CVR Anatomy Flashcards
1
Q
How is the thoracic cavity continuous with the neck?
A
Via the superior thoracic aperture.
2
Q
How is the thoracic cavity separated from the abdominal cavity?
A
By the diaphragm - a sheet of skeletal muscle vital for breathing.
3
Q
What does the thorax contain?
A
- Heart.
- Lungs.
- Trachea.
- Oesophagus.
- Arteries and veins.
- Nerves.
- Lymphatic vessels.
4
Q
What is the thoracic cage composed of? What is its purpose?
A
- The sternum, 12 pairs of ribs, and thoracic
vertebrae. - Semi-rigid and moves with breathing to
allow the lungs to expand. - Protects the thoracic and some abdominal
viscera. - Provides an attachment for the muscles of
breathing and muscles that move the upper
limbs.
5
Q
Where does the sternum lie? What 3 parts is it composed of?
A
- Anteriorly in the midline of the thoracic
cage. - Made up of: manubrium, body, and xiphoid
process (superior -> inferior).
6
Q
What is the notch on the superior border of the manubrium called?
A
Suprastenral (jugular) notch.
7
Q
Where does the manubrium articulate with the clavicle laterally?
A
The sternoclavicular joint.
8
Q
Where does the manubrium articulate with the body of the sternum?
A
The manubriosternal joint, AKA the sternal angle, or the ‘angle of Louis’.
9
Q
What are the anterior parts of the ribs composed of? Why?
A
Costal cartilage, to give the thoracic cage some ‘springiness’.
10
Q
Where do the ribs articulate with their costal cartilages?
A
Costochondrial joints.
11
Q
Where do the costal cartilages of the upper ribs articulate with the sternum?
A
Sternocostal joints.
12
Q
What do the ribs articulate with posteriorly? Where?
A
Thoracic vertebrae, at costovertebral joints.
13
Q
What lies in the intercostal spaces? What do they do?
A
- Intercostal muscles.
- Move the thorax for breathing.
14
Q
Where do the thoracic vertebrae lie? Where do they articulate with each other?
A
- Posteriorly in the midline of the thoracic cage.
- Intervertebral joints.
15
Q
What are the four chambers of the heart? Which are the pumping chambers? What differences do they have?
A
- The right and left atria, and the right and left
ventricles. - The ventricles are the pumping chambers,
so they have thicker muscular walls than the atria.
16
Q
Where are atrioventricular valves found? What are they called?
A
- Between the atria and ventricles.
- The tricuspid valve on the right.
- The mitral valve on the left.
17
Q
Where are semilunar valves found? What are they called?
A
- Between the ventricles and the large blood
vessels that carry blood from them. - Pulmonary valve at the entrance to the
pulmonary trunk. - Aortic valve at the entrance to the aorta.
18
Q
What supplies the myocardium with blood?
A
The coronary arteries.
19
Q
How does the heart work as a muscular pump?
A
Specialised nerve cells and fibres generate and conduct electrical energy that stimulates contraction of the myocardium spontaneously, these cells are under autonomic control.
20
Q
What is the cardiopulmonary circulation?
A
- The circulation between the heart and the
lungs. - Arteries carry deoxygenated blood and
veins carry oxygenated blood. - Opposite for the systemic circulation of the
rest of the body. - Veins carry blood to heart.
- Arteries carry blood away from heart.
- True for cardiopulmonary and systemic.
21
Q
What does parasympathetic stimulation do to heart rate?
A
Decreases.
22
Q
What does sympathetic stimulation do to heart rate?
A
Increases heart rate.
23
Q
What are the steps of cardiopulmonary circulation?
A
- Right atrium gets deoxygenated blood from
superior and inferior vena cava (veins). - Blood flows from right atrium -> right
ventricle. - Right ventricle pumps deoxygenated blood
to lungs via pulmonary arteries. - Gas exchange at lungs.
- Oxygenated blood returns from lungs via
pulmonary veins to the left atrium. - Blood flows from left atrium -> left ventricle.
- Left ventricle pumps oxygenated blood via
aorta to the rest of the body.
24
Q
What are alveoli? Approximately how many alveoli does an adult lung contain?
A
- Microscopic air sacs.
- Around 300 million per lung.
25
How are the lungs divided into lobes? What separates the lobes?
- Right lung has 3 lobes: superior, middle,
inferior.
- Left lung has 2 lobes: superior and inferior.
- Fissures separate the lobes.
26
What is each lung served by? What are their functions?
- One pulmonary artery (deoxygenated blood
into the lung).
- Two pulmonary veins (oxygenated blood
from the lung).
- One main bronchus (air between lung and
trachea).
27
What are the membranes that cover the lungs called?
Visceral and parietal pleura.
28
What is the bronchial tree?
- The branching system of tubes that conduct
air into and out of the lungs.
- Trachea bifurcates -> left and right main
bronchi -> left and right lungs respectively.
- Main bronchi divides -> smaller bronchi,
divides -> bronchioles.
- Bronchioles divide smaller and smaller,
smallest conduct air to/from alveoli.
29
What do the walls of the bronchi and trachea contain?
Smooth muscle and cartilage.
Cartilage acts as a scaffold to ensure they remain open.
30
What do the walls of bronchioles contain?
Smooth muscle only, which can contract and relax.
31
What does parasympathetic stimulation do to bronchioles?
Narrows = bronchoconstriction.
32
What does sympathetic stimulation do to bronchioles?
Opens = bronchodilation.
33
What are the three skills of surface anatomy?
Looking, feeling (palpating), and listening (auscultating).
34
What is a key surface landmark of the thorax?
The sternal angle, as it lies at the same level as the second ribs, allowing us to count the rest.
35
What is the skin of the thoracic wall innervated by?
Spinal nerves T1 -> T12.
36
What are the skeletal muscles of the thoracic wall innervated by?
Somatic motor fibres in spinal nerves T1 -> T12.
37
What innervates sweat glands and the smooth muscle of blood vessels and hair follicles?
Sympathetic fibres.
38
What does the breast contain?
- Fat.
- Glandular/secretory tissue arranged in
lobules.
- Ducts which converge on the nipple.
- Connective tissue and ligaments.
- Blood vessels and lymphatics.
39
What blood vessels is the breast primarily supplied by?
Anterior intercostal arteries (branches from the internal thoracic artery - arises from subclavian artery), and the axillary artery.
40
What supplies somatic nerves and sympathetic fibres to the breast? What do these fibres innervate?
Intercostal nerves.
Somatic sensory fibres -> skin of the breast.
Sympathetic fibres -> smooth muscle in the blood vessel walls and nipple.
41
What are the 5 groups of lymph nodes in the axilla? What do they drain? What is unique about one of these groups?
- Central, pectoral, humeral, subscapular, and apical.
