Thorax dissection Flashcards
What is the origin, insertion, action and innervation of brachiocephalicus?
O= clavicle/clavicular intersection (no clavicle in dog)
I=cleidobrachialis: distal cranial humerus
cleidocervicalis: fibrous raphe of neck
cleidomastoideus: mastoid part of temporal bone
A= advances the limb, extends shoulder, draws the neck and head to the side
In= accessory nerve and ventral branches of cervical spinal nerves
Which muscle forms the dorsal boundary of the jugular furrow?
What about the ventral boundary?
Dorsal: brachiocephalicus
Ventral: sternocephalicus
Where would you raise the jugular vein when taking blood?
Jugular groove at the base of the neck, beside the trachea
What are the cranial and caudal parts of the sternum called?
Cranial: manubrium
Caudal: xiphoid process
Name the bones of the larynx, from cranial to caudal
Epiglottis
Thyroid
Arytenoids (paired)
Cricoid
What is the name of the joint between the mandible and skull?
Temporomandibular joint
What name is given to the joint between the atlas and axis?
Atlanto-axial joint
What name is given to the joint between the atlas and the skull?
Atlanto-occipital joint
Which side of the recurrent laryngeal nerve is more prone to damage in horses?
Why?
What does it cause?
Left
Left nerve is longer, due to its extended length around the base of the heart. Also therefore more common in larger horses
Causes ‘roaring’-unable to fully open the larynx, air makes a whistling/roaring noise as it passes through
What shape are the cartilage rings in cats and dogs?
C-shaped
What is the origin, insertion, action and innervation of sternocephalicus?
O= manubrium of sternum I= mastoid process of skull, nuchal crest of occipital bone A= draws head and neck to the side In= accessory nerve and ventral branches of cervical spinal nerves
Sternothyrohyoideus (paired, left and right) splits into what?
Ventromedially: sternohyoideus
Dorsolaterally: sternothyroideus
Where do the left and right common carotid arteries arise from?
Brachiocephalic trunk
In which direction do the sympathetic and parasympathetic fibres travel in the vagosympathetic trunk?
Sympathetic: preganglionic and postganglionic axons course cranially to structures in the head
Parasympathetic: preganglionic axons course caudally down the neck to thorax and abdomen
Which hormones does the thyroid gland produce?
T3 (triiodothyronine)
T4 (thyroxine)
Where are the parathyroid glands located?
Two on each thyroid gland. One on the lateral aspect of the cranial pole, one on the tracheal surface of the caudal pole
What is the role of the parathyroid gland?
Produces parathyroid hormone, which increases the concentration of Ca2+ in the blood
Where is the recurrent laryngeal nerve located?
Attached to the dorsolateral surface of trachea
What is the origin, insertion, action and innervation of the superficial pectorals?
2 parts
O= cranial sternum
I= cranial part: deltoid tuberosity of humerus
caudal part: medial fascia of forelimb
A= adducts limb
In= cranial pectoral nerves (C7, C8)
What is the origin, insertion, action and innervation of the deep pectorals?
2 parts
O= ventral sternum
I= major portion: lesser tubercle of humerus
caudal part: medial brachial fascia
A= adducts limb
In= C8, T1Which vessel does the axillary artery arise from?
What are the other main branches of this vessel? (4)
Subclavian artery becomes axillary artery
Vertebral artery
Costocervical trunk
Superficial cervical artery
Internal thoracic artery
Where does serratus dorsalis originate and insert?
O= dorsal fascia I= ribs
What is the origin, insertion and action of scaleneus?
O= transverse processes of caudal cervical vertebrae I= first few ribs A= helps to stabilise ribs during inspiration
Which nerves make up the brachial plexus?
C6, C7, C8, T1
In which direction do fibres run of the external intercostals run? What is the function of this muscle?
What about internal intercostals?
Externals: Caudoventrally. Pull ribs cranially and out during inspiration.
Internals: Caudodorsally. Pull ribs caudally and in during expiration.
What would happen if you cut into the parietal pleura of the ribs?
What does this tell you about the pressure inside the pleural cavity?
Lungs would immediately recoil and air would rush into the pleural cavity. Ribs would rise up.
Negative pressure; it is below atmospheric pressure
What is contained within the mediastinum?
Heart, aorta, trachea, tracheal bifurcation, thymus, lymph nodes, oesophagus, vagus nerves, other nerves and vessels
What name is given to the portion of mediastinum covering the heart?
