[0:16]Good morning. This is Dr. Adel Bondok, Professor of Anatomy and Neuroscience, Mansoura University, Egypt. Today I will talk about the anterior abdominal wall muscles.
[0:28]We have five muscles. They are arranged into three oblique and two vertical muscles. The three oblique are the outer layer is the external oblique muscle. The middle layer is the internal oblique muscle, and the inner layer or the deep layer is the transversus abdominis muscle. Each muscle begins by fleshy fibers and ends by aponeurosis. The aponeurosis of one side decussates with the aponeurosis of the other side in the midline to form the Linea alba. The muscles have different direction of fibers. The external oblique muscle, the fibers of the external oblique muscles muscle are directed downward and medially. The fibers of the internal oblique are directed upward and medially. The fibers of the transversus abdominis are directed horizontally. So why, why the direction of fibers of the three muscles is different to strengthen the anterior abdominal wall and to prevent hernia formation? So the direction of fibers of the of the oblique muscles, the external oblique downward and medially. The internal oblique upward and medially. The transversus abdominus horizontally. The two vertical muscles are this one is the as the rectus abdominus muscle. And this small triangular muscle here is the pyramidalis. Okay. Let's let's start by the external oblique muscle. This is the external oblique muscle. And this is the direction of the fibers downward and medially. And the muscle start by fleshy fibers and ends by aponeurosis. Regarding the origin of the external oblique from the lower eight ribs. Regarding the insertion, it is inserted by fleshy fibers and by aponeurosis. The fleshy fibers are inserted into the iliac crest, the outer lip of the iliac crest. Iliac crest is fine. Okay? The aponeurosis, this is the aponeurosis. It has upper border, medial border and lower border. The upper border of the aponeurosis is attached to the xiphoid process and gives origin to the pectoralis major muscle. The medial border is attached to the linea alba which extends from the xiphoid process to the pubic symphysis. The lower border is folded backward upon itself to form the inguinal ligament. So the inguinal ligament it is the lower border of the external oblique muscle. The lower part of the aponeurosis has an opening. This opening is called superficial inguinal ring. It transmits the spermatic cord or the round ligament of the uterus. Extension from the margin of the superficial inguinal ring around the spermatic cord forms the external spermatic fascia. So this is the external oblique muscle. Fibers directed downward and medially. Fleshy fibers inserted into the iliac crest, and this is the aponeurosis. Here inserted into the linea alba. Okay, inserted into the linea alba. And the lower border is folded backward upon itself to form the inguinal ligament. This is the inguinal ligament. The lower part of the aponeurosis has this ring, this opening which is called superficial inguinal ring for the passage of the spermatic cord. From the margin of the ring external spermatic fascia surrounds the spermatic cord. The external oblique muscle is related to a small triangle here, it's called the lumbar triangle. These are the fleshy fibers of the external oblique inserted into the iliac crest. The lumbar triangle is bounded by external oblique muscle, Latissimus dorsi muscle and the iliac crest. The floor of the lumbar triangle is formed by the internal oblique and transversus abdominis. And the clinical importance of this lumbar triangle is it is the site of lumbar hernia.
[5:26]This is the inguinal ligament. We'll talk about the attachment and the deep relation. Attachment of the inguinal ligament.
[5:36]Lateral attachment, it is attached laterally to the anterior superior iliac spine. It is attached medially to the pubic tubercle. It has an extension into the pectineal line called the lacunar ligament. We'll talk about it later. Okay? The deep relation of the inguinal ligament actually the inguinal ligament acts as a retinaculum for these structures, three muscles, pectineus, psoas and iliacus muscle from the medial to the lateral side. Then blood vessels, femoral artery and femoral vein. Then nerves, the femoral nerve, the femoral branch of the genitofemoral nerve, and the lateral cutaneous nerve of the thigh. Of course, fascia. Fascia in front of the femoral vessels, transversalis fascia. And fascia behind the vessels, iliacus fascia. And the nerves, femoral branch of the genitofemoral nerve, femoral nerve and lateral cutaneous nerve of the thigh. And then lymphatics from the deep inguinal lymph nodes to the external iliac lymph nodes.
[7:37]This is the inguinal ligament, extending from the anterior superior iliac spine to the pubic tubercle. It has an extension into the pectineal line called lacunar ligament. So this is the lacunar ligament.
