1-5 Anatomy of the Abdominal Wall & Inguinal Region Flashcards
What are the general boundaries of the abdominopelvic cavity?
extends from the thoracoabdominal diaphragm above to the pelvic diaphragm below
What generally makes up the abdominal wall and what does it do, in a general sense?
bones, fascia and muscles
Encloses the cylinder-like abdominal cavity
Serve to mobilize the abdomen while at the same time protect the abdominal contents
What are the osseous components of the abdominal wall?
1) Ribs 7-12
2) Lumbar vertebrae 1-5
3) Pelvis
What are the fascial components of the abdominal wall?
1) Anterior – rectus sheath
2) Posterior – thoracolumbar fascia
What are the muscular components of the abdominal wall?
1) External abdominal oblique
2) Internal abdominal oblique
3) Transversus abdominis
4) Rectus abdominis
5) Pyramidalis
6) Quadratus lumborum
7) Psoas major and minor
What are some superficial landmarks of the abdomen? For an extra slice of awkward cake, point them out on a partner.
- Xiphoid process (TV10)
- Costal margin
- Linea alba
- Umbilicus (LV 3-4 Interspace)
- Linea transversae (tendinous intersections)
- Linea semilunaris
- Pubic symphysis
- Pubic tubercle
- Inguinal ligament
- Anterior superior iliac spine (ASIS)
- Crest of ilium
What layers make up the superficial fascia in the abdominal wall?
Camper’s - fatty layer
Scarpa’s - membranous layer
Describe Camper’s/fatty layer of superficial fascia.
Description: most news anchors.
Actual description: superficial fatty layer
Where is the membranous layer of the superficial fascia best differentiated? What does it attach to?
Best differentiated below the level of the navel
It has definite attachments to the: Iliac crest Fascia lata below the inguinal ligament Pubic tubercle Pubic symphysis Perineal boundaries of the urogenital triangle
What forms the abdominal scrotal opening?
The abdominal scrotal opening formed by the weak attachment of the membranous layer to the pubic bone between the tubercle and symphysis
What are the specializations of the membranous layer of superficial fascia?
Fundiform ligament
Tunica dartos scroti
What is the fundiform ligament? Where is it located and what does it do?
robust development of membranous connective tissue
extends from the lower linea alba and passes lateral to the penis to end in the scrotal septum
provides support for the scrotum
What is the tunica dartos scroti? What tissues does it contain and what does it do?
Continuation of the fatty and membranous layers of superficial fascia into the scrotum as a single layer
Contains areolar tissue and smooth muscle
Responsible for wrinkling of the scrotal skin
What 3 groups of muscles compose the abominal wall?
Anterior
Anterolateral
Posterior
What muscles make up the anterior abdominal wall?
Rectus abdominis
Pyramidalis
What muscles make up the anterolateral abdominal wall?
External abdominal oblique
Internal abdominal oblique
Transversus abdominis
What muscles make up the posterior abdominal wall?
Psoas major
Psoas minor
Quadratus lumborum
Describe the fiber directions of anterior and anterolateral abdominal wall muscles. Why is this important?
The fiber direction of the anterolateral and anterior abdominal wall musculature is arranged so that successive layers assume a non-congruent orientation, viz., vertical, horizontal, and oblique directions
What is the innervation for the external abdominal oblique?
Intercostal nerves 7-11
subcostal nn
iliohypogastric nn
What is the action for the external abdominal oblique? What bodily fxns does it assist in?
Both sides acting:
flexion of the vertebral column and pelvis abdominal compression in defecation, parturition and forced expiration;
one side acting causes lateral flexion of the trunk with rotation to the OPPOSITE side
What is the innervation for the internal abdominal oblique?
Intercostal nerves 8-11
subcostal nn
iliohypogastric nn
ilioinguinal nn
What is the action for the internal abdominal oblique?
Both sides acting:
flexion of the vertebral column and pelvis
abdominal compression in defecation, parturition and forces expiration
one side acting causes lateral flexion of the trunk with rotation to the SAME side
What is the cremaster muscle derived from?
muscular layer of the spermatic cord derived from the internal abdominal oblique
What is a major difference in origins of the internal and external obliques?
