Anatomy 4200 lower limb

what are myotomes? how do they change in development?

-quickly after gestation, we start to develop myotomes and as they force, they drag sensory and motor nerves along with them to our developping limbs
-upper limb stays pretty straight, but there is rotation that occurs in lower limb (internal rotation)
-so in upper limb, extensors are posterior and flexors are anterior
-but because of this rotation, the extensors switch to anterior side and flexors are posterior, so lower limb is opposite to the way the arm is oriented

explain general features of glenohumeral joint? where does it get most of its stability from?

-glenohumeral joint is still classified a ball and socket synovial joint, but it has very low stability and high mobility
-only about 33% of humeral head fits in glenoid cavity
-there is relatively lax fibrous layer of joint capsule to allow for lot of movement
-so stability mostly comes from tonus of rotator cuff musculature (bc there is unstable bony and ligament connection)

explain general features of hip joint? where does it get most of its stability from?

\-this too is classified a ball and socket synovial joint, but much more stable than glenohumeral joint
\-about 50% of head of femur fits with socket, so highly congruent and has a much better bony fit

\-the fibrous layer of joint capsule has abundant ligamentous thickenings, so ligaments can hold hip in place without musculature actually

\-there is also extensive supporting muscles, but they dont need to contribute to stability -so muscles are there for movement and not only there for support of joint

give two other similarities/differences between upper limb and lower limb

1. shoulder girdle has minimal articulation w vertebral column (only @ clavicle), but pelvic girdle is firmly attached to the vertebral column (two hip ones wedge the sacrum)
2. ulna/radius contribute to pronation and supination, but tibia and fibula produce very little movement

what are the different regions of the lower limb

anteriorly, there is anterior thigh, knee joint, then leg, then ankle joint and then foot
-posterior, there is gluteal region that ends at gluteal fold, then posterior thigh, then leg and foot too

what are all the different bones in the lower limb

there is the pelvic bone, femur, patella, tibia, fibula, tarsals, metatarsals and then phalanges

what are the different compartments of the thigh? how do we normally look at cross sections? compare this to the different compartments of the leg

-we normally view a cross- section like a cut across the limb, then view it from below (looking up superiorly)
-in thigh, there is anterior compartment (extensor), posterior compartment (flexors) and a medial compartment (adductors)
-have no lateral compartments bc leg abduction is done by hip muscles and there is no abduction of knee
-in leg, there is a small anterior compartment for dorsi felxion, small lateral compartment for eversion of foot, and much larger posterior compartment to allow for plantar flexion (used for propulsion)

identify the parts that I blocked out from the lumbosacral plexus

starting from left to right
1. there is the femoral nerve, which is major nerve of anterior compartment, passes under inguinal ligament
2.obturator nerve, major nerve to medial compartment, passes through obturator formane
3. sciatic nerve, this is major nerve to posterior compartment
4. superior gluteal nerve and inferior gluteal nerve

explain general pathway of lower limb blood flow

-there is the aorta, which then splits into the right and left common iliac arteries
-then common iliac artery splits into internal iliac artery (supplied inside pelvis like sex organs, bladder) then has superior gluteal artery, obturator artery, and inferior gluteal artery
-also external iliac artery (more outside pelvis, so blood flow to gluteal muscles) will turn to the femoral artery, which is quite superficial and very large
-

what are the bones that make up the pelvic girdle

-there are 2 pelvic bones (actually 3 bones that are fused together), then sacrum (vertebral bones fused together) and then coccyx

what are the three bones that make up the pelvic bone?

-the largest bone is ilium, then posteriorly there is ischium and anteriorly there is pubis
-all three of these bones kind of meet up at acetabulum
-between the connection of these is the obturator foramen, which is a large hole but few things actually run through here bc its mostly covered in muscle

explain common landmarks on the ilium

-medially, there is iliac fossa and the articulating surface for sacrum and laterally(kind of posterior) there is gluteal surface
-anteriorly, there is the anterior superior iliac spine (ASIS) and then there is anterior inferior iliac spine (AIIS), there is also the arcuate line that moves towards the pubic bone
-posteriorly, there is posterior superior iliac spine (PSIS) - where lumbosacral fascia ends -and posterior inferior iliac spine (PIIS)
-PSIS kind of look like dimples on lower back
-under the PIIS there is greater sciatic notch
-superiorly, there is iliac crest and iliac tuberosity

explain common landmarks on the ischium

-there is the ischial spine, which separates the lesser sciatic notch and the greater sciatic notch
-lower, there is the ischial tuberosity which is what we sit on, had lots of hamstring muscles attach here
-then there is also the ischial ramus that goes towards the pubis

explain common landmarks on the pubis

-this is smallest of the 3 bones
-there is the pectineal line which kind of connects to arcuate line on ilium
-there is superior pubic ramus
-then pubic tubercle with articulating surface on it
-then there is the inferior pubic ramus

what are the different ligaments at the lumbosacral joint

-this is in between L5 and the sacrum, so there is an intervertebral disc between them