- Drain the breast, upper limb, chest wall, scapular region, and the abdominal wall.
- The apical nodes receive lymph from all other lymph nodes in the axilla, because they drain the most, they are often involved in the spread of breast cancer.
42
Which ribs are typical/atypical?
Ribs 3 -> 9 = typical.
Ribs 1 -> 2, and 10 -> 12 = atypical.
43
What forms the boundary of the superior thoracic aperture? What is this?
- The manubrium, the first ribs, and the first thoracic vertebrae.
- The passageway through which structures pass between the neck and the thorax.
44
What are the 3 types of intercostal muscles? What do they do?
- External, internal, and innermost.
- Move the ribs and alter dimensions of the thoracic cavity with inspiration and expiration.
45
Where would you find the pectoralis major?
Most superficial muscle of the anterior chest wall.
Attached to the upper humerus, the clavicle, and the upper six ribs.
46
Where would you find the pectoralis minor?
Deep to the pectoralis major.
Attached to the scapula, and ribs 3 -> 5.
47
Where would you find the serratus anterior?
Superficial muscle sweeping around the lateral aspect of the thoracic cage.
Attached to the scapula, and the upper eight ribs.
48
What are some clinical relevancies of the pectoral region, thoracic cage, and lungs?
- Rib fractures.
- Shingles.
- Breast cancer.
49
What do the intercostal spaces contain?
- Three layers of intercostal muscle and their associated membranes.
- A neurovascular bundle containing an intercostal nerve, artery, and vein.
50
Which direction are the fibres orientated in in the…
A.) external intercostal muscle
B.) internal intercostal muscle
C.) innermost intercostal muscle
A.) Antero-inferiorly.
B.) Postero-inferiorly.
C.) Postero-inferiorly.
51
How does the external intercostal muscle act on the ribs?
Contraction pulls the ribs superiorly, hence is most active in inspiration.
52
How does the internal intercostal muscle act on the ribs?
Contraction pulls the ribs inferiorly, hence is most active in expiration.
53
Where do the external and internal intercostal muscles become membraneous?
External - anterior of the intercostal space.
Internal - posterior of the intercostal space.
54
What lies between the innermost intercostal muscle and the parietal pleura?
The endothoracic fascia.
55
Where do you find the neurovascular bundle in each intercostal space?
In the plane between the internal and innermost intercostal muscle.
Inferior border of the rib, superior to the space.
In a shallow costal groove on the deep surface of the rib.
56
What are the posterior intercostal arteries branches from?
The descending aorta.
57
What do the anterior and posterior intercostal veins drain into?
Anterior - the internal thoracic vein.
Posterior - azygos system of veins.
58
Describe the intercostal nerves. What do they innervate?
Somatic, containing motor and sensory fibres. Also carry sympathetic fibres.
Innervate the skin of the chest wall, and the parietal pleura.
59
Describe the pleurae.
Parietal pleura - lines inside of the thorax, visible with the naked eye.
Visceral pleura - covers surface of the lungs and extends into the fissures, not visible with the naked eye.
Pleural cavity - thin space filled with pleural fluid, lying between the pleurae.
60
Describe where you would find the different parts of the parietal pleura.
Cervical pleura - covers the apex of the lung.
Costal pleura - adjacent to ribs.
Mediastinal pleura - adjacent to the heart.
Diaphragmatic pleura - adjacent to the diaphragm.
61
Which nerves innervate the two pleural layers? Effects on sensation?
Parietal pleura - intercostal nerves, somatic sensory fibres carry sensation to consciousness -> very painful.
Visceral pleura - autonomic sensory nerves, doesn’t usually reach conscious perception.
62
Describe the fissures in the lobes of the lungs.
Both lungs have oblique fissures.
- Left: separates the superior and inferior lobes.
- Right: separates the superior and middle lobes from the inferior lobe.
Right lung has a horizontal fissure.
- Separates the superior and middle lobes.
63
Describe the positioning of the surfaces of the lung.
Costal surface - adjacent to ribs.
Mediastinal surface - adjacent to heart.
Diaphragmatic surface - inferior surface of the lung.
64
Describe the borders of the lungs.
Anterior border - sharp and tapered.
Posterior border - thick and rounded.
Inferior border - sharp and tapered.
65
Where is the root of the lung found? What does it contain?
Between the heart and the lung.
The pulmonary artery, pulmonary veins, and main bronchus. Pleura encloses it.
66
Where is the hilum of the lung found? What does it contain? Discuss the position of these components.
Mediastinal surface of the lung.
Where the pulmonary artery, pulmonary veins, and main bronchus enter and exit the lung.
Hilum of right lung - pulmonary artery is anterior to the main bronchus.
Hilum of left lung - pulmonary artery is superior to the main bronchus.
Pulmonary veins most anterior and inferior in both.
67
Where does the trachea bifurcate? How is this marked internally?
The sternal angle.
Marked by a ridge of cartilage called the carina.
68
When a foreign body enters the trachea, which bronchi is it more likely to enter? Why?
The right main bronchus.
Shorter, wider, and descends more vertically.
69
Describe the branching system of the bronchial tree. Include quantities.
Main bronchus -> lobar bronchi (3 in the right, 2 in the left - 1 for each lobe).
Lobar bronchus -> segmental bronchi (~10 in each lung to serve the 10 bronchopulmonary segments).
Segmental bronchus -> bronchioles (get smaller with each division, smallest = alveoli for gas exchange).
70
What is the space between the inferior border of the lungs and the inferior extent of the parietal pleura called?
The costodiaphragmatic recess.
71
Describe the locations of the borders of the lung using surface anatomy.
Apex - projects into the lower neck, just superior to the medial end of the clavicle.
Inferior border lies at:
- 6th rib anteriorly (midclavicular line).
- 8th rib laterally (midaxillary line).
- 10th rib posteriorly (at the vertebral column).
72
Describe where the parietal pleura extends to using surface anatomy.
- 8th rib anteriorly (midclavicular line).
- 10th rib laterally (midaxillary line).
- 12th rib posteriorly (at the vertebral column).
73
Describe the location of the fissures of the lobes using surface anatomy.
Oblique fissure - 4th rib posteriorly, to 6th costal cartilage anteriorly.
Horizontal fissure - anteriorly from the 4th costal cartilage, intersects the oblique fissure.
74
Describe the diaphragm and its function.
Broad, thin, domed sheet of skeletal muscle separating the thoracic and abdominal cavities.
Central part is not muscular but fibrous - the central tendon.
Essential to the mechanics of breathing.
75
What is the diaphragm attached to? Which nerves innervate the diaphragm?
The xiphoid process, costal margin, and the lumbar vertebrae.
