Anterior abdominal wall Layers of Anterior Abdominal Wall

Anterior abdominal wall

Layers of Anterior Abdominal Wall n n n In human anatomy, the layers of the abdominal wall are (from superficial to deep): Skin Fascia n n Camper's fascia - fatty superficial layer. Scarpa's fascia - deep fibrous layer. n Muscle -Rectus abdominis -External oblique muscle -Internal oblique muscle -Transverse abdominal muscle Pyramidalis muscle Cremasteric n n Fascia transversalis Parital Peritoneum

Fascia of Ant. Abdominal Wall 1 - there is no deep fascia 2 -the superficial fascia is formed of a single layer above the ambilicus , but below the ambilicus it differentiated into 2 layers: a- superficial fatty layer (Camper’s fascia) - contains variable amount of fat. b- deep membranes layer (Scarpa’s fascia) -continuous with the superficil perineal fascia (colle’s fascia)

Linea Alba An extensive aponeurosis which extend from the xiphoid process to the symphsis pubis. Linea Semilunaris the lateral margin of rectus abdominis is marked by a line on the anterior abdominal wall called linea semilunaris

Muscles of the anterior abdominal wall Classified into 2 groups: 1 - paramedian muscles -Rectus abdominis muscle - Pyramidalis muscle 2 - anterolateral flat muscles -external abdominal oblique m. -internal abdominal oblique m. -transversus abdominis m.

Abdominal external oblique muscle n the largest and the most superficial of the three flat muscles of the lateral anterior abdomen.

Origin : lower 8 ribs (outer surface) Direction of the fibers : downwards , forwards & medialy Insertion : -iliac crest ( anterior half of the outer lip) -anterior superior iliac spine -pubic tubercle -pubic crest -linea alba …………….

Inguinal ligament -It is the infolded lower border of the external oblique m. -The inguinal ligament runs from the anterior superior iliac spine to the pubic tubercle.

Abdominal internal oblique muscle Origin : 1 - iliac crest (ant. 2/3 of its intermediate line) 2 - inguinal ligament ( lateral 2/3 of its inner surface). 3 - lumbar fascia. Direction of the fibers : upwards , forwards and medialy Insertion : 1 - linea alba 2 - lower 4 or 5 ribs 3 - the lower fibers forms an arched fibers called the conjoint tendon.

Conjoint tendon -Formed by the lower arched fibers of both internal oblique and transversus abdominis muscles where the fiberous pass directly from origin to insertion -Function : The contraction of the conjoint tenden leads to closure of the inguinal canal (shutter mechanism ) -So , it prevent passage of intestine through the canal (Indirect inguinal hernia).

Transversus abdominis muscle Origin : -the lateral third of the inner surface of inguinal ligament -anterior 2/3 of the medial lip of the iliac crest -the inner surfaces of the cartilages of the lower 8 ribs -the thoracolumbarl fascia. Direction of the fibers : -horizontaly. Insertion: a- linea alba b-the lower fibers form an arched fibers together with the lower fibers of internal oblique muscle conjoint tendon) (conjoint

Rectus abdominus m. Site : it lies in the middle part of the abdominal muscle layer inside the tendinous sheath called rectus sheath. Origin : symphysis pupis and pubic crest. Insetion: 5 th, 6 th & 7 th costal cartilages-The muscle is divided by 3 tendinous intersections as follows: -These tendentious intersections are present on the anterior surface of the muscle and indicate that the muscle arises from different myotomes.

Action : -flexion of the trunk. Surface anatomy : the lateral margin of rectus abdominis is marked by aline on the anterior abdominal wall called linea semilunaris.

Cremastric muscle: n n It is formed by loops of muscle fibres from the lower part of the internal oblique it extends down through the spermatic cord & return behind it to be attached to the pupic tubercle n its n. supply is the genital branch of the genitofemoral n. n action: n elevation of testis upwards in the cold weather. n Cremastric reflex: n Scratching of the upper & medial parts of the thigh (L 1) leads to elevation of the testis.

Pyramidalis muscle : origin : pubic crest and symphysis pubis insertion : into the lower part of the linea alba nerve supply : subcostal nerve action : it stretches the linea alba

Action of the anterior abdominal wall muscles 1 -support the viscera and keep them in their position 2 -contract to increase the intra-abdominal pressure during urination and defection (mainly the trunsversus abdominis). 3 -expiratory action : -the abdominal muscles contract during expiration and relax during inspiraion. 4 -movement of the trunk : a-contraction of rectus abdominis muscle ……. . forward flexion. b-contraction of one side of the oblique muscles ………. lateral flexion. c. combined action of external oblique with the oppisite internal oblique ……rotation of the trunk. 5 - elevation of the testis ………. . by the cremastric m.

Inguinal canal n Definition: It is an oblique intermuscular canal (4 cm) above the medial part of the inguinal ligament. n Openings: -it starts at the deep inguinal ring and ends at the superfascial inguinal ring.

a-Superfascial Inguinal Ring Site: it is a triangular or inverted V shaped opening in the external oblique aponeurosis. its margins give the external spermatic fascia to cover the spermatic cord. Surface anatomy: It lies just above the pupic tubercle. Structures passing through it: -illio-inguinal nerve. -Spermatic cord ( in male) or round ligament ( in female)

B -Deep Inguinal Ring Site: It is a small opening in the lower part of fascia transversalis. Its margins give the internal spermatic fascia to cover the spermatic cord. Surface anatomy: - It lies ½ an inch above the midpoint of the inguinal ligament. Structures passing through it: -Spermatic cord (in male) or round ligament ( in female).

Arteries of the Anterior Abdominal wall A- Above the umbilicus 1 -superior epigastric artery 2 -musculo-phrenic artery 3 -lower two posterior intercostal and subcostal arteries