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Anatomy of the Pelvis

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Anatomy of the Pelvis Amel Ibrahim MBBS BSc www.iwanttobeasurgeon.blogspot.com www.iwanttobeasurgeon.com Amel.ibrahim_at_imperial.ac.uk Q3) On sphincters of the anus A ... – PowerPoint PPT presentation

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Title: Anatomy of the Pelvis


1
Anatomy of the Pelvis
  • Amel Ibrahim MBBS BSc
  • www.iwanttobeasurgeon.blogspot.com
  • www.iwanttobeasurgeon.com
  • Amel.ibrahim_at_imperial.ac.uk

2
Contents
  • Intro and definitions
  • Bones et al
  • Muscles
  • Vasculature
  • Lymphatics
  • Nerves
  • Organs
  • Special places
  • QUIZ
  • Preview
  • Further reading

3
Intro Definitions
  • Pelvic Brim (green line)
  • Imagine a line drawn between promontory of the
    sacrum, arcuate line of the ilium, pectineal line
    (pectin of pubis) and pubic crest.
  • Greater (False) pelvis
  • All of the bony pelvis ABOVE pelvic brim
  • Lesser (True) pelvis
  • All of pelvis BELOW pelvic brim.

4
Bones et al
  • Bones
  • Ilium (one on each side) crest, anterior
    superior and inferior iliac spines and greater
    sciatic notch.
  • Pubic bone (one on each side) lesser sciatic
    notch, tubercle and symphysis
  • Ischium (one on each side) lesser sciatic notch,
    spine and tuberosity
  • Sacrum foramina for spinal nerves
  • Coccyx

5
More bones
  • Vertebral column 5 fused sacral and 3-5 fused
    coccygeal vertebrae
  • Ilium, pubic bone and ischium meet to form
    acetabulum for hip joint
  • Obturator foramen made by articulation of ischium
    with pubic bone

Ilium
Pubic bone
Ischium
6
Ligaments
  • Anterior longitudinal runs down entire vertebral
    column. Prevents hyperflexion
  • Inguinal ligament arched fibres of external
    oblique
  • Pubic Symphysis secondary cartilaginous joint
  • Sacroiliac joints anteriorly
  • Posterior sacrotuberous, posterior sacrospinous
    and sacrospinous
  • Ligaments provide strengthand stability of hip

7
Male Vs Female
  • Bones pelvis taller, narrower and more compact.
    Evolutionary optimised for bipedal locomotion.
    Acute angle between pubic rami (70 degrees).
  • Contents rectum, bladder, prostate, anus and
    male reproductive organs
  • Bones wider and broader with larger inlet.
    Optimised for childbirth without compromising
    bipedal locomotion. Wide angle between pubic
    rami (100 degrees). Wider acetabulum.
  • Contents rectum, bladder, anus and female
    reproductive apparatus

8
Muscles
pubococcygeus
  • Greater Pelvis
  • Quadratus Lumborum from iliac crest to insert
    into 12th rib and L1-4. Lateral flexor
  • Psoas Major from lumbar veterbrae to lesser
    trochanter of femur. Hip flexor.
  • Iliacus from internal iliac fossa to lesser
    trochanter. Joins with Psoas major ILIOPSOAS
    (hip flexor and trunk flexor)
  • Piriformis from greater sciatic notch and
    anterior sacrum to greater trochanter. Lateral
    rotator
  • Lesser Pelvis
  • MUSCLES CONTROL SPHINCTERS
  • Diaphragm pubococcygeus, coccygeus,
    puborectalis, (pubovaginalis) and illiococcygeus
  • Levtor ani a sling made by puborectalis, pubo-
    and ilio-coccygeus. Prevents incontinence.
  • Sphincter urethrae
  • (Sphincter prostatae)
  • External anal sphincter
  • pubovaginalis elevates vagina

iliococcygeus
coccygeus
Psoas major
piriformis
iliacus
9
Vasculature Arteries
  • Gonadal artery (branch of abdo aorta, origin L2)
  • Internal Iliac (anterior posterior divisions)
  • Superior vesical
  • Inferior vesical (vaginal artery in female)
  • Middle and inferior rectal (superior rectal from
    inferior mesenteric)
  • Inferior and superior gluteal
  • Uterine (uterus, vagina, ureter)
  • Internal Pudendal (perineum, penis and urethra)