Right and left phrenic nerves innervate the right and left sides. These are somatic nerves formed in the neck by fibres from C3 -> C5 spinal nerves, hence contain motor and sensory fibres.
76
What happens to the diaphragm during inspiration?
Diaphragm contracts, muscle fibres of right and left sides pulled towards their peripheral attachment -> domes flatten = increased intrathoracic volume for lungs to expand.
77
What happens to the diaphragm during expiration?
Diaphragm relaxes and domes superiorly = decreased intrathoracic volume for lungs to expand, driving expiration of air from the lungs.
78
Which three planes do the dimensions of the thoracic cavity change in during ventilation?
Vertically: due to contraction/relaxation of diaphragm.
Laterally: due to contraction of the intercostal muscles moving the ribs.
Anterior-posteriorly (AP): due to movement of the sternum secondary to rib movement.
79
What is the importance of the pleural fluid?
Creates and maintains surface tension, keeping the lung and the thoracic wall ‘together’, preventing the lung from ‘collapsing’ away.
If the surface tension is broken, the ventilation may become dysfunctional.
80
Describe inspiration.
Diaphragm and external intercostal muscles contract -> increased intrathoracic volume. (Diaphragm flattened, ribs are pulled superiorly and laterally, and sternum pulled superiorly and anteriorly).
Lungs expand with the thoracic wall due to surface tension.
Pressure in lungs decreases below atmospheric pressure and air is drawn into the lungs.
81
Describe expiration.
Diaphragm and external intercostal muscles relax, internal intercostal muscles contract -> decreased intrathoracic volume.
(Diaphragm domes superiorly, internal intercostal muscles pull ribs inferiorly, ribs pull the sternum inferiorly and posteriorly).
Lungs recoil.
Pressure in lungs increases above atmospheric pressure and air is expelled from the lungs.
82
Which muscles are involved in different types of breathing?
Normal - diaphragm mainly.
Vigorous - intercostal muscles become important.
Very vigorous/forced - accessory muscles of breathing contribute.
83
What are some clinical relevancies of the thoracic cage, the pleura, and the lungs?
- Pleuritic chest pain.
- Pneumothorax and haemothorax.
- Pleural effusion.
- Lung cancer and mesothelioma.
- Pulmonary embolism.
- Dyspnoea.
- Paralysis of the diaphragm.
84
Where is the mediastinum?
- Lies between the lungs, extends from
superior thoracic aperture superiorly ->
diaphragm inferiorly, and the sternum
anteriorly -> thoracic vertebrae posteriorly.
85
What does the mediastinum contain?
- Heart and pericardium.
- Greater vessels that go in/out of heart.
- Veins that drain the chest wall.
- Trachea and main bronchi.
- Oesophagus.
- Nerves.
- Lymphatics.
- The thymus gland.
86
How is the mediastinum divided?
- Superior and inferior, line runs from sternal
angle -> T4/5 junction.
- Inferior split into anterior, middle, and
posterior.
87
What can be found in/where are the different sections of the inferior mediastinum?
Anterior -> sternum to pericardial sac, thymus gland in children, remnant in adults.
Middle -> heart inside pericardial sac, pulmonary trunk, and ascending aorta.
Posterior -> pericardial sac to the vertebrae.
88
What are the main contents of the superior mediastinum?
- Arch of the aorta, and its three branches.
- Superior vena cava, left and right
brachiocephalic veins.
- Trachea.
- Oesophagus.
- Phrenic nerves and vagus nerves.
- Thoracic duct.
- Thymus gland.
89
What are the three parts of the aorta? Describe them and their locations.
- Ascending aorta: short, first part. Gives rise
to coronary arteries, which supply the
myocardium.
- Arch of the aorta: curves posteriorly. Lies in
the superior mediastinum.
- Descending (thoracic) aorta: descends
through posterior mediastinum and into the
abdomen posterior to the diaphragm.
90
What are the three major branches that the arch of the aorta gives rise to?
- The brachiocephalic trunk, bifurcates ->
right common carotid artery (supplies right
side of head, neck and brain), and right
subclavian artery (supplies right upper limb).
- Left common carotid artery (supplies left
side of head, neck and brain).
- Left subclavian artery (supplies left upper
limb).
91
Which receptors can be found in the aortic bodies in the arch of the aorta? What do they do?
- Chemoreceptos which monitor arterial
oxygen and CO2.
- Visceral sensory info -> CNS via vagus nerve,
resulting in reflex responses that regulate
ventilation.
92
What is the ligamentum arteriosum?
- Fibrous, cord-like connection between
pulmonary trunk and the arch of the aorta.
- Remnant of ductus arteriosus (fetal
circulatory shunt).
93
Describe the superior vena cava.
- Returns blood to the heart from the head,
neck and upper limbs.
- Lies in superior mediastinum.
- Formed by left and right brachiocephalic
veins, which are each formed by the unions
of internal jugular veins and subclavian
veins.
94
Describe the inferior vena cava.
- Returns blood to the heart from all regions
inferior to the diaphragm.
- Thoracic part is very short, entering the right
atrium as soon as it enters the thorax.
95
Describe the trachea.
- Conducts air to and from the left and right
main bronchi.
- Semi-rigid due to C-shaped rings of cartilage
in its walls.
- Extends from the larynx in the neck to the
superior mediastinum.
- Palpable superior to the suprasternal notch.
- Terminates at level of sternal angle/ T4 and
T5 junction, bifurcates -> left and right main
bronchi.
96
Describe the oesophagus, in relation to the superior mediastinum.
- Muscular tube extending from phaynx in the
neck to the stomach.
- Waves of smooth muscle contractions move
food and fluid distally (peristalsis).
- In the superior mediastinum it lies
posteriorly to the trachea.
97
Describe the phrenic nerves.
- Formed by fibres from C3 -> C5 spinal
nerves, innervate the diaphragm.
- Somatic nerves containing motor and
sensory fibres.
- Descend through neck, enter thorax
through superior thoracic aperture, course
over pericardium, and pierce the
diaphragm.
98
Describe the vagus nerves.
- CN X.
- Arise from brainstem; contain somatic
sensory and motor, and parasympathetic
fibres.
- Descend through neck alongside internal
carotid artery and internal jugular vein,
enter thorax via superior thoracic aperture.
- Each give rise to a recurrent laryngeal nerve,
ascend back up to neck to innervate larynx
muscles.
- Vagus nerves descend in thorax posterior to
root of the lung.
- Contribute parasympathetic fibres to heart,
lungs, and oesophagus.
- Traverse the diaphragm, conveying
parasympathetic fibres to most abdominal
viscera.
99
Describe the thoracic duct, in relation to the superior mediastinum.
- Major channel for lymphatic drainage.
- Ascends through posterior mediastinum,
into the superior mediastinum, where it
empties into venous system at the union of
the left internal jugular vein and left
subclavian vein.
