Surface anatomy & Abdominal wall Flashcards
What is the upper extent of the abdominal cavity?
Anteriorly the under surface of the diaphragm reaches the 5th intercostal space.
Describe the 9 regions of the abdominal wall.
Draw two vertical lines down from the midpoint of the clavicles
Draw a horizontal line across the lowest point on the thoracic cage
Draw a horizontal line across the tubercles of the iliac crest
You now have nine abdominal areas. The three down the midline are; epigastrium,
umbilical and suprapubic from top down. The three lateral areas are hypo-chondrium, flank
and iliac fossa from top down
Describe the nerve supply to the skin of the abdominal wall.
The dermatomes of the abdominal wall start at thoracic 5 in the upper epigastrium,
with thoracic 10 being at the umbilicus and thoracic 12 being just above the hair bearing
area in the lower suprapubic area. Each dermatome starts at the back at the level of the
named vertebra; the dermatomes run downwards as they pass round the trunk to the
front
foregut – greater splanchnic t5-t9
midgut – lesser splanchnic t10-t11
hindgut – lowest splanchnic t12
How is the rectus sheath formed?
How is the rectus sheath formed?
In the upper 2/3 of the abdomen the aponeurosis of the external oblique muscle
passes in front of rectus abdominis and the aponeurosis of transversus abdominis passes
behind. The aponeurosis of internal oblique sends fibres both in front and behind rectus
abdominis. In the lower 1/3 of the abdomen all three aponeuroses pass in front of rectus
abdominis.
What is the surface marking of the aortic bifurcation?
The level of the umbilicus
intertubercular plane – level of tubercles of iliac crests
In which regions of the abdomen is pain from the three parts of the bowel felt?
Foregut; epigastrium
Midgut; umbilical
Hindgut; suprapubic
7 Describe the anatomy of a ‘six pack’?
The rectus abdominis muscle runs vertically from the pubis up to the costal margin. Along its length there are three places where it becomes a tendon. When exercised the muscle hypertrophies (becomes bigger) but the tendinous part stays the same. The result is three bulges (of muscle) between the tendons. This occurs on either side of the midline; six bulges in all.
The abdominal wall is formed from sheets of muscle and their corresponding sheets of tendon which we call
aponeuroses
These muscles of the abdominal wall hold the abdominal viscera within the abdominal cavity and play an important part in… and How
rotating the body and in respiration, coughing, sneezing, micturition, defecation and childbirth by contracting to increase intra-abdominal pressure
What is a Hernia
Weaknesses in the muscle wall are common and may allow the bowel (or other organs) to protrude out of the abdomen, this is called a Hernia
Surgical access to the abdominal contents is done in such a way as not to
produce weakness nor interfere with the blood or nerve supply.
Either side of the midline lies a pair of vertical muscles, the
rectus abdominis muscle
What is the rectus abdominis muscle attached to and surrounded by
It is attached to the the sternum and costal margin superiorly and to the pubis inferiorly and is surrounded by the rectus sheath
Lateral to the rectus sheath are three sheets of muscle which have fibres running in different directions;
1 obliquely downwards and inwards (external oblique), 2 obliquely upwards and inwards (internal oblique) and 3 transversely (transversus abdominis).
As these three muscle layers pass forwards towards the rectus sheath the muscles become aponeurotic what does this do
and it is these aponeuroses that form the sheath for rectus abdominis
Inferiorly the lowest most extent of the external oblique muscle is aponeurotic throughout its length and is attached to the
anterior superior iliac spine laterally and the pubic tubercle medially; this is the inguinal ligament
Just above the inguinal ligament is the inguinal canal which, in the male,
ransmits all the structures to and from the testis, together these are the spermatic cord
xiphisternum
the lowest part of the sternum
Iliac Crest
the iliac crest is the curved superior border of the ilium
The anterior superior iliac spine
The anterior superior iliac spine (abbreviated: ASIS) is a bony projection of the iliac bone
It refers to the anterior extremity of the iliac crest of the pelvis, which provides attachment for the inguinal ligament, and the sartorius muscle
The pubic tubercle
The pubic tubercle is a prominent forward-projecting tubercle on the upper border of the medial portion of the superior ramus of the pubis. The inguinal ligament attaches to it.
