Download ANTERIOR ABDOMINAL WALL

ANTERIOR ABDOMINAL WALL
Learning objectives
 At the end of the lecture the student should be able to:
 Know the details of anterior abdominal wall.
 Identify the layers of abdominal wall.
 Identify the fascia, muscles of wall.
Abdominal wall
 Abdominal wall represents the boundaries of the abdominal cavity.
 Abdominal wall is split into:
 Posterior (back)
 Lateral (sides)
 Anterior (front).
Borders of the Abdomen
 Superior:
Costal cartilages 7-12.
Xiphoid process: Level of 10th cartilage = L3
 Inferior:
Pubic bone and iliac crest: Level of L4.
 Umbilicus:
Level of IV disc L3-4
Lines of the Anterior Abdominal Wall
 Linea alba:
Located along the midline = connective tissue raphe.
 Linea semilunaris:
Along each lateral border of rectus abdominis.
 Linea transversa:
Tendinous bands of rectus abdominis
Linea Alba
 Median raphe
 Extends from xiphoid to pubic
symphysis.
 Lies between paired rectus abdominus
muscles.
 Fusion of aponeuroses of transversus
abdominus, internal oblique, and
external oblique.
Surface Features
 Linea semilunaris:
o Along lateral margin of rectus abdominus.
o Crosses costal margin near tip of 9th costal cartilage.
 Arcuate line:
o Lower free edge of posterior lamina.
o Lies midway between umbilicus and pubis.
Layers of abdominal wall
 Layers of the abdominal wall are (from
superficial to deep):
 Skin
 Fascia
 Camper's fascia - fatty superficial layer.
 Scarpa's fascia - deep fibrous layer.
 Muscle
 Three large flat sheets connecting rib
cage to hip bone.
 Muscles posteriorly and laterally.
 Aponeurosis anteriorly and medially
• Rectus abdominis
• External oblique muscle
• Internal oblique muscle
• Transverse abdominal muscle
 Fascia transversalis
 Peritoneum
Fascia
 Superficial:
o
o
o
o
Camper’s fascia
Continuous with fascia over thorax and thigh.
Fatty layer.
It is areolar in texture, and contains in its
meshes a varying quantity of adipose tissue.
 In men, this superficial layer continues over the
penis and, after losing its fat and fusing with the
deeper layer of superficial fascia, continues into
the scrotum where it forms a specialized fascial
layer (the dartos fascia).
 In women, this superficial layer retains some fat
and is a component of the labia majora.
Fascia
 Deep Superficial:
Scarpa’s fascia
Membranous layer.
 It continues into the anterior part of the
perineum where it is firmly attached to the
ischiopubic rami and to the posterior margin
of the perineal membrane. Here, it is referred
to as the superficial perineal fascia (Colles'
fascia).
Deep:
Thin layer covering abdominal muscles.
Muscle Layers
 5 muscles
 3 horizontal
 External oblique.
 Internal oblique.
 Transversus abdominus.
 2 vertical
 Rectus abdominus.
Rectus sheath
 Rectus sheath:
Encloses rectus abdominus.
Formed by fusion of fascia of other three layers of
abdominal muscles.
Anterior and posterior laminae. (layers)
 Arcuate line is the lower free edge of the posterior
lamina
Lies midway between umbilicus and
Rectus abdominis muscle
 Two parallel muscles
 Separated by a midline band of connective tissue
called the linea alba
 Attachment




