Part 1: Anterior Abdominal Wall Flashcards
What is the origin and insertion of external oblique muscle?
O: 8 digitations to anterior angles lower 8 ribs. Upper 4 digitate with SAM, lower 4 with LD
I: Outer 1/2 iliac crest. From ASIS forms aponeurosis which inserts to inguinal ligament, pubic tubercle, anterior rectus sheath, linea alba to xiphisternum
What is the action and innervation of external oblique muscle?
A: Supports expiration, raises intrabdominal pressure, abducts and rotates trunk
N: Ant primary rami (T7-T12)
What is the origin and insertion of the internal oblique muscle?
O: Lumbar fascia, anterior 2/3 iliac crest, lat 2/3 inguinal ligament
I: Costal margin, aponeurosis of rectus sheath, conjoint tendon to pubic crest
What is the action and innervation of internal oblique muscle?
A: Supports expiration, raises intraabdominal pressure.
Abducts and rotates trunk
N: Ant primary rami (T7-T12)
Conjoint tendon supplied by ilioinguinal N
What is the origin and insertion of transverse abdominis?
O: Costal margin, lumbar fascia, iliac crest and lateral 1/2 inguinal ligament
I: Aponeurosis of post and anterior rectus sheath, conjoint tendon to pubic crest and pectineal line
What is the action and innervation of transverse abdominis?
A: Support expiration, conjoint tendon supports inguinal canal
N: Ant primary rami (T7-T12), conjoint tendon supplied by ilioinguinal nerve
What is the origin, insertion, action and innervation of rectus abdominis?
O: Pubic crest and pubic symphysis
I: 5-7 costal cartilages, med inferior costal margin and post aspect of xiphoid
A: flexes trunk, aids forced expiration and increases intra-abdominal pressure
N: Ant primary rami (T7-T12)
What is the origin, insertion, action and innervation of pyramidalis muscle?
O: Pubic crest ant to origin of rectus abdominis
I: Lower linea alba
A: Reinforces rectus sheath
N: subcostal nerve (T12)
What are the layers of anterior abdominal wall?
Superficial to deep:
skin, Camper’s fascia, scarpa’s fascia, external oblique, internal oblique, transerve abdominus, transversalis fascia, peritoneum
What forms the rectus sheath?
Aponeurosis of internal + external oblique muscles and transversus abdominis. EOM pass anterior, TAM posterior and IOM splits behind and in front
What forms the arcuate line?
The point at which all layers of rectus sheath become anterior. Occurs a little below umbilicus
What is the semilunar line?
Shallow and bloodless groove from pubic tubercle to costal margin along lateral border of rectus muscle
What is the linea alba?
Strong midline fibrous structure which is firmly attached to xiphoid process and pubic symphysis and which abdominal muscles aponeurosis attach
What nerves supply the anterior abdominal wall?
Lower intercostals and subcostal nerves (T7-T12) supply all abdominal muscles.
In addition lowest fibres of IOM + TAM are supplied by iliohypogastric and ilioinguinal nerves (L1). This is important as these fibres maintain integrity of inguinal canal.
What is the blood supply of anterior abdominal wall?
Superior and inferior epigastric arteries
Deep circumflex iliac artery (branch of ext iliac)
Lumbar arteries
Describe the lymph drainage of abdominal wall
Superficial drainage is in quadrants. To pectoral group above umbilicus either side and superficial inguinal group below umbilicus either side.
Deep lymph drains to mediastinal nodes above and external iliac and para-aortic nodes below
What are the actions of abdominal muscles?
Move trunk
Depress ribs
Compress abdomen (heavy lifting, defecation)
Support viscera
Where does the inguinal canal commence and how long is it?
Medial 1/2 of inguinal ligament. 6cm long.
What is the contents of inguinal canal?
Spermatic cord - males
Round ligament - females
Ilioinguinal nerve (note enters via anterior wall not deep ring but leaves through superficial ring)
What is the anterior wall of inguinal canal?
EOM and more laterally IOM
Fibres run parallel to lower border, diverge to make V-shape opening of superficial ring. Medial crus to pubic crest, lateral to pubic tubercle
What is the floor of inguinal canal?
Rolled lower edge of inguinal ligament, reinforced medially by lacunar ligament
What is the roof of inguinal canal?
Formed by lower edge of IOM and TAM aponeuroses. Forms conjoint tendon. Arch in concentric fashion to insert to PT and pectoral line.
What is the posterior wall of the inguinal canal?
Conjoint tendon medially and weak TAM fascia laterally.
What is the interfoveolar ligament consist of?
Fibres of TAM attaches to inguinal ligament to form functional medial edge of deep ring
Where does the inferior epigastric artery arise and how does it relate to inguinal canal?
Arises from external iliac. Passes medial to deep ring. Gives off cremaster branch which supplies coverings of spermatic cord
What are the coverings of the spermatic cord?
Coverings picked up from abdominal wall.
Inner most:
Internal spermatic fascia (from transversalis fascia)
Cremasteric fascia and muscles (from IOM and TAM)
External spermatic fascia (EOM)
What are the constituents of the spermatic cord?
- Ductus deferens
- Arteries - artery to ductus and cremasteric artery
- Veins - panpiniform plexus
- Lymphatics - deep to para-aortic, superficial to external iliac
- Nerves - genital branch of genitofemoral, sympathetic twigs
- Processus vaginalis - obliterated remains of peritoneal connection
What is the covering of testis?
Immediately tunica albuginea (thick fibrous tissue) and sits with in tunica vaginalis.
How is the epididymus related to testis?
Joins at sinus of epididymus. Lies behind testis and otherwise only bound by fibrous tissue with no other direct attachments
What is the blood supply of the testis?
Testicular artery - direct from aorta
What is the venous drainage of the testis?
Drained by pampiniform plexus. Acts as counter current heat exchange. L drains to renal vein, R to IVC.
What is the lymph drainage of testis?
Via lymph capillaries between seminiferous tubules. Drain with testicular artery to para-aortic nodes. (overlying scrotal skin drains to inguinal nodes)
What is the nerve supply of the testis?
Sympathetic supply - T10 from splanchnic nerve to coeliac ganglion. No parasympathetic supply
What is the structure of testis?
Septa radiate from mediastinum testes dividing testes into 400 lobules each containing 2-4 seminiferous tubules 60cm long. These open into rete testis, pass into vasa efferentia (15-20) which pass to epididymis.
What are the sustentacular cells?
Supporting cells of testis that secrete androgen binding protein to keep high concentration of testosterone
What are the functional cells of testis responsible for testosterone secretion?
Leydig cells - interstitial cells scattered around connective tissue
Where does spermatogenesis occur?
Starts in seminiferous tubules - however not completed until epididymis and takes 64-70days
When does descent of the testes occur?
At 4th month lie in deep inguinal ring
7th month is in deep ring and rapidly progresses to scrotum
Processus vaginalis precedes descent as does gubernaculum
Failure of obliteration of processus vaginalis cause what to occur?
indirect hernia, partial persistence can cause hydrocele of cord
Describe paramedian, right subcostal and gridiron incisions?
paramedian - 3cm from midline, sheath split
