Anterior Abdominal Wall Structure, muscles and surface anatomy Curricular Objectives By the end of this session students are expected to: Practical 1. Identify the hip and distinguish the three bones forming it 2. Label the main landmarks on the hip bone with emphasis on internal surface 3. Locate the main surface landmarks of the anterior abdominal wall 4. Distinguish the layers of superficial fascia and its extensions 5. Mark the inguinal ligament and palpate its attachment points 6. Recognize the muscles of anterior abdominal wall and the related structures 7. Identify the anterior and posterior layers of the rectus sheath and its extensions 8. Divide the anterior abdominal wall into nine regions using imaginary lines 9. Distinguish the major dermatomes of the anterior abdominal wall Theory 1. Define the abdomen and outline its boundaries and content 2. Relate the abdominal cavity to the chest wall 3. List the layers making the anterior abdominal wall 4. State the direction of cleavage lines of abdominal skin 5. Explain the relation between cleavage lines of abdominal skin and surgical incisions 6. Describe the two layers of superficial fascia 7. Outline the fate of the membranous layer above, laterally and below 8. Acknowledge that extravasated urine may collect deep to membranous layer 9. Review the muscles of anterior abdominal wall and their attachment 10. Summarize the fiber direction, nerve supply, and functions of these muscles 11. Describe the rectus sheath (location, formation and content) 12. List the organs and viscera located in each of the nine abdominal regions Selected references and suggested resources Clinical Anatomy by Regions, Richard S. Snell, 9th edition Grant's Atlas of Anatomy, 13th Edition McMinn's Clinical Atlas of Human Anatomy, 7th Edition Anatomy for Babylon medical students (facebook page) Human Anatomy Education (facebook page) Human anatomy education (you tube channel) This session has been reviewed by Anatomy team at the Department of Anatomy and Histology/ College of Medicine/ University of Babylon/ 2016 Medical students/ Stage 2 Page 1
Session check list Clinical importance Knowledge on the anatomy of anterior abdominal wall is highly needed in fields of surgery, medicine & obstetrics. EX.: performing surgical incisions or examining patient`s abdomen Examples of clinical conditions related to the anterior abdominal wall include abdominal hernia, Liposuction, caput medusa, and various stria Abdomen What does the term abdomen refer to? Which part of the abdominal cavity is protected by the chest wall? Bones of the abdominal region Task: Use a lab model to identify the followings Hip bone Ilium: Anterior superior iliac spine (ASIS) Iliac crest and tubercle Pubis Superior ramus/ Inferior ramus/ Pectineal line Body/ Pubic tubercle/ Pubic crest/ Symphesis pubis Ischium Five Lumber vertebra Lower eight Ribs Anterior abdominal wall Task (watch and respond): Watch this video then respond accordingly https://www.youtube.com/watch?v=6xtsk0blag4&index=28&list=pl9d9c288df039d834 What are the layers forming the anterior abdominal wall? The superficial vessels run along which layer? What are the three flat muscles of the anterior abdominal wall? How the fibers of the three muscles directs? Where does the neurovascular plane of the anterior abdominal wall located? Name the vertical muscles of the anterior abdominal wall What is the rectus sheath and what makes its anterior and posterior layers? What divides the rectus abdominis muscle into segments? Skin Discuss the statement: Knowing the direction of the cleavage lines of skin of the anterior abdominal wall, can help you decide the direction of the surgical incision and predict the outcome of scar thereafter. Superficial fascia Fatty layer (fascia of Camper) Membranous layer Scarpa s fascia What is the fate of this layer below Medical students/ Stage 2 Page 2
Muscles of Anterior abdominal wall Task (identify and respond): identify the following structures and respond accordingly External oblique Origin: _ Posterior free border Extends between above and below Inguinal ligament Is a backward fold of the aponeurosis of external oblique Extends from laterally and medially Superficial inguinal ring: Locate it and name the structures passing through it Internal oblique Lower free border: Lowest fibers of the muscle arch between laterally, and medially Transversus Lower free border: Lowest fibers of the muscle arch between laterally, and medially Conjoint tendon Formed by the joining together of lowest fibers of and muscles Where it attaches medially? Rectus abdominis Linea semilunaris: It extends from to The muscle is mostly covered by the rectus sheath except Tendinous intersections: Where do each of these lie? To which layer of the rectus sheath they are firmly attached? Pyramidalis Medical students/ Stage 2 Page 3
Rectus sheath Arcuate line: (the backdoor of the rectus sheath) What surface landmark lie at the level of this line? What vessel pass between this line and the rectus muscle? Content: Surgical Note: the posterior wall of rectus sheath is not attached to the rectus abdominis. This allow sideway retraction of the muscle during surgical operations Linea alba: Extends between and Formed by Actions and functions of the muscles Task: Write a report on the actions and functions of the anterior abdominal wall muscles. Note: the report will be reviewed by the anatomy team and the best three reports will have the opportunity to present their report in a seminar and be awarded marks Surface anatomy Homework activity Ask a family member to examine his abdomen, fulfill the following tasks, then answer the questions in the report form provided Locate (by inspection and palpation) the following structures 1. Xiphoid process 2. Costal margin 3. Iliac crest and tubercle 4. Anterior superior iliac spine 5. Pubic tubercle 6. Symphesis pubis Draw imaginary lines dividing the wall into nine regions (Fig.4.12/page122/Snell, can help) Look at the umbilicus/segments of rectus abdominis Draw a circle representing the site of superficial inguinal ring on anterior abdominal wall Feel by your hands each one of the nine regions of the wall Medical students/ Stage 2 Page 4
REPORT FORM FOR ANTERIOR ABDOMINAL WALL HOMEWORK ACTIVITY Please fill the report form after you finish the required tasks then submit it to your lab instructor You are encouraged to talk about your experience in your own words Could you feel a difference between the iliac crest and tubercle? Express what you felt At which vertebral level lie the Iliac crest ( ), Iliac tubercle ( ) and ASIS ( ) Was it difficult to feel the pubic tubercle? If yes, what do you think the reason is? Name the imaginary lines you draw 1. 2. 3. Write a brief description on how you draw your lines Is it clinically important to divide the abdomen into regions? Elaborate Was the umbilicus everted, slightly inverted or deeply inverted? Why it look so? Could you see the segments of the rectus abdominis muscle? Why? Where did you draw the superficial inguinal ring? Could you feel the linea semilunaris? Near to which surface landmarks you should feel it? Medical students/ Stage 2 Page 5