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BLOCK 3 Explain the location, parts, features (external & internal) and relations of stomach Location: The stomach is situated in the upper abdomen, between the esophagus and the small intestine. It is positioned in the left upper quadrant of the abdominal cavity, beneath the diaphragm and the lower...

BLOCK 3 Explain the location, parts, features (external & internal) and relations of stomach Location: The stomach is situated in the upper abdomen, between the esophagus and the small intestine. It is positioned in the left upper quadrant of the abdominal cavity, beneath the diaphragm and the lower ribs. Parts of the Stomach: The stomach can be divided into several anatomical regions: 1. Cardia: The proximal part of the stomach near the esophagus. 2. Fundus: The rounded, superior portion of the stomach that lies above the level of the cardia. 3. Body: The main central portion of the stomach, between the fundus and the pyloric region. 4. Pylorus: The distal part of the stomach that connects to the duodenum of the small intestine. It consists of the pyloric antrum and the pyloric canal. External Features: The stomach has a curved, J-shaped appearance. It has two main curvatures: the lesser curvature (concave) and the greater curvature (convex). The greater curvature of the stomach is longer and extends inferiorly, while the lesser curvature is shorter and faces medially. The anterior surface of the stomach is covered by peritoneum, forming the visceral peritoneum, while the posterior surface is in contact with other abdominal organs. Internal Features: The inner lining of the stomach is composed of mucous membrane that contains numerous gastric glands. The mucous membrane is folded into numerous ridges called gastric folds or rugae, which allow for expansion of the stomach. The gastric glands secrete gastric juices, including hydrochloric acid and pepsin, which aid in the digestion of food. The stomach has several layers of smooth muscle in its wall: the inner oblique layer, the middle circular layer, and the outer longitudinal layer. These muscles facilitate mixing and churning of food during digestion. Relations of the Stomach: Anteriorly, the stomach is related to the liver, diaphragm, and anterior abdominal wall. Posteriorly, it is in contact with structures such as the pancreas, spleen, left kidney, left adrenal gland, and transverse colon. Superiorly, the stomach is related to the left dome of the diaphragm and the left lobe of the liver. Inferiorly, it is continuous with the duodenum of the small intestine. Explain the peritoneal folds of stomach 1. Lesser Omentum: The lesser omentum is a double layer of peritoneum that extends from the lesser curvature of the stomach and the proximal part of the duodenum to the liver. It consists of two components: Hepatogastric ligament: Extends from the lesser curvature of the stomach to the liver's visceral surface. Hepatoduodenal ligament: Extends from the proximal part of the duodenum to the porta hepatis of the liver, containing the portal vein, hepatic artery, and common bile duct. 2. Greater Omentum: The greater omentum is a large apron-like fold of peritoneum that hangs down from the greater curvature of the stomach and drapes over the intestines. It consists of four layers of peritoneum and contains adipose tissue, lymph nodes, and blood vessels. The greater omentum serves as a protective barrier, helping to isolate and contain infections or inflammatory processes within the abdomen. 3. Gastrosplenic Ligament (Lienorenal Ligament): The gastrosplenic ligament extends from the greater curvature of the stomach to the spleen. It contains the short gastric arteries, which supply blood to the fundus and upper part of the greater curvature of the stomach. 4. Gastrocolic Ligament: The gastrocolic ligament extends from the greater curvature of the stomach to the transverse colon. It is a double layer of peritoneum that contains blood vessels, lymphatics, and fat. Explain the applied anatomy of stomach 1. Location and Position: Knowledge of the stomach's location in the upper abdomen and its relationship to other abdominal organs is essential for physical examination, palpation, and diagnostic imaging techniques such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI). 2. Surface Anatomy: Understanding the surface anatomy of the stomach helps clinicians locate anatomical landmarks during physical examination and diagnostic procedures. For example, the greater and lesser curvatures of the stomach can be palpated to assess for tenderness or masses. 3. Peritoneal Attachments: Awareness of the peritoneal attachments of the stomach, including the lesser omentum, greater omentum, and various ligaments, is important for surgeons performing abdominal surgeries and procedures such as laparoscopic interventions. 4. Blood Supply and Vascular Anatomy: Knowledge of the arterial blood supply to the stomach, including the branches of the celiac artery such as the left gastric artery, splenic artery, and common hepatic artery, is crucial for understanding the pathophysiology of gastric ischemia and for planning surgical interventions. Familiarity with the venous drainage of the stomach, including the portal venous system, helps clinicians assess for complications such as portal hypertension and portal vein thrombosis. 5. Innervation: Understanding the innervation of the stomach by the vagus nerve (cranial nerve X) and sympathetic nerves is important for assessing gastric motility, secretion, and sensation. It is also relevant in conditions such as gastroparesis and functional dyspepsia. 6. Histology and Microscopic Anatomy: Knowledge of the microscopic anatomy of the stomach, including the mucosa, submucosa, muscularis externa, and serosa, is essential for diagnosing and understanding histopathological conditions such as gastritis, peptic ulcer disease, and gastric cancer. 