Perineum I Lab Introduction 2024 PDF

Disclosure I have NO conflict of interest to disclose related to the subject of this Lab introduction: Perineum I (The Anal Triangle). Maly. Date: Monday, October 7, 2024 Reading Assignments: Moore’s Essential Clinical Anatomy, Anne M. R. Agur, Arthur F....

Disclosure I have NO conflict of interest to disclose related to the subject of this Lab introduction: Perineum I (The Anal Triangle). Maly. Date: Monday, October 7, 2024 Reading Assignments: Moore’s Essential Clinical Anatomy, Anne M. R. Agur, Arthur F. Dalley 7th Ed, 2024. Pp. Plus Clinical Boxes. PollEv.com/maly2022  OBJECTIVES: Describe the Bony landmarks of the pelvis Identify the major ligaments of the pelvis Describe the boundaries of the perineum Describe the various components of the pelvic diaphragm Describe the boundaries and contents of Ischiorectal (ischio-anal) fossa Identify the various parts and attachments of the anal sphincters. Describe the general and applied Anatomy of the anal canal canal Describe the clinical and anatomical features of the External and internal hemorrhoids (piles)  BONY LANDMARKS PELVIS Iliac crest MEDIAL VIEW Iliac tubercle ASIS ILIUM AIIS Obturator canal Obturator membrane Greater sciatic notch Superior pubic ramus ISCHIUM Ischial spine PUBIS Lesser sciatic notch Obturator foramen Ischial tuberosity Inferior pubic ramus Ischial ramus Ischiopubic ramus BONY LANDMARKS POSTERIOR VIEW  Perineum osteology. This is the view of the articulated pelvis as a clinician would encounter it during the pelvic examination of a female  Boundaries of Perineum Sacrospinous lig. Coccyx Sacrotuberous lig. Pubic symphysis Ischial tuberosity Ischiopubic rami Ischiopubic rami  PELVIS BONY LANDMARKS AND LIGAMENTS Posterior sacroiliac lig. Greater sciatic foramen Sacrotuberous lig. Sacrospinous lig. Greater sciatic foramen Lesser sciatic foramen Anterior sacroiliac lig. Ischial tuberosity POSTERIOR VIEW Sacrospinous lig. Sacrotuberous lig. Lesser sciatic foramen Superior pubic ramus Pubic tubercle ANTERIOR VIEW  PERINEUM PERINEUM: The perineum consists of that part of pelvic outlet caudal to the Pelvic diaphragm (levator ani and Coccygeus muscles). - A line joining the anterior parts of the ischial tuberosities divides the perineum into a large posterior Anal triangle and a smaller anterior Urogenital triangle. Pubic Symphysis - It is diamond in shape. BOUNDARIES: Anteriorly: - Pubic symphysis Urogenital triangle Anterolaterally: - Inferior pubic rami Anal triangle Posteriorly: - The tip of the coccyx Ischial Postero-laterally: tuberosity - The Sacrotuberous ligament reinforced by Gluteus maximus muscle. Ischial spine The Perineum can be divided into two Tip of coccyx Triangles: i) Urogenital Triangle anteriorly and ii) Anal Triangle posteriorly, by an imaginary line drawn between the two ischial tuberosities.  THE PELVIC DIAPHRAGM: Deep dorsal v. of clitoris i) Separates Pelvic cavity from the Perineum Urethra ii) Supports the Pelvic viscera. Tendinous arch Vagina Puborectalis iii) Provides a sphincteric action at the Rectum anorectal junction, which is important for Pubococcygeus fecal continence. Iliococcygeus iv) Helps to resist increased intraabdominal pressure (e.g. when coughing, defecating) litoris Piriformis (Ischio)Coccygeus v. of c orsal pd Dee Pelvic Diaphragm Superior view Urethra The Pelvic Diaphragm is composed of: Vagina 1. Levator ani: - Puborectalis - Pubococcygeus - Iliococcygeus Rectum 2. (Ischio) Coccygeus In between these bony attachments, levator ani attaches to a band-like thickening on the fascia of obturator internus called Arcus tendineus (tendinous arch of the levator ani). Pelvic Diaphragm Inferior view  ISCHIORECTAL (ANAL) FOSSA The Ischioanal fossae surround the wall of the Anal canal. - They are wedge-shaped, fat-filled regions that lie between the skin of the Anal region and the Pelvic diaphragm. BOUNDARIES: Base: Skin and fascia. Apex: Where the obturator internus muscle meets with levator ani Obturator muscle. internus muscle and Lateral wall: Ischium, with inferior part of fascia obturator internus and its fascia, which Pudendal canal encloses the Pudendal (Alcock’s) canal. with