[7:59]The lateral border is related to the femoral canal or the femoral ring. We have an extension from the lacunar ligament on the pectineal line. This extension is called Cooper's ligament or pectineal ligament. So what is Cooper's ligament? Cooper's ligament is lateral extension of the lacunar ligament on the pectineal line. It lies behind the femoral canal or the femoral ring. This is the lacunar ligament. It is related to the femoral canal and this is femoral hernia. The lacunar ligament and the femoral canal are related to this artery, abnormal obturator artery. So the abnormal obturator artery which is enlarged pubic branch of the inferior epigastric artery, this abnormal obturator artery is related to the lacunar ligament and femoral canal and it may be injured in operations of the femoral hernia.
[9:07]Second muscle is the internal oblique muscle. This is the internal oblique muscle. Fibers are directed upward and medially. Okay, let us talk about the origin. Okay, this is the origin, linear origin. Number one. Okay, lateral 2/3 of the inguinal ligament. And then iliac crest, the middle area. And then the lumbar fascia or thoracolumbar fascia. So origin, lateral 2/3 of the inguinal ligament, intermediate area of the iliac crest and lumbar fascia. Regarding the insertion, fleshy fibers and aponeurosis. The fleshy fibers are inserted into the last three ribs. The aponeurosis is inserted into the next three costal cartilages, seven, eight and nine. And then xiphoid process and linea alba, and then pubic crest and pectineal line. It is very important to know the arrangement of the aponeurosis of the internal oblique muscle. This is the internal oblique muscle, fleshy fibers and this is the aponeurosis. You should know the arrangement of the aponeurosis. This is the rectus abdominis muscle. So at the lateral border of the rectus muscle, this is the lateral border. This is the rectus. At the lateral border of the rectus muscle, the aponeurosis splits into two layers to form the rectus sheath. Anterior layer fuses with the external oblique aponeurosis to form the anterior role of the rectus sheath. Posterior layer fuses with the transversus abdominis aponeurosis to form the posterior role of the rectus sheath. This is the external oblique, internal oblique and transversus abdominis. So this is the first point. The second point is the lower part of the muscle, this is the internal oblique. The lower part of the muscle fuses with the lower part of the transversus abdominis to form the conjoint tendon. So the conjoint tendon this is the conjoint tendon. It is the lower fused fibers of the internal oblique and transversus abdominis. Regarding the aponeurosis, this is the aponeurosis of the internal oblique. Okay. The lower border of the aponeurosis of the internal oblique fuses with the lower border of the aponeurosis of the transversus abdominis to form the arcuate line. So this is the arcuate line which is the fused lower border of the aponeurosis of the internal oblique and transversus abdominis. So again, regarding the arrangement of the muscles, okay, we'll see it in the next slide. Okay. Regarding the arrangement of the muscles, of the aponeurosis. This is the external oblique, internal oblique, transversus abdominis. At the lateral border of the rectus muscle, the aponeurosis splits into two layers. Anterior layer and posterior layer. Anterior layer fuses with the external oblique aponeurosis to form the anterior role of the rectus sheath. Posterior layer fuses with the transversus abdominis aponeurosis to form the posterior role of the rectus sheath. This is the conjoint tendon. Okay, and this is the arcuate line. The arcuate line is the fused lower border of the aponeurosis of the internal oblique and transversus abdominis.
[12:58]The lower part of the internal oblique and transversus abdominis fused together to form the conjoint tendon. This is the conjoint tendon. Then the transversus abdominis muscle. This is the transversus abdominis muscle. The fibers are directed horizontally. Regarding the origin, it is linear origin. Okay? Linear origin from lateral third of the inguinal ligament. Yes, this is the linear origin.
[13:32]Lateral third of the inguinal ligament. And then outer lip. Inner lip. Sorry, inner lip of the iliac crest. The outer lip is for the external oblique. The intermediate area for the internal oblique. And the inner lip is for the transversus abdominis. Then lumbar fascia and then the last three costal cartilages. Lower three or last three costal cartilages from number seven to number 12. Okay? So again origin of transversus abdominis. Linear origin. Number one, lateral third of the inguinal ligament. Inner lip of the iliac crest. Lumbar fascia. Lower six costal cartilages. Regarding the insertion here, it is inserted into xiphoid process and linea alba. Okay? And then pubic crest and pectineal line. Actually, the attachment to the pubic crest and pectineal line is through the conjoint tendon. This is the transversus abdominis muscle. Okay? Transversus abdominis muscle. Fibers are directed horizontally. Let us see some landmarks. This is the rectus sheath containing the rectus muscle. This is the anterior role of the rectus sheath, and this is the posterior role of the rectus sheath. So the first landmark or first feature of the transversus abdominis, it forms the posterior role of the rectus sheath with the posterior layer of the internal oblique aponeurosis. Number two. This is the arcuate line. This arcuate line is the fused lower border of the internal oblique aponeurosis and transversus abdominis aponeurosis. This is the third feature, this part. Conjoint tendon. This one. The okay. Transversalis fascia. This transversalis fascia lines the transversus abdominis. Regarding the conjoint tendon, it is the fused lower fleshy fibers of the internal oblique and transversus abdominis. We have another. Ligament or tract is called iliopubic tract. This iliopubic tract is second band of transversalis fascia over the external iliac vessels. So the transversus abdominis muscle. Forms the posterior role of the rectus sheath. Forms the arcuate line with the internal oblique. Forms the conjoint tendon with the internal oblique. Lined by transversalis fascia. This transversalis fascia forms a band called iliopubic tract. And the transversalis fascia has an opening here is called deep inguinal ring for the passage of the spermatic cord.
