Muscles (O, I, A) P. 6-8

Question 1

M. scalenus

Answer 1

O:
> M. scalenus dorsalis: Proc. transversus of C4-6
> M. scalenus medius: Proc. transversus of C6-7

I:
> M. scalenus dorsalis (2 parts):
* dorsally situated, inserts on the cranial border of the first 4 ribs
* ventrally situated, inserts on the cranial border of the first 8-9 ribs
> M. scalenus medius: cranial border of the 1st rib.

A: Inspiration
~ Unilateral contraction: flex neck ventrally,
~ Bilaterally contraction: flex neck laterally)

Question 2

M. serratus dorsalis caud.

Answer 2

O: Caudally on superf. layer of fascia thoracolumbalis

I: Proximally on ribs 11-13

A: Expiration

Question 3

M. rectus thoracis

Answer 3

O: 1st rib

I: Ventral ends of ribs 2-4

A: Inspiration

Question 4

M. retractor costae ultimae

Answer 4

O: Proc. transversus of L1-4, caudal part of fascia thoracolumbalis

I: Margo caudalis of last rib

A: Expiration

Question 5

Mm. levatores costarum

Answer 5

O: Proc. transversus of Th1-12

I: Margo cran. near angulus costae

A: Inspiration

Question 6

M. transversus thoracis

Answer 6

O: Inner surface of sternum (close to midline)

I: 2-8th costal cartilage

A: Expiration

Question 7

Mm. intercostales

Answer 7

O & I:
> M. intercostales externus (fibres run caudovent. (\\\) ): From margo caudalis of one rib, to margo cranialis of the next rib.
> M. intercostales internus (muscle fibres rund cranioventrally (///) ): From margo cranialis of one rib, to margo caudalis of the next rib.

A:
~ M. intercostales externus - inspiration
~ M. intercostales internus - expiration

Question 8

M. subcostalis

Answer 8

O & I: Crossing medial surface of ribs 9-11 (cranioventrally (///) direction), inside thoracic cavity

A: Expiratory

Question 9

M. latissimus dorsi

Answer 9

O: superf. layer of fascia thoracolumbalis (from proc. spinosus of last 7-8 Th + lumbar), also attachment prox. to last few ribs

I: Tuberositas teres major (together w/ M. teres major)

A: Flexor of shoulder (with teres major), and draws free limb caudally

Question 10

M. trapezius

Answer 10

O: C3-Th9 region
> pars cervicalis - raphe of neck
> pars thoracica - lig. supraspinosus

I:
> pars cervicalis - prox. ¾ of spina scapula
> pars thoracica - prox. 3rd of spina scapula

A: Supports trunk, elevates (lifts) forelimb, draws it cranially

Question 11

M. Rhomboideus

Answer 11

O:
> pars capitis - Crista nuchae
> pars cervicis - Raphe of neck + proc. spinosus of Th1-3
> pars thoracis - Proc. spinosus of Th4-7

I: Dorsomedial border of scapula

A: Elevates limb, pulls base of scapula against trunk forward and backwards

Question 12

M. pectoralis profundus

Answer 12

O: All sternebrae of sternum + costal cartilage of true ribs

I: Tuberculum minus (small part on tuberculum majus)

A: Supports trunk, draws limb caudally, adduct forelimb

Question 13

M. pectoralis superf.

Answer 13

O:
> M. pectoralis descendens - manubrium sterni
> M. pectoralis transversus - 1-3rd sternebrae

I: Crista tuberculi majoris

A: Ventral connection (or attachment) to forelimb, adduction, draws limb cranially/caudally