Inguinal MD124 2023-2024 Notes PDF

MD124 (AY: 2023-2024) (Anterolateral Abdominal Wall review &) Inguinal Region Alexander Black Bourgery, Marc Jean, 1797-1849. Traité complet de l'anatomie de l'homme comprenant la medecine operatoire, par le docteur Bourgery. Avec planches lithographiées d'après nature par N.H. Jacob. Paris: C. Dela...

MD124 (AY: 2023-2024) (Anterolateral Abdominal Wall review &) Inguinal Region Alexander Black Bourgery, Marc Jean, 1797-1849. Traité complet de l'anatomie de l'homme comprenant la medecine operatoire, par le docteur Bourgery. Avec planches lithographiées d'après nature par N.H. Jacob. Paris: C. Delaunay, 1831-1854. INGUINAL REGION: Learning Objectives After studying this material you will be able to: ✓ Define the boundaries of the inguinal canal and differentiate it from the inguinal ligament; ✓ Outline why the inguinal canal is a potential site for herniation ✓ Be able to differentiate a direct inguinal hernia from an indirect inguinal hernia ✓ Distinguish the fascial layers of the scrotum in relation to the associated layers of the anterior abdominal wall ✓ Discuss and outline the following clinical correlates: ✓ Cremasteric reflex ✓ Inguinal Hernias and the importance of Hesselbach’s triangle Recommended reading: Reading – Gray’s Anatomy for Students: pp 284-291 Acland’s – 3.3.11 – 3.3.13 REVIEW OF ABDOMEN SUPERIOR Abdominal Surface of Diaphragm Inferior thoracic aperture Xiphisternal joint (Xiphoid) Costal margin 11th and 12th ribs T12 vertebra INFERIOR Pelvic inlet Pubic symphysis Pubic crest Pubic tubercle Iliopectineal line Sacral alae Sacral promontory ANTEROLATERAL Anterior abdominal wall muscles Rectus abdominis m. External oblique m. Internal oblique m. Transversus abdominis m. POSTERIOR Vertebrae Posterior abdominal wall muscles Quadratus lumborum m. Psoas major m. Iliacus m. ANTEROLATERAL MUSCLES Two ‘vertical’ Rectus abdominis Pyramidalis Three ‘flat’ External oblique Internal oblique Tranversus abdominis Rectus sheath Incomplete protective ‘pocket’ for: Rectus Abdominis Epigastric Vessels Anterior Rami of spinal nerves T7T12 Composed of the aponeuroses of the three flat muscles as they converge in the midline to form the median linea alba Overview: Development Primordial ovaries of the Inguinal Canal in Females Upper Gubernaculum becomes Suspensory Ligament of the Ovary Deep Inguinal Ring Lower Gubernaculum becomes Round Ligament of the Uterus Superficial Inguinal Ring Round Ligament (of uterus) 8 weeks 15 weeks Deep inguinal ring Round ligament (of uterus) Superficial inguinal ring Mature Clinically Orientated Anatomy (2014)3 Overview: Development of the Inguinal Canal in Males Primordial testes Gubernaculum Site of future Deep Inguinal Ring Site of deep inguinal ring Site of future Superficial Inguinal Ring Gubernaculum becomes the scrotal ligament Processus vaginalis Gubernaculum becomes the tunica vaginalis (positioned posterior to process us vaginalis) 7 weeks7 weeks 28 weeks Tunica vaginalis (the serous sheath of the testis and epididymis) Right testis New Born (42 weeks) Clinically Orientated Anatomy (2014)4 Overview: Development of the Inguinal Canal in Males Parietal peritoneum Extraperitoneal fascia Transversalis fascia Processus vaginalis becomes the tunica vaginalis Transversus abdominis m. Internal oblique m. External oblique m. Primordial testis Gubernaculum Gubernaculum becomes the scrotal ligament (positioned posterior to processus vaginalis) 7 weeks 28 weeks Ductus (vas) deferens Scrotal ligament New Born (42 weeks) Gray’s Anatomy for Students (2005)5 Inguinal Region: Relationship to the anterior abdominal wall Linea semilunaris Linea alba EO m. IO m. Anterior superior iliac spine Anterior lamina of rectus sheath TA m. Location of deep Inferior epigastric vessels inguinal ring External oblique aponeurosis Conjoint tendon Location of superficial inguinal ring Spermatic cord Inguinal ligament Inguinal Ligament & associated ligaments Superficial inguinal ring Lacunar ligament: Deeper fibers of external oblique aponeurosis pass posteriorly to attach LATERAL to the pubic tubercle to form an arch Acetabulum Inguinal ligament (of Poupart): ▪ ▪ ▪ The fibrous, thickened, folded margin (inferior edge) of the external oblique aponeurosis Forms the floor of the inguinal canal Extends from: Anterior Superior Iliac Spine (ASIS) Pubic