Download anterior abdominal wall and inguinal area

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Anterior Abdominal Wall And Inguinal Area
I.
Landmarks and surface anatomy
A. bony landmarks: xiphoid process, costal margin, pubic symphysis, pubic crest,
pubic tubercle, anterior superior iliac spine, iliac crest, tubercle of the crest,
posterior superior iliac spine, lumbar spine
B. soft tissue landmarks: umbilicus, linea alba, linea semilunaris (lateral rectus line),
groove of the groin, superficial inguinal ring, inguinal ligament
C. abdominal regions
1. planes identifying 9 regions (for convenience 2 horizontal & 2 vertical lines)
a. 2 horizontal lines
(1) transpyloric plane - cuts through pylorus, tips of ninth costal cartilage,
and lower border of L1 (above this line is the subcostal zone)
(2) transtubercular plane - corresponds to iliac tubercles, cuts through L5
(above this line, the umbilical zone and below it, the hypogastric zone)
b. 2 vertical lines
(1) a right and left lateral line
(a) drawn vertically through points half way between the anterior superior
iliac spines and the midline (umbilicus)
c. the subcostal zone is divided by the right and left vertical lines into
(1) a middle epigastric and two lateral hypochondriac regions
d. the umbilical zone is divided by the right and left vertical lines into
(1) a middle umbilical and two lateral lumbar regions
e. the hypogastric zone is divided by the left and right vertical lines into
(1) a middle hypogastric and two lateral iliac or inguinal regions
2. quadrants (less specific) can also be used instead of the nine regions
a. vertical midsagittal line through umbilicus
b. horizontal line through umbilicus
(1) form the upper right and left quadrants
(2) and the lower right and left quadrants
D. organs to be projected to surface - use texts or atlases to observe and appreciate
a. diaphragm
b. liver
c. gallbladder
d. spleen
e. kidney
f. appendix
g. ascending colon
h. descending colon
i. duodenum
j. pancreas
k. stomach
l. abdominal aorta
m. vertebral levels
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II.
Skin
A. dermatomes
1. T6 goes over the skin of the xiphoid process
2. T10 goes over the region of the umbilicus
3. L1 goes over the inguinal ligament
B. lymphatic drainage
1. skin above the level of the umbilicus usually drains to the axillary region
2. skin below the umbilicus usually drains into the upper thigh
III. Superficial fascia
A. layers: outer fatty Camper's) layer and inner membranous (Scarpa's) layer
B. blood vessels: from the segmental lower intercostal, subcostal, and lumbar arteries as
well as from the below named arteries
1. superficial epigastric - the parent vessel is in the femoral region
a. the vein communicates with the lateral thoracic vein to form the
thoracoepigastric vein that serves as collateral circulation for the vena cava
IV.
Muscles
A. external abdominal oblique muscle
1. arises from the lower eight ribs
2. inserts on the linea alba, pubic symphysis, crest and tubercle, and the crest of the
ilium
3. lower free margin of its aponeurosis forms the inguinal ligament that attaches
to the anterior superior iliac spine and the pubic tubercle
a. fibers run downward, forward, and toward the midline
4. action: flexes and rotates the trunk as well as compresses and supports the
abdominal viscera
B. internal abdominal oblique muscle
1. arises from the crest of the ilium and inguinal ligament
2. inserts on the costal margin, linea alba, pubic crest, and pectineal line
3. fibers run upward, forward, and toward the midline, except those that help form
the falx inguinalis (conjoint tendon)
4. action: flexes and rotates trunk as well as compresses and supports the
abdominal viscera
C. transversus abdominis muscle
1. arises from the inner surface of costal margin, lumbar transverse processes by
way of the anterior lamella of the thoracolumbar fascia, crest of ilium, and
inguinal ligament
2. inserts on the linea alba, pubic crest, and pectineal line
3. action compresses and supports the abdominal viscera
D. rectus abdominis muscle
1. arises on the pubic bones
2. inserts on ribs 5,6, and 7
3. has three tendinous inscriptions
4. action: flexes as well as compresses the abdominal viscera
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E. rectus sheath
1. formed by the aponeurosis of the external oblique, internal oblique, and
transversus abdominis muscles
2. divided into a uniquely constructed superior and inferior parts
3. superior part
a. anterior lamella of the rectus sheath
(1) from the costal margin down to the level of the L4 it consists of the
aponeurosis of the external oblique and half of the fibers of the aponeurosis
of the internal oblique
b. posterior lamella of the rectus sheath
(1) consists of the aponeurosis of half of the fibers of the internal oblique and
the aponeurosis of the transversus abdominis
(2) lower free margin of the posterior lamella is called the arcuate line or
linea semicircularis at the level of L4
4. inferior part
a. below the level of L4 there is only an anterior lamella that consists of the
aponeuroses of all three abdominal muscles
b. above the pubic bone, the aponeuroses in the internal oblique and the
transversus abdominis fuse to form the conjoint tendon (falx inguinalis)
V.
