Anal Canal.pptx

Lecture notes for medical students

1. Tips on using my ppt. You can freely download, edit, modify and put your name etc. Don’t be concerned about number of slides. Half the slides are blanks except for the title. First show the blank slides (eg. Aetiology ) > Ask students what they already know about ethology of today's topic. > Then show next slide which enumerates aetiologies. At the end rerun the show – show blank> ask questions > show next slide. This will be an ACTIVE LEARNING SESSION x three revisions. Good for self study also. See notes for bibliography.

2. Anal Canal

3. Anal Canal Most distal portion of the alimentary canal. Extends for a distance of about 3 cm from the anorectal ring to the hairy skin of the anal verge.

4. Features Anterior wall shorter than posterior wall Surrounded by sphincter ani muscles Canal closed except during defaecation Measurements Length (adult) 3.8 cms Breadth when empty lateral walls approximated ( antero -posterior slit)

5. RELATIONS In front: Perineal body In male – bulb of penis & spongy urethra In female – Lower part of post. wall of vagina Behind: Ano-coccygeal raphe Fibro-fatty tissue bet’ peri -anal skin & raphe On each side : Ischio -rectal fossa and its contents

6. INTERIOR OF ANAL CANAL

7. INTERIOR OF ANAL CANAL Divided by pectineal line & Hilton’s line into 3 areas Upper (15 mm) Intermediate (15 mm) Lower (8 mm) (Anal verge) Pectinate / dentate line Hilton’s line

8. PECTINATE LINE Muco-cutaneous junction of anal canal Corresponds with position of anal valves Situated at the middle of internal sphincter Divides anal canal into upper and lower areas ( proctodeum ) which are different in development, blood supply, lymph drainage and in nerve supply

9. Distinction Above Pectinate line Below Pectinate line Destination of lymph drainage Internal iliac lymph nodes ( pararectal lymph nodes) Superficial inguinal lymph nodes (Below Hilton’s line) Epithelium Columnar epithelium Stratified squamous epithelium , non keratinized Embryological origin Endoderm Ecotoderm Artery Superior rectal artery> Inf. Meseteric Middle & inferior rectal arteries> Internal iliac Vein Superior rectal vein> Inf. Meseteric Middle & inferior rectal veins> Internal iliac Hemorrhoids classification Internal hemorrhoids (not painful) External hemorrhoids (painful) Nerves Inferior hypogastric plexus Symp L1,L2 & parasymp S2,S3,S4 Inferior rectal nerves > pudendal nerve

10. HILTON’S LINE It is a color contrast bet’ bluish pink area above and black skin below The line is represented by inter- sphincteric groove at the lower end of the internal sphincter Indicates lower end of internal sphincter Anal intermuscular septum is attached carrying the fibres of levator ani and longitudinal muscle of rectum Ischiorectal abscess when communicates with anal canal usually opens at or below Hilton’s line

11. ANAL GLANDS Floor of the sinus receives the ducts of the tubular anal glands, which ramify in the sub-mucous coat of the anal canal and sometimes penetrate the internal sphincter muscle. These glands are occasionally Infected and act as a source of anal fistula.

12. SPHINCTERS OF THE ANAL CANAL Two – Internal & external, surround the anal canal.

13. External sphincter Extension of levator ani around anorectum Voluntary sphincter Supplied by pudendal nerver 3 compnents : Subcutaneous Superficial Deep

14. INTERNAL SPHINCTER

15. INTERNAL SPHINCTER Involuntary sphincter Thickening of circular muscle of lower part of rectum Surrounds upper 3/4 th of anal canal Lower end corresponds with Hilton’s line Middle corresponds with pectinate line Nerve supply: Sup.Hypogastric & pelvic splanchnic

16. Blood supply

17. Blood supply Arterial supply: Superior rectal artery > Inf. Mesenteric The middle rectal arteries arise from the internal iliac arteries. The inferior rectal arteries, branches from the internal pudendal arteries. Venous drainage : Above dentate line : Int. hem. plexus sup rectal vein  Inf. Mesenteric vein Below dentate line : Ext. hem. Plexus Middle rectal vein Int. iliac vein OR Inf. Rectal vein  pudendal vein  Int. iliac vein

18. Nerve supply

19. Nerve supply Below the dentate line, cutaneous sensations conveyed by afferent fibers in the inferior rectal nerves. Above the dentate line : parasympathetic fibres

20. PR - Per rectal examination

21. Proctoscopy

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