tubercle Pectineal ligament: Most lateral lacunar ligament fibers continue to run along pecten pubis MEDIAL to femoral canal Reflected inguinal ligament: Superior fibers of external oblique aponeurosis and lacunar ligament fan upwards crossing the linea alba instead of inserting into the pubic tubercle Boundaries of the Inguinal Canal It starts deep It ends superficially Boundaries of the Inguinal Canal Inferior Epigastric Vessels Anterior wall: External oblique aponeurosis → EXIT of the inguinal canal is located in this wall SUPEROLATERAL to the pubic tubercle Posterior wall: Transversalis fascia → ENTRANCE of the inguinal canal is located in this wall LATERAL to the inferior epigastric artery and vein Roof: Conjoint tendon → This forms from the arching fibers of internal oblique & transversus abdominis aponeuroses Floor: Inguinal ligament Inguinal Canal Openings: External oblique m. (reflected) Internal oblique m. Superficial Inguinal Ring Rectus abdominis m. The superficial inguinal ring: Superficial inguinal ring ▪ Also known as the “external” (open/cut) inguinal ring ▪ Opening in the external oblique aponeurosis Inguinal ligament Medial crus ▪ Exit of the inguinal canal ▪ Located superolateral to the pubic tubercle ▪ *N.B.*MEDIAL to the inferior epigastric vessels (artery and vein) Deep fascia of the thigh External oblique aponeurosis Spermatic cord Inguinal Canal Openings: Internal oblique m. Transversalis fascia Deep Inguinal Ring Conjoint tendon The deep inguinal ring: Deep inguinal ring Rectus abdominis m. ▪ Also known as the “internal” inguinal ring ▪ ‘Opening’ (invagination) in/of the transversalis fascia ▪ Entrance of the inguinal canal ▪ Located ½ way along the inguinal ligament ▪ *N.B.*LATERAL to the inferior Inguinal ligament Deep fascia of the thigh Spermatic cord epigastric vessels (artery and vein) Inguinal Canal: Contents Internal oblique m. The inguinal canal passes obliquely and inferomedially. It runs for about 4cm. Parietal peritoneum Scarpa’s fascia ▪ Females (narrower canal):  Round ligament of the uterus  Ilioinguinal nerve  Genital branch of genitofemoral nerve  Blood and lymphatic vessels ▪ Males (wider canal): ▪ Spermatic cord ▪ Ilioinguinal nerve ▪ Genital branch of genitofemoral nerve ▪ Blood and lymphatic vessels Transversus abdominis m. External oblique aponeurosis Transversalis fascia Inguinal ligament Lacunar ligament Ilioinguinal nerve Spermatic cord & contents: Artery to ductus (vas) deferens Ductus (vas) deferens Lymphatics Testicular a. Cremasteric a. and v. Obliterated processus vaginalis Pampiniform plexus of vv. Genital branch of genitofemoral n. Fascia lata Superior pubic ramus Pectineus m. Round ligament of the Uterus Terminates in the Labium majus (R & L) Vulva – the term for external aspects of the female reproductive tract Mons pubis, Labia majora, Labia minora, Clitoris, Vestibular bulbs, Vestibule, Bartholin's glands, Skene's glands, Urethra, and Vaginal opening (vaginal introitus) Copyrights apply Round ligament of the Uterus One of the suspensory ligaments of the uterus Helps keep the uterus in place Travels through the inguinal canal Terminates in the Labia majora (singular: labium majus) Round ligament of the Uterus Lies POSTERIOR to Inf Epigastric vessels Male reproductive system: external aspects Superficial inguinal ring Testicular a. Ductus deferens & artery to ductus deferens Cremaster fascia and muscle External spermatic fascia Dartos fascia and muscle Skin Pampiniform plexus Head of Epididymis Spermatic Cord The spermatic cord suspends the testis in the scrotum and contains the structures that run to and from the testis. Begins at: Deep inguinal ring Travels through: Inguinal canal Emerges at: Superficial inguinal ring Ends in: Scrotum (at posterior border of the testis) External spermatic fascia Internal spermatic fascia Spermatic Cord: Coverings Internal oblique m. Transversus abdominis m. External oblique m. Transversalis fascia ① External spermatic fascia: ❖ Parietal peritoneum Scarpa’s fascia Derived from the investing fascia of external oblique muscle Skin ② Cremaster fascia and muscle: Internal spermatic fascia Cremaster m. & fascia External spermatic fascia SPERMATIC CORD Ductus (vas) deferens ❖ ❖ Epididymis Parietal layer Visceral layer Tunica vaginalis Derived from the investing fascia of internal oblique