-there are lots of ligaments, bc this joint needed to be very strong since there is a lot of weight on this spot
-there is the lumbosacral ligament which goes from sacrum to transverse process of L5?
-there is also iliolumbar ligament which attaches transverse process of L5 to illiac crest
-these work to keep articular movement of L5 to a minimum

what is the sacral promontory?

-this is the most anterior portion of the sacrum, where it connects with L5

what are the ligaments of the sacroiliac joint?

-these are ligaments connecting the sacrum to the ilium
-there is the anterior sacroiliac ligament, kind of looks like a fan
-then also have posterior sacroiliac ligament, which overlies the interosseus sacroiliac ligament, which is smaller piece underneath

what is the pubic symphysis? what are the ligaments surrounding it

the pubic symphysis is between the articulating surfaces of the 2 pubic bones, with a disc in between them
-there is a superior pubic ligament anteriorly and inferior pubic ligament posteriorly

what are the ligaments of the lateral pelvic walls? what spaces do they form? what is their function?

-there is the sacrospinous ligament, which ran from the sacrum to the ischial spine
-then there is also the sacrotuberous ligament which runs from ischial tuberosity to the sacrum
-above the sacrospinous ligament, formed by greater sciatic notch, there is the greater sciatic foramen
-then below the sacrospinous lig, formed by lesser sciatic notch is the lesser sciatic foramen
-as we gain weight on our upper body, the pelvis wants to tip forward, but these ligaments stop it from tilting into lordosis

what is the difference in shape between the pelvic inlet and outlet

pelvic inlet(aka pelvic brim) is kind of shaped like a circle, defined by sacral promontory, arcuate line, coming around to pectinate line, crossing pubic symphyses and back
-this is where we move from abdomen to pelvis area
-whereas the pelvic outlet is made of some bones and some ligaments
-anteriorly, there is ischial rami and pubic symphyses
-then posteriorly the borders are the sacrotuberous ligament to the coccyx
-in childbirth there is some laxity with these ligaments to open this area up more
-there is no actual "floor" to the pelvis, but there is a musculature called perineum

explain the true pelvis vs the false pelvis

-the true pelvis is past the pelvic inlet, so surrounded by bones of the pelvis
-the false pelvis is part of the abdomen, from the iliac crest to the pubic symphysis (so above pelvic inlet)
-false pelvis is where baby is formed bc it cant expand in pelvis since its encased in bone

where is the inguinal ligament formed

inguinal lig runs from ASIS to pubic tubercle, doesnt really offer any support but acts like a gateway to lower limb

what is the difference between the female pelvis and the male pelvis

-F tilts forward for childbearing but M has less tilt to support heavier build
-F has true pelvis that defines the birth canal but cavity of M true pelvis is deep and narrow
-F has smaller acetabula compared to M
-F has much wider pelvic arch (80-90 degrees) and in M is much smaller (50-60 degrees)
-F has more wedge shaped sacrum and wider facing ilium, so wider hips in general
-F has lighter, less dense bones

give general landmarks on the proximal femur

-there is the shaft, then neck and then head of the femur
-there is the greater trochanter laterally, which offers attachment sites for muscles
-then there is divet between trochanter and neck called the trochanteric fossa
-then medially and lower there is the lesser trochanter and has trochanteric line between the two anteriroly and posteriorky there is the intertrochanteric crest
-a bit lower posteriorly there is the gluteal tuberosity
-there is the pectineal line (spiral line) that kind of loops around from the intertrochanteric line and joins to make linea aspera (separates medial and anterior thigh muscles

what is the use of the divet in centre of femur head

-this is area where lig of head of femur (ligamentum teres) attaches to the base of acetabulum
-ligament also holds in place the artery to head of femur

give general landmarks of the distal femur

-cross section of femur shows that it is NOT a perfect circle but the linea aspera projects posteriorly and this line runs down the shaft
-at distal portion, there is the medial and lateral epicondyles and condyles
-anterior there is patellar surface
-there is also adductor tubercle on medial side which is major attachment point