Originate on different sides of abdominopelvic cavity
External oblique interdigitates with serratus anterior and lats, originates lower 8 ribs
Internal obliques originate on thoracolumbar fascia and inserts on lower ribs
What is the innervation of the transversus abdominis?
Intercostal nerves 8-11
subcostal n
iliohypogastric n
ilioguinal n.
What are the actions of the transversus abdominis? What doesn’t it do?
Contraction causes compression of the abdomen and its contents
no sidebends or flexion
What is the innervation of the rectus abdominis?
Intercostal nerves 7-11
subcostal n
What is the action of the rectus abdominis? What doesn’t it do?
Flexes the vertebral column and pelvis, assists in compression of the abdomen. – no sidebends
What determines if you have a 6-pack? An 8-pack?
Time of night? Whether or not you’re doing PTA?
Actually, due to tendinous intersections, which fuse to the anterior rectus sheath
What is the innervation for pyramidalis?
Subcostal nerve
What is the action for pyramidalis?
Small - tenses linea alba
What is the rectus sheath composed of?
combined aponeuroses of the external oblique, internal oblique, and transversus abdominis muscles
What is the linea semilunaris?
Marks the transition of the muscular portions of the three anterolateral abdominal wall muscles to aponeurosis
The three layers are fused along this line and denote the beginning of the rectus sheath
Usually found at the margin between rectus abdominis and anterolateral wall muscles
How is the upper rectus sheath divided?
The upper three-fourths of the sheath is divided into anterior and posterior laminae due to the splitting of the internal oblique aponeurosis around the rectus abdominis muscle
What is the anterior rectus sheath made up of? The posterior?
Anterior sheath - composed of the fused aponeuroses of the external and internal oblique muscles
Posterior sheath - composed of the fused aponeuroses of the internal oblique and transversus abdominis muscles
How does the rectus abdominis traverse the rectus sheath?
Above the umbilicus: (superficial to deep)
external oblique aponeurosis
internal oblique aponeurosis, split by rectus abdominis
transversalis abdominis aponeurosis
transversalis fascia
Below the umbilicus: (superficial to deep) external internal oblique aponeurosis transversalis abdominis aponeurosis rectus abdominis mm transversalis fascia
Why does the rectus abdominis lie where it does inferior to umbilicus?
Underlies 3 aponeurosis because it is thought that this provides more support to abdominopelvic cavity when someone is standing upright
What is the arcuate line? What does that have to do with the rectus sheath?
Arcuate line is where posterior rectus sheath ends and where the aponeurosis fuse and run in front of/anterior to rectus abdominis
- happens midway between umbilicus and pubic symphysis
Allows passage of inferior epigastric artery and vein
What are the layers of tissue at the umbilicus?
- Skin
- Superficial fascia (fatty layer, membranous layer)
- Anterior rectus sheath
- Rectus abdominis muscle
- Posterior rectus sheath
- Transversalis fascia
- Extra peritoneal connective tissue
- Peritoneum
What is the abdominal wall internal to the posterior rectus sheath composed of?
From superficial to deep these are:
transversalis fascia
extra peritoneal connective tissue (also referred to as subserous fascia)
parietal peritoneum.
When peritoneum overlays a structure embedded in the extraperitoneal connective tissue it is referred to as…?
fold or ligament
What are depressions between these peritoneal folds?
fossae
What are the umbilical folds?
Median, medial, and lateral umbilical folds
What makes up the median umbilical fold?
Formed by the median umbilical ligament, the remnant of the urachus (allantois)
What makes up the medial umbilical fold?
Formed by the medial umbilical ligaments (obliterated umbilical arteries)
What makes up the lateral umbilical folds?
formed by the inferior epigastric vessels
What are the inguinal fossae?
- Supravesicle fossa - fossae above the bladder between the median and medial umbilical folds
- Medial inguinal fossa- fossa between the medial and lateral umbilical folds
- Lateral inguinal fossa - fossa lateral to the lateral umbilical fold
What makes up the superficial arterial supply to the anterior and lateral abdominal walls?