Pubic Symphysis
The pubic symphysis is a secondary cartilaginous joint (a joint made of hyaline cartilage and fibrocartilage) located between the left and right pubic bones near the midline of the body. More specifically, it is located above any external genitalia and in front of the bladder.
The 9 regions are delineated by two vertical and two horizontal lines. The vertical line on each side extends from
from the mid-clavicular point (half way along the clavicle) to the mid-inguinal point (midway between pubic symphysis and anterior superior iliac spine)
The lower transverse line is drawn between the
tubercles of the iliac crests (intertubercular plane) and the upper transverse line is the subcostal plane (line joining the lowest part of the costal margins on both sides).
The three central regions, from superior to inferior are:
epigastric, umbilical and suprapubic (or hypogastric)
The three lateral regions are
hypochondrium, flank and iliac fossa
Extending towards the back from the flank is the
loin and further still the lumbar region
Transpyloric plane of Addison
This plane passes horizontally across the epigastrium and reaches the costal margin at the most lateral part of the rectus abdominis muscle. This is at the tip of the 9th costal cartilage and where the midclavicular line crosses the costal margin.
What lies on the Transpyloric plane of Addison
The gall bladder, pancreas, pylorus of the stomach and duodeno-jejunal flexure all lie on this plane.
Sub-costal Plane
This plane lies at the lowest points of the costal margin.
McBurney’s point
This point lies 2/3 of the way along a line joining the umbilicus to the right anterior superior iliac spine. It marks the usual site of the base of the appendix. It also gives a guide to the position of the caecum during clinical examination of the abdomen.
Umbilicus
This variable and usually unreliable landmark marks the point of insertion of the umbilical cord during embryonic life and (only in the thin recumbent patient) the level of the L3 vertebra.
Intertubercular plane
This is a plane which lies at the level of the tubercles of the iliac crests and marks the position of the bifurcation of the abdominal aorta.
Intercristal plane
This plane lies across the highest point of the pelvis, it cannot be felt with the patient lying on their back. It is used for examinations and procedures on the back whilst the intertubercular plane is used for the front.
The foregut is supplied by the greater splanchnic nerve which arises from
T5 to T9
pain from the foregut is usually felt
anteriorly in the midline at this level (T5-T9), i.e. in the epigastrium
Midgut pain, supplied by the lesser splanchnic nerve this arises from where and is felt where?
(T10 and T11) is referred to the periumbilical area
pain from the hind gut
(lowest splachnic nerve, T12) to the suprapubic area.
Why is a disease process involves the abdominal wall is it felt very directly
The peritoneum covering the inside if the abdominal wall has the same sensory nerve supply as the skin overlying the same area of the abdominal wall. If a disease process involves the abdominal wall, such as an inflammed appendix the pain is felt very precisely directly over the appendix.
The under surface of the diaphragm is supplied by sensory nerves from the
the phrenic nerve (cervical 3,4,5 nerve roots),
diseases which may irritate the diaphragm, such as
7

cholecystitis (inflammation of the gall bladder), may be felt as referred pain in the
C3, C4, C5 distribution,The pain is felt in the shoulder, despite the disease being in the abdomen.
The sensory innervation of the kidney is via the sympathetic plexus which accompanies the … at what vertebrae
renal artery (T10, 11, 12), the same plexus supplies the gonad
Pain from the kidney can be referred along the cutaneous nerves of… how is the pain described as
of T10, 11, 12, most commonly T12, the pain is often described as radiating from the loin to the groin. Renal pain can also be felt in the gonadal area and conversely gonadal pain can be felt in the loin.
Infection in the abdomen is common and can arise from a variety of sources;
the appendix, gall bladder, uterine tudes or divirticular disease of the colon etc
Once bacteria are in the cavity
they can spread rapidly and widely. They tend to ‘gravitate’ to the lowest place which is
behind the right lobe of the liver when lying flat and into the pelvis when upright. Tumours may also spread through the cavity.
