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39. Bones, muscles and ligaments of the pelvis. The blood vessels and nerves of the pelvis. The bone tissue. Gastrulation, early differentiation of the intraembryonic mesoderm

9 Jan

39. Bones, muscles and ligaments of the pelvis. The blood vessels and nerves of the pelvis. The bone tissue. Gastrulation, early differentiation of the intraembryonic mesoderm

Flash Cards:

Bones of Pelvis

Bones of Pelvis

Bones of Pelvis 2 - sciatic foramens

Bones of Pelvis 2 - sciatic foramens

Blood Supply of Pelvis

Blood Supply of Pelvis

Blood Supply 2

Blood Supply 2

Nerve Supply of Penis

Nerve Supply of Penis

Autonomic Nerves of Pelvis

Autonomic Nerves of Pelvis

Anatomy: Bones, muscles and ligaments of the pelvis. The blood vessels and nerves of the pelvis.

Bones & Ligaments of Pelvis

Pelvis bony girdle
2 hip bones = ox coxae, = 3 bones fused together = ilium, ischium, pubis
sacrum
coccyx

Pelvic Diameters of female: important for birthing processes

  • Conjugate diameters – b/w symphysis and sacral promontory = 11cm
  • Tranverse diameters – mid point of brim on each side  = 13cm
  • Oblique diameters – iliopubic eminence –> sacroiliac joint = 17.5cm
  • To set axis correctly = ASIS +pubic tubercle in vertical line

diameters-of-pelvis


Structures to show on pelvic girdle:

  1. Pubic symphyis
  2. Iliac crest
  3. Ant sup iliac spine (attachment of inguinal lig, plus part of way to find McBurney’s pt)
  4. Greater/Lesser sciatic forament
  5. sacral promontory
  6. ischio pubic rami
  7. inf pubic rami
  8. obturator foramen
  9. acetabulum
  10. ischial spine
  11. ischial tuberosities

Pelvic Girdle

Pelvic Girdle

parts-of-hip-bones
Divided by pelvic brim:

false pelvis above = b/w iliac wings
true pelvis below = b/w pelvic brim and outlet

Pelvic brim = pelvic inlet

Borders:

  • post = sacral promontory, massa lata of sacrum
  • lat/post =arcuate line of ilum
  • lat/ant = iliopubic eminence, then pectinate line
  • ant = pubic crest, pubic symphysis


Pelvic Outlet

  • ant = inf border of pubic symphysis, arcuate ligament, inf pubic rami (making subpubic angle)
  • lat = ischial tuberosities, sacrotuberous ligaments
  • closed off by pelvic and urogenital diaphragms


M of wall of true pelvis:
*
Show these on speciment of dried pelvis:

  • piriformis – triangular shaped m, can identify b/c the tendon will go to gr. trochanter of femur, and you will sciatic n emerge below it
  • ob internus m – can identify b/c only n. running to obturator foramen on the inside of pelvic cavity, will wrap around and cover the obturator foramen
  • pelvic diaphragm = coccygeus + levator ani m – point to muscles that attach to coccyx
  • UG diaphragm = deep transverse perineal m, fascia *may not be able to show this*


Differences b/w Male & Female Pelvis

  • Bones thinner, smaller, lighter in female
  • Inlet heart shaped in male, oval in female – in male, sacral promontory juts into to lesser pelvis
  • Outlet larger in female > male
  • Pelvic cavity wider/shallower in female
  • subpubic angle < 90 degrees in male, and obtuse in female (>90)
    • **Good one to tell difference, if asked if pelvis is male or female
    • If the subpubic angle is the distance as you making a peace sign with your fingers = male
    • if it is the same as the angle b/w you spreading your thumb/forefinger = female
  • female sacrum shorter and wider than male
  • obturator foramen is oval or triangular in female and round in male

male-v-female-pelvis
Joints of Pelvis

  1. Lumbosacral joint b/w L5-sacrum, held by IV disk and supported by iliolumbar ligaments, iliolumbar a from int iliac a run next to this vertically
  2. Sacroiliac joint – synovial joint of plane type b/w articular cartilage of sacrum and ilium
    • ant/post sacroiliac ligaments
    • interossesus ligaments
    • transmit weight of body from vertebral column to pelvic girdle
  3. Sacrococcygeal joint – cartiliagenous joint b/w sacrum & coccyx
    • ant, post, lat sacrococygeus lig
  4. Pubic symphysis – fibrocartiliginous joint b.w pubic bones in medial plane, anteriorally


