1. Anatomy of the Pelvis Amel Ibrahim MBBS BSc
Pelvis is latin for basin

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 iliococcygeus coccygeus Psoas major piriformis
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
ILIOPSOAS HELPS YOU DO SIT-UPS
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)
Pudendal from latin for shame as supplies sexual organs...

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
Renal obstruction on left sided causes varices

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
S2, 3, 4 keep your erection, urine and faeces off the floor.

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
The inferior hypogastric plexus is a major meshwork of nerves that are located on either side of the rectum, cervix, and lateral vagina in the female, or on either side of the rectum, prostate, and seminal vesicles in the male.

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 :

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
Common peroneal branch of sciatic nerve

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 Alcock’s 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: Bladder: 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 Anus: 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
Portant anal cancers squamous in origin whilst rectal are adenocarcinomas.
Note point where each of the rectal veins originates is site for haemorrhoid formation due to eakening of mucosa. Thus haemorrhoids are found at 3, 7 and 11 o’clock positions which is where superior, middle and infderior rectal veins are found.

24. Female pelvic viscera Uterus: Ovaries: Fallopian tubes: Vagina:
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
Venous drainage from pelvic floor plexus to internal iliac
Clitoris:
Female equivalent of penis
Nerve supply via pudendal

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
Receives ejaculatory ducts, bulbourethral and urethral glands
Arterial supply from urethral artery, deep artery to penis and dorsal artery of penis
Drainage via superficial and deep dorsal veins of penis
Nerves are sympathetic and parasympathetics for ejaculation and erection. Sensory supply to skin and glans of penis from pudendal nerve
Left sided renal obstruction by e.g. Tumour causes varicocoeles

27. Special places Inguinal canal: Alcock’s canal: Pubic tubercle:
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
Alcock’s 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 cloquet’s lymph node
Anterior border is inguinal ligament
Posterior border is pectineal ligament
Medial border is lacunar ligament
Lateral border is femoral vein
Site of bowel herniation
Pubic tubercle:
Herniae above ad medial are inguinal and those below and lateral are femoral

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
Netter’s atlas
(Anatomy recall)
Websites:
(down for construction at present)
Apps:
Gray’s anatomy (2 quid!)
Netter’s flash cards (twenty pounds but useful for revision on tube)
DVD:
Acland’s (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 :(
(excellent for uestions on cadaveric dissections)