Fascial Layers & Abdominal Wall Anatomy PDF

Fascial Layers: Superficial Layers: 1. Camper's Fascia: Fatty Layer - Origins & Attachments: 2. Scarpa's Fascia: Membranous/Fibrous Layer - Attches to the thigh fascia inferior to inguinal ligament Deeper Layers: 1. Fascia from each muscle 2. Transversalis Fascia: Covers the innermost surface of...

Fascial Layers: Superficial Layers: 1. Camper's Fascia: Fatty Layer - Origins & Attachments: 2. Scarpa's Fascia: Membranous/Fibrous Layer - Attches to the thigh fascia inferior to inguinal ligament Deeper Layers: 1. Fascia from each muscle 2. Transversalis Fascia: Covers the innermost surface of the deepest anterior wall muscle -- > derived posteriorly from the thoracolumbar fascia Muscles of the Anterior Abdominal Wall 1. External Abdominal Oblique Attachments: Originates in between ribs 5-12 and it inserts on the illiac crest and linea alba with the lower extent of the muscle's aponeurosis forming the inguinal ligament Innervation: T7-T12 Actions: Compress abdominal organs during strenous activities such as coughing and maximal expiration 2. Internal Abdominal Oblique Attchments: Originates from the illiac crest/inguinal ligament and inserts on the inferior border of ribs 9-12 Innervation: T7-T12 & L1 Actions: Compress abdominal organs during strenous activities such as coughing and maximal expiration 3. Transversus Abdominus Attachments: It originates at the illiac crest and its aponeuorosis inserts onto the linea alba, pubic crest --> forms the conjoint tendon with the aponeurosis of the internal abdominal Innervation: T7-T12 & L1 Actions: Compress abdominal organs during strenous activities such as coughing and maximal expiration 4. Rectus Abdominis Attachments: It orginates at the level of the pubic tubercle and inserts onto ribs 5-7  Innervation: T7-T12 Actions: Compress abdominal organs during strenous activities such as coughing and maximal expiration Rectus Sheath Dense connective tissue sheath that surrounds the rectus abdominis muscle. The anterior and posterior layers contain the aponeuroses of the EO, IO, and TA muscles --> these meet at the linea semilunaris and then fuse at the linea alba. Aponeurosis of External Oblique: Contribues to the anterior portion of the rectus sheath Aponeurosis of the Internal Oblique: Contribues to both anterior and posterior portions Aponeurosis of the Transversus: Contributes to the posterior portion of the rectus sheath BELOW THE UMBILICUS AND AT THE ARCUATE LINE THINGS CHANGE: The rectus sheath no longer has the aponeurosis of certain muscles contributing to it posteriorly, instead all of the aponeurosis of the muscles fused and are a part of the sheath anteriorly, leaving the rectus sheath directly in contact with the transversus fascia posterioly Transversalis Fascia Deepest fascia derived posteriorly form the thoracolumbar fascia Extraperitoneal Connective Tissues is in between the transversalis fascia and the parietal peritoneum Cutaneous Nerves of the Anterior Abdominal Wall + Functions 1. Thoracoabdominal Nerves (T7-T11) 2. llioinguinal Nerve (L1) - Provides sensation to the scrotum and labia majus as well as the upper middle thigh --> goes through the inguinal canal 3. Illiohypogastric Nerve (L1) 4. Subcostal Nerve (T12) Dermatomes: Xiphoid: T7 Umbilicus: T10 Pubic: L1 Vasculature of the Anterior Abdominal Wall Arteries: Superior Epigastric Artery: Branch of the ITA. Descends within the posterior rectus sheath to anastomose with the inferior epigastric artery Inferior Epigastric Artery: Branch of the external illiac artery. Ascends inferior the inguinal ligament, penetrates the transversalis fascia and anastomoses with the superior epigastric artery Veins: Lumbar Vein: Drains into azygous system. Anatomoses with the Superior and Inferior Epigastric Veins Subcostal Vein: Drains into azygous system. Anastomoses with the Superior & Inferior Epigastric Veins Thoracoepigastric Vein: Longtiduinal veins drains into SVC via lateral thoracic vein and into IVC via superficial epigastric vein. Branches near the umbilicus and anastomoses with the paraumbilical veins which themselves connect to the portal vein. Caput Medusae: Blocked blood flow through the portal vein --> get retrograde bloodflow through the paraumbilical veins and thoracoepigastric Lympathics: Superficial Lympathics: Drain into axillary and superficial inguinal lymph nodes Muscle Lympathics: Drain along the superior and inferior epigastric veins to reach the lumbar, parasternal and external iliac nodes Inguinal Canal Lie parallel and superior to the inguinal ligament Transmits the ductus deferns/round ligament **Femoral vessels pass inferior to the inguinal ligament Contents: 1. Illioinguinal Nerve (L1) 2. Genitofemoral Nerve (L1-L2) --> Sensory and motor innervation to scrotum/labia majora and lower abdomen skin 3. Spermatic cord (contains vas deferens)/Round ligament of the uterus (connects uterus to labia majora) 4. Cremaster muscle --> muscle that contracts to raise and lower testes (innervated by genitofemoral nerve) Walls: Floor: Laterally --> Inguinal Ligament Medially --> Lacunar Ligament Anterior Wall: Laterally --> External oblique aponeurosis and internal oblique fibers Medially --> External oblique aponeurosis (superificial ring) Posterior Wall: Laterally --> tranversalis fascia (deep ring) Medially --> conjoint tendon Spermatic Cord Internal Spermatic Fascia: Invagination of transversalis fascia --> deep ring formed Middle Spermatic (Cremasteric) Fascia: Fascia derived from internal abdominal oblique External Spermatic Fascia: Fascia derived from the external abdominal oblique Inguinal (Hasselbach's) Triangle: Weak area in the abdominal wall bounded by the inguinal ligament, inferior epigastric vessels and the rectus abdominis muscle Direct v Indirect Inguinal Hernias Direct: Portrusion of abdominal contents through the inguinal triangle --> originates medial to the inferior epigastric artery Indirect: Portrusion of abdominal content through inguinal canal --> originates lateral to inferior epigastric artery (more common in men)