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Anatomy > Thorax > Flashcards

Thorax Flashcards

1
Q

1st rib: Description

A

The ribs are the main structural element of the thorax.

Function: Protection, respiration

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2
Q

Rib: Gross Anatomy

A

There are 12 ribs which are separated by intercostal spaces.

The first 7 ribs increase in length the lower five decrease in length.

The 1st, 11th and 12th ribs are considered atypical ribs.

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3
Q

Ribs: Description

A

True ribs – First 7 attached to the sternum directly by their own costal cartilage

False ribs – 8th to 10th, converge anteriorly via the costal cartilage to the 7th costal cartilage thus have indirect connection to the sternum.

Floating ribs – the 11th and 12th have no anterior direct or indirect sternal attachment

The first rib is the most superior of the twelve ribs. It is an atypical rib because of number differentiating features and is an important landmark for the borders of the superior thoracic aperture.

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4
Q

1st Rib: Features

A
  • Compared to a typical rib the first rib is short and thick.
  • It has a singular articular facet of the costovertebral joint.
  • The first rib has a head, neck and shaft but lacks a discrete angle.
  • Groove for the subclavian artery – laterally
  • Groove for the subclavian vein – anterior to the scalene turbicle
  • Transverse tubercle – Posterior and lateral to the neck it bears a facet for the transverse process of T1
  • Scalene tubercle – anterior between the grooves for the subclavian artery and vein.
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5
Q

1st Rib: Articulation

A
  • Costovertebral joint
  • Costotransverse joint
  • Costochondral joint
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6
Q

1st Rib: Attachments

A
  • Anterior and middle scalene
  • Intercostal muscles
  • Subclavius muscle
  • Serratus anterior
  • Costoclavicular ligaments
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7
Q

1st Rib: Neurovasculature

A

Blood supply:

Arterial: internal thoracic and superior intercostal arteries, venous: intercostal veins

Innervation: first intercostal nerve

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8
Q

1st Rib: Relations

A
  • Anterior: Sympathetic trunk over the neck, superior intercostal artery, ventral T1 nerve root
  • Superior: lower trunk of the brachial plexus, subclavian artery and vein, clavicle
  • Inferior: Intercostal vessels and nerves, parietal pleura
  • Medial: contents of the superior thoracic aperture
  • Lateral: Axillary artery and vein, divisions and cords of the brachial plexus
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9
Q

1st Rib: Variants

A
  • First cervical rib
  • Bifid (forked) rib
  • Hypoplastic rib
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10
Q

Sternum: Description

A

The sternum completes the anterior chest wall as the ventral breastplate.

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11
Q

Sternum: articulations

A

The sternum is composed of a manubrium, a body and the xiphoid process. These articulations are via hyaline cartilage with a fibrocartilaginous intervening disc.

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12
Q

Sternum: Articulations

A

Manubrium with:

Sternal body

Clavicles

Costal cartilage of the first rib

Body:

With manubrium superiorly and xiphoid inferiorly

Costal cartilages of ribs 2 to 7

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13
Q

Sternum: Muscular attachments

A
  • sternocleidomastoid, intercostal muscles, pectoralis major, sternohyoid, sternothyroid and transversus thoracis.
  • the xiphisternum attaches to linea alba
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14
Q

Sternum: Ligaments

A

sternopericardial ligaments secure the fibrous pericardium to it

interclavicular ligament

anterior and posterior sternoclavicular ligaments (thickenings of the sternoclavicular joint capsule)

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15
Q

Sternum: Neurovasculature

A

Blood supply:

Internal thoracic arteries and veins

Nerve supply:

nerve supply is via anterior intercostal nerves

Lymphatics:

chain of internal mammary lymph nodes

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16
Q

Sternum: Variants

A
  • Sternal foramen
  • Unfused
  • Pectus
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17
Q

Diaphragm

A

The diaphragm is a domed shaped muscle in that separates the thoracic cavity frim the abdominal cavity, enclosing the interior thoracic aperture.