muscle. Cremaster muscle is striated and innervated by the genital branch of the genitofemoral nerve to elevate the testis (GSE) (draws testis closer to body for protection) Skin Dartos m. & fascia ③ Internal spermatic fascia: ❖ Derived from transversalis fascia Scrotum The scrotum is part of the male external genitalia and is a cutaneous, muscular sac that has a variable (wrinkled) appearance. ▪ Rugose (wrinkled) appearance is due to smooth muscle fibers ▪ known as Dartos muscle that are extremely thin and insert onto the skin. ▪ ▪ Derived from SCARPA’S FASCIA The scrotum can protect the testes by passively raising them towards the trunk Scrotum: Coverings Internal oblique m. Transversus abdominis m. External oblique m. Transversalis fascia Parietal peritoneum Scarpa’s fascia ① Skin ② Dartos muscle & Superficial fascia Skin Derived from Scarpa’s fascia Internal spermatic fascia Dartos muscle is smooth and receives autonomic innervation (GVE) Works in conjunction with the striated cremasteric muscle Cremaster m. & fascia Ductus (vas) deferens External spermatic fascia ③ SPERMATIC CORD Epididymis External spermatic fascia Derived from external oblique m./fascia Parietal layer Visceral layer ④ Skin Dartos m. & fascia Tunica vaginalis External spermatic fascia Cremasteric fascia Internal spermatic fascia Cremaster fascia and muscle ⑤ Derived from internal oblique m./fascia Internal spermatic fascia Derived from transversalis fascia Scrotum: Arterial Supply External pudendal artery Internal iliac artery Femoral artery Internal pudendal artery Perineal artery Anterior scrotal branches Posterior scrotal branches Scrotum: Venous and Lymphatic Drainage Ilioinguinal nerve Common iliac lymph nodes Femoral v. Great saphenous v. External iliac lymph nodes Internal iliac lymph nodes Deep inguinal lymph nodes ▪ Anterior scrotal veins → External pudendal v. ▪ Posterior scrotal veins → Internal pudendal v. Lymph from the skin of the scrotum initially drains → Superficial Inguinal lymph nodes Testes (Testis = singular) The testis is a firm yet mobile (paired) organ Skin Dartos fascia External spermatic fascia Cremaster muscle & fasica Internal spermatic fascia Tunica vaginalis: suspended within the scrotum (by the spermatic cord) Each is anchored inferiorly by the scrotal ligament. ▪ These paired ovoid reproductive glands produce: Sperm (spermatozoa) Male hormones (testosterone) ▪ Approximately 5cm in length – highly variable ▪ Function optimally below body temperature Epididymis The epididymis is an elongated, tightly coiled, Head convoluted tube that is located on the posterior surface and superior pole of the testis. Body ▪ Stores spermatozoa until maturation occurs ▪ Arterial supply is provided by the testicular artery Tail ▪ Three parts of the epididymis: 1. Head: Receives efferent ductules (approx. 12-14) 2. Body: Narrower in diameter 3. Tail: Continuous with ductus deferens Visceral layer of tunica vaginalis withthe white tunica albuginea layer seen immediately deep Epididymis The epididymis is an elongated, tightly coiled, Head convoluted tube that is located on the posterior surface and superior pole of the testis. Body ▪ Stores spermatozoa until maturation occurs ▪ Arterial supply is provided by the testicular artery Tail ▪ Three parts of the epididymis: 1. Head: Receives efferent ductules (approx. 12-14) 2. Body: Narrower in diameter 3. Tail: Continuous with ductus deferens Visceral layer of tunica vaginalis withthe white tunica albuginea layer seen immediately deep Testes: Arterial Supply Pampiniform plexus (testicular veins) Testicular artery Artery of ductus (vas) deferens L Veins of ductus (vas) deferens Cremasteric artery Testicular arteries branch directly (anterolaterally) from the abdominal aorta at approx. L2 Testes: Venous Drainage Pampiniform plexus (testicular veins) Inferior Vena Cava Left renal vein Testicular artery Artery of ductus (vas) deferens R L Veins of ductus (vas) deferens Cremasteric artery Right testicular vein Left testicular vein Location of inguinal canal Pampiniform: Like a tendril of a vine Pampiniform plexus of veins Clinical Correlates 31 Hesselbach’s Triangle Mnemonic: R I P Direct inguinal hernia’s through the triangle Hesselbach’s inguinal triangle is located between the medial and lateral peritoneal (umbilical) folds and is a weak area in the posterior