Gross - Spring - Thoracic Cavity I - Mt2

Front 1

What are the OIAI's of scalenus medius m. in the horse?

Back 1

Scalenus medius m. (both the ventral and middle parts in the picture)

Separated into two parts

Cervical roots of the brachial plexus emerge between two parts

O: cranial border and lateral surface of the first rib

I: dorsal part – transverse process of C7 vertebra

I: ventral part – transverse processes of C4-C6 vertebrae

Action: flex the neck, bend the neck laterally, draw first rib cranially to assist with inspiration

Innervation: ventral brs. of cervical spinal nn.

Front 2

What are the OIAI of the scalenus m. of the ruminant? What are its parts?

Back 2

Scalenus dorsalis m. - absent in sheep

O: transverse processes of C4-C6 vertebrae

I: 4th rib in ox, 2nd rib in goat

Scalenus ventralis m.

O: transverse processes of C3-C7 vertebrae

I: first rib

Action: flex the neck, bend the neck laterally, draw first rib cranially to assist with inspiration

Innervation: ventral branches of cervical spinal nn.

Front 3

What are the OIAI of the rectus thoracis m. of the large animal?

Back 3

O: lateral surface of the first rib, ventral to scalenus
I: Horse – cartilage of the 4th rib (may extend to the 5th rib and sternum), aponeurosis joins rectus abdominis
I: Ruminant – cartilages of 3rd and 4th or 5th ribs and adjacent parts of sternum
Action: draw cartilages and ribs cranially and laterally to assist in inspiration
Innervation: intercostal nn.

Front 4

What are the OIAI of serratus dorsalis cranialis m.?

Back 4

O: thoracolumbar fascia (and dorsoscapular ligament in the horse)
I: lateral surfaces of 5th/6th to 11th/12th ribs in the horse; 6th to 9th ribs in the ruminant
Action: draw the ribs cranially and laterally assisting in inspiration
Innervation: thoracic spinal nn.

Front 5

What is the OIAI of serratus dorsalis caudalis m.?

Back 5

O: thoracolumbar fascia
I: lateral surfaces of the last 7 or 8 ribs in the horse; last 3-4 ribs in the ruminant
Action: draw the ribs caudally assisting with expiration
Innervation: thoracic spinal nn.

Front 6

What are the OIAI of the external intercostal mm. of the large animal?

Back 6

O: caudal borders of the ribs
I: cranial borders and lateral surfaces of succeeding ribs
Action: draw the ribs cranially to assist with inspiration
Innervation: intercostal nn.

Front 7

What are the OIAI of the internal intercostal mm. of the large animal?

Back 7

O: cranial border of the ribs and their cartilages
I: caudal borders of the preceding ribs and cartilages
Action: draw ribs caudally to assist with expiration

Front 8

What is the action of the intercostal muscles when working together?

Back 8

Act together to narrow the intercostal spaces and to prevent the thoracic wall from being pushed out or pulled in during respiration

Front 9

What are the origins of the external abdominal oblique m of the large animals?

Back 9

O: Horse – lateral surfaces of 4th-18th ribs and the fascia over the external intercostal mm.; thoracolumbar fascia
O: Ruminant – caudal border and lateral surface of 6th-13th ribs and the fascia over the external intercostal mm.

Front 10

What is the OIAI of transversus thoracis m.?

Back 10

Located on the thoracic surface of the sternum and the cartilages of the sternal ribs
O: sternum
I: costal cartilages and ribs 2-8
Action: draw the ribs and their cartilages medially and caudally, assisting with expiration
Innervation: intercostal nn.

Front 11

What are the three epaxial muscles atop the thoracic cavity?

Back 11

Iliocostalis thoracis m.
Longissimus thoracis m.
Transversospinalis muscle system

Front 12

How many ribs do horses and ruminants have?

Back 12

18 ribs in the horse
13 ribs in the ruminant

Front 13

What is the ligament coursing between the heads of the ribs?

Back 13

Intercapital ligaments

Front 14

What are the rib landmarks of the caudal border of the scapula, the supraglenoid tubercle, and the olecranon in the horse and ox?

Back 14

Caudal border of the scapula:
Horse – 7th rib; Ox – 6th rib
Supraglenoid tubercle:
Horse – just cranial to the 1st rib
Olecranon:
Horse – 5th rib or 5th IC space ventrally
Ox – 5th IC space ventrally

Front 15

How far up does the diaphragm extend into the thoracic cavity of the horse and ox?

Back 15

Horse – diaphragm extends cranially to the 6th intercostal space or 6th rib
Ox – diaphragm extends cranially to the 6th rib

Front 16

What are the boundaries of the thoracic cavity of the horse and ox?

Back 16

Cranial boundary – thoracic inlet
Caudal boundary – diaphragm
Dorsal boundary – longus colli and thoracic vertebrae
Ventral boundary – sternum and transversus thoracis
Lateral boundary – ribs and internal intercostal muscles

Front 17

What separates the pleural cavity in the horse and ox? In which species is the separation thicker?

Back 17

Pleural cavities
Only contains a scant amount of serous fluid
Separated by the mediastinum
Mediastinum is not complete in the horse; delicate
Thicker in the ruminant

Front 18

What is in the mediastinum?

