A9 - Mm. cingulorum membri thoracici et pelvini

Question 1

Give the muscles of the pectoral girdle

Answer 1

Superficial layer:

• M. trapezius
  
  • ​Pars cervicalis
  • Pars thoracica
• M. sternocleidomastoideus
  
  • ​M. sternocephalicus
  • M. brachiocephalicus
• M. omotransversarius
• M. latissimus dorsi
• Mm. pectoralis superficialis
  
  • ​M. pectoralis descendens
  • M. pectoralis transversus

Deep layer:

• M. pectoralis profundus
• M. subclavius (ø ca)
• M. rhomboideus
  
  • ​Pars capitis (ca, su)
  • Pars cervicis
  • Pars thoracis
• M. serratus ventralis
  
  • ​Pars cervicis
  • Pars thoracis

Question 2

M. trapezius

Answer 2

• Divided into:
  
  1. Pars cervicalis
  2. Pars thoracica
• Origin: C3 → Th9 region
  
  • Pars cervicalis: From raphe of neck
  • Pars thoracica: from supraspinous ligament
• Insertion: Spina scapula
  
  • Pars cervicalis: proximal ³/₄ of spina scapula
  • Pars thoracica: proximal thrid of spina scapula
• Action:
  
  • Elevate (lift) and abduct the forelimb
  • Stabilize the shoulders

Question 3

Give the division of m. sternocleidomastoideus

Answer 3

Question 4

M. sternocephalicus

Answer 4

• Origin: manubrium sterni
• Insertion:
  
  • ​Divided into:
    
    1. M. sternomastoideus: mastoid part of os temporale
    2. M. sternooccipitalis: c**rista nucha of os occipitale
• Action: Draw the head and neck to the side

Question 5

M. brachiocephalicus

Answer 5

From humerus to head and neck

• Divided into:
  
  1. M. cleidobrachialis
     
     • Origin: Clavicle
     • Insertion: Distal part of christa humeri
  2. M. cleidocephalicus
     
     1. M. cleidomastoideus
        
        • Origin: Processus mastoideus of os temporale
        • Insertion: Iscription clavicularis
     2. M. cleidocervicalis
        
        • Origin: The dorsal midline over the cranial half of the neck
        • Insertion: Inscription clavicularis
• Action:
  
  • If forelimb is fixed: unilateral contraction of the muscle moves head into the lateral direction, bilateral contraction fixes head and neck (or bends downward)
  • If limb is free (it’s in an elevated position), it will move forelimb cranially

Question 6

M. omotransversarius

Answer 6

• Origin: Spina scapula on ventral part
• Insertion: Ala atlantis, caudal border
  
  • Eq: also C2-4 on processus transversus
• Action:
  
  • Advance the limb (draw the shoulder cranially
  • Flex the neck laterally
• Innervation: N. accessorius (XI)

Question 7

M. latissimus dorsi

Answer 7

• Origin:
  
  • Superficial layer of thoracolumbar fascia
  • From spinous process of last 7-8 thoracic and lumbar vertebrae
  • Proximally to the last few ribs
• Insertion: Tuberositas m. teres major (together with m. Teres major)
• Action:
  
  • Draws free limb caudally
  • With teres major: Flexes shoulder
• Innervation: N. thoracodorsalis

Question 8

Mm. pectoralis superficialis

Answer 8

• Origin:
  
  • M. pectoralis descendens: Manubrium sterni
  • M. pectoralis transversus: From sternebrae 1-3
• Insertion:
  
  • Crista tuberculi majoris of humerus
  • Upper part of crista humeri
• Action:
  
  • Ventral connection to forelimb
  • Adduction
  • Draws limb cranially or caudally depending its position
• Innervation: N. pectoralis cranialis

Question 9

M. pectoralis profundus

Answer 9

• Origin:
  
  • All sternebrae
  • Costal cartilage of true ribs
• Insertion:
  
  • Ca: T**uberculum major of humerus
  • Eq: Tuberculum major and tuberculum minor of humerus
  • Sus: Tuberculum minor of humerus
• Action: Support the trunk, strong retractor and adductor of the forelimb
• Innervation: N. pectoralis caudalis

Question 10

M. subclavius

Answer 10

Ø Car

• Origin: Manubrium sterni and adjacent parts of the sternum and ribs
• Insertion:
  
  • Cranial border of the scapula
  • Clavicle
• Innervation: N. pectoralis cranialis

Question 11

M. rhomboideus

Answer 11

• Origin:
  
  • Pars capitis (ca, su): Crista nuca of os occipitale
  • Pars cervicis: From raphe of neck to Th1-3 on processus spinosus
  • Pars thoracis: Processus spinosus of th4-7.
• Insertion: Dorsomedial border of scapula
• Action:
  
  • Elevates limb
  • Pulls base of scapula against trunk forwards or backwards (depending on which part will contract more)

Question 12

M. serratus ventralis

Answer 12

• Divided into:
  
  1. Pars cervicalis
  2. Pars thoracis
• Origin:
  
  • Pars cervicalis: C2-7 on processus transversus
  • _Pars thoraci_s: Middle of rib 1-8
• Insertion: Facies serrata on scapula (medially)
• Action:
  
  • Supports trunk
  • Helps inspiration
  • Carries shoulder cranially or caudally with respect to position of forelimb
• Innervation: N. thoracicus longus

Question 13

Give the muscles of the pelvic girdle

Answer 13

• M. psoas minor
• M. iliopsoas
  
  • ​M. psoas major
  • M. iliacus
• M. quadratus lumborum

Question 14

M. psoas minor

Answer 14

• Origin: Last few thoracic and first few lumbar vertebrae, on corpus
• Insertion: Eminentia iliopubica
• Action:
  
  • When the vertebral column is fixed: To draw the pelvis into a deeper position
  • When the pelvis is fixed: To stabilize and arch the lumbar and vertebral column dorsally

Question 15

M. psoas major

Answer 15

• Origin: Lumbar vertebrae, on corpus and processus transversus
• Insertion: Trochanter minor of femur
• Action: Draw the thigh forewards by flexing the hip and turning the stifle outwards

Question 16

M. iliacus

Answer 16

• Origin: Arising between linea arcurata and lateral border of os iliaca (sacroiliac joint)
• Insertion: Trochanter minor of femur (medially) between m. Rectus femoris and m. Pectineus (together with M. psoas major)
• Action: Enforcement of the sacroiliac joint

Question 17

M. quadratus lumborum

Answer 17

• Origin:
  
  • 11-13 thoracic vertebra ventrally
  • Last two ribs
  • Lumbar vertebra on processus transversus
• Insertion: medial surface of iliac wing (between articular surface and cranial ventral iliac spine of tuber coxae)
• Action: fixation and dorsal flexion of vertebral column