Herbivore thorax

18

How many pairs of ribs do horses have

Withers

Topographic landmark that corresponds to the spinous processes of T2-T8

Topographic landmark that corresponds to the spinous processes of T2-T8

What are the withers of a horse

Cutaneous trunci

Cutaneous omobrachialis (muscle of shoulder and arm under the skin)

What are the cutaneous muscles of the equine thorax (2)

Pectorals- superficial (descending and transverse), deep, subclavius

Trapezius

Serratus ventralis

Latissimus dorsi

What are the extrinsic limb muscles of the equine that are associated with the thorax (4 groups)

Serratus dorsalis cranialis/caudalis

Serratus ventralis

Scalenus

External intercostal

Internal intercostal

Rectus thoracis

Transversus thoracis

What are the muscles of the equine thoracic wall (7)

Muscles dorsal to the transverse processes of the thoracic vertebrae

What are epaxial muscles

Spinalis system

Multifidus system

Longissimus

What are the 3 epaxial muscle groups of the equine thorax

Muscles located ventral to the transverse processes of the vertebrae

What are hypaxial muscles

Longus colli

Transversus thoracis- thoracic wall muscle

-ventral floor of thoracic cavity

What are the hypaxial muscles of the equine thorax (2)

Aorta

Right azygos vein

Thoracic duct

What structures travel through the aortic hiatus

Open thoracic inlet

What is the cranial border of the thorax

Line where the pleura reflects onto the ribs and caudally on the diaphragm

What is the line of pleural reflection

At the 4th-6th intercostal space

Where is the tracheal bifurcation in a horse

Cranial lobe

Caudal lobe

Cardiac notch at ribs 3-6

What is the structure of the equine left lung

Cranial lobe

Caudal lobe

Accessory lobe medially

Cardiac notch at ribs 3-4

What is the structure of the equine right lung

The caudal aspect of the lung in a normal relaxed space

What is meant by the basal border of the lung

Line that crosses along:

Ventral rib 6-> middle rib 11-> dorsal rib 16

What is the basal border of the lungs in an equine

Intercostal spaces 2-6

More vertical in position than in the dog

The long axis of the heart is directed caudoventrally and towards the left of the median plane

What is the positioning of the heart in the equine thorax

Conus arteriosus

The funneling of the right ventricle as it forms the pulmonary trunk

The funneling of the right ventricle as it forms the pulmonary trunk

What is the conus arteriosus

Ligamentum arteriosum

String of tissue connecting the aorta to the pulmonary trunk

String of tissue connecting the aorta to the pulmonary trunk

Remnant of the fetal ductus arteriosus that transfers blood between the great vessels

What is the ligamentum arteriosum

Interatrial septum

Divides the left and right atria

Interventricular septum

Divides the left and right ventricles

Crosses the lumen of the ventricles. Purkinje fiber passage for coordinated contraction

Constant in right ventricle

Variable in left ventricle

Where are the trabecula septomarginalis located in a horse

3rd IC space

Low

Area of auscultation for the equine pulmonary valve

4th IC space

High

Area of auscultation for the equine aortic valve

5th IC space

Low

Area of auscultation for the equine left AV valve

3rd-4th IC spaces

Low

Area of auscultation for the equine right AV valve

Everything comes off of the brachiocephalic trunk

-left subclavian

-right subclavian

-bicarotid trunk

What is the structure of the branches off the equine aortic arch

Costocervical trunk

-dorsal scapular a

-supreme intercostal a (first 3-4 IC spaces/aa)

Deep cervical a- deep cervical mm

Vertebral a- into vertebral column

Internal thoracic a- ventrally inside sternum

-gives rise to ventral intercostal aa

Superficial cervical a

What are the branches of the equine left subclavian artery

Left common carotid a

Right common carotid a

What are the branches of the equine bicarotid trunk

Costocervical trunk

-deep cervical a

-dorsal scapular a

-supreme intercostal a

Vertebral a

Internal thoracic a

Superficial cervical a

What are the branches of the equine right subclavian artery

Dorsal intercostal aa- wrap around and go down caudal aspects of ribs

Ventral intercostal aa (off of internal thoracic)- wrap up and anastomose with dorsal intercostals at mid-rib

Bronchoesophageal a (1st branch)- provides nutrients to tissue of lungs and muscle of esophagus

What are the branches of the equine dorsal/descending aorta

Pulmonary veins (oxygenated blood from lungs to heart)

Cranial vena cava

Caudal vena cava

Right azygos vein

-dorsal intercostal vv

What are the veins of the equine thorax

Parasympathetic NS

The ____ is craniosacral in origin

Craniosacral

Parasympathetic NS is ___ in origin

Sympathetic NS

The ____ is thoracolumbar in origin

Thoracolumbar

The sympathetic NS is ____ in origin

CN X- Vagus nerve

Vagosympathetic trunk

Recurrent laryngeal nerve

Cardiac nn

Dorsal and ventral vagal branches

Dorsal and ventral vagal trunks

What are the components of the equine parasympathetic NS (6)

Ramus communicans

Sympathetic trunk (and ganglia)

Cervicothoracic ganglion

Vertebral nerve

Ansa subclavia

-cardiac nn

Middle cervical ganglion

Vagosympathetic trunk

What are the components of the equine sympathetic NS (8)

Nerve tract. Mix of CnX and sympathetic fibers from the thorax

Parasympathetic signals travel caudally down the trunk

Sympathetic signals travel cranially up the trunk

What is the vagosympathetic trunk and how is information spread through it

Collection of sympathetic ganglia coming down from the communicating branches in each IC space (ramus communicans)

What is the sympathetic trunk

Signal located in the thoracolumbar spinal cord

Ramus communicans

Ganglia in the sympathetic trunk

Cervicothoracic ganglion

Ansa subclavia

Middle cervical ganglion

Vagosympathetic trunk (traveling cranially)

Head

What is the pathway of a sympathetic impulse from the spinal cord to the brain

Do that here

Describe the pathway of the recurrent laryngeal nerve

Originates from C4-C6 spinal nerves

Motor innervation to the diaphragm

NOT ANS

What is the phrenic nerve

Cranial mediastinal

Middle mediastinal

Caudal mediastinal

Tracheobronchial (dorsal to bifurcation)

Intercostal

Sternal

What are the lymphocenters of the equine thorax (6)

13

How many pairs of ribs do ruminants have

Very narrow thoracic inlet

Possibility of choking- cows are indiscriminate eaters

What is unique about the thoracic inlet of a cow

Cranial lobe

-cranial part

-caudal part

Caudal lobe

What is the structure of a cow left lung

Cranial lobe

-cranial part

-caudal part

Middle lobe

Caudal lobe

Accessory lobe

What is the structure of a cow right lung

Lung septa

Scaly texture typical of a ruminant lung

Scaly texture typical of a ruminant lung

What are lung septa

Tracheal bronchus

Extra bronchus proximal to the bifurcation in cows and pigs

Extra bronchus that comes directly off the trachea proximal to the tracheal bifurcation

Present in cows and pigs

Supplies the right cranial lung lobe

What is the tracheal bronchus

Ossa cordis

Bone inside the interventricular septum of a ruminant heart

Bone inside the interventricular septum of a ruminant heart

Supports the heart wall (because heart is very large)

Starts as cartilage and ossifies with age

What is the ossa cordis

Caudal mediastinal lymph nodes

Large lymph nodes ventral to the aorta in a ruminant