Pericardial mediastinal pleura
The mediastinum can be divided into which 3 parts?
Cranial part (lying cranial to heart) Middle part (containing the heart) Caudal part (lying caudal to heart). Thin.
Why does the caudal mediastinum deviate to the left?
Follows on from the left apex of the heart
What does the visceral pleura coat?
What is it derived from?
Outer surface of lungs
Splanchnic mesoderm
What does the parietal pleura coat?
What is it derived from?
Lines the thoracic cavity
Somatic mesoderm
What is the pleural cavity?
What does it contain?
A potential space between the visceral and parietal pleura in the thorax.
Contains a small amount of serous fluid which allows smooth movement between the lungs and chest walls, and between individual lobes. Also provides surface tension, keeping the lungs close to the thoracic walls. Therefore allows the volume of the lungs to change with the volume of the thoracic cavity
Which 3 layers make up the parietal pleura?
Mediastinal pleura
Costal pleura
Diaphragmatic pleura
What is the phrenicocostal sinus?
What happens to it during inspiration?
A potential space in the pleural cavity, at the posterior-most ends of the cavity, located at the junction of the costal pleura and diaphragmatic pleura.
Diaphragm contracts, space gets bigger lungs expand into the space.
Fluid collects here during pleural effusion
What is the cupula pleura?
Cranially, the costal and mediastinal pleura adjoin to form a ‘dome’ of pleura which extends to the thoracic inlet
What is the parietal pleura innervated by?
Intercostal nerves
What is the visceral pleura innervated by?
Vagus nerve and sympathetic fibres
What is the cardiac notch?
Position of the heart amongst the lungs. Located on the right lung at the fourth and fifth intercostal space. The apex of the notch is continuous with the fissure between the cranial and middle lobes. Right ventricle occupies this area.
What is the plica vena cava?
A reflection of mediastinal pleura, caudal to the heart, that surrounds the caudal vena cava
Which nerve is the origin of the phrenic nerve?
C5
Which groove is located on the right side of the heart?
What about the left?
Right= subsinusoidal Left= paraconal
What is the name of the membrane that surrounds and protects the heart?
Pericardium
Which ganglia combine to form the stellate ganglion?
Inferior cervical ganglion and first thoracic ganglion
What is a ramus?
A branch connecting 2 nerves or 2 arteries
Why do cattle often remain alive for a few seconds after their throats are cut during halal slaughter?
The vertebral arteries are not severed, which supply the brain with blood
Are white and grey rami distinguishable?
White rami appear more white because they contain more myelinated than unmyelinated fibres, unlike grey rami
Where do the right and left subclavian arteries originate?
Right= brachiocephalic trunk Left= aortic arch
Why are the left and right internal thoracic arteries also called the internal mammary arteries?
They give off the cranial and caudal epigastric arteries
Which groove can be seen when viewing the heart ventrally (ie looking down at the chest)?
Which chambers can be seen?
Paraconal groove. Left side of heart.
Left ventricle, left auricle, right auricle, right ventricle
Which vessels empty into the right atrium?
What about the left atrium?
Right= cranial and caudal vena cavae Left= left and right pulmonary veins
Where does the left ventricle pump blood to?
What about the right?
Left= aorta Right= pulmonary artery
What is the mediastinum?
The central compartment of the thoracic cavity that contains all structures within the thorax (except the lungs). Enclosed on the left and right by pleurae.
Which muscle bridges the gaps between the cartilage rings of the trachea?
Where is it located in cats and dogs?
What about other species?
Trachealis
Placed externally
Other species-placed internally
Where does the oesophagus lie in relation to the trachea?
Dorsally to trachea
Where is the trachea positioned in the thorax?
Where does it bifurcate?
Cervical part of trachea lies in the median position
Thoracic part crosses the aortic arch, thus its positioning is moved slightly to the right
The trachea bifurcates at the level of the 4th-6th intercostal space
What are the 4 heart valves?
2 atrioventricular valves: mitral (left) and tricuspid (right)
2 semilunar valves: aortic and pulmonary
How many cusps does each heart valve have?
Mitral= 2 Others= 3
How are the heart valves anchored to the walls of the ventricles?
Chordae tendinae-prevent the valves from inverting. Are attached to papillary muscles
What are heart murmurs caused by?
Turbulence in the flow of blood through the heart
What is the action of sternohyoideus and sternothyroideus?
What are they innervated by?
Draw the larynx and tongue caudally
Ventral branches of cervical spinal nerves
