A8 - Costae, sternum, their junctions, mm. respiratorii

Question 1

Give the respiratory muscles

Answer 1

Inspiration:

1. M. serratus dorsalis cranialis
2. M. intercostalis externus
3. Mm. levator costarum
4. M. rectus thoracicus
5. M. scalenus
   
   • M. scalenus ventralis (ø ca)
   • M. scalenus medius
   • M. scalenus dorsais (ø eq)
6. Diaphragma

Expiration:

1. M. serratus dorsalis caudalis
2. M. intercostalis internus
3. M. transversus thoracis
4. M. retractor costae ultimae
5. M. subcostales

Question 2

M. serratus dorsalis cranialis

Answer 2

Dog:

• Origin:
  
  • Thoracolumbar fascia by a broad aponeurosis
  • Th 1-7 on processus spinosus
• Insertion: Rib 2-10, proximal
• Action:
  
  • Extends neck and raises head
  • Unilateral contraction draws head laterally
  • Inspiration
• Innervation: Nn. intercostalis

Horse:

• Origin:
  
  • ​By an aponeurosis fro:
    
    • Spinocostotransverse fascia
    • Thoracolumbar fascia
• Insertion: Rib 5-11 on cranial border and lateral surface (lateral to m. iliocostalis)

Question 3

M. intercostalis externus

Answer 3

• Origin and insertion:
  
  • Muscle fibers run caudoventrally (\)
  • From caudal border of one rib to cranial border of the next rib
• Action: Inspiration
• Innervation: Nn. intercostalis

Horse:

• More horizontally arranged
• In the region of the last rib blend with the m. obliquus abdominalis externus

Question 4

Mm. levator costarum

Answer 4

• Origin: Th 1-2, processus transversus
• Insertion: Rib, cranial border, near angulus costae (covered by m. erector spinae)
• Action: Inspiration
• Innervation: Nn. intercostalis

Question 5

M. rectus thoracicus

Answer 5

• Origin: First rib
• Insertion: Ventral ends of ribs 2-4
• Action: Inspiration
• Innervation: Nn. intercostalis

Horse:

• Extends over the 3 or 4 ribs
• Often forming a direct contact with m. rectus abdominalis

Question 6

M. scalenus

Answer 6

M. scalenus dorsalis: (ø eq)

• Origin: Processus transversus of C4-C6
• Insertion:
  
  • ​Dorsal muscular part: rib 1-4
  • Ventral muscular part: rib 1-9

M. scalenus medialis

• Origin: Processus transversus of C6-C7
• Insertion: Rib 1

M. scalenus ventralis: (ø ca)

• Origin: Processus transversus of C4-6?
• Insertion: Rib 1
• Action:
  
  • ​Inspiration
  • Unilateral contraction: flexes nack laterally
  • Bilateral contraction: flexes neck ventrally
• Innervation: R. ventralis ex nn. spinalis cervicalis

Question 7

Diaphragma

Answer 7

• Origin: Corona muscularis with sternal, costal and lumbar part
• Insertion: Centrum tendineum
• Action: Inspiration
  
  • As the diaphragm contracts, the volume of the thoracic cavity increases and air is drawn into the lungs
• Layers: (from cranial to caudal)
  
  1. Pleura + fascua endothoracica
  2. Fascia transversa thoracis
  3. M. phrenicus
  4. Fasciae abdominalis transversus
  5. Peritoneum
• Culpula diaphragmatica:
  
  • ​Curves upwards projecting into the thoracic cavity
  • The superior surface of the dome forms the floor of the thoracic cavity
  • The inferior surface the roof of the abdominal cavity
• Arcus lumbocostalis:
  
  • ​Lumbal and costal parts are connected by this arch
  • Tendinous fascia that arches over the psoas major muscle as it passes through the diaphragm
• Trigonum lumbocostale:
  
  • ​Space between the costal and lumbar parts of the diaphragm
  • Formed by muscle attachment
  • Ø m. phrenicus (ulnerable space for herniation)

M. phrenicus:

• Origin: corona muscularis
  
  • ​Parts of corona muscularis:
    
    • ​Pars sternalis (from processus xyphoideus)
    • pars costalis (from rib 6-12)
    • Pars lumbalis (from Th12, L1-2)
      
      • Crus dexter
        
        • Extends more ventrally
        • Surrounds esophageus
      • Crus sinister
        
        • Formation of hiatus aorticus?
• Innervation: N. phrenicus

Horse:

• Taller and wider
• Characterized by the size of its centrum tendineum
• Pars costalis
  
  • ​Origin: laying between those of the transverse muscle
  • Insertion: rib 8-14, at the costochondral junction
• Pars sternalis
  
  • ​Not distinctly separated from the costal part
  • Origin: cart. xiphoideus
• Pars lumbalis
  