100
Describe the thymus gland.
- Lymphoid organ.
- Lies anteriorly in the superior mediastinum.
- Important in children, atrophies with age.
101
Describe the pericardium.
- Tough, fibrous sac, enclosing the heart like a loose-fitting bag, with 2 layers.
- Tough, outer fibrous layer: attached
superiorly to the great vessels, and inferiorly
to the central tendon of the diaphragm.
- Thin, inner serous layer, made up of 2 parts:
parietal layer lining the inner aspect of the
fibrous pericardium, and the visceral layer
covering the surface of the heart (2 parts are
continuous with each other).
102
What is the space between the two serous layers of pericardium? What does it contain and what does it do?
Pericardial cavity, contains small amount of pericardial fluid. Lubricates the membranes allowing them to slide over each other with movement of the heart.
103
What are some of the clinical relevancies of the superior mediastinum and the external heart?
- Patent ductus arteriosus (PDA).
- Hoarseness of the voice and lung cancer.
- Pathology of the pericardium: pericardial
effusion and cardiac tamponade.
104
What are the main branches of the right coronary artery (RCA), and what territories do they supply?
- Branches to sinoatrial node and
atrioventricular node, supplying these major
components of the electrical conducting
system of the heart.
- Right marginal artery, supplies inferior
border of the heart.
- Posterior interventricular artery, which is
continuation of the RCA on the inferior
surface of the heart, supplies both
ventricles.
105
What are the main branches of the left coronary artery (LCA), and what territories do they supply?
- Short course = left main stem -> two large
terminal branches:
- Anterior interventricular artery / left anterior
descending artery (LAD): runs in anterior
ventricular sulcus towards the apex,
supplies both ventricles.
- One/two diagonal branches arise from LAD.
- Circumflex artery: around the heart onto the
inferior surface, supplies left atrium, part of
the right ventricle, and the left ventricle.
- Left marginal artery arises from circumflex,
supplies left ventricle.
106
Describe right-dominant coronary circulation.
- Posterior interventricular artery arises from the right coronary artery.
- Both the right and left coronary arteries supply the left ventricle.
- Occlusion of the left main stem would only impair blood flow to part of the left ventricle, not all of it.
107
Describe left-dominant coronary circulation.
- Posterior interventricular artery arises from
circumflex artery.
- Left coronary artery supplies the entire left
ventricle.
- Occlusion of the left main stem would
occlude blood flow to the entire left
ventricle.
108
Describe the right atrium.
Receives deoxygenated blood from the body via the superior and inferior vena cavae, and from the heart via the coronary sinus.
Contains:
- Interatrial septum: separates from left
atrium.
- Fossa ovalis - depression in the interatrial
septum, remnant of fetal foramen ovale.
- Crista terminali - muscular ridge separating
smooth-walled posterior, and
muscular-walled anterior (pectinate muscles
= ridges).
- Thinner walls then ventricles.
109
Describe the right ventricle.
Receives deoxygenated blood from the right atrium via the right atrioventricular valve, aka the tricuspid valve. Mostly passive, but the left atrium does contract to empty fully.
Contains:
- Interventricular septum: separates from left
ventricle.
- Trabeculae carneae: muscular ridges on
internal wall.
- Papillary muscles: modified regions of
trabeculae carneae.
- Chordae tendineae: fibrous cords with
connect tips of papillary muscles -> tricuspid
valve.
- Moderator band - modified region of
trabeculae carneae, connect interventricular septum -> one of the papillary muscles.
- Thicker walls than atria.
Pumps deoxygenated blood -> pulmonary trunk -> bifurcates to left and right pulmonary arteries.
110
Describe the left atrium.
Receives oxygenated blood from the lungs via the pulmonary veins (two from each lung).
Contains:
- Likewise structures to the right atrium.
- Thinner walls than ventricles.
111
Describe the left ventricle.
Receives oxygenated blood from the left atrium via the left atrioventricular valve, aka the mitral valve. Mostly passive, but the left atrium does contract to empty fully.
Contains:
- Likewise to the right ventricle.
- Thicker walls than atria.
- Thicker wall than right ventricle.
Pumps oxygenated blood -> aorta -> branches to coronary arteries.
112
Describe how atrioventricular valves function.
- Ventricles contract -> pressure in ventricles
rises.
- Tricuspid and mitral valves close during
contraction to prevent regurgitation of
blood -> atria, ensuring blood can only flow
one way, via the great vessels.
- Papillary muscles and chordae tendineae
don't close the valves, but allow them to
resist pressure generated inside the
ventricles.
113
Describe how semilunar valves function.
- Semilunar valves have three semi-
circular/half-moon shaped cusps.
- Each cusp is attached to the inner wall of
the vessel, with a free edge projecting into
the lumen.
- Each cusp forms a sinus between its free
edge and the vessel wall.
- Blood can pass through by flattening the
valve cusps against the wall.
- If blood tries to flow back into the ventricle
after the pressure had dropped, it is caught
in the valve cusps.
- The sinuses fill and the cusps balloon out so
that the free edges touch one another in the
lumen, closing the valve orifice.
- In the aorta, the RCA and the LCA arise from
2/3 aortic sinuses, hence why they fill during
ventricular relaxation.
114
Where are the auscultatory areas for each valve?
- Aortic = 2nd intercostal space, just right of
sternum.
- Pulmonary = 2nd intercostal space, just left
of sternum.
- Tricuspid = 5th intercostal space, just left of
the sternum.
- Mitral = 5th intercostal space, left
midclavicular line.
115
Describe the conducting system of the heart.
- Cells in the sinoatrial node generate
electrical impulses spontaneously
('pacemaker' of the heart).
- SA node located at the superior end of the
crista terminalis.
- Impulses from SA node stimulate contraction of the atria.
- Impulses conducted to atrioventricular
node.
- AV node located at the inferior end of the
interatrial septum.
- Conducting fibres from AV node form
atrioventricular bundle (Bundle of His)
- Bundle of His divides into two -> right and
left bundle branches.
- Right and left bundle branches give rise to
Purkinje fibres that enter the myocardium of
the left and right ventricles respectively,
stimulating contraction.
116
Explain anatomical variation in blood supply to the conducting system.
- SA node supplied by RCA in approx. 60% of
people, by LCA in approx 40%.
- AV node usually supplied by posterior
interventricular artery, most people's PIV
arises from the RCA.
- In most people, the LCA supplies the Bundle
of His.
- Occlusion of either coronary artery can
therefore = conduction abnormalities, in addition to myocardial ischaemia.
117
What are some clinical relevancies of the coronary arteries and internal heart?
- Myocardial infarction.
- Congenital cardiac anomalies: patient
foramen ovale and ventricular septal defects.
