Sem 2 RA week 2 Flashcards
Lumbosacral plexus?
Sacral plexus?
L4 + L5 nerve roots form a lumbosacral trunk that joins S1 nerve root at the start of the sacral plexus
The sacral component of the plexus is formed from S1 to S4 roots
Largest nerve in sacral plexus?
Roots?
Pathway?
Identified?
Function?
Sciatic nerve
L4-S3
Forms on anterior surface of piriformis muscle on lateral internal wall of the pelvis → passes out of pelvis via greater sciatic notch into gluteal region
Easy to identify in gluteal region = very large nerve passing from beneath piriformis to posterior surface of thigh
Function = supplies posterior compartment of thigh (hamstrings) + divides into branches that supply all muscles of the leg and foot, also carries sensory fibres
Gluteal nerves?
Roots?
Function?
superior (L4, L5, S1) + Inferior (L5, S1, S2) gluteal nerves = supply gluteal muscles
Superior = supplies gluteus medius + minimus
Inferior = supplies gluteus maximus
superior (L4, L5, S1) + Inferior (L5, S1, S2) gluteal nerves = supply gluteal muscles
Superior = supplies gluteus medius + minimus
Inferior = supplies gluteus maximus
Nerve to obturator internus roots?
Function?
Roots = direct L5-S1
Function = supplies obturator internus + superior gemellus muscle
Nerve to piriformis function?
Roots?
Supplies piriformis muscle
Roots = S1-S2
Levator ani + coccygeus innervated by?
Roots?
Levator ani = pudendal nerve + nerve to levator ani (direct S4)
Coccygeus = nerve to coccygeus (S4, S5)
Pudendal nerve function?
Roots?
Pathway?
Landmark?
Supplies external (voluntary) urethral sphincter + anal canal (so important in maintenance of continence), levator ani, bulbospongiosus, ischocavernosus - also sensory fibres to perineum
roots = S2-S4
Pathway = from S2-S4 nerve roots close to pelvic floor → through greater sciatic foramen → aaround ischial spine → through lesser sciatic foramen → ischioanal (rectal) fossa → perineum
ischial spine used as landmark during pudendal nerve block
Erectile tissues of perineum supplied by?
Specifically?
Found?
Supplied by autonomic nerves
superior hypogastric plexus = sympathetic, sits at bifurcation of aorta into common iliac arteries
inferior hypogastric plexus = mix of symp. + parasymp., sits on internal lateral wall of pelvis (one each side)
Sympathetic supply to pelvic organs?
Roots? Function?
Sympathetic supply to the pelvic organs = lumbar and sacral splanchnic nerves derived from the sympathetic chains
Pelvic splanchnic nerves = roots S2 to S4, supply parasympathetic innervation to the pelvis
The diagram shows the interaction with the superior and inferior hypogastric plexus, in life there are splanchnic nerves on the left and right sides.
Sympathetic response pelvic organs?
i.e. rectum, sphincters, bladder, vas deferens, uterus, arteries
Rectum = decrease movement
Contract internal anal + urethral sphincters
Relax bladder detrusor
Ejaculation = contract ductus deferens + seminal vesicles
Uterus = relax/contract (hormonal)
Vasoconstriction of arteries
Parasympathetic supply pelvis?
parasympathetic response pelvic organs?
i.e. rectum, sphincters, bladder, vas deferens, uterus, arteries
Pelvic splanchnic nervs S2, S3, S4
Increase motility of rectum + anal canal
Relax internal anal sphincter
Bladder = contracts detrusor + inhibits contraction of internal sphincter
no effect on seminal vesicles, ductus deferens or uterus
vasodilaton of arteries = erection
Nerve supply of perineum (male)?
Note - pudendal nerve carries both motor and sensory fibres
Nerves of perineum (female)?
Large role played by pudendal nerve
Dermatomes perineum?
Named sensory nerves?
Sacral nerves supply perineum
Sensory to anterior skin = ilioinguinal, genitofemoral + pudendal
Pudendal = sensory to genitalia
Aorta bifurcates into? Where?
