Thoracic Cage: represents the bone structure of the cavity - ribs, sternum. Thoracic Cavity: everything within the bony structure plus cranial to the diaphragm
Thoracic - cage, - cavity
Thoracic Cage - varies among species/breeds. Some dogs have a deeper chest some dont.
"The shape and extent of the thoracic cavity do not correspond to the expectations
raised by the conformation of the living animal" Dyce & Wensing.
B Massive musculature of forelimbB Outlines of back, brisket and costal
arch ≠ thoracic cavityB Shape of diaphragm
–concave dome within rib cage occupied by abdominal viscera not thoracic viscera
We usually overestimate the size of the thoracic cavity - even though it is actually quite small.
Conformation & Surface Anatomy
B Massive musculature of forelimbs• limb strength a function of area (x2), resp.
capacity a function of volume (x3)• ~60% of body weight borne by forelimbs• larger (heavier) animal = larger proportion
composed of musculoskeletal tissue– lungs of dog relatively massive compared to that
of horse or cow
Thoracic cage ≠ thoracic cavity
Diaphragm
The ribs go past the thoracic cavity.
Pectum excavatum (flat chest syndrome)
Yaygingulet al., 2016
Cat - sternum has a inward growth. Usually it is fixable. If you breed this animal it will pass it on genetically to their offspring.
Dog thorax - dorsal view
Massive musculature of the forelimb
Ribs are in yellow
Mediastinum is this division.
Dog thorax - dorsal view
Diaphragm
1. Crura of diaphragm2. Crura of diaphgramn3. aortic hiatus4. esophageal hiatus5. mediastinum 6. 7. central tendon8. plica vena cava9. vena cava foramen.
Ribs
B Basic formB Costo-chondralB ArticulationsB Joint types
6
Body of the rib
Tubercle (1) and Head (2) of the Rib
Rib joins with the thoracic vertebrae (b/w 2 vertebrae). Head joins with the thoracic process of the thoracic vertebrae.
1. tubercle2. head3. neck4. angle5. body6. costochondral junction7. costal cartilage8. intervertebral disk9. vertebra of same # as ring.
Vertebral articulations
B Costo-vertebral– Intercapital lig.
B Costo-transverse– c-t lig.
Samantha Bray
b/w tubercle of the rib and transverse process of the vertebrae
1. lamina of vertebra2. intercapital ligament3. tubercle of rib4. head of rib5. intervertebral disk6. dorsal longitudinal ligament7. costovertebral joint8. costotransverse joint covered by costotransverse ligament
costotransverse joint
costotransverse ligament
Costo vertebral joint
intercapital ligament
Ribs & Sternum
B Species differencesB ArticulationsB Joint types
Sternebrae - segments of the sternum. 1) Manubrium2) 1st rib3) sternebra4) costochondral junction5 ) Xyphoid cartilage - around the level of the 8th rib. 6) Costal Arch7) Floating RibSome ribs reach the sternum by a single cartilage = sternal ribs (AKA True Ribs)Some ribs reach from multiple cartilage = asternal ribs (AKA False Ribs). Sometimes the last rib doesn’t join the cartilage = floating rib.
• number of thoracic vertebrae = number of ribs• rib # corresponds to vertebra of caudal attachment • 1 sternebra less than no. of sternal ribs (includes manubrium and xiphoid)
Sternal Ribs are ribs that connect to the sternum.
Omo goes from spine of the scapula to the transverse processes of the cervical vertebrae.
4 & 5
15
Extrinsic or girdle muscles of the forelimbThoracic girdle = Synsarcosis
Deep layer:B RhomboideusB Serratus ventralisB Deep pectoral
7) trapezius.
5
6
8
Dog – right lateral
Dog –cranial view
B BrachiocephalicusB SternocephalicusB Jugular grooveB Thoracic inlet
Sternocephalicus - goes from sternum to the head.Jugular groove (in large animals). Jugular vein b/w the brachiocephalicus and sternocephalicus. Thoracic Inlet - opening where all the organs will be. Is the cranial opening of the rib cage.
Muscles of the thoracic wall
B ScalenusB Serratus dorsalisB IntercostalsB Rectus thoracis
Popesko
Scalenus - transverse processes of vertebrae and first 2-3 ribs. Serratus dorsalisIntercostals - go from 1 rib to adjacent rib - has a certain fiber orientation. Rectus thoracis - later continues as the rectus abdominis.
Epaxialmuscles
3 Groups: from the sacrum/ilium up to the neck or the head.1)Transversospinalis System 2) Longissimus System3) Iliocostalis System
Epaxial & hypaxial muscles
Muscles of thoracic & abdominal walls
5) serratus dorsalis cranialis6) serratus dorsalis caudalisTwo different intercostals: internal or external. Differ in direction of the fibers: external intercostals: fibers are in a caudal/ventral direction. Internal intercostals are in the cranial ventral direction (point towards the forelimb).
Internal Intercostals (7) is muscular all the way throughout the intercostal space. External Intercostals (6) shows a muscular part from the dorsal part of intercostal space to the junction.