[16:23]Regarding the two vertical muscles, the two vertical muscles are rectus abdominis muscle and pyramidalis. This is the pyramidalis, the triangular muscle. Regarding rectus abdominis muscle, it takes origin from here. So we'll talk about the origin and insertion. Origin from the pubic crest and pubic symphysis. Insertion up here. Inserted into the costal cartilages number five, six and seven and xiphoid process. So inserted into the fifth, sixth and seventh costal cartilages and xiphoid process. Regarding the pyramidalis, this pyramidalis muscle is a small triangular muscle that may be absent.
[17:16]Actually, I like to remind you with the muscles which may be absent. We have seven muscles that may be absent. Seven Ps. Seven muscles. Each one starts by P. So the first one will be the pyramidalis. The second one in the abdomen is the psoas minor. We have two muscles in the lower limb. Plantaris and peroneus tertius.
[18:00]We have one muscle in the upper limb, palmaris longus. We have one muscle in the hand and one muscle in the foot. The one muscle in the hand, first palmar interosseous muscle. And similar to this muscle in the foot, the first plantar interosseous muscle. So again, the five muscles which may be absent. The first one, five P. seven the seven muscles that may be absent. Seven Ps. Pyramidalis. Psoas minor. Plantaris. Peroneus tertius. Palmaris longus. First palmar interosseous. And the first plantar interosseous. Regarding the pyramidalis, it takes origin from the pubic crest. It is inserted into the linea alba. So the action will be stretching the linea alba. Regarding the landmarks of the rectus abdominis muscle. This is the rectus abdominis muscle inside the rectus sheath. Rectus abdominis muscle. The lateral border of the rectus muscle. This lateral border is called linea semilunaris. So linea semilunaris is the lateral border of the rectus muscle. Number two. The rectus muscle is divided into four segments. One, two, three and four by three tendinous intersections. These three tendinous intersections are located at the following points. The first tendinous intersection, it at the level of the xiphoid process. The third or the second at the level of the umbilicus. And the middle one is midway between the xiphoid process and the umbilicus. These tendinous intersections indicate that the rectus abdominis muscle develop from several myotomes. And these tendinous intersections don't extend through the whole thickness of the rectus muscle. Regarding the nerve supply of the anterior abdominal wall muscles, they are supplied by. Lower six thoracic nerves and iliohypogastric and ilioinguinal nerves. Regarding the rectus abdominis muscle. Rectus abdominis muscle is supplied by the lower six thoracic nerves. It is not supplied by L1. So rectus abdominis, lower six thoracic nerves. External oblique, internal oblique and transversus abdominis. Lower six thoracic nerves and L1. L1, iliohypogastric and ilioinguinal nerves. Regarding the pyramidalis, it is supplied by the subcostal nerve. Regarding the action of the anterior abdominal wall muscles. The oblique muscles are responsible for rotation of the trunk and lateral flexion of the trunk. So rotation of the trunk is done by the oblique muscles. Regarding the rectus abdominis muscle, flexion of the trunk and stabilization of pelvis. The anterior abdominal muscles, pyramidalis stretches the linea alba. Anterior abdominal wall muscles are accessory muscles of respiration. They relax during inspiration and they assist in forced expiration like coughing and sneezing. They protect, of course, the abdominal viscera and keep them in position. And they raise the intraabdominal pressure. So the oblique muscles for rotation of the trunk and lateral flexion of the trunk. Rectus abdominis muscle for flexion of the trunk and stabilization of the pelvis.
[22:46]And thank you very much, best wishes and good luck.