Further divisions
Blood supply to pelvis?
@L4 aort bifurcates into common iliac arteries
Common iliac arteries divide into internal + external iliac arteries
Blood supply to pelvis = internal iliac arteries, each internal iliac artery further divides into anterior + posterior division
Vessels of pelvis?
Branches of anterior division of internal iliac artery?
Umbilical artery ends as piece of connective tissue but before this - gives off arteries that supply bladder → superior vesical arteries
Obturator artery passes through obturator foramen and into medial compartment of thigh - this vessel is often absent, instead a small vessel crosses superior ramus of pubic bone from femoral or external iliac arteries + passes through obturator foramen
Inferior vesical artery usually replaced by vaginal/uterine artery in female
Middle rectal artery supplies rectum in both sexes + prostate gland in males
Inferior gluteal artery passes through greater sciatic notch to supply gluteal region
Final branch is internal pudendal artery - gives inferior rectal artery in anal triangle + several branches to perineum
Branches of anterior division of internal iliac artery in MALES?
Prostate, seminal vesicles + ductus deferens = supplied by inferior vesical + middle rectal arteries
Testis = testicular artery from abdominal aorta @L2 (i.e. NOT internal iliac)
Branches of anterior division of internal iliac artery in FEMALES?
Ovaries = ovarian arteries from abdominal aorta @L2
Bladder = inferior vesical artery does not exist in females but instead is replaced by vaginal or uterine arteries that also supply the bladder
Distal parts of vagina = supplied by perineal branches of internal pudendal artery
Branches of posterior division of internal iliac artery?
Iliolumbar artery = supplies part of posterior abdominal wall
Lateral sacral artery = vertebral canal
Superior gluteal artery = gluteal region
Summary of pelvic arteries
Note: majority of pelvic organs supplied by branches of internal iliac artry
Also note: many structures supplied by more than one vessel
Veins of pelvis?
Correspond to arteries i.e. drain into internal iliac veins
There are also small venous plexus associated with some pelvic structures e.g. prostate gland, rectum + sacrum
Boundaries of the pelvis?
Anterior = pubic bodies, pubic rami, pubic symphysis
Posterior = sacrum, coccyx, piriformis
Floor = pelvic diaphragm
Roof = open to abdominal cavity
Pelvis formed from?
Features?
2 innominate bones that articulate with eachother + the sacrum
Features:
- Greater + lesser sciatic notches → allow passage of nerves, arteries, veins, muscles from internal surface of pelvis to perineum (turned into foramina by presence of ligaments)
- Obturator foramen → almost completely closed by obturator internus, obturator externus + obturator membrane, they are pierced by obturator nerve and vessels
- Ischial spine = provides attachment site for muscles e.g. coccygeus, also important landmark for pudendal nerve
- Acetabulum = synovial ball and socket joint formed with femur
Iliac blades?
Iliac crest?
ASIS?
AIIS?
Pubic tubercle?
Lumbosacral joint + pubic symphysis?
Iliac blades = muscle attachment for iliacus anteriorly + gluteal muscles posteriorly
Iliac crest = attachment for muscles of abdominal wall
ASIS = attachment for sartorius muscle + inguinal ligament
AIIS = attachment for rectus femoris
Pubic tubercle = attachment for inguinal ligament
Lumbosacral joint + pubic symphysis = both 2ry cartilagenous joints (allow cushioning of stresses passing into pelvis)
Sacrum formed from?
Articulates with?
Sacral foramina?
Bony sacrum formed from 5 fused vertebra and articulates with L5 vertebrae + the coccyx
Sacral nerves pass through sacral foramina to exit vertebral column and supply structures within pelvis and lower limb
Sacral ligaments?
Attachments?
Function?
Inguinal ligament formed from? Attachments?
2 large ligaments attach to sacrum = sacrotuberous + sacrospinous ligaments
Sacrotuberous = passes from sacrum to ischial tuberosity
Sacrospinous = passes from sacrum to ishcial spine
They form the posterior boundaries of greater + lesser sciatic foramina
Inguinal ligament formed by aponeurosis of external oblique, attaches from ASIS to pubic tubercle
Sacroiliac joints?