  • ​Crus sinister
    
    • ​Lateral limb
    • Ventral limb
  • Crus dexter
    
    • ​Lateral limb
    • Arises from the 1^st-2^nd lumbar vertebrae
    • Broadens out to the left of hiatus aorticus
• Hiatus esophageus:
  
  • ​Formed by strong muscle bundles of the ventral limb of the right crus
• Foramen vena cavae:
  
  • ​Situated in the lateral part
  • About the level of the 7^th intercostal space
  • Formed by strong tendon tracts which merge with the right part of the ventral limb of the right crus
• Function:
  
  • ​Form the abdominal wall
  • Maintains abdominal pressure (urination, defecation, parurition)
  • Protection of abdominal organs

Question 8

M. serratus dorsalis caudalis

Answer 8

Dog:

• Origin: Caudal on superficial layer of fascia thoracolumbalis
• Insertion: Rib 11-13, proximal
• Action: Expiration
• Innervation: Nn. intercostalis

Horse:

• Origin:
  
  • ​By an aponeurosis from:
    
    • Spinocostotransverse fascia
    • Thoracolumbal fascia
• Insertion: Rib 11-18, caudal border​

Question 9

M. intercostalis internus

Answer 9

• Origin and insertion:
  
  • Muscle fibers run cranioventrally (///)
  • From cranial border of one rib to caudal border of the previous rib
• Action: Expiration
• Innervation: Nn. intercostalis

Horse:

• Cranial half:
  
  • Fleshy by the first 8 intercostal spaces
  • Lie beliw the m. serratus ventralis thoracicus
• Caudal half: tendinous

Question 10

M. transversa thoracica

Answer 10

Dog:

• Origin: Inner surface of sternum
• Insertion: 2-8th costal cartilages
• Action: Expiration
• Innervation: Nn. intercostalis

Horse:

• Origin: arise bilaterally from the middle limb of the sternal ligament
• Insertion: rib 2-8, at the costochondral junction

Question 11

M. retractor costae ultimae

Answer 11

• Origin: L1-4, processus transversus
• Insertion: Last rib, caudal border
• Action: Expiration
• Innervation: N. costoabdominalis

Horse:

• Between thoracolumbar facisa → last rib

Question 12

Mm. subcostalis

Answer 12

• Origin and insertion: Crossing medial surface of ribs 9-11 in a cranioventral direction (///), inside the thoracic cavity
• Action: Expiration
• Innervation: Nn. intercostalis

Question 13

M. intercarilagineus

Answer 13

Horse:

In the region of the false ribs applied to the lateral surface of the costal cartilage

Question 14

Ribs

Structures to metion

Answer 14

• Ribs forms the lateral wall of the thorax
• Spatia intercostalia (space between ribs)
• Each rib is divided into:
  
  • Os costae
    
    • ​Bony portion
    • Situated proximally
  • Cartilago costae
    
    • ​Cartilagenous portion
    • Situated dorsally
    • Articulates with sternum
      
      • 1^st pari of ribs articulates with manubrium sterni
      • The subsequent sternal ribs (ø last pair) from joints – which are situated between the adjacent sternal segments
    • Cartilages of asternal ribs are longer - forming costal arches
      
      • Angulus arcuum costalium
        
        • ​Formed by both costal arches ventrally
        • Inserted into processus xiphoideus
• Costae verae [sternales]
  
  • The cranial ribs conjoin directly by their cartilages with sternum
  • “Bearing ribs” - suspends the trunk
• Costae spuriae [asternales]
  
  • The remainder ribs do not form a direct junction with sternum
  • “Respiratory ribs” - highly mobile, allowing free movement of thorax during respiration
  • Their cartilages unite with one another to form arcus costalis
  • No direct junction with the sternal ribs, their cartilages unite with one another → form arcus costalis → attaches to sternum
• Costae fluctuantes
  
  • Their ends are free
  • Ca: last pair of ribs

Os costale:​

• Extremitas vertebralis
  
  • Caput costae (articulate with two vertebral bodies)
  • Sulcus capitis costae
  • Cristae capitis costae
  • Facies articularis capitis costae cranialis (⟷ fovea costalis caudalis)
  • Facies articularis capitis costae caudalis (⟷ fovea costalis cranialis)
• Collum costae (distally)
• Tuberculum costae (protrudes laterally)
  
  • Facies articularis tuberculi costae (⟷ fovea costalis transversalis)
• Angulus costae (distal to tuberculum costae, intervening portion of corpus costae)
• Corpus costae
• Tuberositas m. scaleni ventralis (ø ru??) (on the 1^st rib)
• Tuberositas m. longissimi (at the level of angulus costae)
• Tuberositas m. iliocostalis (on the caudolateral border
• Sulcus costae (medial. For intercostal vessels and nerves)
• Extremitas sternalis
  
  • ​Costochondral junction (distal extrimity with rib cartilage)
  • Genu costae (angulation of the rib with costal cartilage)
    
    • Ca: formed by costal cartilage
    • Other: occures at the costochondral junction
• Sulcus muscularis