A superficial vascular bed coursing in the subcutaneous connective tissue layer
originating:
above from perforating branches of deeper vessels found within the muscular layer below from branches of the femoral artery
What makes up the deep arterial supply to the anterior and lateral abdominal walls?
A deep vascular bed coursing within the muscular layer
originating:
above from the subclavian artery
in mid abdomen from the aorta
below from the external iliac artery
What arteries supply the superficial aspect of the superior abdomen above the umbilicus?
accomplished by perforating branches of arteries located in the muscular layer:
1) Superior epigastric aa.
2) Musculophrenic aa.
3) Intercostal aa.
4) Subcostal aa.
5) Lumbar aa.
What arteries supply the superficial aspect of the inferior abdomen below the umbilicus? What opening must they cross and why?
accomplished by branches of the femoral artery. These branches, after traversing the saphenous opening of the groin, course within the membranous layer of the subcutaneous connective tissue to their respective destinations
1) Superficial epigastric a. - umbilical region
2) Superficial circumflex iliac a. - iliac region
3) Superficial external pudendal a. - suprapubic, pubic and genital regions
What arteries provide deep circulation for the abdomen?
Musculophrenic artery Superior epigastric artery Posterior intercostal arteries (10 & 11) Subcostal arteries Lumbar arteries Inferior epigastric artery Deep circumflex iliac artery
What is the musculophrenic artery a terminal branch of? Where does it go? What does it anastamose with?
1) One of the terminal branches of the internal thoracic a.
2) Courses deep to the costal cartilages of ribs 7-11
3) Provides anterior intercostal aa. 7-11
4) Passes into the anterolateral abdominal wall between the internal oblique and transversus abdominis muscles
5) Anastomoses with 10th & 11th posterior intercostal & subcostal aa. and ascending branch of the deep circumflex iliac a.
What is the superior epigastric artery a terminal branch of? Where does it go and what does it anastamose with?
1) One of the terminal branches of the internal thoracic a.
2) Pierces the posterior rectus sheath
3) Courses between the sheath and the rectus abdominis muscle
4) Anastomoses with the inferior epigastric a. near the umbilicus
What do the posterior intercostal arteries and subcostal arteries anastomose with?
Anastomose within the muscle layer with branches of the musculophrenic, superior epigastric, lumbar, and deep circumflex iliac arteries
What do the lumbar arteries arise from? What do they supply?
Abdominal counterpart of thoracic intercostal arteries
Four paired branches arise from the abdominal aorta at the upper level of the first four lumbar vertebrae
Pass laterally for a short distance to provide branches mainly to the posterior and posterolateral abdominal wall musculature
What do the inferior epigastric arteries arise from? Where does it go?
Arises from the external iliac a. prior to its passing beneath the inguinal ligament
Passing medial to the deep inguinal ring, it angles toward the umbilicus within in the extraperitoneal connective tissue layer raising the lateral umbilical fold
Ascending the anterior abdominal wall internally & enters the posterior rectus sheath
What does the inferior epigastric artery anastomose with? What does it supply?
enters the posterior rectus sheath where it will anastomose with the superior epigastric a. above the level of the umbilicus
Near its origin it provides branches to:
the spermatic cord
round ligament of the uterus
dorsum of the pubis
along its course it anastomoses with branches of the lower six posterior intercostal aa. close to the lateral border of the posterior rectus sheath
What is the course of the deep circumflex iliac artery?
Arises from the external iliac a. distal and lateral to the origin of the inferior epigastric artery
Courses lateralward toward the ASIS to perforate the transversus abdominis muscle to run between it and the internal oblique along the iliac crest
What are the anastomoses of the deep circumflex iliac arteries?
Provides an ascending branch which anastomoses with the last two posterior intercostal, subcostal and musculophrenic aa.
The direct continuation of the deep circumflex iliac a. anastomoses with the iliolumbar a.
How are the cutaneous and subcutaneous layers of the abdomen drained?
Accomplished by venae comitantes of the arteries which supply this region
1) superiorly to the axillary vein
2) inferiorly to the greater saphenous vein
How is the musculature of the abdominal wall drained?
superiorly to the subclavian vein
laterally and posteriorly to the SVC and IVC
inferiorly to the external iliac vein.