Combination of plane synovial joint anteriorly protected by the anterior sacroiliac ligament + a fibrous joint supported by the posterior sacroiliac ligament posteriorly
Male and female pelvic morphology?
Features of female pelvis?
Pelvic inlet/outlet shapes?
Male and female pelvic morphology differs due to childbirth
There are several features that increase the internal diameter of the pelvis in a female – pubic angle at pubic symphysis is wider, ischial spines do not protrude into pelvic cavity as much + the sacrum is flatter when compared to male
There is variation of shape of the pelvic inlet and outlet in females. Classic female shape at the pelvic inlet is described as gynecoid
Class male pattern is android
There are also shapes such as a more flattened inlet (in AP direction) called a platypelloid shape
And inlet that is wider in AP direction called an anthropoid shape (similar to shape seen in apes)
Pelvic wall muscles?
Iliacus
Psoas
Obturator externus
Obturator internus
Piriformis
Iliacus pathway?
Function?
Innervation?
Originates from iliac fossa of iliac blade → joins psoas as iliopsoas and inserts into lesser trochanter of femur
Function = hip flexion
Innervation = femoral nerve
Psoas pathway?
Function?
Innervation?
Originates from T12-L4 VBs (superficial) and L1-L5 (deep) → join iliacus as iliopsoas and insert into lesser trochanter of femur
Function = hip flexion, bend trunk laterally (one), raise trunk from supine position (both)
Innervation = lumbar plexus direct branches L2-4 anterior rami
Obturator externus attachments?
External surface of obturator membrane to trochanteric fossa of femur
Obturator internus attachments?
Gluteal region?
Function?
Innervation?
Fascia?
From internal surface obturator membrane to → through lesser sciatic notch → medial surface of greater trochanter of femur
When seen in gluteal region it is only a tendon but is closely associated with superior + inferior gemelli muscles (lie either side)
Function = lateral rotation of hip + supports lateral pelvic wall by covering opening of obturator foramen
Innervation = nerve to obturator internus direct from sacral plexus (L5, S1)
thickened fascia above obturator internus provides an attachment site for iliococcygeus part of levator ani
Piriformis attachments?
function?
Innervation?
Landmark?
Originates from anterior surface of sacrum → through greater sciatic foramen → gluteal region to reach greater trochanter of femur
Function = lateral rotation of hip + supports pelvic wall by partially covering opening of greater sciatic foramen
Innervation = nerve to piriformis direct branch of sacral plexus (S1, S2)
Piriformis is useful landmark in gluteal region = superior and inferior gluteal nerves + vessels lie either side of piriformis, sciatic nerve also descends from greater sciatic notch beneath it
Also landmark in pelvic region = sciatic nerve and pudendal nerve on superior surface
This slide shows the lateral pelvic wall in a Thielembalmed cadaver. Piriformis and the sciatic nerve seem to disappear as they pass out of the pelvis through the greater sciatic foramen to reach the gluteal region.
This concludes this presentation, the next presentation describes the structures of the pelvic floor.
pelvic diaphragm function?
What is it? + specific?
muscular floor to prevent prolapse
pelvic diapragm = levator ani (anteriorly) + coccygeus (posteriorly)
levator ani is miscular roof of the anal triangle
coccygeus attachments?
function?
Innervation?
attach = from ischial spine + sacrospinous lig → coccyx and inferior sacrum
flexes coccyx + forms posterior part of pelvis floor = supports pelvic viscera
innervation = direct branches from sacral plexus (S4, S5)
Levator ani made up of?
further divided?
Function?
Innervation?
Divided into 2 parts:
Pubococcygeus = most medial, wrap around and support vagina/prostate gland + rectum
Iliococcygeus = lateral, anterior to coccygeus (fills space between pubococcygeus + coccygeus)
pubococcygeus divided into puborectalis, levator prostate (puboprostaticus) + pubovaginalis
function LA = supports pelvic organs (contract during forced expiration/coughing), relaxes to allow urination + defecation
Innevration LA = nerve to levator ani + pudendal nerve
The slide shows levatorani and coccygeus filling the space between the bones of the pelvis to create a diaphragm in the floor of the pelvis. Structures in the ‘gap’ near the pubic bones are supported by the urogenital diaphragm. The diagram on the right shows pubococcygeus medially, iliococcygeus more laterally (and posterior) that together form levatorani.
