Lecture 2 Flashcards
What composes the Superior Boundary of the abdomen?
Diaphragm
Inferior Thoracic Aperture (bottom of rib cage)
-Abdomen pops up 1/2 way into Thoracic cavity (rib 5) changes with inspiration and expiration
What composes the Inferior Boundary of the abdomen?
Illiac Crest
Inguinal Ligament
Pelvic Inlet (everything below is pelvic region)
What composes the Posterior Boundary of the abdomen?
Lumbar Vertebral Column
Psoas Major
Quadratus Lumborum
(abdominal wall muscles)
What composes the Lateral and Anterior Boundary of the abdomen?
Abdominal Wall Muscles
9x Layers of the Abdominal Wall (External –> Internal)
1. Skin Superficial Fascia (x2) 2. Camper's Fascia (thick yellow fatty, all over abdomen) 3. Scarpa's Fascia (Below Umbilicus, more orange, continuous with Dartus fascia and Collis fascia in you pertioneum) Muscle 3x 4. External Oblique 5. Internal Oblique 6. Transversus Abdominis 7. Transversalis Fascia 8. (Extra peritoneal Fascia) 9. Parietal Peritoneum
What is the variation between the Superficial Fascia as you go down the abdomen?
Above Umbilicus: Superficial fascia is same as everywhere else in body (thick, fat yellow layer)
Below Umbilicus: divides into 2x layers:
Superificial (fatty)= Campers Fascia= contains BV and nerves
Deep (membranous)= Scarpa’s Fascia
Where does the Abdomen span from?
Inferior Thoracic Aperture –> Top of the Pelvis
up into Thorax - down into the pelvis
What are the functions of the abdominal wall muscles?
- Stability (hold thorax and core up)
2. Allows Abdominal Viscera to move (flexible wall for movement/eating/pregnancy)
Rectus Abdominis
Longitudinal muscle, running down midline
Origin: Pubic Tubercle, Crest and Symphysis (Midline on Pubi bones)
Insertion: Costal Cartilages ribs 5-7 & Xiphoid Process (not on ribs or inferior thoracic aperture)
Action: - Flex Trunk. (pelvis more stable) -Support/compress Abdominal Wall (secondary respiratory muscle: tense abdominal muscles to compress abdominal cavity, and force luns up = forced expiration)
Nerve: Anterior Rami of Thoracic Spinal Nerves
External Oblique
Origin: Ribs 5-12
Insertion: Iliac Crest & Linea Alba (Inguinal Ligament) via aponeruosis (has no bone, so forms strong tendinous attachment)
Aponeruosis: From xiphoid process to pubic symphosis (lower border forms inguinal ligament)
-inguinal ligament= Rolled border of external oblique . Creates a gap for Femoral vessels to pass underneath.
Action: -Flex trunk (both) -turn to Opposite side/bend trunk to same side (single)
Nerve: Anterior Rami of thoracic Spinal Nerves
Fibre Direction: Infero-medial (hands in pockets)(downwards orientation)
Internal Oblique
Origin: Thoracolumbar Fascia (back), Inguinal Ligament & Illiac Crest
Insertion: Ribs 9-12
Action: -Flex trunk (both). -bend & turn trunk to Same side (single)
Nerve: Anterior Rami of Thoracic Spinal Nerves (some L1)
Fibre Direction: Supero-medial (as originates off inguinal ligament)
What is the relationship between External and Internal Oblique when they’re both firing?
Both flex trunk
Antagonisticly with other side
Turn to left: Right external and Left Internal fire
(works with opposite side)
Transversus Abdominis
Origin: Thoracolumbar Fascia (back), Iliac Crest, Inguinal Ligament, Costal Cartilage Rib 7-12
Insertion: Linea Alba (midline meeting of all aponeurosis’), Pubic crest, Pectineal Line (same place as rectur abdominis)
Action: Supports abdominal wall (not much of a movement function)
Nerve: Anterior Rami of thoracic spinal nerves (some L1- nerve run inbetween transversus abdominus and internal oblique, and innvervates a little bit along the way)
Fibre Direction: Transverse
Rectus Sheath
Over Rectus Abdominus
Aponeurosis of all other muscles to meet in midline
Supportive
Tough tendinous
Upper 3/4= all 3x abdominal muscles fully surround- Internal oblique splits (other 2x stay)
Lower 1/4 = below Arcuate Line= all 3x abdominal muscle are infront of rectus abdominus =(behind is Transversalis Fascia and Parietal Peritoneum) (not supported at back, relatively weak area, allows vessels to pass through, can result in hernia) (clinically important to know you have this deficit)
Arcuate Line (Rectus Sheath)
Roughly half way along line from Umbilicus to Pubic bones = Posterior wall of rectus sheath stops. Only have transversalis Fascia.