Posterior surface of the abdominal wall
A. deep fascia
1. inner surface of the muscular wall of the abdomen is lined by deep fascia
2. general term for this fascia is the endoabdominal fascia or more specifically
the transversalis fascia (some parts of it named for the muscles it covers)
B. extraperitoneal tissue
1. internal to the transversalis fascia
2. embedded in this tissue in the midline is the median umbilical ligament,
(obliterated urachus), thus forming the median umbilical fold
3. lateral to this are the medial umbilical ligament (atrophied umbilical arteries)
thus forming the medial umbilical folds
4. more lateral to this are the inferior epigastric vessels, hence forming the lateral
umbilical folds
5. the folds within the peritoneum create fossae between them
a. from the midline to lateral
(1) supravesicular fossa -between the median and medial umbilical folds
(2) medial inguinal fossa - between the medial and lateral umbilical folds
(3) lateral inguinal fossa - lateral to the lateral umbilical fold
C. parietal peritoneum - lines the peritoneal cavity
VI.
blood and nerve supply of the abdominal wall
A. superficial epigastric vessels - from the femoral vessels
B. superior epigastric vessels - from the internal thoracic vessels
C. inferior epigastric vessels - from the external iliac arteries
D. deep circumflex iliac vessels - from the external iliac vessels
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E.
F.
G.
H.
I.
lumbar vessels - from the abdominal aorta
musculophrenic vessels - from the internal thoracic vessels
superficial circumflex iliac vessels - from the femoral vessels
posterior intercostal vessels
thoracoepigastric vein
1. important collateral route between the vena cava
J. paraumbilical veins
1. important collateral route in portal hypertension
K. spinal nerves T6 to L1
1. innervates both muscles and skin
VII. inguinal canal
A. the space occupied by the constituents of the spermatic cord or the round
ligament of the uterus while they pass through the abdominal wall
B. walls of the inguinal ligament
1. anterior - external oblique aponeurosis reinforced by internal oblique
muscle fibers
2. posterior - transversalis fascia reinforced by the common tendon of the internal
oblique and transversus abdominis muscles - the conjoint (falx inguinalis) tendon
3. roof - arching fibers of internal oblique and transversus abdominis muscles
4. floor - inguinal ligament reinforced by the lacunar ligament medially
a. lacunar ligament - medially rolled fibers of the inguinal ligament
b. deep inguinal ring
(1) inguinal canal begins as the deep inguinal ring located just rostral to the
inguinal ligament and lateral to the inferior epigastric vessels
(2) the mouth of an evagination of the transversalis fascia
(a) continues over the spermatic cord as the internal spermatic fascia
(innermost covering of the spermatic cord)
c. an evagination of the internal oblique muscle creates the cremasteric muscle
and fascia (second covering of the spermatic cord)
d. superficial inguinal ring
(1) the mouth of an evagination of the external oblique aponeurosis
(a) the margins are call crura
e. the external abdominal oblique's aponeurosis continues over the inguinal
canal's contents as the external spermatic fascia
5. contents of the inguinal canal in the female
a. round ligament of the uterus (also has the fascias)
6. contents of the inguinal canal in the male
a. ductus deferens
b. testicular artery
c. pampiniform plexus of veins
d. testicular autonomic nerves
e. lymphatics draining the testes
7. during development a processus vaginalis, an evagination of the peritoneum,
accompanies the testes through the canal and forms the tunica vaginalis of the
testes
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VIII. hernias - the protrusion of an organ, part of an organ, or other tissue through the
wall of a cavity, which normally contains it
A. inguinal hernias - located in the inguinal region; exits the body at the superficial
inguinal ring
1. indirect inguinal hernia
a. omentum or intestine enters the deep inguinal ring (lateral to the inferior
epigastric vessels) and follows the inguinal canal, sometimes into the scrotum
b. usually congenital
2. direct inguinal hernia
a. enters inguinal canal through the inguinal triangle (Hesselbach's triangle)
and then continues through the superficial inguinal ring
b. usually occurs in adults
c. inguinal triangle is bounded by the inguinal ligament, inferior epigastric
vessels, and lateral border of the rectus abdominis
B. umbilical hernias
1. congenital - present at birth; failure of the midgut to return to the abdominal
cavity during fetal life
2. acquired infantile - small in scar of umbilicus, usually disappear
3. acquired adult - paraumbilical, more common in women
C. femoral hernias - pass under the inguinal ligament through the femoral canal and
end in the femoral triangle in anterior thigh
IX.
Scrotum
A. an evagination of the anterior abdominal wall containing
1. testes
2. epididymis
3. lower part of the spermatic cord
B. its the median raphe that indicates the embryological line of fusion of the two halves
C. wall of the sac consists of skin and superficial fascia / Dartos fascia
1. contains smooth muscle that wrinkles the scrotal sac
D. the testis invaginates the tunica vaginalis (a serous cavity)
1. tunica albuginea
a. a thick capsule
b. forms the outside covering derived from peritoneum of the testes
2. inside, connective tissue septa form compartments of the seminiferous tubules
F. epididymus - consists of a head, body, and tail
G. lymph drainage of the scrotal wall is to the superficial inguinal lymph nodes while
that of the testes is to the aortic nodes
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