10
(from instant anatomy website)
11
veins
  • Veins from pelvis follow arteries
  • Drain to IVC (common iliac joins at L5)
  • Left testicular drains to left renal not directly
    into IVC

12
(From Instant anatomy)
13
lymphatics
  • Lateral pelvic drain everything EXCEPT
  • Para aortic drain gonad fallopian tube
    uterus ureter
  • Inferior mesenteric drain upper rectum
  • All ultimately drain into lymphatic duct and
    cisterna chyli

14
Nerves
  • Dermatomes T12 (suprapubic), L1 (groin), L2
    (upper thigh), S1, 2, 3, 4, 5 (buttocks,
    perineal and perianal). S1, 2 (genitals).
  • Sympathetic from lumbo-sacral trunk (L1-S5).
  • Parasympathetic S2-4
  • Lumbar plexus L1-5 roots lie on Psoas M.
    Branches
  • 3 lateral to Psoas (lateral cutaneous nerve,
    iliohypogastric, ilioinguinal and
  • 1 anterior to Psoas genitofemoral
  • 2 medial to psoas femoral, obturator
  • Sacral Plexus S1-4
  • Pudendal S2-4. mixed sensory/autonomic
  • Coccygeal

15
Dermatomes
16
Autonomic
  • Sympathetic
  • Parasympathetic
  • Hypogastric nerves preganglionic fibres travel
    to hypogastric plexus and synapse there then
    travel to viscera as hypogastric nerves.
  • Sacral splanchnic nerves fibres synapse at
    sympathetic chain and postganglionic fibres
    travel to hypogastric plexus as a splanchnic
    nerve.
  • Pudendal nerve mixed autonomic and sensory. S2-4
  • Pelvic splanchnic nerves preganglionic fibres
    from S2-4 travel to hypogastric plexus ad from
    there nerves travel to and synapse at viscera.
  • Cause erection and sphincter relaxation for
    micturition/defaecation

17
Divisions of Lumbar plexus
  • lateral cutaneous nerve sensory to lateral thigh
  • Iliohypogastric motor to transversus and
    internal oblique, sensory to mon pubis
  • Ilioinguinal motor to internal oblique,
    transversus and conjoint tendon. Sensory to upper
    medial thigh, labia majora, scrotum and root of
    penis
  • Genitofemoral motor to cremaster. Sensory to
    scrotum, anterior thigh, spermatic fascia and
    tunica vaginalis.
  • Femoral (L2,3,4) motor to iliacus, pectineus and
    quadriceps femoris. Sensory to anterior thigh.
  • Obturator

18
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19
Sacral Plexus
  • Formed by L4, 5, S1-5
  • Lies on piriformis
  • Branches
  • 6 nerves from sacral roots
  • Nerve to piriformis
  • Posterior femoral
  • Perforating cutaneous
  • Perineal branch to levator ani
  • Pelvic splanchnic
  • Pudendal
  • Anterior division
  • Nerve to Quadratus femoris
  • Nerve to Obturator internus
  • Tibial branch of sciatic nerve
  • Posterior division
  • Superior gluteal
  • Inferior gluteal

20
Pudendal Nerve
  • Somatic and autonomic
  • Origins S2-4
  • Exits through greater sciatic foramen and
    re-enters pelvis via lesser sciatic foramen
  • Travels with pudendal vessels along ischiorectal
    fossa in Alcocks canal
  • Supplies sphincters and genitalia via perineal,
    dorsal root of penis/clitoris and inferior anal
    nerves
  • Promotes ejaculation, sexual arousal, anal and
    bladder sphincter control.

21
Coccygeal Nerve
  • 31st spinal nerve
  • Forms coccygeal plexus with S5
  • Coccygeal plexus gives rise to annococcygeal
    nerve which supplies sacroccygeal joint and skin
    over coccyx.

