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Anorectal anatomy and physiology
Surgical anal canal ≈ 5 cm up to the Anorectal ring
Anatomic anal canal ≈ 3 cm up to the dentate line
The rectum
1/3 division Peritoneal coverage Valves of Houston Anorectal angle Fascial attachments; lateral ligament,
Denonvillier fascia, rectosacral fascia
Anorectal anatomy and physiology
Dentate line (pectinate) Anoderm Transitional area Columns of Morgagni Internal hemmorrhoidal plexus
Anorectal anatomy and physiology
Anatomy of the anal canal
Anal glands Anal sphincters Levator ani Anococcygeal raphi Perianal spaces
External sphincter
Levator ani
Anorectal angle
Perianal & perirectal spaces
Blood supply of the anorectum
Portal circulation; inferior mesenteric artery → superior rectal artery
Systemic circulation; middle rectal artery, inferior rectal artery, middle sacral artery
Blood supply
Venous drainage
Lymphatic drainage of anus& rectum
Perirectal nodes Inferior mesenteric nodes Internal iliac nodes Superficial inguinal nodes
Lymphatic drainage of rectum
Lymphatic drainage of anus
Nerve supply of the rectum
Sympathetic L1-3 Parasympathetic S2-4 (nervi ergentes) The hypogastric plexus Pelvic plexus
Nerve supply of the anus
Pudendal nerve (S2-4) Sensory; internal pudendal Motor
Internal sphincter; sympathetic & parasympathetic External sphincter; inferior rectal branch of internal
pudendal n, perineal branch of S4
Nerve supply
Physiology of defecation
Reflex Sensation; receptive relaxation of the rectum,
anal sampling, rectoanal reflex Center; S2-4, cortical Effectors; sphincters, rectal contraction,
abdominal muscles, levator
Physiology of defecation
Continence mechanism
Sensory function; proprioception, touch Rectal reservoir function Internal sphincter; involuntary, resting tone External sphincter; voluntary, squeeze
pressure Levator ani Anorectal angle Anal cushions
Anal incontinencetypes
Major; solid feces Minor; gas, liquid stools, night soiling
Anal incontinenceCauses
Structural damage; Rectal disease Sphincter injury; birth trauma , surgery ….
Neurologic ; Idiopathic
Anal incontinencediagnosis
History Rectal examination; tone, squeeze pressure ,
soilage, …. Endoscopy Endoanal U/S Manometry Nerve studies
Endoanal Ultrasonography
Anal incontinenceTreatment
Diet and drugs Biofeedback Sphincteroplasty Gracilis flap ± electrical stimulator Sacral nerve stimulation= neuromodulation Artificial anal sphincter colostomy
Sphincteroplasty
Artificial anal sphincter