Rectus Sheath Flashcards
What is the rectus sheath?
Aponeurotic sheath covering the rectus abdominis
How many walls does the rectus sheath have?
Two � anterior and posterior
What is the status of the anterior wall of the rectus sheath?
Complete, covering the muscle from end to end
How is the anterior wall of the rectus sheath attached to the rectus muscle?
Firmly adherent to tendinous intersections
What is the status of the posterior wall of the rectus sheath?
Incomplete � deficient above costal margin and below arcuate line
How is the posterior wall related to the rectus muscle?
Free from the rectus muscle
What is the fusion of all aponeuroses in the midline called?
Linea alba
Where does the linea semilunaris extend from and to?
From tip of 9th costal cartilage to pubic tubercle
What forms the anterior wall of the rectus sheath above the costal margin?
External oblique aponeurosis
What forms the posterior wall of the rectus sheath above the costal margin?
Deficient � rectus muscle rests on 5th, 6th, and 7th costal cartilages
What forms the anterior wall of the rectus sheath between the costal margin and the arcuate line?
External oblique aponeurosis + anterior lamina of internal oblique aponeurosis
What forms the posterior wall of the rectus sheath between the costal margin and the arcuate line?
Posterior lamina of internal oblique aponeurosis + transversus abdominis aponeurosis
What is the arcuate line?
Free lower border of posterior rectus sheath
Where is the arcuate line located?
Midway between the umbilicus and pubic symphysis
What forms the anterior wall of the rectus sheath below the arcuate line?
Aponeuroses of external oblique, internal oblique, and transversus abdominis
What is the relationship of the aponeuroses of the transversus and internal oblique below the arcuate line?
Fused together
What forms the posterior wall of the rectus sheath below the arcuate line?
Deficient � rectus muscle rests on fascia transversalis
What is the chief and largest content of the rectus sheath?
Rectus abdominis
Which muscle lies in front of the lower part of the rectus abdominis (if present)?
Pyramidalis
What artery enters the sheath by passing between costal and xiphoid origins of the diaphragm?
Superior epigastric artery
What does the superior epigastric artery supply?
Rectus abdominis muscle
With which artery does the superior epigastric artery anastomose?
Inferior epigastric artery
How does the inferior epigastric artery enter the sheath?
Passes in front of the arcuate line
What vein accompanies the superior epigastric artery?
Superior epigastric venae comitantes
Into which vein does the superior epigastric vein drain?
Internal thoracic vein
What vein accompanies the inferior epigastric artery?
Inferior epigastric venae comitantes
Into which vein does the inferior epigastric vein drain?
External iliac vein
What nerves are present in the rectus sheath?
Terminal parts of lower six thoracic nerves
Which nerves include the lower five intercostal nerves and the subcostal nerve?
Lower six thoracic nerves
How does the rectus sheath increase the efficiency of the rectus muscle?
Checks bowing of the rectus muscle during contraction
How does the rectus sheath help the anterior abdominal wall?
Maintains strength
How is the rectus sheath formed according to the new concept?
Decussation of fibres from three abdominal muscles of each side
What type of aponeurosis is formed at the medial border of each abdominal muscle?
Bilaminar aponeurosis
In which direction do the fibres from the anterior leaves run?
Obliquely upwards
In which direction do the fibres from the posterior leaves run?
Obliquely downwards
What forms the anterior sheath of the rectus?
Both leaves of external oblique aponeurosis + anterior leaf of internal oblique aponeurosis
What forms the posterior sheath of the rectus?
Posterior leaf of internal oblique aponeurosis + both leaves of transversus abdominis aponeurosis
How do the fibres of each layer interact in the rectus sheath?
Decussate to the opposite side
How do the fibres decussate between the anterior and posterior sheaths?
At right angles to each other
How are the three lateral abdominal muscles described in relation to the rectus sheath?
Digastric with a central tendon in the form of linea alba
What is the linea alba?
Tendinous raphe between xiphoid process and pubic crest
Where is the linea alba broader?
Above the umbilicus
To what is the superficial layer of the linea alba attached?
Symphysis pubis
To what is the deep layer of the linea alba attached?
Posterior surface of pubic crest
What happens to the rectus muscle at the arcuate line?
Posterior sheath ends, and muscle rests on fascia transversalis
What structures are deficient in the posterior sheath above the costal margin?
5th, 6th, and 7th costal cartilages
What arteries are found in both the anterior and posterior sheaths?
Superior and inferior epigastric arteries
What prevents bowing of the rectus muscle?
Firm adherence of anterior sheath to tendinous intersections
How are the fibres of the transversus abdominis positioned relative to the arcuate line?
Behind rectus above arcuate line
Which structure lies just beneath the rectus muscle below the arcuate line?
Fascia transversalis