what are all the ligaments that support the head of femur into acetabulum

-remember that this is hip joint, so needs synovial fluid and capsule, but the ligaments are exterior to this to block excessive movement
-there is iliofemoral ligament that runs from AIIS to intertrochanteric line and kind of forms a spiral action
-then there is pubofemoral ligament that goes from iliopubic eminence to neck
-then posteriorly there is ishiofemoral lig that goes from ishium to right by the greater trochanter
-these ligaments mostly help w stopping extension of hip backwards

what are all movements of the hip joint

-there is flexion and extension
-abduction is lessening angle between femur and hip, then adduction is increasing that angle
-note: you can still abduct the pelvis on a fixed femur
-then there is medial and lateral rotation (how we move toes either facing inwards or outwards, only moves 5-7 cm in either way
-finally can do hip circumduction which is combo of flexion, extension, abduction, and adduction in sequence

what is the general anatomy of the proximal tibia

-there are the lateral and medial condyles that articulate w femur
-then there is the tibial tuberosity anteriorly for attachment of muscles (quadriceps)
-there is articular facet for the head of fibula at the lateral side
-soleal line cuts on a diagonal posteriorly

do dermotomes and myotomes overlap

-dermotomes will overlap with other dermatomes in the area between sections of 2 nerves, and the same for myotomes
-note: the dermatomes are much better organized and give a nice map compared to the myotomes
-knowledge of area supplied by individual nerve roots is helpful in diagnosing nerve root damage

what is the fascia lata?

-this is just below the skin and subcutaneous fat, there is fascia lata, which is thick layer of connective tissue that holds muscles together and good for blood pressure regulation
-the fascia arises at the iliac crest, surrounds the butt, also attaches to the thoracolumbar and abdominal fascia, then carries down to foot
-there is a thickening laterally called the iliotibila tract
-only the superficial veins run above the fascia, exverything else is deep

explain the characteristics and names of the veins in the lower limb

-the femoral vein, which is deep to the fascia lata, is the main vein that drains the leg
-there is the long (great) saphenous vein that runs superficial to the fascia and then pierces fascia and empties into the femoral vein
-a bit more distally, there is the popliteal vein that carries blood upwards to dump into the femoral vein (basically turns into femoral vein
-the short saphenous vein is also superficial to fascia and empties into the popliteal vein superficially

what are the different muscle compartments of the thigh? what separates them

-there is anterior, posterior, and medial compartments, and they all have attachments onto the linea aspera posteriorly
-there is the fascia lata surrounding all the muscles, but there is also invaginating fascia to make intermuscular septae to define all the compartments

what are the important structures that pass at the anterior crease of thigh and pelvis superficially

-acronym is NAVEL, so nerve, artery and vein, then lymphnode
-so there is femoral nerve, femoral artery, femoral vein, then inguinal lymph nodes
-inguinal ligament crosses these horizontally, starts the definition of the limb

what are the origins, insertion, innervation, and action of the psoas muscle and iliacus muscle

-origin of psoas is transverse process and bodies of vertebrae T12-L5
-origin of iliacus is iliac fossa, so anterior/medial side of ilium
-they have a common tendon onto the lesser trochanter, so known as iliopsoas
-there is also a psoas mino that inserts on superior ramus of pubic
-their innervation is anterior rami of femoral nerve (L1-L3)
-their main action is flexes thigh at hip, also lateral rotation at hip

other than iliopsoas, what are the two additional hip flexors

-these are minor ones that come from the anterior thigh, so help but dont have as big of an effect
-there is sartorius, and rectus femoris

what is the origin, insertion, innervation, and action of tensor fascia latae?

-this is a msucle thickening of the iliotibial band, so originates on ASIS, then IT band goes all the way down to Gerdy's tubercle on proximal/lateral tibia
-innervation is superior gluteal n
-action is at hip, helps w stabilization, medial rotation and abduction of hip, then lateral rotation at knee?

what is the origin, insertion, innervation, and action of sartorius

-this is longest muscle in body (aka tailors muscle)
-originates on ASIS (along w tensor fascia lata) and inserts on pes ansnerinus (superior medial aspect of tibia); so corsses 2 joints
-action is flexes, abducts, and laterally rotates thigh at the hip joint
-then also flexes the knee joint
-innervation is femoral nerve, so L2, 3 and 4

what are the 4 muscles of the quadriceps? where do they originate and innervate?