- Valve dysfunction.
- Cardiomyopathies.
- Conducting system abnormalities.
- Heart failure.
- Cardiac arrest.
118
Describe the innervation of the heart.
- Sympathetic and parasympathetic fibres act
upon the SA node and can change the rate
and force of myocardial contraction.
- Sympathetic increases heart rate and force
of contraction.
- Parasympathetic decreases heart rate and
force of contraction.
- Visceral afferent fibres contract sensory info
from the heart -> CNS
- Usually doesn't reach conscious perception,
but if ischaemic may be perceived as pain,
burning, tightness or pressure in the chest.
- Can't be pinpointed typically, but generally
in chest, left side of neck and/or left arm -
aka referred pain.
119
What does the posterior mediastinum contain?
- Descending (thoracic) aorta.
- Azygos veins.
- Oesophagus.
- Thoracic duct.
- Sympathetic trunk and splanchnic nerves.
- Posterior intercostal vessels and nerves.
120
Where does the posterior mediastinum lie?
Behind the heart and the pericardium.
121
What branches does the descending aorta give rise to? What do they supply?
- Posterior intercostal arteries, supply intercostal
spaces.
- Bronchial arteries, supply the lungs.
- Oesophageal branches, supply the oesophagus.
- Pericardial branches, supply the pericardium.
- Phrenic branches, supply the diaphragm.
122
At what level does the aorta pass through the diaphragm?
T12.
123
Describe the positioning of the azygos system of veins in the body?
Arise in the abdomen at level of L1/2, traverse the diaphragm to enter the posterior mediastinum, and lie on the bodies of the thoracic vertebrae.
124
What do the azygos system of veins do?
Drain blood from the posterior thoracic wall and return it to the superior vena cava.
125
What does the azygos system of veins comprise of?
- Azygos vein on right side of vertebral bodies.
- Shorter hemiazygos vein on left side.
- One or more veins connecting the above to each
other.
126
Which structures does the azygos system of veins receive blood from?
- Posterior intercostal veins.
- Oesophageal veins.
- Bronchial veins.
127
Where does the oesophagus lie relative to the aorta?
To the right of the aorta.
128
What supplies the oesophagus with blood?
Oesophageal arteries from the descending aorta.
129
What type of control is the smooth muscle of the oesophagus under?
Autonomic control.
130
At what level and where does the oesophagus pass through the diaphragm?
T10, through the oesophageal hiatus in the diaphragm.
131
Where does the thoracic duct lie?
Between the azygos vein and the aorta.
132
What does the thoracic duct do?
Return most of the body's lymph to the venous system.
133
Describe the movement of lymph -> venous system via the thoracic duct.
- Lymph from lower limbs, pelvis and abdomen ->
cisterna chyli, a sac-like swelling that gives rise to the
thoracic duct, which ascends into the thorax.
- In the thorax, the duct receives lymph from
intercostal spaces and lymph nodes.
- Duct ascends into neck, receives lymph from left side
of head and neck, and from left upper limb.
- Terminates by opening into venous system at
junction of left internal jugular vein and left
subclavian vein.
- Right side of head and neck, and right upper limb
are drained by ducts that enter the venous
system at junction between right internal jugular and
right subclavian vein.
134
Where do the sympathetic trunks lie?
Either side of the vertebral column, posterior to the parietal pleura.
135
Describe how sympathetic fibres are distributed to all parts of the body.
- Preganglionic sympathetic fibres exist in spinal cord in
spinal nerves T1 -> L2/3.
- Almost immediately separate from spinal nerves and
enter the sympathetic trunk via white ramus
communicans.
- Once in the trunk, the preganglionic axon either:
synapses in the ganglion at level of entry,
ascend/descend before synapsing in a ganglion, or
travel through a ganglion and the trunk without
synapsing.
136
Describe the sympathetic trunks.
Thin, longitudinal fibre tracts, regularly interspersed with ganglia (collections of cell bodies outside CNS).
Trunk extends from skull base -> coccyx.
137
What happens when the preganglionic axon synapses in a ganglion?
- Postganglionic axons leave the ganglia.
- Enter spinal nerves via grey ramus communicans,
fibres enter all 31 pairs of spinal nerves.
- Form visceral nerves that convey sympathetic fibres
to the head.
- Form visceral nerves that convey sympathetic fibres
to the thoracic viscera (cardiopulmonary splanchnic
nerves).
138
What happens when the preganglionic axon does not synapse in a ganglion?
- Preganglionic axons travel through sympathetic
trunk.
- Fibres exit the trunk and form the abdominopelvic
splanchnic nerves.
139
What are the abdominal splanchnic nerves?
- Greater splanchnic nerve (from T5 -> 9).
- Lesser splanchnic nerves (from T10 -> 11).
- Least splanchnic nerve (from T12).
- Lumbar splanchnic nerves (from L1 -> 2).
140
Which splanchnic nerves are formed in the posterior mediastinum? Where do these go?
- The greater, lesser, and least splanchnic nerves.
- Traverse the diaphragm -> abdomen.
141
What do the posterior intercostal spaces contain?
- Intercostal muscles.
- A posterior intercostal artery.
- A posterior intercostal vein.
- A posterior intercostal nerve.
142
How are the thoracic vertebrae innervated?
- By sympathetic and parasympathetic fibres that
have coordinated, but generally opposing actions.
- Cardiopulmonary splanchnic nerves convey
postganglionic sympathetic fibres.
- Vagus nerves convey parasympathetic fibres.
143
Which autonomic plexuses can be found in the thorax?
- Cardiac plexus.
- Pulmonary plexus.
- Oesophageal plexus.
144
Describe the role of the cardiac plexus.
- Innervates the sinoatrial node of the heart.
- Sympathetic fibres increase heart rate and force of
contraction.
- Parasympathetic fibres decrease heart rate and
force of contraction.
145
Describe the role of the pulmonary plexus.
- Innervates the bronchi.
- Sympathetic stimulation relaxes the bronchi.
- Parasympathetic stimulation constricts bronchi.
146
Describe the role of the oesophageal plexus.
- Overlies anterior surface of oesophagus.
- Sympathetic fibres inhibit peristalsis.
- Parasympathetic fibres stimulate peristalsis.
147
What do visceral afferents do?
Relay sensory information from thoracic viscera -> CNS via vagus and thoracic splanchnic nerves.
148
Describe cardiac referred pain.
Patients with angina or myocardial infarction usually experience pain in the central chest, left side of the neck, and the left arm. This is an example of referred pain - pain from one part of the body is felt in another.
149
Give some clinical relevancies of the posterior mediastinum.
- Aortic dissection.
- Horner's syndrome.
- Hiatus hernia.
150
Why is the neck an extremely vulnerable area?
- Very flexible.
