Anatomy 9 Flashcards
What does the abdominal cavity contain?
Gastrointestinal Tract
Hepatobilliary System
Urinary System
Endocrine System
Spleen
Great Vessels
What are the anterior, lateral and posterior walls of the abdomen composed of?
Skin
Subcutaneous tissue
Muscles
Associated aponeuroses (flat tendons)
How many lumbar vertebrae contribute to the posterior wall of the lumbar cavity?
5
What are the functions of the abdominal wall?
- Protect the abdominal viscera
- Increase intra-abdominal pressure (e.g. for defecation and childbirth)
- Maintain posture and move the trunk
What is the internal aspect of the abdominal wall lined with?
Serous membrane called parietal peritoneum
What bony landmarks define the boundaries of the abdominal cavity?
- Xiphisternum
- Costal margin
- Iliac crests
- Anterior superior iliac spines (ASIS)
- Pubic tubercles
- Pubic symphysis (a fibrocartilaginous joint).
What are the 4 quadrants?
Right upper and lower quadrants and the left upper and
lower quadrants.
The anterior abdominal wall is divided into these quadrants by two invisible lines:
* a vertical line that runs down the midline through the lower sternum, umbilicus,
and the pubic symphysis
* a horizontal line that runs across the abdomen through the umbilicus.
What are the nine regions?
The abdomen is divided into nine regions by four imaginary lines:
- the right and left midclavicular lines, which extend vertically from the midclavicular point to the mid-inguinal point (halfway between the anterior superior iliac spine and the pubic tubercle)
- the subcostal line - a horizontal line drawn through the inferior-most parts of the right and left costal margins (through the 10th costal cartilage)
- the intertubercular line - a horizontal line drawn through the tubercles of the right and left iliac crests and the body of L5.
- The central regions, from superior to inferior, are the epigastrium, the umbilical region and the hypogastric (suprapubic) region.
- On the right, the regions from superior to inferior are the right hypochondrium, the right lumbar region and the right iliac fossa (region).
- On the left, the regions from superior to inferior are the left hypochondrium, the left lumbar region and the left iliac fossa (region).
What is the Transpyloric plane?
A horizontal line that passes through the tips of the right and
left ninth costal cartilages.
It lies between the superior border of the manubrium and the pubic symphysis. It transects the pylorus of the stomach, the gallbladder, the pancreas and the hila of the kidneys.
What is the Transumbilical plane?
This is an unreliable landmark as its position varies depending
on the amount of subcutaneous fat present.
In a slender individual it lies approximately at the level of L3.
What is the Intercristal plane?
A horizontal line drawn between the highest points of the right
and left iliac crests.
It cannot be palpated from the anterior aspect of the abdominal
wall.
It is used to guide procedures on the back (e.g. lumbar puncture).
What is the McBurney’s point?
The surface marking of the base of the appendix.
It lies two thirds of the way along a line drawn from the umbilicus to the right anterior superior iliac spine.
What are the 4 pairs of muscle that compromise the anterolateral abdominal wall?
- External oblique (diagonally orientated fibres)
- Internal oblique (diagonally orientated fibres)
- Transversus abdominis (horizontally orientated fibres)
- Rectus abdominis (rectus = straight).
Where do the vertical right and left rectus abdominis muscles lie?
Lie either side of the midline
What is the rectus abdominis attached to?
Sternum and costal margin superiorly
Pubis inferiorly
What is the rectus abdominis surrounded by?
Aponeurotic rectus sheath
What sheets of muscles are found lateral to the rectus abdominis?
External oblique
Internal oblique
Transversus abdominis
What are the external obliques?
Is most superficial.
The fibres of EO run medially and inferiorly, towards the midline.
What are the internal obliques?
Lies deep to EO.
The fibres of IO are orientated perpendicular to those of EO (they run medially and superiorly).
What are the transversus abdominis?
Lies deep to internal oblique.
Its fibres are orientated horizontally.
When do the EO, IO and TA become aponeurotic, and what happens?
Anteriorly
The fibres of the aponeuroses fuse with each other and, in the midline, they fuse with the aponeuroses of the opposite side, forming a tough midline raphe (= seam) called the linea alba (‘white line’).
The aponeuroses of these muscles also form the rectus sheath, which encloses the rectus abdominis.
Where do the right and left rectus abdominis lie?
Either side of the linea alba
What is the rectus abdominis compromised of?
Comprised of muscle segments interspersed with horizontal tendinous bands.
When the muscle segments hypertrophy with exercise, they bulge either side of the tendinous bands and can been seen on the anterior abdominal wall as bulges the ‘six-pack’.
What does the aponeurosis of IO split into?
Anterior and posterior layers