wall of the inguinal canal Three boundaries of Hesselbach’s triangle: ① Medial border: Lateral border of Rectus abdominis m. ② Lateral border: Inferior epigastric vessels ③ Inferior border: 2 Deep inguinal ring location Inguinal ligament of Poupart 1 3 Superficial inguinal ring location Herniation A hernia is when part of an organ is displaced and protrudes through the wall of the cavity containing it, often involving the intestine at a weak point in the abdominal wall. ▪ Umbilical hernia ▪ Femoral hernia - more common in females ▪ Direct inguinal hernia ▪ Indirect inguinal hernia ▪ Incisional hernia If the cause is “acquired” → pushes through the posterior wall of the inguinal canal If the cause is “congenital” → moves through a patent (open) processus vaginalis Indirect Inguinal Direct Inguinal Hernia Hernia Inferior epigastric a. LATERAL to the inferior epigastric artery Originates from the deep inguinal ring Technically there is no defect as this opening is already transmitting the ductus deferens or round ligament of the uterus! Travels through all of the inguinal canal Emerges from superficial inguinal ring Herniated content is covered by all 3 layers of spermatic cord plus peritoneum Easier to fully enter the scrotum More common in young males Inferior epigastric a. MEDIAL to the inferior epigastric artery Originates from Hesselbach’s triangle Takes a dramatic shortcut – pushes through weak area! Travels through medial part of the inguinal canal Emerges from superficial inguinal ring Herniated content is only covered by transversalis fascia and parietal peritoneum Less likely to fully enter the scrotum More common in older males Treatment: Herniorrhaphy Hernia can be treated by many different surgical techniques that act to repair and reconstruct the posterior aspect of the anterior abdominal wall and this procedure is known as hernioplasty or herniorrhaphy Causes of groin herniation: ▪ Obesity ▪ Pregnancy ▪ Heavy lifting ▪ Chronic obstructive pulmonary disease ▪ Straining (e.g. constipation) ▪ Congenital connective tissue disorders ▪ Defective collagen synthesis ▪ Cigarette smoking ▪ Ascites Chance of reoccurrence after repair is 10-15% Spermatic Cord Torsion Testicular torsion or “twisting of the spermatic cord” can occur at any age although is most common during adolescence (particularly between 12-16 years of age) Surgical EMERGENCY! Neonatal Testicular Torsion Driver & Losty (1998) British Journal of Urology ▪ The venous drainage of the testis becomes obstructed and consequently results in arterial Potential Symptoms: ▪ Sudden, severe onset of pain in the scrotum ▪ Swelling/Redness of the scrotum ▪ Lower quadrant pain in the abdomen ▪ Nausea ▪ Vomiting (a.k.a. emesis) ▪ Fever Can be tested using the cremasteric reflex! ischemia, edema & hemorrhage ▪ Advised to undergo surgery 4-6 hours after the onset of pain to prevent infertility or necrosis of the testis ▪ Torsion usually occurs above the upper pole of the testis ▪ Surgery involves fixing the testes to the scrotal septum in order to prevent reoccurrence Cremasteric Muscle Reflex The cremasteric muscle reflex causes rapid elevation of the testis Elicited by stroking the skin of the ipsilateral thigh ① Elicited by stroking the skin on the medial aspect of the proximal, superior part of the thigh:  General Somatic Afferent (GSA / Sensory) Femoral branch of genitofemoral nerve Ilioinguinal nerve ② Contraction of the cremaster muscle within the loops of cremasteric fascia raise the testis to “safety”:  General Somatic Efferent (GSE / Motor) Genital branch of genitofemoral nerve Reference: Summary of Layers Reference: Inguinal Canal – Internal Aspect Deep inguinal ring Superficial inguinal ring Reference: Female vs. Male Round ligament Ilioinguinal n. of the uterus Genital branch of genitofemoral n. Testicular a. Pampiniform plexus of vv. Ductus (vas) deferens Ilioinguinal n. Internal spermatic fascia Cremasteric fascia Artery and vein of the round ligament interspersed with muscle Genital branch of genitofemoral n. Female External spermatic fascia Male Reference: Inguinal Canal and Spermatic Cord Internal spermatic fascia Pampiniform plexus of veins External spermatic fascia will be “picked up” after the contents emerge from the superficial inguinal ring! Cremasteric muscle and fascia External oblique aponeurosis (reflected)