#1 is rectus femoris, which originates on AIIS spine, has a straight head and a reflected head
-#2 is vastus lateralis, which originates on lateral femur
#3 is vastus medialis, originates on medial side of femur
-#4 is vastus intermedius, which is deep to rectus femoris; has large origin on femur
-all 4 of these combine onto quadriceps tendon which goes to patella (sesamoid bone), then turns into patella ligament to tibila tuberosity, which goes from patella to tibial tuberosity
-innervation is femoral n too

what is the origin, insertion, innervation, and action of pectineus?

-origin: pectineal line of the pubis
-insertion: pectineal line of femur, so just inferior to lesser trochanter
-action: adduction and flexion at hip (not great at flexion), and assists w medial rotation of thigh
-innervation is femoral n, sometimes obturator n (so either in anterior or medial compartment)

what is the common nerve and action of the muscles of medial thigh?

common nerve obturator n (L2-4), there is a small foramen from muscles and membrane over the obturator formane that allows this nerve to get to outside of pelvis
-the common actions are to adduct, flex, and rotates at hip joint (but depends on what orientation the limb is in; will change the action of the muscle)

what is patellofemoral syndrome?

-this is when there is pain in knees, common cause of this is imbalance in quadriceos muscles, so lateral side (vastus lateralis + rectus femoris) is stronger than vastus medialis, which pulls patella laterally
-this is also more common in females bc of bony architecture
-so Q angle is between line of femur and line of tibia and women tend to have wider hips, so bigger Q angle and bigger lateral pull

explain the arterial supply of the upper portion of the lower limb

the descending aorta separates quickly into 2 branches called iliac arteries, then these turns to internal and external iliac arteries
-obturator artery is branch off of internal iliac artery
-external iliac arteries turns into femoral artery
-then there is deep artery of thigh (aka femoris profunda)
-off of femoris profunda, there is the lateral and medial circumflex arteries, which have a lot of variation and could form anastomosis but dont have to

explain how arterial supply of anterior thigh interacts with muscles in medial compartment

-the femora profunda (off femoral artery) kind of lies between vastus intermedius, has perforating branches that supply these muscles
-the adductor magnus (very deep) has hiatuses in it by the femur, and the performatic branches will pierces through to supply the muscle and wrap around the femur
-at distal femur, there is the adductor hiatus, which is bigger hole that the femoral artery goes through to get to posteriro and femoral vein comes through to go anteriorly

what is cutaneous innervation of the anterior lower limb

-muscle is by the femoral nerve (L2-L4)
-on anterior thigh there is the cutaneous branches of femoral nerve
-on anterior leg there is saphenous nerve (from femoral nerve)

what are the borders of the femoral triangle? what is in femoral triangle?

-superiorly there is inguinal ligament, then laterally there is sartorius, and medially there is adductor longus
-from lateral to medial, there is the femoral nerve, then artery, and then femoral vein
-also has lymphnodes!

what does the linea aspera turn into at the distal femur?

The linea aspera moves down the femur posteriorly and then splits into two lines: the medial and lateral supracondylar lines that lead to the medial and lateral epicondyles

where does the inguinal ligament run from

-goes from the ASIS to the pubic tubercle, it is basically a rolling layer of fascia from abdominal area to form pathways and mark start of lower limb

what are all the divisions that the obturator nerve makes?

-obturatpr nerve comes from L2-L4, leaves the same route as femoral, but dives into the obturator foramen
-there is an anterior and posterior division once it leaves the obturator formane
-anterior division: Pectineus (sometimes), articular branch for hip joint (for position and pain), adductor longus, adductor brevis, gracilis
-posterior division: obturator externus, adductor magnus, and then articular branch for knee joint (position and pain)
-then also gives cutaneous innervation for skin of groin and anus

what is the origin and insertion, innervation, and action of obturator externus?

-it is not really part of the medial group, but innervated by obturator nerve
-originates on external part of the obturator membrane, then tendon reaches posterior to neck of femur and inserts onto this oval depression on posterior side thats by the greater trochanter (the trochanterior fossa)
-performs multiple actions, but depends on what orientation the hip is in
-when hip is extended: externally rotates the femur
-when the hip is flexed: it abducts the thigh
-with other muscles around the hip joint, it contributes to the joint stability and movement refinement
-innervation is posterior branch of obturator n

what is the general rule for innervation for for medial thigh, and what are the exceptions

-everything is by the obturator nerve
-BUT, biggest and smallest muscles think they are special
-pectineus: uses whatever is handy, so femoral n but potentially obturator n (bc it runs underneath)
-adductor magnus has 2 functional parts: adductor part (obturator n) and hamstring portion (sciatic n)

explain the depth of the adductors muscles?