Attachments pubococcygeus?
Innervation?
Males = most medial fibres pass around prostate and insert into perineal body = levator prostatae (puboprostaticus)
Females = most medial fibres pass around vagina and insert into perineal body = pubovaginalis
Both sexes = puborectalis
Motor innervation from pudendal nerve + nerve to levator ani
puborectalis attachment?
Importance?
Innervation?
fibres mix with external anal sphincter, modified as sling around the rectum to help maintain faecal continence
Especially important immediately after the rectum has filled (internal anal sphincter open)
Innervation = pudendal nerve (S2-4) and nerve to levator ani (S4)
Iliococcygeus attachment?
feature?
attachment area?
innervation?
attaches to fascia of obturator internus → annococcygeal body/ligament/levator plate
more fibrous than pubococcygeus
thickened fascia of obturator internus = tendinous arch of levator ani (to acknowledge its function as attachment site for iliococcygeus)
Innervation = pudendal nerve + nerve to levator ani
The slide shows a hemisectionof the pelvis of a Thielembalmed cadaver. The bladder has been reflected to reveal the muscular pelvic floor, the thin fibres of iliococcygeus can be seen passing medially from the fascia above obturator internus.
perineal body?
Function?
small piece of tough connective tissue that lies in the pelvic floor at the edge of the urogenital diaphragm between the openings of the vagina (female)/urethra (male) + the anal canal
Levator prostatae, pubovaginalis, external anal sphincter and perineal muscles attach here
The slide shows a transverse MRI of the pelvic floor. The red dotted line and arrow indicate the position of the fibres of puborectalis as they pass around the rectum.
Fascia of the pelvis?
Function?
Condensations?
Parietal pelvic fascia covering the internal wall – thickened over obturator internus to form tendinous arch of the pelvis (and levator ani)
anterior = puboprostatic ligament (male), pubovesical ligament (female)
visceral pelvic fascia = covers pelvic organs, parietnal and visceral blend as organs pierce the pelvic floor
lateral extension of visceral fascia from vagina to tendinous arch = paracolpium
Endopelvic fascia acts as a packing material around the organs, 2 basic types: loose and condensed
loose fills “spaces” in the pelvis e.g. retropubic (pre-vesical) space
condensations are thickenings of fascia, for example the primary condensation is the hypogastric sheaths running along the posterolateral walls of the pelvis
The slide shows how the fascia contributes to the strength and support of the pelvic structures in a female and that it communicates between bony attachment areas, the pelvic organs and the pelvic diaphragm. Damage to the muscles or fascia of the pelvis will weaken the pelvic floor and make prolapse of organs more likely.
This final slide is a reminder that the pelvic contents are subperitoneal – they are covered by a continuation of the peritoneal lining of the abdominal cavity, which forms pouches in females and males.
lumbar plexus nerves?
femoral branch of genitofemoral nerve = cutaneous innervation of parts of skin of lower limb
lat cutaneous = cutaneous innervation to the thigh
femoral = enters into anterior aspect of thigh, supplies muscles of ant compartment + cutaneosu branches
obturator nerve = travels along lateral wall of the pelvis to supply medial compartment of the thigh, gives both motor + sensory branches
lumbosacral trunk = L4 + L5 will unite with S1-S3 to form sciatic nerve which will pass into gluteal region (without supplying anything), supplies structures in posterior thigh + leg
How does sciatic nerve enter lower limb?
Gluteal nerves + vessels?
Obturator nerve + vessels?