Tough tendinous sheath –> see-through shimmery layer (lost strong aponeurotic tissue)
-Arcuate line is where arterial supply enters/gets in
Arterial Supply
Superior Epigastric A. (from Internal Thoracic) Inferior Epigastric A. (from External Illiac)- more dominant/much larger Both run underneath Rectus Abdominus - (ontop of Transversalis Fascia - Within rectus Sheath) (Inferior epig, pierces through transversalis fascia, runs ontop and into rectus sheath) Anastomose together(in middle) Also: Deep Circumflex illiac, Musculophrenic branches, intercostal, lumbar, illiolumbar
Venous Drainage
Thoraco-epigastic Veins: Drain to Axillary (to armpit)
Superficial Epigastic Veins: Drains to femoral
Nerves
Lateral Cutaneous Branches 7-12 intercostal nerves + iliohypogastric nerve (L1) (lateral branches span around innervating lateral part)
Anterior Cutaneous branches of 7-12 intercostal nerves (anterior branches poke through lateral to rectus abdominis, innervating anteriorly)
-lower 6 interocstal nerves + hypogastic L1
-travel in neurovascular plane b/w Internal Oblique and Transversus Abdominis (analagous to nerves of intercostal plane)
Abdominal Dermatomes
1x nerve= 1 band (segmental spinal nerves which innervates 1x band)
Skin + Muscle + Parietal Peritoneum = supplied by T7-T12(intercostal) & L1 (illiohypogastric/Illioinguinal) spinal nerves
All= Anterior Rami (lateral and anterior)
T4-5= nipples
T10= umbilicus
Neurovascular plane: b/w Transversus Abdominis and Internal Oblique -analagous to Intercostal Neurovascular Plane - before piercing muscular wall to reach skin
(Referred pain in gut)
Lymphatic Drainage
Superficial Inguinal (inferiorly) Anterior Axillary (superior) Posterior Axillary
Peritoneum
Visceral: covers abdominal viscera (organs) + forms Mesentary -anchors viscera to Posterior body wall) (viscera comes back around on itself)
- GI tract/tube suspended in space by mesentery. 2x layers of visceral pertioneum. how BV come from Aorta and get into gut by travelling within mesentery.
Parietal: Lines body wall
Continuous with one another
Small amount of serous fluid between layers: reduces friction (created by movement)
-allows abdominal viscera to move without causing ulceration
Sensation of Peritoneum
Parietal: Sensitive to pain, touch, temperature and pressure. (body wall)
-Nervous supply by 1. Somatic nerves to body wall (Thoracic + Lumbar nerves) 2. Phrenic nerve (up by diaphragm) 3. Obturator nerve (down in pelvis)
Visceral/Mesenteries: Sensitive to stretch - Autonomoic NS Afferent fibres. (woudlnt feel if you poke gut)
-Stretching/Distension (eat too much)
Mesenteric Peritoneum
GI tract/gut tube passively suspended by Mesenteries
Mid + Hind gut= suspended by only 1x mesentery (Dorsal)
Foregut= suspended by BOTH ventral and dorsal mesentery. Where Umbillical cord enters, Umbillical veins go to liver, Liver part of Foregut (Mesenteric route for veins to enter) -gut embryology + ligaments of foregut
Intraperitoneal
completely contained in Visceral peritoneum
Suspended by Mesentery
-Spleen, Liver, Gall bladder, Spleen, Proximal Duodenum, Small Intestine, Appendix, Transverse Colon, Sigmoid Colon
(GI, most of foregut, bits of mid + hindgut)
