSO a good flexor of thigh at hip
• All innervated by femoral nerve

Question 31

iliopsoas muscle:

What is it the best at?

Answer 31

• Best flexor of the thigh at the hip!
  
  • (One of the anterior thigh muscles. The best even though it’s small.)
  • It’s completely anterior to the hip joint.
• It’s a combination of the psoas major + iliacus

Question 32

Femoral triangle

• What are the boundaries?
• What comes through it?

Answer 32

• Formed by the inguinal ligament, sartorius muscle, adductor longus muscle
• Contains the major neurovascular bundle that supplies the anterior thigh: the femoral nerve, femoral artery, femoral vein (most medial)
  
  • ​Femoral artery and femoral vein supply the entire lower limb

Question 33

rectus femoris:

What makes it different from the other quadriceps muscles?

Answer 33

• All quadriceps muscles (rectus femoris, and the vastus muscles) can extend the leg at the knee, since their tendon attaches there
• Only the rectus femoris can also flex the thigh at the hip
• all of them are innervated by femoral nerve

Question 34

quadriceps femoris tendon:

what is it, and what’s the name change?

Answer 34

• quadriceps muscles converge at quadriceps femoris tendon,
  
  • Embedded in the tendon is the patella (the knee cap, a seed-like bone)
• Quadriceps femors tendon changes name after the patella –> called the patellar tendon/ligament

Question 35

What is the blood supply to entire lower limb?

• Name changes?

Answer 35

• One tube, that changes its name 3 times
  
  • Start as external iliac artery
  • Once the external iliac artery crosses behind the inguinal ligament, it becomes the femoral artery
    
    • ​Doesn’t care about the thigh. Its goal is to supply the leg and the foot.
  • Once it crosses through adductor hiatus, becomes popliteal artery and supplies leg and foot
• The deep/profunda femoral artery supplies the thigh
  
  • ​Gives rise to lateral circumflex and medial circumflex arteries
  • Gives rise to perforating branches to supply posterior thigh
    
    • So hamstrings are only supplied by these little guys. So takes longer to heal, lousy blood supply.

Question 36

where do arteries pass relative to joints?

(True for both upper and lower limbs)

Answer 36

• Arteries pass on flexor side of joints
  
  • Anterior to the hip, anterior to shoulder, anterior to wrist
  • But posterior to the knee, because the flexor side of knee is posterior. (Limb rotation.)
• This is why the femoral artery passes through adductor hiatus to become the popliteal artery, behind the knee

Question 37

What nerve courses with the popliteal artery and vein?

Answer 37

• The tibial nerve
  
  • Courses with popliteal artery and vein, starting on posterior side of knee, as goes into posterior leg

Question 38

Name the arteries that supply the:

• Anterior thigh
• Posterior Thigh
• Medial thigh
• Leg
• Foot

Answer 38

• Anterior thigh = deep femoral artery
• Posterior Thigh = perforating branches of the deep femoral artery (lousy)
• Medial thigh = deep femoral artery (branches = the medial and lateral femoral circumflex arteries)
• Leg = popliteal artery (branches = anterior and posterior tibial arteries)
• Foot = popliteal artery (branches = anterior and posterior tibial arteries)

Question 39

What does the profunda femoral artery supply?

Answer 39

Profunda femoral artery supplies:

• Anterior thigh
• Medial Thigh
• Posterior thigh (perforating branches)
• Hip joint and head of femur (medial circumflex femoral branch)
  
  • Femoral neck fractures commonly result in avascular necrosis of the femoral head.

Question 40

Which nerves innervate anterior thigh, medial thigh, posterior thigh?

Answer 40

• Anterior = Femoral nerve
• Medial = Obturator nerve
• Posterior (hamstrings) = Tibial nerve
  
  • Small exception is the short head of biceps

Question 41

Name the main nerve involved for each of these actions at the hip joint:

• Flexion:
• Extension:
• ADduction:
• ABduction:
• Medial rotation:
• Lateral rotation:

Answer 41

At hip joint:

• Flexion: femoral nerve
  
  • (Rectus femoris, sartorius, iliapsoas)
• Extension: inferior gluteal (for gluteus maximus) and tibial branch of sciatic (for true hamstrings)
• ADduction: obturator
  
  • Adductors longus/brevis/magnus, gracilis
• ABduction: superior gluteal
  
  • Gluteus minimus and medius
• Medial rotation: superior gluteal
  
  • Gluteus minimus, medius, tensor fascia latae
• Lateral rotation: inferior gluteal
  
  • Gluteus maximus

Question 42

Name the main nerve involved for each of these actions at the knee joint:

• Flexion:
• Extension:
• Lateral rotation of leg:
• Medial rotation of leg:

Answer 42

At the knee joint:

• Flexion: tibial branch of sciatic nerve
  
  • Hamstring muscles (the semis and the biceps long head)
• Extension: femoral nerve
  
  • Quadriceps femoris (the rectus femorus and the vastus’s)
• Lateral rotation of leg: inferior gluteal (gluteus maximus), superior gluteal (tensor fasciae latae), etc
• Medial rotation of leg: tibial (popliteus, semimembranosus and semitendinosus), obturator (gracilis), femoral (sartorius)

Question 43

What are the clinical findings of an inferior gluteal nerve injury?

Answer 43

• Difficulty getting up from a chair without using upper limbs
• because innervates gluteus maximus - extensor from flexed position