Sem 2 RA week 2 Flashcards

Question

Pelvis formed from? Features?

Answer 1

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

Answer 2

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)

Answer 3

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

Answer 4

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

Answer 5

Combination of **plane synovial joint** anteriorly protected by the anterior sacroiliac ligament + a **fibrous joint** supported by the posterior sacroiliac ligament posteriorly

Answer 6

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)

Answer 7

Iliacus Psoas Obturator externus Obturator internus Piriformis

Answer 8

Originates from iliac fossa of iliac blade → joins psoas as iliopsoas and inserts into lesser trochanter of femur Function = hip flexion Innervation = femoral nerve

Answer 9

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

Answer 10

External surface of obturator membrane to trochanteric fossa of femur

Answer 11

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

Answer 12

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

Answer 13

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.

Answer 14

muscular floor to prevent prolapse pelvic diapragm = levator ani (anteriorly) + coccygeus (posteriorly) levator ani is miscular roof of the anal triangle

Answer 15

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)

Answer 16

Divided into 2 parts: ## Footnote **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

Answer 17

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.

Answer 18

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

Answer 19

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)

Answer 20

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

Answer 21

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.

Answer 22

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

Answer 23

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.

Answer 24

**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

Answer 25

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.

Answer 26

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.

Answer 27

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

Answer 28

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

Answer 29

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

Answer 30

superficial inguinal lymph nodes

Answer 31

most is from femoral nerve (anterior cutaneous)

Answer 32

called fascia latae in thigh but crural fascia in leg

Answer 33

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

Answer 34

inguinal ligament (base) sartorius (laterally) adductor longus (medially) iliopsoas + pectinues (floor)

Answer 35

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)

Answer 36

potential space medially **within** femoral sheath contains fat and lymphatic vessels

Answer 37

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.

Answer 38

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.

Answer 39

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.

Answer 40

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.

Answer 41

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.

Answer 42

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.

Answer 43

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.

Answer 44

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.

Answer 45

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.

Answer 46

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.

Answer 47

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.

Answer 48

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.

Answer 49

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.

Answer 50

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.

Answer 51

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.

Answer 52

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.

Answer 53

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.

Answer 54

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.

Answer 55

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.