Perineum –Part 1 Anatomy lab - PowerPoint Presentation

1. Perineum –Part 1Anatomy lab Ass.lec. Reham saad Anal Triangle

2. Perineum The cavity of the pelvis is divided by the pelvic diaphragm into the main pelvic cavity above and the perineum below Diamond in shape Bounderies Ant.: symphysis Pubis Post. Tip of cocygeus bone Lateral . Ischial tuberosityThe perineum divided into two triangles(urogenital triangle (Ant), and (Anal triangle(post) )

3. Anal triangleUrogenital Triangle

4. Anal triangle Anal triangle consist of ( anal canal + Ischiorectal fossa ) 1. Anal canal About 1.5 in. (4 cm) long Passes downward and backward from the rectal ampulla to the anus RelationsPosteriorly: The anococcygeal body, which is a mass offibrous tissue lying between the anal canal and the coccyx Laterally: The fat-filled ischiorectal fossae Anteriorly: In the male, the perineal body, the urogenitaldiaphragm, the membranous part of the urethra, andthe bulb of the penis .In the female, the perineal body, the urogenital diaphragm, and the lower part of the vagina

5. Mucous Membrane of anal canal Upper half of anal canal Lower half of anal canal 1. Derived from hindgut entoderm1. Derived from ectoderm of the proctodeum2. lined by columnar epithelium2. It is lined by stratified squamous epithelium3. It is thrown into vertical folds called anal columns,which are joined together at their lower ends by smallsemilunar folds called anal valves3. There are no anal columns, no valves 4. The nerve supply is the same as that for the rectal mucosaand is derived from the autonomic hypogastric plexuses. Sensitive only to stretch 4. The nerve supply is from the somatic inferior rectalnerve; it is thus sensitive to pain, temperature, touch,and pressure (p2T2)5. The arterial supply is that of the hindgut—namely, thesuperior rectal artery, a branch of the inferior mesentericArtery, and venous drainage , by the superior rectal vein, a tributary of the inferior mesenteric vein, and the portal vein5. The arterial supply is the inferior rectal artery, a branchof the internal pudendal artery (see Fig. 8.3). The venousdrainage is by the inferior rectal vein, a tributary of theinternal pudendal vein, which drains into the internaliliac vein 6. The lymphatic drainage is mainly upward along thesuperior rectal artery to the para rectal nodes andthen eventually to the inferior mesenteric nodes6. The lymph drainage is downward to the medial group ofsuperficial inguinal nodes .

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7. NoteThe pectinate line indicates the level where the upper half of the anal canal joins the lower half . Muscle CoatAs in the upper parts of the intestinal tract, it is divided into an outer longitudinal and an inner circular layer of smooth muscle . Anal SphinctersThe anal canal has an involuntary internal sphincter and a voluntary external sphincter. The internal sphincter is formed from a thickening of the smooth muscle of the circular coat at the upper end of the anal canal. The internal sphincter is enclosed by a sheath of striped muscle that forms the voluntary external sphincter .

8. The external sphincter can be divided into three parts: A subcutaneous part, which encircles the lower end of the anal canal and has no bony attachments. A superficial part, which is attached to the coccyx behind and the perineal body in front A deep part, which encircles the upper end of the anal canal and has no bony attachments .

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11. Blood SupplyArteriesThe superior artery supplies the upper half and the inferior artery supplies the lower half .VeinsThe upper half is drained by the superior rectal vein into the inferior mesenteric vein, and the lower half is drained by the inferior rectal vein into the internal pudendal vein. Lymph DrainageThe upper half of the anal canal drains into the pararectal nodes and then the inferior mesenteric nodes. The lower half drains into the medial group of superficial inguinal nodes

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14. 2. Ischiorectal fossa The ischiorectal fossa (ischioanal fossa) is a wedge-shaped space located on each side of the anal canal The base of the wedge is superficial and formed by the skin.The edge of the wedge is formed by the junction of the medial and lateral walls. The medial wall is formed by the sloping levator ani muscle and the anal canal. The lateral wall is formed by the lower part of the obturator internus muscle, covered with pelvic fascia.

15. Contents of Ischiorectal Fossa & Pudendal canal The ischiorectal fossa is filled with dense fat, which supports the anal canal and allows it to distend during defecation.The pudendal nerve and internal pudendal vessels are embedded in a fascial canal, the pudendal canal, on the lateral wall of the ischiorectal fossa, on the medial side of the ischial tuberosity The inferior rectal vessels and nerve cross the fossa to reach the anal canal.Branches of pudendal nerves 1.Inferior rectal nerve: supplies the external anal sphincter, the mucous membrane of the lower half of the anal canal, and the perianal skin 2.Dorsal nerve of the penis (or clitoris): This is distributed to the penis (or clitoris) 3. Perineal nerve: This supplies the muscles in the urogenital triangle

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17. Internal Pudendal ArteryThe internal pudendal artery is a branch of the internal iliac artery and passes from the pelvis through the greater sciatic foramen and enters the perineum through the lesser sciatic foramen.Branches1. Inferior rectal artery: This supplies the lower half of the anal canal 2. Branches to the penis in the male and to the labia and clitoris in the female

18. Dorsal nerve of clitoris Deep branch of perineal n Bulb of vestibule Inferior rectal nervePudendal nGreater vestibular gland External anal sphincter m Superficial perineal nPosterior labial n