Femoral nerve + vessels?
sciatic nerve = passes through greater sciatic foramen
gluteal nerves and vessels travel with sciatic nerve through greater sciatic foramen
femoral nerve passes deep to inguinal ligament in subinguinal space, accompanied by femoral artery + vein
obturator nerve travels along lateral wall of pelvis through obturator canal to enter medial compartment
femoral + obturator nerve roots?
supply?
sciatic nerve roots?
supply?
superficial veins of lower limb?
what drains into great saphenous vein?
what will you see in some individuals?
pathway?
2 main superficial veins: great + short saphenous veins
great saphenous begins on dosrum of the foot just proximal to the great toe, passes anterior to medial malleolus, travels up medial side of leg, will pass more posteriorly at knee joint, pass up to anteromedial aspect of thigh passing around to empty into the femoral vein
superficial circumflex iliac + superficial epigastric vein drain into great saphenous + into femoral vein directly
in some individuals will see accessory saphenous vein coming anteriorly from the thigh and draining into great saphenous
short saphenous vein only found in foot + leg - passes behind lateral malleolus, midline posterior aspect of leg, drains into popliteal vein behind knee joint
nodes of the lower limb?
groups?
superficial inguinal lymph nodes
cutaneous innervation anterior thigh?
most is from femoral nerve (anterior cutaneous)
deep fascia of the lower limb?
attachments?
function?
called fascia latae in thigh
but crural fascia in leg
femoral triangle?
roof?
deficient area of fascia latae?
triangular shape on upper anterior thigh
roof = fascia latae, cribriform fascia, subcutaneous tissue, skin
saphenous hiatus = cribriform fascia, great saphenous vein drains to femoral vein in this area
boundaries of the femoral triangle?
inguinal ligament (base)
sartorius (laterally)
adductor longus (medially)
iliopsoas + pectinues (floor)
Contents of the femoral triangle?
femoral sheath?
blends with?
important to note?
fascia surrounding vascular structures
blends superiorly with transversalis + iliopsoas fascia
blends inferiorly with adventitia of femoral vessels
Note: femoral nerve is NOT part of femoral sheath, more closely associated with iliopsoas muscle, will enter anterior thigh on surface of iliopsoas
(in pic can also see great saphenous vein coming through saphenous hiatus)
femoral sheath?
femoral canal?
Contents?
potential space medially within femoral sheath
contains fat and lymphatic vessels
Although you will concentrate on the nerves and branches of the internal iliac arteries during dissection, there are also branches of the internal iliac veins present in the pelvis. The photograph shows the veins which are usually flatter in shape and darker in colour than the arteries. The smaller veins are given equivalent names to their arterial counterparts and there are venous plexus associated with structures such as the prostate gland. The blood from the pelvic organs drains into the internal iliac veins, then the common iliac veins to reach the inferior vena cava. The exceptions are the ovaries/testes which drain via gonadal veins to the inferior vena cava on the right and to the renal vein on the left side. The superior parts of the rectum drain into the inferior mesenteric vein and therefore into the portal vein – creating a portal-systemic anastomosis.
The aorta bifurcates at L4 into the left and right common iliac arteries. Each common iliac artery then divides into an external iliac and an internal iliac artery (shown in photograph A). The external iliac artery supplies the lower limb and the internal iliac artery supplies most of the structures found in the pelvis. To do this, it first divides into an anterior and a posterior division (shown in photograph B).
This is a standard pattern of division and the following description of the branches of the each division also follows the standard textbook description. In the DR it is apparent that many variations from this pattern exist. It is therefore easier to remove all of the fat and fascia from around the vessels before attempting to identify each branch.
The first branch of the anterior division of the internal iliac artery is the umbilical artery. This vessel becomes fibrous in an adult and passes towards the anterior abdominal wall. Before it does this, it forms several superior vesical branches that supply the bladder. This is shown in photograph A. The second branch is usually the obturator artery but in the individual shown in photograph A the obturator artery showed a variation, forming instead from the external iliac artery (shown on the next slide).
As the anterior division descends into the pelvic cavity it forms middle rectal arteries in both sexes and the uterine or vaginal branches in females and an inferior vesical artery in males (shown in photograph B). The inferior vesical artery supplies the seminal vesicles and the prostate gland in addition to the bladder.