- Many vital structures packed into small region with
little protection.
151
What does the neck contain?
- Structures of the respiratory tract: pharynx, larynx,
and trachea.
- Structures of the GI tract: pharynx and oesophagus.
- Thyroid and parathyroid glands.
- Arteries and veins.
- Nerves.
- Several groups of muscles (platysma = very thin,
deep to skin of neck).
152
Describe the cervical vertebrae in the neck.
- Small.
- Articulate at facet joints, orientated obliquely to
allow for a good range of flexion/extension.
153
What is the hyoid bone? What does it do?
- Slender bone situated anteriorly in the upper neck,
inferior to the mandible.
- Helps to keep pharynx open and provides
attachment point for several muscles in the neck and
the tongue.
154
What is the larynx? What does it do?
- The 'voice box' is composed of a 'skeleton' of small
cartilages connected by membranes and small joints.
- Protects the airway.
- Muscles attach to the laryngeal cartilages and move
them, in turn moving the vocal cords and allowing
phonation.
155
Describe the 'triangles' structure of the neck.
Anterior and posterior triangles, separated by the sternocleidomastoid (SCM) muscle.
156
Describe the sternocleidomastoid muscle.
- Attached to the sternum, clavicle, and mastoid
process.
- Can act unilaterally or bilaterally.
- Innervated by the accessory nerve (cranial nerve XI).
157
What are the boundaries of the anterior triangle of the neck?
Anteriorly: midline of neck.
Posteriorly: anterior border of SCM.
Superiorly: lower border of the mandible.
158
What does the anterior triangle of the neck contain?
- Trachea.
- Larynx.
- Thyroid and parathyroid glands.
- Submandibular salivary gland.
- Suprahyoid muscles.
- Infrahyoid muscles.
- Common carotid artery and its terminal branches
(external and internal carotids).
- Branches of the external carotid artery.
- Internal jugular vein.
- Branches of the facial nerve (CN VII), the
glossopharyngeal nerve (CN IX), the vagus nerve (CN
X), and the hypoglossal nerve (CN XII).
- The ansa cervicalis.
159
Describe suprahyoid muscles.
- Four paired muscles: mylohyoid, geniohyoid,
stylohyoid, and digastric.
- Lie superior to hyoid bone.
- Connect hyoid -> skull.
- Form the floor of the mouth.
- When they contract, they raise the hyoid and larynx
during speech and swallowing.
160
Describe infrahyoid muscles.
- Four paired 'strap' muscles: sternohyoid, omohyoid,
sternothyroid, and thyrohyoid.
- Inferior to the hyoid bone. Just lateral to anterior
midline of the neck.
- Connect hyoid -> sternum (sternohyoid) and scapula
(omohyoid).
- Sternothyroid attaches sternum -> thyroid,
thyrohyoid attaches thyroid -> hyoid.
- Draw the hyoid and larynx inferiorly during speech
and swallowing.
161
Describe the ansa cervicalis.
Fibres from C1 -> 3 that innervate the infrahyoid muscles.
162
What are the boundaries of the posterior triangle of the neck?
Anteriorly: posterior border of SCM.
Posteriorly: anterior border of trapezius.
Inferiorly: clavicle.
163
What does the posterior triangle of the neck contain?
- Muscles that move the head (WILL NOT STUDY).
- Part of the subclavian artery and the subclavian vein.
- The external jugular vein.
- The accessory nerve (CN XI).
- Roots of the brachial plexus.
- The cervical plexus.
- The phrenic nerve.
164
What does the external jugular vein in the neck do?
Drains the scalp and face.
165
Describe the brachial plexus.
Spinal nerves that supply the upper limb.
166
Describe the cervical plexus.
Fibres from C1 -> 4.
167
Describe the structure and location of the thyroid gland.
- Composed of right and left lobes.
- Lie lateral to the lower larynx and upper trachea.
- Each lobe lies deep to the sternothyroid muscle.
- Two lobes joined by isthmus, anterior to the trachea.
168
What does the thyroid gland do?
Produces hormones which play an important role in regulation of metabolic processes.
169
What does the pituitary gland do in relation to the thyroid gland?
Pituitary gland regulates hormone secretion from the thyroid gland.
170
From which structures does the thyroid gland get its blood supply from?
- Left and right superior thyroid arteries, branches of the
external carotid arteries.
- Left and right inferior thyroid arteries, branches of the
thyrocervical trunks, which are branches of the
subclavian artery.
171
Describe the structure and location of the parathyroid glands.
- Usually four: right and left superior and inferior glands.
- Posterior to the thyroid gland.
172
What do the parathyroid glands do?
Produce parathyroid hormone which plays a role in calcium regulation.
173
Where do they parathyroid glands get their blood supply from?
The inferior thyroid arteries.
174
Where are the common carotid arteries in the neck, and what do they bifurcate into?
- Ascend in the right and left sides of the neck
respectively.
- Bifurcate into external and internal carotid arteries.
175
Where can the pulsation of the internal carotid be palpated?
Immediately lateral to the larynx.
176
Describe the internal carotid artery in the neck.
- Does not give rise to any branches.
- Enters cranium and supplies the brain.
177
Describe the external carotid artery in the neck.
- Gives rise to several branches that supply the head
and neck including the pharynx, scalp, thyroid gland,
tongue, and the face.
178
What is the small swelling at the point of bifurcation of the carotid artery? What happens here?
- The carotid sinus.
- Baroreceptors constantly monitor arterial BP, this
visceral sensory information -> CNS via
glossopharyngeal nerve, resulting in reflexes to
regulate BP.
179
Describe the subclavian artery in the neck.
- Gives rise to several vessels.
- Supplies the upper limb.
- Large branch: thyrocervical trunk, gives rise to
inferior thyroid artery.
180
Describe the internal jugular vein in the neck and its unions.
- Drains blood from the brain and part of the face.
- Unites with subclavian vein (returns blood from
upper limb) -> brachiocephalic vein.
- Right and left brachiocephalic veins unite -> superior
vena cava.
181
Describe the external jugular vein in the neck and its unions.
- Drains blood from the scalp and face.
- Unites with the subclavian vein.
182
What does the facial nerve (CN VII) supply in the neck?
Platysma in the neck.
183
What does the glossopharyngeal nerve (CN IX) supply in the neck?
- Pharynx.
- Carotid sinus.
184
What does the vagus nerve (CN X) supply in the neck?
- Muscles of the pharynx.
- The larynx.
185
Describe the carotid sheath above and below the bifurcation of the carotid arteries.
Fascial sleeve.
Above bifurcation of carotid:
- Vagus nerve between internal jugular vein and internal carotid artery.
Below bifurcation of carotid:
- Vagus nerve between internal jugular vein and common carotid artery.