22
Organs
  • RENAL TRACT
  • Ureters
  • Originate at renal hilum at L2
  • Path initially medial to vertebrae and at pelvic
    brim take infero-posterior path
  • Oblique entry into bladder avoids urinary reflux
  • Crossed by gonadal artery in pelvis
  • Posterior to it are psoas and genitofemoral nerve
  • Under it are uterine artery and vas deferens
  • Arterial supply via gonadal, renal, vesical,
    vaginal and aortic branches
  • Autonomic innervation
  • Bladder
  • Trigonal structure.
  • Wall has 3 layers of smooth muscles inner
    circular and middle/outer longitudinal layers
  • Arterial supply from superior and inferior
    vesicalnerves sympathetic closes bladder neck
    whilst parasympathetic relaxes detrusor muscle to
    allow for miturition

23
Rectum and anus
  • Rectum
  • Columnar epithelium
  • Superior 1/3 covered by peritoneum anteriorly and
    laterally, middle 1/3 anterior peritoneum only
    and inferior 1/3 bare
  • Arteries superior rectal from inferior
    mesenteric and middle rectal from internal iliac
    inferior rectal from pudendal artery
  • Veinous drainage from internal venous plexus
    which drains to
  • superior rectal which then drains to inferior
    mesenteric vein, middle rectal which drains to
    internal iliac vein and inferior rectal vein
    which drains into pudendal vein
  • Anus
  • Starts at anorectal junction aka dentate line
  • Squamous epithelium continuous with skin
    gradually transforming to columnar as rectum
    approached
  • External anal sphincter is skeletal muscle with
    somatic innervation thus voluntary
  • Internal anal sphincter is smooth muscle and
    under autonomic control

24
Female pelvic viscera
  • Uterus
  • Held at lateral walls by double fold of
    peritoneum aka broad ligament
  • Uterine artery
  • Sympathetic and parasympathetic innervation from
    pelvic plexus
  • Venous plexus drain to rectal and vesical veins
  • Ovaries
  • Attached to posterior aspect of broad ligament
  • Ovarian artery
  • Right ovarian vein drains to IVC whilst left to
    left renal vein
  • Sympathetics from aortic plexus and
    parasympathetics from pelvic plexus
  • Fallopian tubes
  • Run in free edge of broad ligament
  • Ovarian and uterine arteries
  • Vagina
  • Opens into vaginal vestibule
  • Vaginal artery
  • Sympathetic supply from pelvic plexus and somatic
    sensory innervation from ilioinguinal and
    pudendal nerves

25
Male pelvic viscera
  • Scrotum
  • layers are skin, dartos muscle, external
    spermatic fascia, cremaster muscle, internal
    spermatic fascia, tunica vaginalis and tunica
    albuginea
  • Testis
  • Testicular (gonadal artery)
  • pampiniform plexus drain to testicular veins
  • Testicular vein drains to IVC on right and left
    renal artery on left
  • Prostate
  • Multi-lobar (5) with posterior groove. Apex at
    the bottom and base at top
  • Smooth muscle
  • Entered by the vasa deferens and seminal vesicals
  • Contains prostatic urethra
  • Arterial supply from inferior vesical, middle
    rectal and occasionally pudendal arteries
  • Drains to venous plexus and then to internal
    iliac vein
  • Sympathetic nerves promote ejaculation and smooth
    muscle contraction whilst parasympathetics
    promote erection
  • Penis and Urethra
  • Pre-prostatic, prostatic, membranous and penile
    urethra

26
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27
Special places
  • Inguinal canal
  • 4 cm long running from Anterior superior iliac
    spine and pubic tubercle.
  • Contains spermatic cord (or round ligament) and
    ilioinguinal nerve.
  • Spermatic cord contains 3 structures (vas
    deferens, cremaster muscle and pampiniform
    plexus), 3 arteries (artery to vas, artery to
    cramster and testicular artery) and 3 nerves
    (sympathetic, parasympathetic and genitofemoral)
  • Floor fibres of external oblique inguinal
    ligament
  • Roof transversus abdominis and internal oblique
  • Anterior external oblique and internal oblique
  • Posterior transversalis fascia and conjoint
    tendon
  • Alcocks canal
  • Where pudendal nerve, vein and inetrnal pudendal
    artery run.
  • Formed by obturator internus fascia
  • Runs on the lateral wall of ischiorectal fossa
  • Femoral canal
  • Contains lymphatic vessels and cloquets lymph
    node
  • Anterior border is inguinal ligament
  • Posterior border is pectineal ligament
  • Medial border is lacunar ligament
  • Lateral border is femoral vein

