Anatomy & nerve supply of birth canal .pptx

1. Anatomy & nerve supply of
birth canal
DR.ZIKRULLAH MALLICK

2. Birth canal
 The passageway through which the fetus is expelled during parturition,
leading from the uterus through the cervix and the vagina
 Also consists of vulva

3. VULVA
 Mons veneris
 Labia majora
 Labia minora
 Clitoris
 Vestibule
 Perineum

4.  Mons veneris/ Mons pubis :
Pad of subcutaneous adipose connective tissue lying in front of pubis
Covered with hair
 Labia majora :
Vulva on either side bound by elevation of skin and subcutaneous
tissue
Join medially to form posterior commissure infront of anus
Squamous epithelium
Contain sebacious glands , sweat glands , hair folllicles

5.  Labia minora :
Two thin folds of skin, devoid of fat
Anteriorly enclose clitoris
Unite with each other in front and behind clitoris to form prepuce and frenulum
Lower portion fuses across midline to form fourchette
Between fourchette and vaginal orifice : Fossa navicularis
 Clitoris
Small , cylindrical , erectile body
2.5cm
Glans , body and two crura
Squamous epithelium
Rich nerve supply

6.  Vestibule
Triangular space : Anterior - clitoris
Posterior - Fourchette
Lateral -Labia minora
4 openings : Urethral , Vaginal orifice and hymen,opening of Bartholin
ducts occasionally two skene ducts

7.  Blood supply of Vulva
Arteries
Br. of internal pudendal artery
Labial A.,
Transverse perineal A.,
A to vestibular bulb,
 deep & dorsal arteries to clitoris
Br. of Femoral A :Superficial & deep external pudendal A
Veins
Internal pudendal vein
Vesical/ vaginal venous plexuses
Long saphenous vein

8. • Nerve supply
• Ant-sup part
• Ilio inguinal & genital br. of genitofemoral N (L1,L2)
• Post-inf part
• Pudendal br. of post.cut. N of thigh (S123)
• In between
• Labial & perineal br.of Pudendal N (S234)
• Lymphatics
• Superf. Inguinal nodes
• Gland of Cloquet
• Ext. & Int. Iliac nodes

9. VAGINA
 Fibromuscular membranous sheath
 Excretory channel
 Organ of copulation
 Birth canal of parturition
 45° with horizontal
 2.5cm diameter
 distensibility

10.  Walls
Ant : 7cm
Post : 9cm
2 lateral walls
 Fornices :
Ant : shallow
2 lateral
Post : deep

12.  Structures:
Mucous coat – Stratified squamous epithelium without glands
Submucous layer of loose areolar vascular tissues
Muscular layer : inner circular, outer longitudinal
Fibrous coat:endopelvic fascia
 Secretions:Acidic (4-5 pH)
Doderlein’s bacilli
Oestrogenic activity

13. • Blood Supply of vagina
• Arteries
• Cervicovaginal br. of uterine A
• Vaginal A
• Middle rectal A
• Internal pudendal
• Anastomose---form 2 azygos arteries ant and post
• Veins drain into:
• Internal iliac V
• Internal pudendal V

14.  Lymphatics :
Upper one third : External iliac group
Middle one third upto hymen : Internal Iliac group
Lower one third : superficial inguinal group
 Nerve supply
Lower one third pain sensitive- pudendal nerve nerve through the
inferior rectal and posterior labial branches of the perineal nerve
The upper two-thirds of the vagina are pain insensitive and are
supplied by sympathetic LI, L2 and parasympathetic segments S2, S3
nerves derived from the inferior hypogastric and uterovaginal
plexuses

15. UTERUS
 Hollow, pyriform muscular organ in pelvis
 Position: anteversion & anteflexion
uterus dextrorotated
cervix levorotated
 Measurements
7.5cm long
5cm wide, 2.5 cm thick
Weight : 30-40gm

16.  PARTS OF UTERUS
Body/Corpus
Fundus : 1.5 cm
Body proper: 3.5 cm
cornua
Isthmus
Constricted part
0.5 cm
Between anatomical & histological internal os (of Aschoff)

17.  Cervix
2.5cm, cylindrical
Supravaginal & infravaginal(portio vaginalis) parts
Cervical canal
External os opening shape
Secretion: alkaline & thick, rich in fructose, NaCl and mucoprotein

19. RELATIONS OF THE UTERUS
Anterior
Above int.os : uterovesical pouch
Below int.os: separated from UB by loose areolar
tissue
Posterior
Pouch of Douglas with coils of intestine

20. Lateral
Broad ligament
Mackenrodt’s ligament
Uterine A & ureter

21.  Structures
Body
Perimetrium : Invests entire organ except on lateral borders
Myometrium : Smooth muscle fibres held by connective tissue
Endometrium : mucous lining
Cervix : Squamocolumnar junction at external os

22.  Blood supply
Arteries:
Uterine A
Ovarian & Vaginal A.
Veins drain into
Internal iliac veins

24.  Nerves
Sympathetic
Motor : T5 & T6
Sensory : T10 – L1
Somatic distribution of uterine pain : area of abdomen T10 to L8
Parasympathetic
Pelvic N ( S2,3,4) : both motor & sensory : ends in ganglia of
Frankenhauser

25. Supports of the uterus
 Primary
 Muscular or active : Pelvic / Pelvic floor
Perineal body
Urogenital diaphragm
 Fibromuscular or mechanical : Uterine axis
Pubocervical ligament
Transverse cervical – Mackenrodt
Uterosacral ligament
Round ligament of uterus
 Secondary : Broad ligament
Uterovesical fold of peritoneum
Rectovaginal fold of peritoneum

26. Fallopian tubes
 10 cm in length
 3 layers : Serous
Muscular
Mucous membrane

27.  Blood Supply
Arteries
Uterine A
Ovarian A
Veins
Through pampiniforn plexus into ovarian veins
 Lymphatics
Para-aortic nodes
 Nerve supply
Uterine & ovarian nerves

28. Ovary
 Oval in shape
 3cm in length , 2cm in breadth and 1cm in thickness
 Relations of ovary
Mesovarium / anterior border
Posterior border : free
Medial surface : fimbrial part of the tube
Lateral surface : in contact with ovarian fossa on lateral pelvic
wall

29. • Lined single layer of germinal epithelium of Waldeyer
(cuboidal epi.)
• Tunica albuginea : stromal cells thickened beneath
germinal epithelium
• Contain primordial follicles
• Corpus albicans/ atretic follicles
Cortex
• Loose connective tissues, blood vessels, nerves, muscles
• Hilus cells : homologous to interstitial cells of testes
Medulla

30.  Blood Supply
Arterial : Ovarian A
Veins :
Through pampiniform plexus to form ovarian V.
Lt. Renal Vein IVC
 Lymphatics
Para-aortic nodes
 Nerve supply
Sympathetic supply from T10 along ovarian A.