186
What does the accessory nerve (CN XI) supply in the neck?
Sternocleidomastoid and trapezius muscles.
187
What does the hypoglossal nerve (CN XII) supply in the neck?
- Doesn't supply anything in the neck, runs through it.
- Motor to the muscles of the tongue.
188
What are some clinical relevancies of the anterior neck and thyroid gland?
- Thyroidectomy.
- Carotid artery stenosis.
- Penetrating injuries to the neck.
- Central line insertion into the internal jugular vein.
189
What is the pharynx? Where does it lie? What systems is it a part of?
- Muscular tube which lies in the neck.
- Respiratory and GI systems.
190
Describe the walls of the pharynx.
- Outer layer of circular muscle.
- Inner layer of longitudinal muscle.
- External circular composed of three constrictor muscles: superior, middle, and inferior; which overlap each other.
- They contract superior -> inferior.
191
What are the three parts of the pharynx? Where are they located?
- Nasopharynx: posterior to nasal cavity.
- Oropharynx: posterior to oral cavity.
- Laryngopharynx: posterior to the larynx (aka hypopharynx).
192
Describe the role of the pharynx in swallowing.
- During swallowing, food pushed into oropharynx by the tongue.
- Soft palate rises and closes off the nasopharynx.
- Food enters laryngopharynx and constrictor muscles move the food into the oesophagus.
- Epiglottis closes off the laryngeal inlet and prevents entry to the larynx.
193
What are the tonsils?
Collections of lymphoid tissue in the upper parts of the pharynx.
194
Where is the pharyngeal tonsil found?
In the roof of the nasopharynx.
195
Where is the tubal tonsil found?
Surrounding the opening of the auditory tube (which connects nasopharynx -> middle ear).
196
Where is the palatine tonsil found?
Next to the pharyngeal wall in the oropharynx.
197
Where is the lingual tonsil found?
The posterior aspect of the tongue.
198
Describe the innervation of the pharynx.
Sensory fibres from glossopharyngeal nerve, and motor fibres from vagus nerve.
199
Which nerves lie close to the posterior pharyngeal wall?
- Cervical part of sympathetic trunk and superior cervical ganglion.
- Superior laryngeal nerve.
- Hypoglossal nerve.
- Glossopharyngeal.
200
What are some clinical relevancies of the pharynx?
- Gag reflex.
- Swallowing difficulties after a stroke.
201
How many cartilages is the larynx composed of? How many are paired/unpaired?
- Nine cartilages.
- Three paired.
- Three unpaired.
202
What are the three paired cartilages of the larynx?
- Arytenoids.
- Cuneiforms (very small).
- Corniculate cartilages (very small).
203
What are the three unpaired cartilages of the larynx?
- Epiglottis.
- Thyroid cartilage.
- Cricoid cartilage.
204
Describe the thyroid cartilage.
- Composed of two flat cartilages (laminae).
- Meet in midline to form laryngeal prominence (Adam's apple).
- Posteriorly, laminae form extensions = superior and inferior horns.
- Superior horns attach to hyoid bone.
- Inferior horns articulate with cricoid cartilage below.
205
Describe the cricothyroid membrane.
Connects inferior border of thyroid and superior border of the cricoid.
206
Describe the epiglottis.
- Attached to superior aspect of thyroid cartilage, where the two laminae meet.
- During swallowing, covers entrance to larynx to protect the airway from food/drink.
207
Describe the arytenoids.
- Sit on superior surface of cricoid cartilage.
- Articulate with cricoid cartilage at small joints.
- Vital for phonation as vocal cords attach to them.
- Movement of arytenoids = movement of vocal cords.
208
What are the two pairs of folds in the larynx? What are they made of?
- Vestibular folds superiorly = false vocal cords.
- Vocal folds inferiorly = true vocal cords.
- Mucous membrane folds, pairs separated by a narrow space.
209
How are the true vocal cords formed?
Vocal folds cover and protect vocal ligaments to form vocal cords.
210
What is the space between the vocal cords called?
Rima glottidis.
211
Where are the vocal ligaments?
- Attached anteriorly to internal aspect of laryngeal prominence, and posteriorly to arytenoid cartilages.
212
Describe the effects of adduction and abduction of the vocal cords. Discuss phonation.
- Adduction closes rima glottidis.
- Abduction opens rima glottidis.
- Phonation requires adduction and closure of the RG.
- Abduction opens the RG to a small degree when whispering, partially in normal breathing, and fully in forced breathing.
213
What are the two groups of muscles that act on the pharynx?
Extrinsic and intrinsic muscles.
214
Describe how extrinsic muscles affect the larynx?
Suprahyoid and infrahyoid muscles move the larynx as one with speech and swallowing.
215
Describe how intrinsic muscles affect the larynx?
Move the individual laryngeal cartilages -> moves the vocal cords. Injury to nerves innervating these can affect speech.
216
What are some of the intrinsic muscles of the larynx?
- Left and right cricothyroid muscles anteriorly.
- Left and right posterior cricoarytenoids (each attached to ipsilateral arytenoid).
- Transverse arytenoid (connects the two arytenoid cartilages).
217
Describe the left and right cricothyroid muscles function.
Contraction places tension on the vocal cords.
218
Describe the left and right posterior cricoarytenoids function.
Abduct the vocal cords and open the rima glottidis.
219
Describe the transverse arytenoids function.
Adduct vocal cords and close the rima glottidis.
220
Describe the innervation of the intrinsic muscles of the larynx.
- Superior laryngeal nerve innervates cricothyroid muscle, and is sensory above the vocal cords.
- Recurrent laryngeal nerve innervates all the intrinsic muscles other than the cricothyroid, and is sensory below the vocal cords.
221
What are some clinical relevancies of the larynx?
- Vocal cord palsy.
- Laryngeal cancer.
- Endotracheal intubation.
- Emergency airway.
222
How are the left and right nasal cavities separated from one another?
By a thin midline septum, formed of cartilage and bone.
223
What are the nasal cavities separated from inferiorly and how?
The oral cavity, by the hard palate (the floor of the nasal cavity).
224
What are the nasal cavities separated from superiorly and how?
The brain, by bone (the roof of the nasal cavity).
225
What do the nasal cavities communicate with?
- Nasopharynx posteriorly.
- Paranasal sinuses.
- Middle ear.
226
Describe the midline nasal septum.
- Formed of cartilage anteriorly.
- Posteriorly, the perpendicular plate of the ethmoid bone forms the superior part, and the vomer forms the interior part.
227
What are the three projections of bone from the lateral wall of the nasal cavity?
The superior, middle, and inferior conchae / turbinates.
228
What are the spaces inferior to the conchae called?
Meatuses:
Superior meatus = inferior to superior concha. Etc.
229
What do the meatuses do to inspired air?