28
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29
Quiz
  • Q1) On the bony pelvis
  • A) true pelvis lies between iliac crests T/F
  • B) the acetabulum formed by contributions from
    all parts of hip bone T/F
  • C) male pelvic inlet more oval than female in
    shape T/F
  • D) angle between pubic rami wider in male T/F
  • E) pelvic out let is between symphysis pubis and
    sacral tuberosity T/F

30
Quiz
  • Q1) On the bony pelvis
  • A) true pelvis lies between iliac crests T/F
  • B) the acetabulum formed by contributions from
    all parts of hip bone T/F
  • C) male pelvic inlet more oval than female in
    shape T/F
  • D) angle between pubic rami wider in male T/F
  • E) pelvic out let is between symphysis pubis and
    sacral tuberosity T/F

31
  • Q2) Levator Ani
  • A) has fibres which assist continence by pulling
    rectum backwards T/F
  • B) lies inferior to ischiorectal fossa T/F
  • C) is supplied by anterior rami of S1-2 T/F
  • D) Contracts during defaecation T/F

32
  • Q2) Levator Ani
  • A) has fibres which assist continence by pulling
    rectum backwards T/F
  • B) lies inferior to ischiorectal fossa T/F
  • C) is supplied by anterior rami of S1-2 T/F
  • D) Contracts during defaecation T/F

33
  • Q3) On sphincters of the anus
  • A) the anus contains longitudinal and circular
    muscle T/F
  • B) External sphincter composed of involuntary
    muscle T/F
  • C) external sphincter continuous with muscle of
    rectum T/F

34
  • Q3) On sphincters of the anus
  • A) the anus contains longitudinal and circular
    muscle T/F
  • B) External sphincter composed of involuntary
    muscle T/F
  • C) external sphincter continuous with muscle of
    rectum T/F

35
  • Q4) on the inguinal canal
  • A) contains spermatic cord and splanchnic nerve
    T/F
  • B) posterior border is transversus abdominis and
    internal oblique T/F
  • C) floor is inguinal ligament T/F
  • D) carries round ligament in females T/F

36
  • Q4) on the inguinal canal
  • A) contains spermatic cord and splanchnic nerve
    T/F
  • B) posterior border is transversus abdominis and
    internal oblique T/F
  • C) floor is inguinal ligament T/F
  • D) carries round ligament in females T/F

37
  • Q5) on origins of nerves
  • A) lumbar plexus from L1-5 T/F
  • B) pudendal arises from S2-4 T/F
  • C) parasympathetic plexus arises from S2-4 T/F
  • D) hypogastric nerves carry postganglionic fibres
    T/F

38
  • Q5) on origins of nerves
  • A) lumbar plexus from L1-5 T/F
  • B) pudendal arises from S2-4 T/F
  • C) parasympathetic plexus arises from S2-4 T/F
  • D) hypogastric nerves carry postganglionic fibres
    T/F

39
Preview
40
Fin
  • Useful books
  • Instant anatomy good for surface anatomy, blood
    vessels and nerves
  • Netters atlas
  • (Anatomy recall)
  • Websites
  • www.iwanttobeasurgeon.com (down for construction
    at present)
  • www.iwanttobeasurgeon.blogspot.com
  • www.instantanatomy.net
  • Apps
  • Grays anatomy (2 quid!)
  • Netters flash cards (twenty pounds but useful
    for revision on tube)
  • DVD
  • Aclands (AMAZING and free from Warwick
    University website or youtube. 130 for DVD set)
  • Exam Material
  • Pastest has over 800 anatomy questions and even
    more useful when you sit finals Have to pay
    though (
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