B28 - Pleural cavity, mediastinum

Question 1

Structures to mention in cavum thoracis

Answer 1

• Cavum pleurae (Potential space between pleura parietalis and pulmonalis and between the lobes of the lung)
• Fascia endothoracica (Connective tissue lining the thoracic walls outside of the pleura parietalis)
• Pleura (Serous membrane that lines the thoracic cavity on either side of the mediastinum, and covers the lung. Pleura parietalis is continuous with the pleura pulmonalis at the radix pulmonis and the lig. pulmonale)
  
  • Cupula pleurae (Blind end of the pleural cavity at the thoracic inlet)
  • Pleura pulmonalis [= pleura visceralis] (Serous covering of the lung)
  • Pleura parietalis (Lining the walls of each pleural cavity)
    
    • Pleura mediastinalis (Part of pleura parietalis that covers the mediastinum)
      
      • Pleura pericardiaca (Part of the pleura mediastinalis that covers the pericardium fibrosum)
    • Pleura costalis (Part of the pleura parietalis that lines the ribs and the intercostal muscles)
    • Pleura diaphragmatica (Part of the pleura parietalis covering the diaphragm)
• Mediastinum (Deviant connective tissue septum and pleurae mediastinales between the right and left pleural cavities, contains most of the structures in the thoracic cavity, ø lungs)
  
  • Mediastinum craniale (Cranial to pericardium. Contains great vessels, trachea and esophagus)
  • Mediastinum ventrale (Between pericardium and sternum)
  • Mediastinum medium (Contains heart and pericardium)
  • Mediastinum dorsale (Between pericardium and vertebrae)
  • Mediastinum caudale (Dorsal part contains: aorta, esophagus. Ventral part is thin and attached to the left side of the diaphragm)
• Lig. pulmonale (Formed by the continuity of pleura mediastinalis and pulmonalis caudal to the root of the lung)
• Plica venae cavae (From pericardium → diaphragm)
• Recessus pleurales (Clefts between reflected layers of pleura parietalis)
  
  • Recessus costodiaphragmaticus (Between pleura costalis → pleura diaphragmatica. Caudoventral to the basal border of the lung)
  • Recessus costomediastinalis (Between pleura costalis → pleura mediastinalis)
  • Recessus lumbodiaphragmaticus (ca, su) (Pleura extends caudal to the vertebral end of the last rib to the first lumbar vertebrae)
  • Recessus mediastinodiaphragmaticus sin. (From recessus mediastini → diaphragm)
• Cavum mediastini serosum [=Bursa infracardiaca / Cavum Sussdorfi] (On the right side of the esophagus in the mediastinum caudale. Extension of bursa omentale)
• Recessus mediastini (Evagination of the right pleural cavity between the mediastinum caudale → plica venae cavae. Contains lobus accessorius of right lobe)

Question 2

Name the serous cavities present in the trunk

General knowledge

Answer 2

There are 4 serosal cavities

• Cavum pleurae
  
  • ​Left and right
  • Formed by pleura
• Cavum pericardii
  
  • ​Formed by pericardium serosum
• Cavum peritonei
  
  • ​Fromed by peritoneum

Question 3

Name the serous membranes

General knowledge

Answer 3

• Parietal serosa
  
  • ​Covers a large part of the inner surfaces of the body wall
  • Depending on the location it is called:
    
    • Parietal pleura in the thorax
    • Parietal peritoneum in the abdomen and pelvis
  • Prefix: peri
• Connecting serosa
  
  • ​Serosal membranes extending between organs or connecting organs to parietal serosa
  • Usually referred to as mesenteries, but they also form the omenta and ligaments
• Visceral serosa
  
  • ​Extends from the dorsal body wall, and covers the intrapleural and intraabdominal organs
  • Prefix: epi

Question 4

Thoracic cavity

Structures to mention

Extra

Answer 4

• Apertura thoracica cranialis
• Apertura thoracica caudalis
• Fascia endothoracica
  
  • ​Lig. sternopericardia (eq, ru)
  • Lig. phrenicopericardia (ca, sus)

Question 5

Pleura

Answer 5

• Serous membranes within the pectoral cavity
  
  • Pectoral cavity: thoracic cavity cranial to diaphragm
• Covers:
  
  • Lungs
  • Walls of pectoral cavity
• Forms two complete sacs
  
  • Left and right
  • Mediastinum: space between the left and right sac
• There is a thin fluid film between pleura pulmonalis and pleura parietalis
• Pleura are attached to undelrying muscles, ligaments and bones by endothoracic fascia
• Pleura can can be subdivided, based on the structure it covers:
  