-most superficial, from medial to lateral: there is pectineus, longus, and gracilis
-deeper: underneath adductor longus there is brevis
-deepest : basically spans the entire deep layer is adductor magnus

what is the origin, insertion, action, and innervation of adductor longus

-origin is body of pubis inferior to the pubic crest, so pretty medial
-insertion is the medial lip of the lower linea aspera, so medial portion of posterior femur
-action is adducting adducting and flex the thigh
-but since it inserts behind the femur, doesnt have the best angle of pull to flex the hip
-innervation is obturator nerve (L2-L4)

what is the origin, insertion, action, and innervation of adductor brevis

-this is deep to longus
-origin is pubis, the inferior ramus and body
-then inserts on medial lip of the upper linea aspera (so inserts above the where longus inserts on the femur
-action is to adducts the thigh, doesnt have good actionable moment to flex the hip
-innervation is obturator nerve

what is the origin, insertion, action, and innervation of adductor magnus

-this is deep to all the adductors
-origin is the ischial and pubic rami and ischial tuberosity; so basically inferior ramus and where it turns to ischium(adductor portion), then piece of hamstring portion attaches to ischial tuberosity
-the insertion is the linea aspera, the medial supracondylar line and the hamstring portion attaches to adductor tubercle of femur (which will form the adductor hiatus between these 2 sections)
-action: posterior fibres adduct and flex thigh (adductor portion)
-then posterior fibres synergistic w hamstrings during thigh extension, so extends hip
-innervation is obturator n for adductor portion and sciatic nerve (tibial component) for hamstring portion

what is the origin, insertion, action, and innervation of gracilis

-this is the superficial medial side
-origin is inferior ramus and body of pubis and the ischial ramus
-then inserts on medial surface of tibia, the pes anserinu!
-since it crosses two joints, the action will be adducting thigh, flexing leg (at knee), medially rotation leg (at knee) (important when walking)
-innervation is obturator nerve (L2-L4)

what are the three muscles that attach to the pes anserinus?

-there is sartorius (anterior), semitendonosis (posterior), and gracilis (medial), they have common insertion on anterior medial portion of tibia
-the sartorial insertion is larger and more curved medially, then other two insertion are more lateral to it

what is the use of a gracilis transplant?

-gracilis is a weak adductor, so can be removed without noticeable functional loss
-then can be used to for functional transplants: facial reconstruction, restore arm function in post-brachial plexus injury
-anal sphincter reconstruction (so wraps around sphincter to prevent incontinence)
-ACL reconstruction

what causes a groin pull?

-this is caused by active contraction and passive stretch of the medial compartment muscles
-so will pull from origin points, doesnt usually pop from distal insertion
-symptoms include bruising and pain
-treatment would be conservative, RICE and Nsaids

what are the different pathways of anterior and posterior branches of the obturator nerve

-posterior division stays underneath the adductor muscles
-anterior division reaches up and innervates these muscles from deep zones

what is the blood supply to the medial compartment

-the obturator artery is branch off of internal iliac artery, will pierces through obturator membrane to supply blood to adductors
-the femora profunda will probably suplly some blood flow as well since its cloe to adductor magnus
-the blood supply is very variable in dif people

explain the different components of surface anatomy of the gluteal region

-the region starts at the top of the iliac crests, which is in line with vertebrae L4 and L5
-the intergluteal cleft is the butt crack
-the ischial tuberosity is what we sit on, this is near lower end of gluteal region
-gluteal region ends at the gluteal folds

what are the 2 nerves that supply the gluteal region?

-there is the superior gluteal n, (L4, L5, S1) and this innervates the the gluteus medius and minimus and the tensor fascia lata
-then inferior gluteal n (L5, S1 S2) will innervate gluteus maximus
-these nerves both exit from the greater sciatic foramen, but they enter gluteal region by exiting above and below the piriformis muscle (part of deep gluteal group)

what are the different groups of muscles in the gluteal region

-there are the superficial gluteal group(from superficial to deep):
-gluteal maximus (extensor)
-gluteals medius and gluteus minimus ( abductors)
-there are the deep gluteal group:
piriformis, obturator internus, gemelli, quadratus femoris)

explain origin, insertion, innervation, and action of the tensor fascia lata and the iliotibial tract

-origin of fascia is the ASIS and anterior iliac crest
-insertion is IT band (gerdy's tubercle, so on lateral side of tibia)
-function is weak hip flexor, weak abductor at hip (not a huge muscle so wont have a huge effect)
-remember tensor fascia lata is a muscle thickening, so muscles helps tense the fascia latae, this tension can help w lateral rotation at the hip
-innervation is superior gluteal n, bc its moving in correct direction and there is no other nerve closer to activate this muscle

what are the different gluteal lines on the ilium?