Major Ligaments of Pelvis
— good time to mention what goes thru gr/lsr sciatic foramen

  1. Sacrospinous – from sacrum –> ischial spine
  2. Sacrotuberous – from sacrum –> ischial tuberosities
  3. ant/post sacroiliac ligaments
  4. ant/post/lat sacrococcygeal lig
  5. ant longitudial lig – runs down front of vert bodies
  6. iliolumbar lig
  7. supraspinous lig

Pelvic ligaments ant view

Pelvic ligaments ant view

pelvic-ligaments-post
Greater Sciatic notch is split into 2 sciatic foramen via sacrospinous/ sacrotuberous ligament

Greater Sciatic foramen

  • Piriformis
  • sup/inf gluteal a/v/n
  • sciatic n * show this*
  • post femoral cut n
  • int pudendal a/v
  • pudendal n


NOTE – Piriformis m further separates the greater sciatic foramen into a supra/infrapiriformic hiatus.
The only structures that go thru suprapiriformic hiatus = sup gluteal a/v/n (Supra =superior)

Rest go thru infrapiriformic hiatus, as well as n to ob internus.

CLINICAL NOTE – Because of the emergence of these structures, anasthesia can only be given in the upper R quadrant of the gluteal region, so as not to paralyze any nerves, or harm blood supply

Lesser Sciatic Foramen

  • Ob internus
  • Int pudendal a/v
  • pudendal n


Remember: the pudendal structures come out of the greater sciatic foramen–> then turn around the ischial spine –> back in thru lesser sciatic foramen –> to Alcock’s canal running in the fascia over obturator int m in ischioanal fossa

Blood Supply of Pelvis

A. Int Iliac a – @ bifurcation of common iliac a, in front of sacroiliac joint, crossed in front by ureter @ pelvic brim

Post Division
: (3) = Iliolumbar a, Lat Sacral a, Sup Gluteal a
1. Iliolumbar a – sup/lat to iliac fossa, deep to psoas major, runs straight up, next to iliolumbar ligaments
Iliac br => iliacus m, ilium
Lumbar br => psoas major, quadratus lumborum

2. Lat sacral a – passes med, in front of sacral plexus, runs immediately to sacrum
spinal br (goes thru ant sacral formina) => spinal meninges, roots of sacral n, musc/skin overlying the sacrum

3.Sup gluteal a – b/w lumbosacral trunk + 1st sacral n
-leaves pelvis thru gr sciatic foramen above piriformis m
=> m. of buttocks

Ant Division (8) = Inf gluteal a, int pudendal, umbilical a, obturator, inf vesical, med rectal, uterine
1.Inf gluteal a – b/w 1&2 or 3&4 sacral n
leaves pelvis thru gr sciatic foramen, infrapiriformic hiatus

2. Int pudendal a – leaves pelvis thru gr sciatic foramen, b/w piriformis & coccygeis  –> perineum via lesser sciatic foramen

3. Umbilical a– v. tortous a, runs along lat pelvic wall & along the side of bladder
a) Prox part –> sup vesicle a => sup bladder
a of ductus deferens => DD, seminal vesicle, lower ureter, bladder

b)Distal part –> becomes obliterated, & goes forward as medial umbilical ligament

4. Obturator a
(can also come from inf epigastric a)
pass across femoral canal –> obturator foramen
ant br => m of thigh
post br => m of thigh
-acetabular br runs to acetabular notch –> head of femur via lig. capitum femoris

5.Inf vesical a (M, vaginal a in F) => prostate, fundus of bladder, DD, seminal vesicle, lower ureter

6.Vaginal a (F from uretine a/v or int iliac a)
numerous br => ant/post wall of vagina & makes logitudinal anatomosis  in med plane to make
ant/post azygos a of vagina

7.Middle rectal a
– run med => musc layer of lower rectum & upper anal canal, prostate gland, ureter (seminal vesicles, vagina)

8.Uterine a
(Deferential a in M) – from int iliac a or w/ vaginal or middle rectal a
run med in base of broad lig –> jxn of cervix & body of uterus & runs in front of /above ureter & near lat fornix of vagina
-sup br => body + fundus of uterus
-vaginal br => cervix + vagina

