Topic 26 - Respiratory muscles

Question 1

The muscles

Answer 1

M.scalenus
M.serratus dorsalis caudalis
M.rectus thoracis
M.retractor costae ultimae
Mm.levatores costarum
M.transversus thoracis
Mm.intercostales: -externus and -internus
M.subcostalis

Question 2

M.scalenus

Answer 2

In dogs it has two parts: M.scalenus dorsalis and m.scalenus medius
O: -dorsalis: Trans.proc. of C4-6, -medius: trans.proc. of C6-7
I: On cran. border of ribs: dors. on the first 4 ribs, the vent. is longer and inserts on the first 8-9 ribs (Øca), the middle on 1.rib
A: Helps in inspiration, bilat. contr.: flexes neck vent., unilat. contr. flex. neck lat.

Question 3

M.serratus dorsalis caudalis

Answer 3

O: Cau. on spf. layer of fascia thoracolumbaria
I: Prox. part of ribs 11-13
A: Expiration

Question 4

M.rectus thoracis

Answer 4

O: First rib
I: Vent. ends of ribs 2-4
A: Inspiration

Question 5

M.retractor costae ultimae

Answer 5

O: Proc.trans. of L.1-4, cau. part of thoracolumbar fascia over lumbar site
I: Caud. border of last rib
A: Expiration

Question 6

Mm.levatores costarum

Answer 6

O: Proc.trans. of Th1-12
I: Cran. borders of ribs near their angles; covered by erector spinae muscles
A: Inspiration

Question 7

M.transversus thoracis

Answer 7

O: Inner surface of sternum, close to midline
I: 2-8 costal cartilages, vent. to costochondral junctions
A: Expiration

Question 8

Mm.intercostales

Answer 8

Two muscle gropus: -externus and -internus

• externus: muscle fibres run caudoventr. from cau. border of one rib to cran. border of next rib. A: inspiration
• internus: muscle fibers run craniovent. from cran. border of one rib to cau. border of previous rib. A: expiration

Question 9

M.subcostalis

Answer 9

Crosses medial surface of ribs 9-11, in a craniovent. direction (//) inside thoracic cavity
A: Expiration

Question 10

M.serratus dorsalis cranialis

Answer 10

O: Fascia thoracolumbaria by a broad aponeurosis, proc.spin. of Th1-7
I: Prox. on ribs 2-10
A: Inspiration