-there is the posterior gluteal line, which is just underneath the iliac crest (where gluteus medius starts)
-there is anterior gluteal line (where minimus originates)
-then lower and closer to acetabulum is the inferior gluteal line

What is the orgin, insertion, innervation, and action of the gluteus maximus?

-origin is dosral ilium, sacrum, and coccyx, so basically near midline of the iliuma nd where it connects to sacrum
-insertion is the iliotibila tract and gluteal tuberosity of femur (this is a tuberosity on posterior side of shaft)
-it acts as the major extensor of thigh and also laterally rotates and abducts the thigh (since it reaches out to IT band)
-innervation is inferior gluteal n

What is the orgin, insertion, innervation, and action of the gluteus medius

origin is between anterior and posterior gluteal lines on the lateral surface of ilium
-insertion is via a tendon into the greater trochanter of the femur (bit more on posterior side)
-action will be to abduct and medially rotate thigh; this will level pelvis during walking or when standing on one foot
-so abduct thigh, but also elevate opposite hip when lower limb is grounded
-innervation is superior gluteal n
-glut medius is actually multipennate, so broad origin and small insertion

What is the orgin, insertion, innervation, and action of the gluteus minimus

-origin is between anterior and inferior gluteal lines on external surface of ilium
-insertion is on greater trochanter of femur; more anterior then medius and may share part of same tendon as medius
-the action is abducting and medially rotating thigh and also steadying the pelvis in one legged stance; same as gluteus medius
-so abduct thigh, but also elevate opposite hip when lower limb is grounded
-innervation is superior gluteal nerve

clinical case: woman who just underwent hip surgery is limp when walking where right hip drops when in swing phase(so only left foot is on ground), aka trendelenburg sign/gait

-this is caused by weakness of the muscles that stabilize hip during gait or one legged stance, specifically the gluteus medius and minimus
-if right hip is dropping, the weakness is on left side
-with the right hip dropping, the left hip is adducting, so muscles that abduct are not strong enough to prevent this
-innervation is superior gluteal nerve

review: what are the ligaments holding the femur into the acetabulum?

-there is illiofemoral ligament (on anterior/superior side), this prevents overrotation in extension or flexion and also not to overly adduct the femur
-anteriorly there is pubofemoral ligament
-posteirorly there is ishiofemoral ligament
-all of these have a corkscrew like orientation to femur so that they would be more tight during extension

summary: what is the difference in action of the glut max vs glut med and min, vs the deep muscles of glut region

-glut max: thigh extension and lateral rotation
-glut med and min: thigh abduction and medial rotation
-deep muscles: main function is external rotation of femur; they insert kind of anterior to femur which allows them to pull femur into external rotation

what is the name of the lateral rotators of the gluteal region? what order so they go in? what is their function depending on orientation of hip

-these muscles all laterally rotate an extended femur
-when hip is flexed, these would abduct the femur (except quadratus femoris which would adduct)
-from superior to inferior, the order is: piriformis, superior gemellus, obturator internus, inferior gemellus, then quadratus femoris

what is origin, insertion, innervation and function of piriformis

-origin is on anterior sacrum, then exists pelvis via the greater sciatic foramen, then inserts onto anterior part of greater trochanter
-innervation is nerve to piriformis
-function is lateralt rotation of thigh, abduction of thigh(very little), and stabilization of hip (compresses joint capsule)
-also major landmark for gluteal region bc sup and infer glut n exit around here along w sciatic nerve and some blood supply

what is origin, insertion,and function of superior and inferior gemellus, and quadratus femoris

-origin are different parts of the ischium (remember the order that they go in from superior to inferior)
-then gemelli muscles insert on greater trochanter (trochanteric fossa)
-then quadratus femoris inserts on intertrochanteric crest (posterior femur)
-we said this already, but function is lateral rotation of hip, abduction of thigh, and stabilization of hip

what is the different innervation of the lateral rotators of the gluteal region

-piriformis is nerve to piriformis
-superior gemellys and obturator internus is nerve to obturator internus
-inferior gemellus and quadratus femoris is nerve to quadratus femoris

explain the pathway of obturator internus in hip (we already know function and innervation)