Pudendal nerves and internal Pudendal vessels Medial wall: Anal canal, covered by external Ischial tuberosity anal sphincter and sloping levator ani muscle. Anteriorly: Urogenital diaphragm. Posteriorly: Gluteus maximus muscle. Ischioanal fossa Internal anal sphincter External anal sphincter CLINICAL NOTE: i) Ischioanal fossa is of considerable surgical importance because of its great tendency to become infected. ii) Infection of Ischioanal fossa may occur from boils or abrasions of perianal skin, from lesions within rectum and anal canal or from infections via blood stream (septicemia). Male Perineum -The anal canal is always closed except for the passage ANAL SPHINCTER of flatus and feces. - It is held closed by the external and internal anal sphincters. - Each sphincter occupies two thirds of the anal canal, so that they overlap at the middle. i) EXTERNAL ANAL SPHINCTER: -Voluntary - Skeletal muscle surrounding the lower two thirds of the anal canal Consists of 3 parts: (each a ring of muscle) - Subcutaneous -no bony attachments - Superficial - attaches to coccyx and perineal body Parts of external anal sphincter - Deep (profundus)- no bony attachments - encircles upper anal canal Deep - blends with Puborectalis Superficial ii) INTERNAL ANAL SPHINCTER: Subcutaneous Involuntary: -Sympathetic stimulation contracts the muscle, parasympathetic stimulation relaxes it. - Occupies the upper two thirds of the anal canal -- down to Hiltons line. Puborectalis - Formed by a thickening of the inner circular layer of smooth muscle.  ISCHIORECTAL (ANAL) FOSSA Testis External anal sphincter. Ischiorectal fossa Levator ani m. Inferior rectal a. & n. Gluteus maximus m. Pudendal n. Anococcygeal body (lig.) -Measures about one and half inches (4 cm) ANAL CANAL Superior 2/3’s of the Anal Canal - Lined by: Columnar epithelium (Endodermal in origin). Innervation: Autonomic innervation. Anal Levator ani muscle Anal column - Responsive only to stretch sinus Longitudinal muscle Anal layer of rectum - The lining of the upper 2/3’s of the anal canal is valves characterized by presence of vertical folds called Anal columns. Circular muscle layer Deep part of external - Anal columns are joined together by semilunar anal sphincter folds called anal valves (remains of the anal Internal anal membrane in the embryo). sphincter Anal canal Superficial part of Malignancies: Adenocarcinomas external anal sphincter Lymphatic drainage to internal iliac and common iliac nodes. Subcutaneous part of Inferior 1/3 of the Anal Canal: external anal sphincter - Lined by: Stratified squamous epithelium derived Pectinate line from ectoderm Innervation: Somatic - inferior rectal nerves - Responsive to Pain, Touch, and Temperature. - Malignancies: Squamous cell carcinomas. - Lymphatic drainage to superficial inguinal nodes  HEMORRHOIDS (PILES) i) INTERNAL: Tributary of superior Anal rectal vein - Prolapsed rectal mucosa containing the column (normally) dilated internal venous plexus Internal anal Internal of veins that are tributaries of the sphincter hemorrhoi Superior rectal vein. d - Occur above the Pectinate line, so are painless. External anal - Typically seen at 3, 7 and 11 o’clock sphincter with the patient in Lithotomy position. Perianal hematoma Anal valves Mucous membrane ii) EXTERNAL: External hemorrhoid - Varicosities of the inferior rectal veins. - Often blood will clot under the skin in the external rectal venous plexus (branches of inferior rectal). 11 o’clock - These occur below the pectinate line, 3 o’clock receive somatic innervation, so are extremely painful. 7 o’clock Lithotomy position HEMORRHOIDS (PILES) i) INTERNAL: - Prolapsed rectal mucosa containing the (normally) dilated internal venous plexus of veins that are tributaries of the Superior rectal vein. - Occur above the Pectinate line, so are painless. - Typically seen at 3, 7 and 11 o’clock with the patient in Lithotomy position. ii) EXTERNAL: - Varicosities of the inferior rectal veins. - Often blood will clot under the skin in the external rectal venous plexus (branches of inferior rectal). - These occur below the pectinate line, receive somatic innervation, so are extremely painful. Venous Drainage