7. Functional Anatomy: Understanding the physiology and functional anatomy of the stomach, including its role in digestion, absorption, and hormone secretion, is essential for managing conditions such as gastroesophageal reflux disease (GERD), gastric ulcers, and gastric motility disorders. Explain the parts, features, relations, blood supply, lymphatic drainage and nerve supply of male urethra Parts of the Male Urethra: 1. Prostatic Urethra: The prostatic urethra is the proximal portion of the urethra that passes through the prostate gland. It receives the ejaculatory ducts and carries semen from the seminal vesicles and vas deferens. 2. Membranous Urethra: The membranous urethra is a short segment that passes through the urogenital diaphragm, located between the prostate gland and the bulb of the penis. 3. Spongy (Penile) Urethra: The spongy urethra is the longest segment of the male urethra, extending from the bulb of the penis to the external urethral orifice at the tip of the penis. It traverses the corpus spongiosum of the penis and carries urine and semen. Features and Relations: The male urethra is surrounded by various structures, including the prostate gland, bulbourethral glands, corpus spongiosum, and erectile tissue of the penis. The prostatic urethra is wider and more dilatable than the membranous and spongy urethra. The urethral sphincters, including the internal urethral sphincter (smooth muscle) and external urethral sphincter (skeletal muscle), help regulate the flow of urine and semen. Blood Supply: The arterial blood supply to the male urethra is primarily derived from branches of the internal pudendal artery, including the prostatic artery, bulbourethral artery, and dorsal artery of the penis. Lymphatic Drainage: Lymphatic vessels from the male urethra drain into the pelvic and inguinal lymph nodes. The prostatic urethra drains into the internal iliac lymph nodes, while the membranous and spongy urethra drain into the superficial inguinal lymph nodes. Nerve Supply: The nerve supply to the male urethra is provided by branches of the autonomic nervous system (parasympathetic and sympathetic) and the somatic nervous system. Parasympathetic fibers, originating from the pelvic splanchnic nerves (S2-S4), regulate smooth muscle contraction during ejaculation and micturition. Sympathetic fibers, originating from the hypogastric plexus, control smooth muscle tone and vasoconstriction in the urethral wall. Somatic innervation, provided by the pudendal nerve (S2-S4), controls voluntary contraction of the external urethral sphincter and sensation in the penile urethra. Explain the location, capsules, surface features, relations and lobes of the prostate. Location: The prostate gland is situated in the pelvis, just below the urinary bladder and anterior to the rectum. It surrounds the prostatic urethra, through which urine and semen pass. Capsules: The prostate gland is encapsulated by a dense fibromuscular capsule, which provides structural support and protection to the glandular tissue within. The capsule is contiguous with the pelvic fascia and is firmly attached to the surrounding structures. Surface Features: The surface of the prostate gland is not smooth but irregular due to the presence of various lobes and sulci. It may exhibit surface features such as grooves, ridges, and depressions, which can vary among individuals. The surface may also be divided into distinct lobes, including the anterior, posterior, lateral, and medial lobes. Relations: Anteriorly: The prostate gland is in close proximity to the pubic symphysis and the pubic bones. Posteriorly: It is related to the rectum, separated by the rectovesical fascia (in front of the rectum) or the rectoprostatic fascia. Superiorly: The base of the prostate gland is adjacent to the urinary bladder, with the urethra passing through its center. Inferiorly: The apex of the prostate gland is located at the inferior end, close to the urogenital diaphragm and perineal membrane. Laterally: The prostate gland is related to the levator ani muscles, pelvic sidewalls, and neurovascular bundles supplying the penis. Lobes: The prostate gland is often described as having several lobes, although the exact number and terminology may vary among anatomists. Commonly recognized lobes include: Anterior lobe: Located anterior to the urethra and seminal vesicles. Posterior lobe: Positioned posterior to the urethra and seminal vesicles. Lateral lobes: Form the bulk of the prostate on each side of the urethra. Median lobe: A small, triangular-shaped lobe located between the ejaculatory ducts and the urethra. Explain the parts, position, features (external & internal) and relations of uterus. Parts of the Uterus: 1. Fundus: The top rounded portion of the uterus. 2. Body (Corpus): The main, central portion of the uterus. 3. Cervix: The narrow, lower portion of the uterus that extends into the vagina. Position: The uterus is situated in the pelvic cavity, posterior to the urinary bladder and anterior to the rectum. It typically lies in a slightly anteverted and anteflexed position, with the body tilted forward over the bladder and the cervix angled posteriorly toward the rectum. External Features: The uterus has an inverted, pear-shaped appearance. It is composed of smooth muscle tissue (myometrium) covered externally by a serous membrane called the perimetrium. The surface of the uterus may exhibit variations in texture and appearance, including indentations or ridges due to underlying blood vessels and ligament attachments. Internal Features: The internal cavity of the uterus is lined by a mucous membrane called the endometrium, which undergoes cyclic changes in response to hormonal fluctuations during the menstrual cycle. The endometrium consists of a basal layer and a functional layer, which thickens in preparation for embryo implantation and sheds during