Back 18

Heart, trachea, esophagus, aorta, lymph vessels, caudal and cranial vena cava, vagus n., phrenic n. (horse shown)

Front 19

What is the cranial extent of the pleural cavity? What side is it larger on?

Back 19

Cupula Pleura - Cranial extent of the pleural cavity – extends cranial to first rib. It's part of the pleura not in the thoracic cavity.

Larger on the right side

Front 20

What is the line of pleural reflection?

Where is this found in the horse and ox?

Why is this must know information?

Back 20

Where the costal pleura is continuous with the diaphragmatic pleura
Horse – from the 8th and 9th costal cartilages dorsocaudally in a gentle curve to the middle of the cranial border of the last rib to the vertebral end of the 17th intercostal space
Ox – (indicated as 4 on the picture) from the 8th costochondral junction to the middle of the 11th rib to the 12th rib dorsally

Clinically relevant because you'll need to know where to access the thoracic cavity and hit lung, not hit lung, hit abdomen or thorax.

MUST KNOW

Front 21

What are the pleural recesses of the large animals?

Back 21

Costomediastinal recess - The blue swath in the picture of the horse
Space ventral to the lungs

Costodiaphragmatic recess
Space caudal to the basal border of the lungs

Front 22

What are the auscultation borders of the horse and ox?

Back 22

horse: Caudal angle of the scapula, point of the elbow, upper end of the 16th rib

ox: Triceps brachii m., muscles of the back, line from olecranon to the 11th rib dorsally
Slightly larger area on right side

Front 23

What is the boundary to perform a pericardiocentesis in the ox? Why are you more likely to do this in an ox then horse?

Back 23

5th IC space, dorsal to costochondral junction, left side

Ruminants are apt to eat something that might puncture their pericardium or heart.

Front 24

What are the boundaries of a thoracocentesis of a horse and ruminant?

Back 24

Horse
Lower part of the 7th IC space, ventral to the margin of the lung
Avoid the superficial thoracic vein (spur vein)

Ruminant
6th or 7th IC space, dorsal to the costochondral junction

Front 25

T/F The right and left lungs of the equine are equal in size.

Back 25

True

Front 26

T/F Equine lungs lobes can be seen externally.

Back 26

False
No evidence of external lobation except accessory lobe of right lung

Front 27

What are the basal borders of the equine lung?

What separates the lungs from the line of pleural reflection?

Back 27

(line 2 in the picture)

Dorsal region of the 16th rib
Middle of the 11th rib
Costochondral junction of the 6th rib
Separated from the line of pleural reflection by approximately 5 cm dorsally and ventrally, 15 cm in the middle

Front 28

What are the lobes of the right and left equine lung?

Where are the cardiac notches?

Back 28

Right:
Cranial, caudal, accessory lobes
Cardiac notch
3rd to 4th IC spaces

Left (shown):
Cranial and caudal lobes
Deep cardiac notch
3rd to 6th IC spaces
Pericardium contacts the thoracic wall at the 3rd and 6th ribs

Front 29

Are the bovine lungs lobulated? Define their tissue septa.

What defines their basal border?

Back 29

Pronounced lobation
Lobulated - thick connective tissue septa

Basal border
6th costochondral junction to 11th rib dorsally
Straight line

Front 30

Which lung is larger in the bovine? What lobes does it have?

Back 30

Right lung larger than left lung
Right lobe - Cranial and caudal parts
Cardiac notch – 3rd to 4th IC space

Middle lobe

Caudal lobe

Accessory lobe

Front 31

Where is the cardiac notch of the right bovine lung?

The left bovine lung?

Back 31

Right Cardiac notch – 3rd to 4th IC space
Left Cardiac notch – 3rd IC space to 5th rib

Front 32

What is unique about the air passage to the right cranial lung lobe of the ruminant?

What is the clinical signifigance of this?

Back 32

Tracheal bronchus courses to the right cranial lung lobe
Present in ruminants

Want to make sure that the tracheal tube ends before the tracheal bronchus or else the right cranial lung lobe won't get oxygenated.

Front 33

What are the lobes of the left bovine lung?

Back 33

Cranial (with Cranial and caudal parts) and caudal lobe

Front 34

What is the pathway of lymph drainage from the lungs in the horse?

Back 34

Lymph from the lungs goes to the pulmonary lymph nodes then to the tracheobronchial lymph nodes then to the mediastinal lymph nodes

Front 35

What are the four lymphocenters of the thoracic cavity of the horse and ox? Which are more developed in the ox?

Back 35

Dorsal thoracic lymphocenter
Intercostal lnn. (4)
Thoracic aortic lnn. (5)

Ventral thoracic lymphocenter
Cranial sternal lnn. (1)
Caudal sternal lnn. (1’)

Mediastinal lymphocenter
Mediastinal lnn. – cranial (2), middle, caudal (6) (caudal mediastinal ln are well-developed in the ox)
Nuchal ln. (3) (technically in the neck region)

Bronchial lymphocenter
Tracheobronchial lnn. – right, left (8), middle (7)
Pulmonary lnn.