Question 15

Ribs

1. Give the number of ribs
2. Give the relationship of sternal:asternal ribs

Answer 15

• Sternal:asternal
• Eq: 18 (8:10)
• Ru: 13 (8:5)
• Ca: 13 (9:4)
• Sus: 14-15 (7:7/8)

Question 16

Ribs

Give the articular surfaces between the ribs and the vertebrae

Answer 16

• Facies articularis capitis costae cranialis ⟷ fovea costalis caudalis
• Facies articularis capitis costae caudalis ⟷ fovea costalis cranialis
• Facies articularis tuberculi costae ⟷ fovea costalis transversalis
• Articulationes costochondrales:
  
  • ​Joint between the ribs and costal cartilage
  • Amphiarthroses (cartilage):
    
    • Bo: 2^nd-10^th ribs
  • Symphysis (fibrous):
    
    • Ca, eq: all ribs

Question 17

Sternum

1. Structures to mention
2. Draw the sternum

Answer 17

• Manubrium sterni
  
  • ​Cranial extremity
  • Articulates with the 1^st pair of ribs
• Corpus sterni
  
  • ​Manubrium sterni articulates with corpus sterni
  • Ca: rectangular shape
  • Ru: dorsoventrally flattened
  • Crista sterni (eq)
    
    • Cartilagenous ventral crest
  • Incisurae costales
    
    • ​Articulation with the cartilages of sternal ribs
• Processus xiphoideus
  
  • Caudal portion
  • Midline continuation of sternum
  • Not connected with ribs
  • Cartilago xiphoidea
    
    • ​Projects between the two costal arches
• Sternebrae
  
  • ​Bony segment
  • United by intervening cartilages or fused by synostoses

Synchondroses sternales:

• Unites sternebrae
• In young animals, ossifies later

Question 18

Sternum

Give the number of sternebrae in different species

Answer 18

• Eq: 5
• Ru: 5
• Ca: 6
• Sus: 4

Question 19

Junctions

Which junctions should be mentioned?

Answer 19

• Art. costovertebrails
  
  • ​Art. capitis costae
  • Art. costotransversaria
• Art. sternocostales
  
  • ​Synchondroses sternales (Unites sternebrae in young animals, ossifies later)
• Artt. costochondrales

Question 20

Junctions

Art. costochondrales

Answer 20

• ​Joint between the ribs and costal cartilage
• Art. sternocostales: Cranial corstal cartilages are joined directly to sternum
• Arcus costalis: Costal cartilage of asternal ribs are jlined together by elastic soft tissue forming arcus costalis
• Amphiarthroses (cartilage):
  
  • Bo: 2^nd-10th ribs
• Symphysis (fibrous):
  
  • Ca, eq: all ribs

Question 21

Juctions

Art. costovertebralis

Answer 21

• Composed of two articulations, with separate joint capsule:
  
  1. Art. capitis costae
     
     • Diarthrosis
     • Speroid joint (multiaxial)
     • Convex articular surface of caput costae → adjacent vertebrae (ø 1^ts rib, articulate with C7)
       
       • Facies articularis capitis costae cranialis ⟷ fovea costalis caudalis
       • Facies articularis capitis costae ⟷ fovea costalis cranialis
  2. Art. costotransversaria
     
     • Amphiarthrosis
     • Flat articular surface of facies articularis tubercululi costae ⟷ fovea costalis transversalis of the thoracic vertebrae of the same serial number

Strucutres of art. capitis costae

• Capsula articularis
• Lig. capitis costae radiatum (capitis costae → corpus vertebrae)
• Lig. capitis costae intraarticulare (crista capitis costae → dorsal vertebrae)
  
  • ​Lig. intercapitale (capitis costae → capitis costae)

Structures of art. costotransversaria

• Capsula articularis
• Lig. costotransversarium (collum costae → proc. transversus)
• Lig. lumbocostale (last rib → proc. transversus of L1)

Question 22

Junctions

Art. sternocostales

Answer 22

• Art. condylaris (biaxial)
  
  • But functioning as a hinge joint
• Between sternum → true ribs
• Eq, su: the first rib have a common articular cavity on manubrium sterni
• Synchondroses sternales
  
  • ​Unites sternebrae in young animals
  • Ossifies later

Structures:

• Capsula articularis
• Ligg. sternocostalia radiata (cart. costalis → sternum)
• Lig. sterni (ø ca)
  
  • Dorsal on sternum
  • Ru, su: From caudal to the first pair of ribs → cart. xiphoidea
  • Eq: From caudal to the first pair of ribs → divides into 3 branches insterting on last sternal ribs and cart. xiphoidea
• Membrana sterni (bo, su) (ligamentous tissue on the ventral surface of the sternum. Binds sternebrae together on the outside of sternum)
• Lig. costoxiphoidea (last sternal rib → processus xiphoideus)

Question 23

Interspecies

Summary from the topic

GAMMEL

Answer 23