menstruation if implantation does not occur. Relations: Anteriorly: The uterus is related to the urinary bladder and the vesicouterine pouch (anterior cul-de-sac). Posteriorly: It is in contact with the rectum and the rectouterine pouch (posterior cul-de-sac or pouch of Douglas). Laterally: The uterus is related to the broad ligaments, which provide support and contain blood vessels, nerves, and lymphatics. Superiorly: The fallopian tubes arise from the superior lateral aspects of the uterus, forming the uterine (fallopian) tubes' ampullary regions. Inferiorly: The cervix of the uterus extends into the upper portion of the vagina and is surrounded by the vaginal fornices. Explain the supports, ligaments, blood supply, lymphatic drainage and nerve supply of uterus Supports of the Uterus: 1. Pelvic Floor Muscles: The uterus is supported by the pelvic floor muscles, including the levator ani muscles and the coccygeus muscle. These muscles provide foundational support and help maintain the position of the uterus within the pelvis. 2. Uterosacral Ligaments: These ligaments extend from the posterior aspect of the cervix to the sacrum. They provide posterior support to the uterus and help anchor it in place. 3. Broad Ligaments: The broad ligaments are large, flat bands of connective tissue that extend from the sides of the uterus to the lateral pelvic walls. They provide lateral support to the uterus and contain blood vessels, nerves, and lymphatics. 4. Round Ligaments: These ligaments extend from the lateral aspects of the uterus through the inguinal canal to the labia majora. They provide anterior support to the uterus and help prevent excessive movement. Blood Supply of the Uterus: The arterial blood supply to the uterus is primarily derived from branches of the internal iliac artery, including: Uterine artery: Supplies the body of the uterus and anastomoses with branches of the ovarian artery. Ovarian artery: Supplies the ovaries and contributes to the arterial supply of the uterus. Venous drainage is via corresponding veins, including the uterine veins, ovarian veins, and vaginal veins, which ultimately drain into the internal iliac vein. Lymphatic Drainage of the Uterus: Lymphatic vessels from the uterus drain into the pelvic lymph nodes, including the external iliac, internal iliac, and obturator lymph nodes. From there, lymphatic drainage continues to the common iliac lymph nodes and ultimately to the lumbar lymph nodes. Nerve Supply of the Uterus: The nerve supply to the uterus is provided by autonomic nerves, including sympathetic and parasympathetic fibers. Sympathetic innervation originates from the superior hypogastric plexus and regulates uterine blood flow, smooth muscle contraction, and sensation. Parasympathetic innervation originates from the pelvic splanchnic nerves (S2S4) and influences uterine motility and glandular secretion. Name the peritoneal folds attached to the uterus 1. Broad Ligaments: The broad ligaments are large, flat bands of connective tissue that extend from the sides of the uterus to the lateral pelvic walls. They provide lateral support to the uterus and contain blood vessels, nerves, and lymphatics. The broad ligaments consist of three parts: the mesometrium (attaches to the lateral pelvic walls), mesosalpinx (encloses the uterine tubes), and mesovarium (attaches to the ovaries). 2. Round Ligaments: The round ligaments are fibrous bands that extend from the lateral aspects of the uterus through the inguinal canal to the labia majora. They provide anterior support to the uterus and help prevent excessive movement. The round ligaments are remnants of the embryonic gubernaculum, which guides the descent of the uterus during fetal development. 3. Uterosacral Ligaments: The uterosacral ligaments extend from the posterior aspect of the cervix to the sacrum. They provide posterior support to the uterus and help anchor it in place within the pelvic cavity. The uterosacral ligaments play a role in stabilizing the uterus and preventing excessive movement or prolapse. Explain the parts and structures present within the broad ligament 1. Mesometrium: The largest part of the broad ligament, extending from the lateral aspects of the uterus to the lateral pelvic walls. It provides lateral support to the uterus and contains blood vessels, nerves, and lymphatics that supply the uterus and surrounding structures. 2. Mesosalpinx: The portion of the broad ligament that encloses and supports the uterine tubes (fallopian tubes). It helps suspend the uterine tubes in place and provides a pathway for the oocytes (eggs) to travel from the ovaries to the uterus. 3. Mesovarium: The fold of the broad ligament that supports and suspends the ovaries within the pelvic cavity. It contains the ovarian blood vessels, lymphatics, and nerves, providing them with a protective and supportive covering. Within the broad ligament, several important structures are contained or attached: Uterine Blood Vessels: The arteries and veins that supply and drain blood from the uterus are located within the layers of the broad ligament. These vessels include the uterine artery, which originates from the internal iliac artery, and the uterine vein, which drains into the internal iliac vein. Uterine Nerves: Nerve fibers innervating the uterus, including sympathetic and parasympathetic fibers, traverse through the broad ligament. These nerves regulate uterine contractions, sensation, and blood flow. Uterine Ligaments: The broad ligament serves as a framework for several uterine ligaments, including the round ligaments, uterosacral ligaments, and cardinal ligaments, which attach the uterus to various structures within the pelvis and provide support and stability. Lymphatic Vessels: Lymphatic vessels draining lymph from the uterus and surrounding tissues pass through the broad ligament. They play a role in immune function and drainage of interstitial fluid.