Anterior abdominal wall Flashcards
Overview of abdominal cavity
-Boundary between thorax and abdomen = diaphragm
-Boundary between abdominal and pelvic cavity = pelvic inlet (imaginary)
-Abdominal cavity can extend superiorly up to 4th intercostal space
-Abdominal cavity is musculo-aponeurotic - providing protection, flexibility, distensibility
Anatomical 9 regions of abdomen
-2 vertical midclavicular lines that pass from midpoint of clavicles to midinguinal points
-Superior subcostal plane that passes through inferior border of the 10th costal cartilage
-Inferior transtubercular plane that passes through iliac tubercles and body of L5 vertebra
Clinical 9 regions of abdomen
-2 vertical semilunar lines that run parallel to lateral edges of rectus abdominus
-Superior transpyloric plane (transects pylorus of stomach)
-Inferior interspinous plane (transects anterior superior iliac spine)
4 quadrants of abdomen
-Transumbilical plane passes through the umbilicus
-Vertical median plane passes longitudinally through the body
Organ locations in abdominal cavity
-Bladder is pelvic organ when empty
-Bladder is abdominal organ when full
Surface anatomy of anterior abdominal wall
Linea alba - visible in lean individuals as a vertical skin groove
Semilunar lines - slightly curved linear impressions in the skin parallel to the lateral edges of the rectus sheath
Inguinal ligament - extends between anterior superior iliac spine and the pubic tubercle
Superficial anatomy of anterior abdominal wall
-Superior to the umbilicus, the subcutaneous tissue is consistent with that found in most regions
-Inferior to the umbilicus, the deepest part of the subcutaneous tissue (superficial fascia) is reinforced by many elastic and collagen fibres
-It has 2 layers: Superficial fatty (Camper’s layer) and Deep membranous (Scarpa’s layer)
Intermediate anatomy of anterior abdominal wall
-Everyone has 6 or 8 packs because of the tendinous junction
Deep anatomy of anterior abdominal wall
-Transversus abdominus (horizontal)
-Rectus abdominus (vertical)
Layers of anterior abdominal wall
-Skin
-Superficial fascia - fatty superficial layer and membranous deep layer
-Muscles and aponeuroses covered by deep fascia
-Endoabdominal (transversalis) fascia - refers to portion of fascia which lines the internal surface of the transversus abdominis muscle and it aponeurosis
-Extraperitoneal fat
-Parietal peritoneum
Features of the external oblique
Origin: External surfaces of 5-12th ribs
Insertion: Linea alba, Anterior half of iliac crest, Pubic tubercle
Action: Lateral flexion of trunk, Rotation of trunk, Stabilisation of pelvis, Compression of abdomen
Innervation: Intercostal nerves (T5-T11), Subcostal nerve (T12), Iliohypogastric nerve (L1)
What does inguinal ligament run between?
-Anterior Superior Iliac Spine (ASIS)
-Pubic tubercle
Features of internal oblique
Origin: Thoracolumbar fascia, Anterior 2/3 of iliac crest
Insertion: Inferior borders of 10-12th ribs, Linea alba
Action: Lateral flexion of trunk, Rotation of trunk, Stabilisation of pelvis, Compression of abdomen
Innervation: Intercostal nerves (T6-T11), Subcostal nerve (T12), Iliohypogastric nerve (L1), Ilioinguinal nerve (L1)
Features of transverse abdominis
Origin: Internal surfaces of 7-12th costal cartilages, Thoracolumbar fascia, Iliac crest
Insertion: Linea alba, Pubic crest
Action: Stabilisation of pelvis, compression of abdomen
Innervation: Intercostal nerves (T6-T11), Subcostal nerve (T12), Iliohypogastric nerve (L1), Ilioinguinal nerve (L1)
Thoracolumbar fascia
-Gives rise to transversus abdominis and internal oblique
-But not the external oblique
Features of rectus abdominis
Origin: Pubic symphysis, Pubic crest
Insertion: Xiphoid process, 5-7th costal cartilages
Action: Flexion of the lumbar spine, Stabilisation of pelvis, Compression of abdomen
Innervation: Intercostal nerves (T5-T11), Subcostal nerve (T12)
Features of pyramidalis
Origin: Pubic crest
Insertion: Linea alba
Action: Tenses the linea alba
Innervation: Subcostal nerve (T12)
Movement of muscles
-Contralateral external and internal oblique muscles work together to rotate the trunk
-Ipsilateral external and internal obliques produce lateral flexion
-Rectus abdominis produce trunk flexion
Features of rectus sheath
-Incomplete fibrous sheath that encloses rectus abdominis and pyramidalis muscles
-Also encloses superior and inferior epigastric arteries, veins, lymphatic vessels and distal portions of spinal nerves T7-T12
-Formed from aponeuroses of 3 abdominal muscles
What is the arcuate line?
-Line between the aponeurotic posterior wall of rectus sheath (covering 3/4 of rectus abdominis) and transversalis fascia (covering 1/4)
Above and below the arcuate line
-Bottom 2 pack is harder to obtain because 3 aponeuroses in the way instead of 1.5
Nerves of anterior abdominal wall
T7-T12
-Distal anterior rami of the T7-T12 spinal nerves - they are the former intercostal nerves distal to the costal margin
-Run in the neurovascular plane between the internal oblique and transverse abdominis muscles to supply the skin and muscles of anterior abdominal wall
Vessels of anterior abdominal wall
Anterolateral abdominal wall receives blood from:
-Superior epigastric artery - branch of the internal thoracic artery
-Inferior epigastric artery - branch of the external iliac artery
-External iliac artery continues as the femoral artery at the inguinal ligament
-Lateral region of abdominal wall supplied by 10th and 11th posterior intercostal arteries and the subcostal artery from descending aorta