-the obturator internus is arising inside the pelvis and covering the obturator foramen; more anterior and inferior compared to superior and posterior of pirirformis
-then to get to trochanteric fossa, the muscle will go through the lesser sciatic foramen (below supraspinous ligament) and this is how it gets to outside of pelvis ; kind of makes 90 degree angle
-reminder that pirifromis would come out greater sciatic foramen
-makes sense that this will pull femur laterally when contracted

what is piriformis syndrome?

since this is a major landmark and there is a lot of neurovasculature surrounding it, inflammatio of piriformis leads to compression of neighbouring structures
-symptoms include pain, numbness, tingling down LL or in gluteal region (could be impingment on sciatic nerve)
-common activities that required excessive use of gluteal muscles like running or ice skating could cause this

give innervation summary of gluteal region? where do all of these nerves pass in relation to piriformis

-there is pudendal nerve w leaves greater sciatic foramen and then goes into inferior sciatic forame to supply sensory to crotch area
-nerve to obturator internus also exits from greater sciatic foramen
-n to quadratus femoris (deep to lateral rotators) runs along w sciatic n (both of these have fibres L5-S1or S2
-posterior cutaneous n of thigh runs by sciatic nerve (S1-S3)
-obvi sciatic n runs underneath piriformis ( L4-S3)
-then there is sup glit n that goes above piriformis (L4,L5,S1)
-there is n to piriformis (L5, S1, S2)
-there is inferior glut n below the piriformis (L5, S1, S2)

how do we normally perform intramuscular injections in gluteal region?

-this is great injection site bc there is lot of muscle and is pretty easy to avoid piercing nerves
-spread hand over hip region by putting index finger on ASIS, and pinky on PSIS, then inject in space between index and middle finger
-the nerves in this region are very small and spread out, so not likely to hit anything

what is the blood supply of gluteal region? what muscles does each artery supply?

-there is superior gluteal artery which exits above piriformis like the nerve
-supplies glut maximus, gluteus medius and minimus, and tensor fascia latae
-inferior gluteal artery exits below the pirifromis, supplied the glut max(lower portion, then dives deeper), obturator internus and gemelli, quadratus femoris, superior portion of hamstrings
-the source of these is the internal iliac artery

what are the muscles of the posterior compartment? what 4 characteristics do they share?

-these form the hamstrings, they are long and most cover the entire length of posterior compartment of thigh
-in general cause extensio of hip and flexion of knee
-there is biceps femoris (most lateral, has long and short heads)
-semitendinosus (medial to biceps femoris)
-semimembranosus ( deep to others)
-4 characteristics they share: all originate from ischial tuberosity
#2 all corss the knee and hip joint, so contribute to more actions
#3 all act to extend the thigh and flex the knee (since they cross both joints)
#4 all innervated by branch of sciatic nerve

what is origin, innervation, and insertion, and action of biceps femoris

-origin: long head from ischial tuberosity and linea aspera; the short head from distal femur (on linea aspera too)
-insertion: common tendon of two heads inserts into the head of fibula and lateral condyle of tibia
-action: extends thigh and flexes knee, laterally rotates lef bc it pulls from posterior lateral side which would externally rotate the knee
-innervation: sciatic nerve division; common tibia n to long head and common fibular (peroneal) n to short head

what is origin, innervation, and insertion, and action of semimembranous

-gets the name bc has very long membranous pieces around the origin and insertion
-origin is ischial tuberosity
-insertion is medial condyle of tibia to lateral condyle of femur? (but mostly think of this as crossing the knee
-action: extends thigh and flexes the knee, medially rotates the leg (tertiary action)
-innervation: tibial branch of sciatic nerve

what is origin, innervation, and insertion, and action of semitendinosus

-underneath semimembranosus!
-origin is ischial tuberosity
-insertion is medial aspect of upper tibial shaft, the pes anserinus!
-action: extends the thigh at hip and flexes knee, and medially rotates leg (tertiary action again)
-innervation is tibial branch of sciatic nerve

explain the pathway of the sciatic nerve in posterior compartment

sciatic nerve from L4-S3 carries sensory, motor, and autonomic fibres passing w blood vessels too
-usually passes underneath piriformis, but there is a lot of variation in this where part can pierce piriformis, go above etc
-the sciatin nerve consists of 2 nerves bundles together: the tibial n and common peroneal (fibular) n, they normally split by knee but there is variation to where they split as well
-this nerve is so large that is also has its own blood suppky (artery to sciatic n)
-nerve passes under and between the hamstring muscles

what is the blood supply to the posterior compartment

-remember that femoral artery on anterior compartment serves the posterior compartment using the perforating arteries (from femora produnda), so serves hamstrigs bfrom underside
-there is also the superio and inferior glut arteries that have small branches to superior part of hamstrings

which nerve innervates which sections of the leg?

most of these are mixed nerves, so innervating muscles then rising superficially to innervate skin too

how do we stand at ease and expend so little energy?

