Abdomen Anatomy 1 Quiz

Abdomen Anatomy 1 Lecture Notes

• Writer: Alaa Alessa
• Reviewer: Ali Aljazeeri
• Date: 2024-2025
• Topic: Abdomen Anatomy 1 lecture

Intended Learning Outcomes

• Students should be able to describe the anterior abdominal wall surface anatomy and landmarks.
• Students should be able to describe the topography and function of anterolateral muscles.
• Students should be able to discuss the rectus sheath anatomy.
• Students should be able to know the neurovascular supply of the anterolateral abdominal wall.

Contents

• Line and landmarks of the abdominal surface
• Abdominal quadrants
• Abdominal regions
• Skin and fascia
• Muscles of the anterolateral abdominal wall
• Structure and contents of the rectus sheath
• Neurovascular supply of the abdominal wall

Body Cavities

• The thoracic wall is mostly bone (ribcage).
• The abdomen is mostly muscle (abdominal wall).
• The thorax and abdomen are separated by the diaphragm.
• The abdomen and pelvis do not have a structural separating barrier.
• Some textbooks combine the abdomen and pelvis into the "abdominopelvic cavity."

Abdominal Regions

• Diagrams/images show the nine regions of the abdomen using midclavicular, subcostal, and intertubercular planes.
• Regional terms such as right upper quadrant (RUQ), left upper quadrant (LUQ), right lower quadrant (RLQ), and left lower quadrant (LLQ) are noted.
• List of organs/structures in each region is noted (e.g. liver, gallbladder, spleen).

Linea Alba

• Median raphe extending from xiphoid to pubic symphysis.
• Lies between paired rectus abdominis muscles.
• Fusion of aponeuroses of transversus abdominus, internal oblique, and external oblique.

Muscles of the Anterior Abdominal Wall

• Functions: protection and stabilization of viscera, contraction assists w/ quiet/forced expiration, coughing/vomiting, involved in actions increasing intrabdominal pressure (parturition, micturition, defecation)
• Rectus abdominis: originates from the 5th, 6th, and 7th costal cartilages; inserted into the pubic crest; important in abdominal incisions
• Tendinous intersections; constant intersections visible on the anterior aspect of rectus abdominis
• The anterior sheath is formed by aponeuroses of external oblique, internal oblique, & transversus abdominis.
• The posterior sheath is formed by the transversalis fascia & peritoneum.
• Layers of the abdominal wall: skin, superficial fascia (Camper's and Scarpa's fascia), muscles (external oblique, internal oblique, transversus abdominus, rectus abdominis, pyramidalis), extraperitoneal fascia, parietal peritoneum.
• Muscle locations/arrangements noted via diagrams.

Rectus Sheath

• Describes the structure and formation of the rectus sheath.
• Divisions include anterior and posterior walls, and specific areas of aponeuroses layers are described.

Arteries

• Superior and inferior epigastric arteries (branches of internal thoracic artery and external iliac artery).
• Deep circumflex iliac artery (branch of external iliac artery).
• Lower two posterior intercostal arteries branches of the descending thoracic aorta).
• Four lumbar arteries (branches of the abdominal aorta).

Veins

• Deep veins correspond to the arteries.
• Superior and inferior epigastric veins
• Deep circumflex iliac veins
• Lumbar veins drain into the inferior vena cava.
• Superficial veins form a network radiating from umbilicus, drained into axillary, femoral veins via lateral thoracic, superficial epigastric, and great saphenous veins
• Paraumbilical veins connect network through umbilicus and along the ligamentum teres to the portal vein

Lymph Drainage

• Superficial lymph vessels drain upwards to the anterior axillary nodes above the umbilicus, or downwards to the superficial inguinal nodes below umbilicus.
• Deep lymph vessels drain into internal thoracic, external iliac, posterior mediastinal, and para-aortic (lumbar) nodes.

Important Dermatomes for the Abdominal Wall

• Importance of dermatomes T-7, T-10, and L-1, locations in relation to abdominal structures.

Additional Information

• Information on the importance of surgical incisions in relation to the location of abdominal organs and structures are noted
• Information on Langer's lines are explained for better understanding of surgical procedures