Abdominal region and muscles Flashcards
What is the purpose of abdominal muscles
Give the body a base of support for the upper limbs to work from and for UL muscle to attach onto
What is the inferior and superior boundary of abdominal region
Inferior boundary= pelvic floor
Superior boundary= diaphragm
How many abdominal regions are there
9
What are the trans-planes of abdominal region
Trans-pyloric plane= halfway b/w supra-sternal and pubic symphysis (about 10th costal cartilage level=L1)
Trans-umbilical plane= umbilicus= L3-4 level
Trans-tubercular plane= tubercles of iliac crest= L5
Subcostal plane= inferior points of costal margin= approx L3
Define the abdominal walls
Anterior wall= RA and obliques
Posteriorly= Lx vertebrae column and muscles (quad lam)
Laterally= 3 abdominal muscles (EO, IO, TA= comibine to form rectus sheath)
What is the linea alba
Linea alba= white line formed from excess cross over of 3 connective tissue layers from abdominal muscles
What is the rectus sheath
sheath of connective tissue that encloses the rectus abdominis and pyramidalis muscle
How is the rectus sheath formed
Made up of 3 antero-lateral muscle aponeurosis:
External obliques–> goes anterior to RA
Internal Obliques–> splits, and goes front and behind RA (encapsulates RA), under umbilical, IQ only goes in front of RA
Transverse abdominis–> goes posterior to RA
All 3 muscles blend from muscle belly to connective tissue/tendon at the semilunar line
These connective tissues attach at the midline, creating a crossing over/doubling up of connective tissue forming a dense line of connective tissue=linea alba
How does the rectus sheath change below the umbilicus
Approx halfway between umbilicus and pubis, all aponeurosis pass anterior to RA
TA and IQ aponeurosis merge and pass superifcially to rectus muscle
What is the arcuate line
The line where TA and IQ pass anteriorly to RA below umbilicus, creates a thick connective tissue called arcuate line
It is halfway between umbilicus and pubis
Above arcuate line= RA has rectus sheath anteriorly and posteriorly
Below arcuate line= all muscles at front, RA resting on transversalis fascia
Why is the arcuate line important
Site of entry of the inferior epigastric artery into rectus sheath
Site of weakness-> site of spigelian hernia
What are the rectus sheath borders
Lateral borders= mid-clavicular line
Anterior and posterior= decussation of fibres
What is the proximal and distal attachments, nerve innervation and action/function of pyramidalis
Origin= pubis and anterior pubic ligament Insertion= linea alba (approx halfway b/w umbilicus and pubis) Innervation= subcostal nerve (ventral rami T12 spinal nerve) Action/function= tension of linea alba
What is the inguinal canal
short passage that extends inferiorly and medially through the inferior part of the abdominal wall
Superior and parallel to the inguinal ligament
Canal serves as a pathway by which structures can pass from the abdominal wall to external genitalia
What is the clinical relevance of the inguinal canal
point of potential weakness in the abdominal wall and hence a common site of herniation
During increased intra-abdominal pressure, abdominal viscera are pushed into the posterior wall of inguinal canal to prevent herniation of viscera into the canal, the muscles of anterior and posterior wall contract and ‘clamp down’ on the canal
What are the boundaries of the inguinal canal
Anterior wall= aponeurosis of external oblique, reinforced by internal oblique muscle laterally
Posterior wall= transversalis fascia and conjoint tendon
Roof= transversalis fascia, internal oblique and TA arching fibres
Floor= Inguinal ligament, thickened medially by lacunar ligament
How is the inguinal ligament formed
it is a ‘rolled up’ portion of the EQ aponeurosis
What are the openings of the inguinal canal
2 openings of inguinal canal= deep and superficial ring
Describe the deep ring of inguinal canal
Deep (internal) ring: found above midpoint of inguinal ligament–> which is lateral to epigastric vessels; rig created by the transversalis fascia which invaginates (actions of being turned inside out) to form a covering of the contents of inguinal canal
Describe the superficial ring of inguinal canal
Superficial/external ring
Marks end of inguinal canal, lies just superior to pubic tubercle
Triangle shaped opening–> formed by envagination (process of turning outward/inside out) of EQ which forms another covering of the inguinal canal contents
Opening contains intercrural fibres which run perpendicular to aponeurosis to EQ and prevent ring from widening= herniation
What are the contents of the inguinal canal in a male
Spermatic cord–> supples and drains the testies
Testicular descent–> brings arteries, veins, nerves, lymphatics and excretory ducts through spermatic cord
2 Stages:
7-12 weeks of fetal life, descents into inguinal canal
7-9 months descents into scrotum
Males are at the greater risk of hernias then females due to the spermatic cord through the canal, hence increasing weakness
What are the contents of the inguinal canal in females
Smaller, round ligament around uterus–> on its way to labia majora
Walls are usually collapsed around their contents, preventing other structures from potentially entering the canal
What is the conjoint tendon
Medial fibres of IQ aponeurosis uniting with deeper fibres of TA aponeruosis
Conjoint tendon then turns inferiorly and attaches onto pubic crest and pectin pubis
Forms part of the posterior wall of inguinal canal
What are the effects of abdominal proturberance
Abdominal laxity produces protuberance
When increased abdominal protuberance is greater than abdominal strength it creates anterior pelvic tilt
t/f increased lordosis
t/f increased potential ‘unstable’ L5-S1 joint
t/f thoracic kyphosis increased (to balance Lx lordosis)
t/f anterior cervical convexity increases (to put head above sacrum)
t/f vertebral body compresssions/disc compressions
chnages in biomechanics
changes in wt distribution through vertebral column
changes in trabeculae pattern
Hence abdominal laxity creates proturerance creates changes in posture