-when we are standing w feet slightly apart, toes pointed, your weight is distributed around centre of gravity (aka centroid)
-this position requires only a few active muscles to maintain, because knee and hips are extended to most stable positions and there is max bone to bone surface contact; the supporting ligaments are also taught so there is stability without muscles needing to contract
-then there are minor postural adjustments made via back muscles, pelvis and calf muscles driven particularly by proprioception (or vision or vestibular system)

what is proprioception?

-aka kinesthesia, is body's ability to communicate with itself
-so tells us where body and limbs are in relation to itself
-this gives us a sense of limb movement(so we know where to move limb without looking at it), sense of joint angles individually and relative to other joints
-this gives us really good control of limbs and precise location knowledge
-there is proprioceptive apparatus oresent in every muscle and joint (ex golgi tendon apparatus, stretch receptors on joint capsule + tendons+ ligaments, and gamma motor units in muscle (for tension))

what is Hilton's law?

-the nerve supplying the muscle extending directly across and acting at a given joint not only supplies the muscle, but also innervates the joint and the skin overlying the muscle

what type of articular cartilage is commonly found in synovial joints?

-this is found on end of the two bones of the joint
-normally made out of hyaline cartilage, which is 1/3 of cartilage types (fibro and elastic cartilage are others)
-it is very glossy, so super low coefficient of resistance
-hyaline is the most abundant type
-but it is not generally repairable, so if damaged then other types of cartilage would go in place

what are the components of an articular capsule? what is inside the joint capsule?

-the articular capsule is a joint bag, so its touch on outside, but soft on the inside
-it is made of fibrous capsule on outside and the inside is lined w synovial membrane, which produces the synovial fluid
-synovial fluid stays in joint cavity and lubricated and nourished avascular joint surfaces (so dont get blood flow)

what are the additional structures that may be present in a synovial joint?

1. articular disk that goes in between the bones; example is menisci in knee or intervetebral discs in spine
2. intracapsular (within capsule) and extracapsular (outside capsule) ligaments
-bigger and more complex joints have thickenings of the joint capsule to prevent it from going in extreme ranges of motion
-

explain the hip joint blood supply

-there is the obturator artery, which is a branch of internal iliac artery; it has a branch that goes to head of femur called the artery to head of femur
-travel via the round ligament (ligamentum teres) to go to fovea to connect to head of femur

identify the hip joint blood supply in this picture

-left section superior to inferior, then right section superior to inferior
1. superior gluteal artery above piriformis
2. inferior gluteal artery, exit below piriformis and could make collateral flow situation w superior one
3. lateral circumflex artery
4. medial circumflex artery, moves towards obturator foramen then goes around head of femur
-on posterior side, its the same 4 vessels but have medial one as 3rd position

what are the 2 joints that are within the knee

-this is a complex synovial joint consisting of both a hinge (femoro-tibial) and a plane (femoro-patellar)
-so gives flexion/extension, then also gliding of patella on top of femur
-this joint also has a joint space between bones, filled w fluid, hyaline cartilage, and menisci

what contributes to knee joint stability?

the bony fit in this joint is really bad, so depends on other things
1. strength and actions of surrounding muscles
2. ligaments connecting femur to tibia and fibula

explain what muscles surround the knee

-there is quadriceps tendon that connects to patella, then patellar ligament that connects to tibial tuberosity
-on lateralanterior side, there is IT band connecting to tibia
-on medial side, there is semitendinosis, gracilis, and sartorius inserting at pes anserinus
-posteriorly, there is semimbranous on medial side of tibia and biceps femoris inserting to fibula
-for lower leg muscles, there is also popliteus and gastrocnemisu that aid stability

what is the pneumonic for pes anserinus muscle locations and their innervations?

SGT FOT (sergeant FOT)
-so from anterior to medial, goes Sartorius, Gracilis, then semiTendinosus
-innervation is F-femoral nerve, O - obturator, T-tibial nerve