B. Median sacral a

unpaired a, arising from post aspect of abdominal aorta just before bifurcation
desc in front of sacrum => post rectum, end in coccygeal body as small vascular mass in front of tip of coccyx

C Sup rectal a
– from inf mesenteric a

D. Ovarian a – one of paired visceral branches of ab aorta,
crosses prox end of ext internal a –> minor pelvis + reaches ovary thru suspensory lig of ovary

pelvic-arteries
Nerve Supply to Pelvis

A. Sacral Plexus
formed by L4-5 ventral rami (lumbosacral trunk) + 1st 4 sacral ventral rami, lies on piriformis m in pelvis, below pelvis fascia

1.Sup gluteal n (L4-5) – leaves pelvis thru gr sciatic foramen, suprapiriformic hiatus
=> gluteus medius,minimus, tensor fascia lata

2.Inf gluteal n (L5-S2)
– leaves pelvis thru gr. sciatic foramen => glut max m

3.Sciatic n (L4-S3) – largest n in body
a) Tibial n = post leg
b) Common fibular = ant/lat leg
deep/sup fibular branches
composed of peroneal & tibial parts
leaves pelvis thru gr sciatic foramen, infrapiriformic hiatus
runs thigh in hollow b/w ischial tuberosity & gr. trochanter

4.N to ob internus m (L5-S2)

leaves pelvis thru gr sciatic foramen, infrapiriformic hiatus
perineum thru lesser sciatic foramen
=> ob internus, sup gemellus m

5. N to quadratus femoris (L5-S1)
leaves pelvis thru gr sciatic foramen, infrapiriformic hiatus
runs deep to gemellus m, ob internus, and ends in deep surface of quadratus femoris
=> quadratus femoris & inf gemellus m

6. Post femoral cut n (S1-S3)

leaves pelvis thru gr sciatic foramen, infrapiriformic hiatus
lie w. sciatic n and desc on back of knee
inf cluneal n, perineal br

7. Pudendal n (S2-S4)

leaves pelvis thru gr sciatic foramen below piriformis –> perineum, thru lesser sciatic foramen => bulbospongiosus, ischiocavernosus, sphincter urethrae, deep/sup transverse perineal m

8. Br to pelvis

  • n to piriformis (S1-2)
  • n to levator ani + coccygeus m (S3-4)
  • n to sphincter ani
  • pelvic splanchnic n


*** Lumbosacral trunk connect sacral/lumbar plexus (L4-S4)

pelvic-nerves-sacral-plexus

pelvic-nerves-sacral-plexus-2

Histology: The bone tissue.

Embryology: Gastrulation, early differentiation of the intraembryonic mesoderm

Gastrulation

  • makes the 3 defined germ layer of embryo = ectoderm, mesoderm, endoderm
  • @ day 21 = called trilaminar germ disk
  • indicated by primitive streak = epiblast cells
    • primtive groove, node, and pit
    • primitive node = cephalic end of streak, elevation around the primitive pit
  • caudal to primitive streak – future anus = cloacal membrane – epiblast/hypoblast fused here
  • epiblast = ectoderm + intraembryonic mesoderm + endoderm of trilaminar disk
  • @ wk 2 – intraembryonic mesoderm begins to form organs
  • @ wk 3 – extraembryonic mesoderm begins to form placenta

Differentiation to Intraembryonic Mesoderm

1. Paraxial mesoderm – right next to midline, become somites

  • first 7 = pharyngeal arches
  • 42-44 pairs of somites from rest of them –> eventually condense to 35 pairs
  • each somite has 3 parts: sclerotome, myotome, dermatome
    • sclerotome = bones, ligaments
    • myotome = muscle
    • dermatome = skin

2. Intermediate Mesoderm – b/w paraxial and lateral mesoderm

  • forms urogenital ridge –> kidney & gonads

3. Lateral Mesoderm

  • intraembryonic coelem forms – splits lat mesoderm into 2 layers
    • somatic
    • visceral

4. Notochord – mesoderm in midline from primitive node –> prechordal plate

  • stimulates ectoderm on top –> neuroectoderm –> neural plate
  • stimulates formation of vertebral bodies & nucleus palposus

5. Cardiogenic region

  • horseshoe shaped region of mesoderm  @ cranial end of embryonic disk
  • is the future heart
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