  • Pleura parietalis
    
    • Pleura mediastinalis
      
      • ​Pleura precaridaca
      • Pleura pericardiaca
      • Pleura postcardiaca
    • ​Pleura costalis
    • Pleura diaphragmatica
  • Pleura pulmonalis [= pleura visceralis
• Several spaces are formed by pleura:
  
  • ​Recessus costodiaphragmatics
    
    • ​Space between diaphragm and cadual lateral wall of the thoracic wall
  • Recessus mediastini
    
    • ​A fold of pleura surrounds vena cava caudalis
  • Cupulae pleurae
    
    • ​Formed by the cranial portion of each pleural sac
• Lig. pulmonale
  
  • ​Continulation of pleura mediastinalis and pleura pulmonalis
  • Caudal to radix pulmonis

Question 6

Pleura

Draw

Answer 6

Question 7

Mediastinum

Location

Answer 7

• Space between left and right pleural sacs
• Divided into 3 parts:
  
  • Precardial mediastinum (cranial)
    
    • Thoracic inlet marks the beginning
    • Within the cranial mediastinum:
      
      • Tr. brachiocephalicus
      • A. subclavia sinistra et dextra
      • Tr. costocervicalis sinistra et dextra
      • Tr. bicaroticus
      • A. thoracica interna sinistra et dextra
      • Vena cava cranialis
      • Tr. sympatheticus sinister et dexter
  • Pericardial mediastinum (middle)
  • Postcardial mediastinum (cadual)

Question 8

Mediastinum

Location

Answer 8

Space between left and right pleural sacs​

Contains most of the organs in the thoracic cavity (ø lungs)

Question 9

Mediastinum

Division

Answer 9

• Divided into 3 parts:
  
  • Precardial mediastinum (cranial)
  • Pericardial mediastinum (middle)
  • Postcardial mediastinum (cadual)

Question 10

Mediastinum

Precardial mediastinum (cranial)

Answer 10

• ​Thoracic inlet marks the beginning
• Cranial to the heart
• Within mediastinum craniale:
  
  • Trachea
  • Esophagus
  • Large vessels supplying:
    
    • Lateral thoracic wall
    • Forelimb
    • Neck
    • Head
  • Vena cava cranialis
  • Truncus sympatheticus
  • N. vagus
  • N. phrenicus
  • N. recurrent laryngeus
  • Cranial mediastinal lymph nodes:
    
    • Ln. cranialis sternalis
    • Ln. cranialis mediastinalis
    • Ln. cerv. prof. caud.
  • End of thoracic duct
  • Thymus (young animals)

Question 11

Mediastinum

Pericardial mediastinum (middle)

Answer 11

• Encloses the heart within the pericardium
• Within mediastinum medium:
  
  • ​Heart and pericardium
  • Aorta ascendens
  • Tr. pulmonalis
  • V. azygous
  • Vv. plulmonales
  • V. cava cranialis
  • V. cava caudalis
  • Tr. bronchoesophageus
  • Ducuts thoracicus
  • V. thoracica interna
  • N. vagus
  • N. phrenicus
  • N. laryngeus recurrens
  • Trachea
  • Esophagus

Question 12

Mediastinum

Postcardial mediastinum (cadual)

Answer 12

• Caudal to the heart
• Whithn mediastinum caudale:
  • ​Aorta thoracica
  • A. thoracica interna
  • V. azygous
  • Tr. sympatheticus
  • N. splanchincus major et minor
  • Ductus thoracicus
  • Tr. vagalis dorsalis et ventralis
  • N. phrenicus sinister (n. phrenicus dexter runs with plica vena cava)
  • Esophagus
  • Caudal mediastinal lymph nodes

Question 13

Mediastinum

Plica venae cavae

Answer 13

• Plica venae cavae forms the recessus mediastini
• Contains:
  
  • Vena cava caudalis
  • N. phrenicus sinistra
  • Lobus accessorius of right lung
• Recessus mediastinalis is bordered:
  
  • Cranially: pericardium
  • Caudally: diaphragm
  • Left: mediastinum
  • Right: vena cava caudalis and its mesentery

Question 14

Mediastinum

Cavum mediastinum serosum

Answer 14

• Serous cavity of the mediastinum in the right side of the esophagus in the mediastinum caudale
• Extendsion of bursa omentalis

Question 15

Mediastinum

Lymph nodes of the mediastinum

Answer 15

• Lc. mediastinalis
  
  • Ln. mediastinales craniales (su, ca)
  • Ln. mediastinales medii
  • Ln. mediastinales caudales (ø car)
• Lc. tracheobronchale (adjacent to hilus pulmonis):
  
  • Ln. tracheobroncales craniales (su, ru)
  • Ln. tracheobroncales sinistri
  • Ln. tracheobroncales medii
  • Ln. tracheobroncales dextri

Question 16

Mediastinum

Draw

Answer 16