A common variant of the obturator artery is shown in photograph A. The obturator artery originates from the external iliac artery instead of the anterior division of the internal iliac artery. It crosses the superior pubic ramus to reach the obturator foramen and pass through the foramen to reach the medial compartment of the thigh. Whether the artery originates from the internal or external iliac artery it will still pass through the obturator foramen and so can be identified as it does this and then traced back to its point of origin. Photograph B shows the obturator artery, vein and nerve as they cross the superior surface of obturator internus to reach the obturator foramen.
The final branches of the anterior division are the inferior gluteal and internal pudendal branches. The internal pudendal artery is shown in photograph A passing towards the ischial spine. It will follow the pudendal nerve to supply inferior rectal branches in the anal triangle and then perineal branches in the urogenital triangle. The inferior gluteal artery passes through the greater sciatic foramen between the S2 and S3 nerve roots that contribute to the sciatic nerve (shown in photograph B) to supply the gluteal region and muscles of the pelvic floor.
Photograph A shows the posterior division of the internal iliac artery (labelled P on the image). Photograph B shows the first branch of the posterior division – the iliolumbar artery that supplies muscles of the posterior abdominal wall.
The other small branch of the posterior division is the lateral sacral artery shown in photograph A. It supplies the vertebral canal and piriformis. Photographs A and B show the superior gluteal artery. It is usually the largest branch of the posterior division. It passes between the S1 and S2 nerve roots of the sciatic nerve to exit the pelvis via the greater sciatic foramen to supply the muscles of the pelvic floor and gluteal region.
The sacral plexus forms from nerve roots S1 to S4. It also receives a contribution from L4 and L5 via the lumbosacral trunk. Although there are many small branches of the sacral plexus, the easiest to identify during dissection of the pelvic cavity are the sciatic nerve and the pudendal nerve. The superior and inferior gluteal nerves are easier to identify during dissection of the gluteal region. The nerves to obturator internus and piriformis are direct branches of the nerve roots that pierce the muscles and are therefore not as simple to identify.
Photograph A shows the formation of the large sciatic nerve from the lumbosacral trunk (L4,L5) and sacral roots S1 to S3. It exits the pelvis via the greater sciatic foramen to reach the gluteal region and then pass down the posterior surface of the thigh. It supplies the muscles of the posterior compartment of the thigh and via its branches all of the muscles of the leg and foot. It will be described further during the lower limb dissection presentations.
The pudendal nerve is shown in photograph B forming from nerve roots S2 to S4. It is the main nerve of the pelvic floor and perineum, supplying both motor and sensory innervation. It passes through the greater sciatic foramen, wraps around the ischial spine and then passes through the lesser sciatic foramen. It forms the inferior rectal nerve in the anal triangle to supply levator ani and the external anal sphincter. Motor supply to the small muscles of the perineum (deep and superficial transverse perineal muscles, bulbospongiosus and ischiocavernosus) is from perineal branches of the pudendal nerve.
Iliacus and psoas both contribute to the musculature of the pelvic walls but both unite to form iliopsoas, attach to the lesser trochanter of the femur and act to flex the hip. You have already observed these muscles during dissection of the posterior abdominal wall.
Obturator internus muscle covers the internal surface of the obturator membrane and sends its tendon through the lesser sciatic foramen to pass into the gluteal region. It is a small lateral rotator of the hip joint and will be discussed further during dissection of the gluteal region as part of your lower limb presentations. The fascia above obturator internus is thickened and provides an attachment site for iliococcygeus – it is described as the tendinous arch of levator ani due to this relationship.
There is an obturator externus muscle on the outer surface of the obturator membrane and this will also be described further during your lower limb presentations.
The sciatic nerve seems to disappear beneath obturator internus as it exits the pelvis through the greater sciatic foramen. The sciatic nerve forms above piriformis muscle, which also passes through the greater sciatic foramen and helps to support the pelvic floor in this area as it does so. Piriformis attaches to the anterior surface of the sacrum, passes through the greater sciatic foramen and then into the gluteal region. It is a small lateral rotator of the hip and will be discussed further during the lower limb presentations.
