Muscles of Expiration

Question 1

Transverse Abdominus
anterolateral ?
origin: 
course:
insertion: 
innervation: 
Function: compress

Answer 1

abdominal muscle of expiration
posterior abdominal wall at vertebral column via thoracolumbar fascia of abdominal aponeurosis
lateral
transverse abdominis aponeurosis and inner surface of ribs 6-12 , “interidigitates” with fibers of diaphragm; pubis
thoracic and lumbar nerves from lower spinal intercostal nerves (derived form T7-T12) and first lumbar nerve, iliohypogastric and ilioinguinal branches
abdomen

Question 2

Internal oblique abdominis
anterolateral ?
origin: 
course: 
insertion: 
innervation: 
function: rotate and flex? compress?

Answer 2

abdominal muscle of expiration
inguinal ligament and iliac crest
fans medially
cartilaginous portion of lower ribs and portion of abdominal aponeurosis lateral to rectus abdominis
thoracic and lumbar nerves from lower spinal intercostal nerves (derived from T7-T12) AND FIRST LUMBAR NERVE, ILIHYPOGASTRIC AND ILIOINGUINAL BRANCHES
trunk/abdomen

Question 3

External Oblique abdominis 
anterolateral ?
origin: 
course: 
insertion: 
innervation: 
function: flex? and compress? rotate?

Answer 3

abdominal muscle of expiration
osseous portion of lower seven ribs
fans downward
iliac crest, inguinal ligament, abdominal aponeurosis lateral to rectus abdominis
thorocoabdominal nerve arising from T7-T11 and subcostal nerve from T12
bilateral contraction: vertebral column/abdomen unilateral contraction: trunk

Question 4

Rectus abdominis
anterolateral?
origin: 
course: 
insertion: 
innervation: 
function: flexion of

Answer 4

abdominal muscle of expiration
originates as four or five segments at pubis (inferiorly)
up and to segment border
xiphoid process of sternum and cartilage of ribs 5-7 and lower ribs
T5-T11 intercostal nerves (thoracoabdominal), subcostal nerve from T12; T7 supplies upper segment, T8 supplies second, T9 supplies remainder
vertebral column

Question 5

Quadratus lumborum 
posterior?
origin: 
course: 
insertion: 
innervation: 
function: bilateral contraction fixes ?

Answer 5

abdominal muscle of expiration
iliac crest
fans up and in
transverse processes of lumbar vertebrae and inferior border of rib 12
thoracic nerve T12 and lumbar nerves L1-L4
abdominal wall to support abdominal compression

Question 6

internal intercostal (interosseous portion) 
thoracic?
origin: 
course: 
insertion: 
innervation: 
function: depress? decrease?

Answer 6

muscle of expiration 
superior margin of ribs 2-12
up and laterally 
inferior surface of rib below 
intercostal nerves - thoracic intercostal nerves arising from T2-T6 and thoracoabdominal intercostal nerves from T7-T11
ribs 1-11/ thoracic volume

Question 7

innermost intercostal (intercostales intimi) 
thoracic?
origin: 
course: 
insertion: 
innervation: 
function: depress? decrease?

Answer 7

muscle of expiration
superior margin of ribs 2-12; sparse or absent in superior thorax
up and laterally
inferior surface of rib above
intercostal nerves (thoracic intercostal nerves arising T2-T6 and thoracoabdominal intercostal nerves from T7-T11)
ribs 1-11/ thoracic volume

Question 8

Transversus thoracis 
thoracic?
origin:
course: 
insertion: 
innervation: 
function: depresses

Answer 8

muscle of expiration
inner thoracic lateral margin of sternum
laterally
inner chondral surface of ribs 2-6
thoracic intercostal nerves and subcostal nerves derived from T2-T12 spinal nerves
rib cage

Question 9

Serratus posterior inferior 
posterior ? 
origin:
course:
insertion: 
innervation:
function:

Answer 9

thoracic muscle of expiration
spinous processes T11, T12, and L1- L3
up and laterally
lower margin of ribs 7-12
intercostal nerves from T9-T11 and subcostal nerve from T12
contraction to pull rib cage down, thus supporting expiratory effort