Pubic crest,
Pubic tubercle
Pubic symphysis
Costal cartilages of ribs V to VII;
xiphoid process
 Anterior rami of lower seven
thoracic spinal nerves (T7 to T12)
 Functions
 Compresses abdominal contents;
 Flexes vertebral column & tense
abdominal wall.
Pyramidalis
 Attachment
 Front of pubis and pubic symphysis Into linea alba.
 Anterior ramus of T12 Tenses the linea alba
External oblique
 Most superficial of the three flat muscles
 Immediately deep to the superficial fascia.
 Large aponeurotic component covers the anterior part of the abdominal wall
to the midline.
Extensions of external oblique
 The lower border of the external oblique
aponeurosis forms the inguinal
ligament on each side.
 This thickened reinforced free edge of
the external oblique aponeurosis passes
between the anterior superior iliac spine
laterally and the pubic tubercle
medially.
 Lacunar ligament is a crescent-shaped
extension of fibers at the medial end of
the inguinal ligament that pass
backward to attach to the pecten pubis
on the superior ramus of the pubic bone.
 Additional fibers extend from the
lacunar ligament along the pecten pubis
of the pelvic brim to form the pectineal
(Cooper's) ligament.
Internal oblique muscle
 Deep to the external oblique muscle is the internal oblique muscle
 This muscle is smaller and thinner than the external oblique, with most of its
muscle fibers passing in a superomedial direction.
 Its lateral muscular components end anteriorly as an aponeurosis that blends
into the linea alba at the midline.
Transversus abdominis
 Deep to the internal oblique muscle is the transversus abdominis muscle.
 So-named because of the direction of most of its muscle fibers.
 It ends in an anterior aponeurosis, which blends with the linea alba at the
midline.
Transversalis fascia
 Each of the three flat muscles is covered on its anterior and posterior
surfaces by a layer of investing abdominal fascia.

These layers are unremarkable except for the layer deep to the transversus
abdominis muscle (the transversalis fascia), which is better developed.
 Deep to the transversalis fascia is a layer of connective tissue, the
extraperitoneal fascia, which separates the transversalis fascia from the
peritoneum
Peritoneum
 Deep to the extraperitoneal fascia is the peritoneum. This thin serous
membrane lines the walls of the abdominal cavity and, at various points,
reflects onto the abdominal viscera, providing either a complete or a partial
covering.
Cutaneous Nerves
 The skin and muscles of the anterolateral abdominal wall
are supplied by T7 to T12 and L1 spinal nerves.
 The intercostal nerves (T7 to T11) leave their
intercostal spaces, passing deep to the costal
cartilages, and continue onto the anterolateral
abdominal wall between the internal oblique and
transversus abdominis muscles.
Cutaneous Nerves
 Ventral rami of T7 through T11:= thoracoabdominal
nerves.
T7 to dermatome over xiphoid process.
T10 at level of umbilicus.
 Subcostal nerve
 Ventral ramus of L1:
Gives rise to:
iliohypogastric nerve.
ilioinguinal nerve.
Arterial supply
 Superior part of the wall
 Musculophrenic artery, a terminal
branch of the internal thoracic
artery.
 Inferior part of the wall
 Superficial epigastric artery
 Superficial circumflex iliac artery,
both branches of the femoral artery
 Lateral part of the wall
 10th and 11th intercostal arteries
 Subcostal artery
Lymphatic Drainage
 Superficial lymphatics:
 Above the umbilicus:
Drain into the axillary and sternal nodes.
 Below the umbilicus:
Drain into the superficial inguinal nodes.
 Deep lymphatic drainage
 Follows the deep arteries back to
parasternal nodes along the internal
thoracic artery,
 lumbar nodes along the abdominal aorta
 external iliac nodes along the external
iliac artery.
Venous Drainage
 Superficial veins are paired with arteries.
 Above the umbilicus:
Drain into the azygos venous system.
 Below the umbilicus:
Drain into the femoral system (via great saphenous).
Folds on Posterior Surface (of anterior wall)
 Median umbilical fold:
Midline peritoneal fold on inner abdominal wall above bladder.
Contains median umbilical ligament:
Remnant of embryonic urachus.
 Medial umbilical fold:
Paired peritoneal folds on either side of median fold.
Contain medial umbilical ligaments:
Remnants of umbilical arteries.
 Lateral umbilical fold:
Paired peritoneal folds lateral to medial folds.
Contain inferior epigastric vessels:
From deep inguinal ring to arcuate line.