What veins contribute to the axillary vein?
Thoracoacromial v.
Lateral thoracic v
What veins contribute to the greater saphenous vein?
Superficial epigastric v.
Superficial circumflex iliac v.
Superficial external pudendal v.
What is the thoraco-epigastric vein a prime example of?
The drainage pattern of the superficial abdominal wall consists of highly anastomic channels
Thoraco-epigastric vein represents an anastomoses of (superiorly) lateral thoracic veins and (inferiorly) superficial epigastric veins
What contributes to the subclavian vein?
Muscular wall drainage
1) Superior epigastric v.
2) Musculophrenic v.
What contributes to the external iliac vein?
Muscular wall drainage
Inferior epigastric v.
Deep circumflex iliac v.
What contributes to the IVC?
Lumbar veins
What contributes to the SVC?
Via the azygos system:
Posterior intercostal vv. 10 & 11
Subcostal v.
Where does lymph drain above the umbilicus? Below the umbilicus?
Above: lymph goes to thorax and axilla
- via parasternal nodes and lateral pectoral nodes, respectively
Below: lymph goes to inguinal region
- via lymph channels that follow subcu. blood vessles to superficial inguinal lymph nodes
What do superficial inguinal lymph nodes receive drainage from?
located just inferior to the inguinal ligament.
Generally, they receive drainage from the lower abdomen, perineum and genitalia, and lower limb.
What is the general scheme for drainage of the abdominal cavity - how is the subcutaneous lymph drainage different from the muscular lymph drainage?
Subcu and scrotal lymphatics generally drain superficially in the subcu tissue of the thigh and axilla
Muscular abdominal wall and testicular lymphatics drain internally to lymph nodes located internally, near the kidneys and vertebral column
What are some major dermatomes and landmark correlations that you should know?
T7 - just below xyphoid process
T10- umbilicus
L1 - suprapubic region
What provides the dermatomes of the abdomen? What is another name for these nerves?
represented by cutaneous branches of ventral rami of spinal nerves T7 - L1
referred to as thoracoabdominal intercostal nn.
Generally speaking, what provides innervation to mm of the abdominal wall?
Innervation to the muscles of the abdominal wall is accomplished by ventral rami of spinal nerves T7 L4
What abdominal nerves originate from the lumbar plexus?
Branches of ventral rami L1 - L4 originate within the lumbar plexus
What cord levels supply the thoracoabdominal intercostal nerves? How are the nerves generally directed? What do they provide branches to?
T7-T11
Generally directed inferomedially
They provide lateral cutaneous branches, muscular branches to all anterolateral and anterior abdominal muscles (except pyramidalis) and terminate as anterior cutaneous nerves
What 3 nerves pierce the transversus abdominis muscle at the posteromedial aspect (near vertebral column) and run between this and internal oblique?
Subcostal nerve
Ilioinguinal nerve
Iliohypogastric nerve
What is the course and innervation of the subcostal nerve?
(T12)
course and distribution similar to the thoracoabdominal intercostal nn., however, its lateral cutaneous branch distributes to the upper gluteal area
provides sole innervation to the pyramidalis muscle
What is the course and innervation of the iliohypogastric nerve?
Pierces the internal oblique muscle medial and superior to the ASIS and runs inferiorly and medially between the internal and external oblique muscles
Provides a lateral branch to the gluteal area
innervates the anterolateral abdominal musculature
communicates with the ilioinguinal nerve
terminates as anterior cutaneous branches to the suprapubic region
What are the cord levels of the iliohypogastric nerve?
L1
50% T12 – L1
What is the course and innervation of the ilioinguinal nerve?
Pierces the internal oblique near the deep inguinal ring
Parallels the course of the iliohypogastric n. on a slightly inferior plane
Courses through the inguinal canal where it runs on the surface of the spermatic cord and follows it through the superficial inguinal ring
Provides muscular branches to the internal oblique and transversus abdominis muscles
Provides cutaneous branches to the upper medial thigh
Terminates as the anterior scrotal/labial branch supplying cutaneous innervation to the root of the penis and scrotum in the male and to the mons pubis and labia majora in the female