Warms, humidifies and filters it.
230
Describe the bone that separates the nasal cavity from the brain, and its function.
- Cribriform plate: delicate section of bone perforated with tiny holes.
- Mucosa in nasal cavity contains olfactory receptors.
- The axons of these form olfactory nerves that travel through the perforations to the brain.
231
Describe the blood supply of the nasal cavity.
- Supplied by several arteries including branches of the maxillary artery (a terminal branch of the external carotid artery).
- An anastomotic network formed supplies the nasal septum (often the site of a nosebleed).
232
Which nerve is responsible for the sensory innervation of the nose?
Branches of the trigeminal nerve (CN V).
233
What are the paranasal sinuses, and what are they called?
Cavities within the skull bones, named according to the bone which they are located:
- Frontal
- Ethmoid
- Sphenoid
- Maxillary
234
Where does the frontal sinus drain to?
The middle meatus.
235
Where does the sphenoid sinus drain to?
The spheno-ethmoidal recess.
236
Where do the ethmoid air cells drain to?
Superior and middles meatuses.
237
Where does the maxillary sinus drain to?
The middle meatus.
238
What does the nasolacrimal duct, which the nasal cavity receives, do?
Drains the fluid (tears) that lubricates the anterior surface of the eye. Runny nose when we cry due to excess fluid in the nasolacrimal duct.
239
Where does the nasolacrimal duct open into?
The inferior meatus.
240
What is the middle ear?
A small cavity within the temporal bone that is modified for hearing.
241
Describe the auditory tube (Eustachian tube).
- Connects middle ear to nasopharynx.
- Allows air to pass into the middle ear, so that the pressure on either side of the tympanic membrane (eardrum) is equal.
242
Where do you find the tympanic membrane?
Between the middle and external ear.
243
Describe the palate.
- Separates the nasal cavities from the oral cavity.
- Anteriorly = hard palate.
- Posteriorly = soft palate.
244
What is the hard palate composed of?
- Palatine process of the maxillae.
- Horizontal plates of the palatine bones.
245
Why is the hard palate functionally important?
- Prevents food/fluid entering the nasal cavity.
- We push our tongue up against the hard palate during the first phase of swallowing and during certain sounds.
246
Describe the soft palate.
- Posterior to the hard palate.
- Midline conical projection = uvula, hangs from posterior border at the back of the mouth.
- Composed of several muscles.
- Muscles innervated by vagus nerve (CN X).
247
Why is the soft palate functionally important?
- Muscles contract during swallowing which elevates the soft palate.
- Nasopharynx closed off from the oral cavity, preventing fluid/food entering the nasal cavity.
248
What are some clinical relevancies of the nasal cavity, paranasal sinuses, and the palate?
- Epistaxis (nosebleed).
- Nose fracture.
- Sinusitis.
- Cleft palate.
249
Describe the boundaries of the oral cavity?
- Superiorly: hard and soft palate (roof of the mouth).
- Inferiorly: soft tissues and muscles (floor of the mouth).
- Laterally: the cheeks (which contain the buccinator muscle).
250
How many teeth do adults have? Where are these embedded?
- 32 teeth.
- 16 embedded in the maxilla (upper jaw).
- 16 embedded in the mandible (lower jaw).
251
Describe the different types of teeth in the upper and lower jaws.
- 4 incisors in each.
- 2 canines in each.
- 4 premolars in each.
- 6 molars in each.
252
What are the teeth composed of?
- Inner pulp containing blood vessels and nerves.
- Dentin, surrounding the pulp.
- An outer, hard coating of enamel.
253
What can happen to enamel and dentin?
Erosion by bacteria or foodstuffs -> decay, inflammation, and infection of the pulp -> pain.
254
What can happen if infection of the pulp spreads to the bone?
Abscess formation.
255
What can be found on the superior surface of the tongue?
Papillae, some of which detect taste (taste buds).
256
Where does the tongue lie?
Anterior part = oral cavity.
Posterior part = extends into oropharynx.
257
What is the space between the posterior tongue and the anterior aspect of the epiglottis called?
The vallecula.
258
What types of muscles is the tongue composed of?
- Intrinsic muscles lie entirely within the tongue, paired bilaterally, fuse in the midline -> change shape of the tongue.
- Extrinsic muscles are attached to the tongue but originate from outside it -> move the tongue.
259
Which nerve innervates the muscles of the tongue?
The hypoglossal nerve (CN XII).
260
Describe the sensory innervation of the tongue.
- Taste in anterior 2/3 = facial nerve (CN VII).
- General sensation in anterior 2/3 = trigeminal nerve (CN V).
- Taste and general sensation in posterior 1/3 = glossopharyngeal nerve (CN IX).
261
Describe the blood supply of the oral cavity.
Supplied by the lingual, maxillary, and facial arteries (branches of the external carotid).
262
Describe the pharyngeal tonsil.
The roof and posterior wall of the nasopharynx. AKA 'the adenoid'.
263
Describe the tubal tonsil.
Surrounding the opening of the auditory tube on the lateral wall of the nasopharynx.
264
Describe the palatine tonsil.
Lies on the lateral wall of the oropharynx. AKA ' the tonsils'.
265
Describe the lingual tonsil.
In the posterior tongue, a collection of lymphoid tissue.
266
What are the three pairs of salivary glands?
- The parotid.
- The submandibular.
- The sublingual.
267
What do salivary glands do? How is this stimulated?
- Secrete saliva into the oral cavity.
- Stimulated by parasympathetic fibres.
268
Describe the parotid gland.
- Largest salivary gland.
- Overlies posterior part of the mandible.
- Saliva empties into the mouth via the parotid duct, opening adjacent to upper second molar.
269
How is secretion from the parotid gland stimulated?
By parasympathetic fibres in the glossopharyngeal nerve (CN IX).
270
How is the parotid gland related to the facial nerve?
- Nerve extst skull, enters deep surface of parotid gland.
- Divides within the gland into five branches.
- Branches emerge to innervates the muscles of facial expression.
- Also related to external carotid artery.
271
Describe the submandibular glands.
- Smaller than parotid
- Lie inferior to body of the mandible, just anterior to the angle.
- Duct opens into the floor of the mouth, under the tongue.
272
How is secretion from the submandibular gland stimulated?
By parasympathetic fibres in the facial nerve (CN VII).
273
Describe the sublingual glands.
- Lie in the floor of the mouth.
- Open via several small ducts into the floor of the mouth.
274
How is secretion from the sublingual gland stimulated?
By parasympathetic fibres in the facial nerve (CN VII).
275
What are some clinical relevancies of the oral cavity?
- Hypoglossal nerve injury.
- Nasal and oral cancer.
- Tonsillitis and tonsillectomy.
- Pathology of the parotid gland.