The floor of the pelvis is formed by a muscular sheet called the pelvic diaphragm (shown in photographs A and B). It passes from the pubic bones, around the openings formed by the vagina and anal canal and attaches to the perineal body and coccyx. It is divided into 2 parts – levator ani and coccygeus.
Coccygeus forms the most posterior part of the pelvic diaphragm. It attaches to the ischial spine and sacrospinous ligament to insert into the sacrum and coccyx. The photograph shows coccygeus as it is commonly seen in elderly individuals – as a thin, semi fibrous sheet. Coccygeus support the pelvic viscera and also acts to flex the coccyx. It is innervated by direct branches of S4 and S5.
Levator ani is the more anterior part of the pelvic diaphragm and can be divided into two main parts, pubococcygeus and iliococcygeus.
Pubococcygeus forms the more medial fibres that pass from the pubic bones and cross the pelvic floor to surround the vagina/prostate gland and the anal canal (shown in photograph A). Fibres of pubococcygeus insert into the perineal body at the posterior border of the urogenital triangle. Different parts of pubococcygeus are given different names, fibres that support the vagina are called pubovaginalis, fibres that support the prostate gland are called puboprostaticus or levatore prostatae. The fibres that wrap around the rectum are called puborectalis and act to bend the rectum to aid faecal continence.
The more lateral part of levator ani is called iliococcygeus (shown in photograph B). It attaches to the thickened fascia above obturator internus and the anococcygeal body or ligament. It supports the pelvic viscera.
Levator ani is innervated by the nerve to levator ani and the pudendal nerve.
Photograph A shows the skin of the anterior thigh of a left thigh, this particular individual was used for training by orthopaedic surgeons and so has an incision at the knee and also in the femoral region that was used as part of the embalming process. If your cadaver has an incision in the femoral region, you may be able to identify the femoral artery more easily as there will be evidence of the access point used to add embalming fluid to this vessel. The area outlined by the black dots shows the area of the femoral triangle.
Photograph B shows the skin removed from a right thigh, the great saphenous vein runs along the medial surface of the thigh and drains into the femoral vein at the femoral triangle.
Photograph A shows the boundaries of the femoral triangle – sartorius is lateral, adductor longus is medial and the base of the triangle is formed by the inguinal ligament. Iliopsoas and pectineus contribute to the floor of the triangle. The fascia that forms the roof has been removed to show the neurovascular structures that lie within the triangle.
Photograph B shows this fascia intact and also some lymph nodes present medial to the femoral vessels.
The contents of the femoral triangle from medial to lateral are: the femoral vein, the femoral artery and the femoral nerve. The femoral nerve is the nerve of the anterior compartment of the thigh and so divides into many branches, including a saphenous nerve that leaves the anterior compartment to innervate skin on the medial side of the leg. The femoral artery supplies the anterior compartment and then becomes the popliteal artery posterior to the knee. It forms several branches in the thigh, including profounda femoris which can be seen in this photograph (labelled PF). The popliteal vein becomes the femoral vein; the femoral vein drains blood from the thigh and is also joined by the great saphenous vein in the femoral triangle. The great saphenous vein is a superficial vein that drains blood from the medial side of the dorsum of the foot, the medial side of the leg and the medial side of the thigh.
As you dissect the lower limb you will see it is divided into compartments. It is easier to learn the structures in each compartment instead of trying to learn all of the structures in several compartments at the same time.
The anterior compartment (photograph A) contains the quadriceps muscle and acts to extend the knee and flex the hip – femoral nerve innervation
The posterior compartment (photograph B) contains the hamstrings and acts to extend the hip and flex the knee – sciatic nerve innervation
The medial compartment (photograph C) contains the adductors and acts to adduct the thigh – obturator nerve innervation
The lateral side of the thigh is mainly composed of tough connective tissue – the iliotibial tract and tensor fascia latae muscle
Remember that the entire limb is called the lower limb, the part between the hip and knee is called the thigh, the part between the knee and ankle is called the leg and finally there is the foot which is divided into dorsal and plantar surfaces.