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18
Q

Diaphragm: Gross anatomy

A

Muscular slips originated around the inferior aspect of the thorax and converge to a common insertion point the central tendon.

Flat muscle structure composed of multiple strips of muscle joining at a central tendon

Divides the thorax and the abdominal cavity

Attaches to: xiphoid process, ribs (lower six), aponeurotic arches and lumbar vertebra (crura)

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19
Q

Ligamentous opening of the diaphragm

A

Median arcuate ligament allows the passage of the psoas and sympathetic trunk

Lateral arcuate ligament allows the passage of the quadratus lumborum and subcostal nerves and vessels

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20
Q

Hiatuses of the Diaphragm

A

The caval hiatus – level T8 allows for the passage of:

  • Inferior vena cava
  • Branches of the right phrenic nerve

Oesophageal hiatus – level T10 allows for the passage of:

  • Oesophagus
  • Vagus nerves
  • Oesophageal arteries

Aortic hiatus – Level T12 allows for the passage of:

  • Aorta
  • Azygos vein
  • Hemi-azygos vein
  • Thoracic duct
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21
Q

Lesser apetures of the diaphragm

A
  • Left phrenic pierces the diaphragm directly
  • Right crus – Right greater and lesser splanchnic nerve
  • Left crus -Left greater and lesser splanchnic nerve
  • Foramen of Morgagni allows the internal thoracic vessels to pass
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22
Q

Lumbocostal arches of the diaphragm

A

Medial lumbocostal arch (medial arcuate ligament) – arch that covers psoas

Lateral lumbocostal arch (lateral arcuate ligament) – covers quadratus lumborum

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23
Q

Diaphragmatic hiatuses

A

Caval hiatus at level T 8

Oesophageal hiatus at level t10

Aortic hiatus at level T12

Lesser apertures

Sternocostal foramina (Morgagni)

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24
Q

Diaphragm: Relations

A

Superior: bases of the lungs and the heart

Inferior the suprehepatic spaces, the liver, the stomach, the spleen, the adrenal glands

Lateral: ribs

Medial: central tendon of the diaphragm

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25
Q

Diaphragm: Neurovasculature

A

Arterial supply:

  • musculophrenic
  • Pericardiophrenic
  • intercostal arteries
  • Superior and inferior phrenic arteries

Venous drainage: same named veins into the system venous system

Innervation:

Bilateral phrenic nerve C3,4,5

Intercostal nerves supply proprioceptive fibres

Lymphatics:

Coeliac nodes and perihilar nodes

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26
Q

Diaphragm: Variants

A

Congenital diaphragmatic eventration

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27
Q

Pec Major

A

Pectoralis major is a large, fan-shaped muscle.

Origin: sternum, superior six costal cartilages and medial half of the clavicle

Insertion: lateral lip of the bicipital groove of the humerus

Arterial: Perforators from the internal thoracic and the thoracoacromial arteries

Innervation: medial and lateral pectoral nerves

Action: flexion, adduction and internal rotation of the shoulder joint

Variant anatomy:

  • Sternalis muscle
  • Poland syndrome
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28
Q

Aortic Arch

A

The aortic arch is a large arterial trunk that connects the ascending aorta the descending aorta

Function: Carries and initial distribution of the majority of the body’s arteries blood supply

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29
Q

Pec Minor

A

Pectoralis minor is a muscle of the anterior chest wall that inserts into the pectoral girdle. It lies deep to and is completely covered by pectoralis major. It divides the axillary artery into 3 parts.

Origin: anterior ribs 3-5 near the costal cartilages

Insertion: coracoid process of the scapula

Innervation: medial and lateral pectoral nerves

Action: depresses shoulder and elevation of ribs 3-5

Arterial: Perforators from the internal thoracic and the thoracoacromial arteries

Variant anatomy:

  • pre-fixed origin: ribs 2-4
  • post-fixed: ribs 4-6
  • Poland’s syndrome also
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30
Q

Trapezius

A

origin: superior nuchal line, inion, nuchal ligament and spinous processes of C7-T12 vertebrae
insertion: clavicle and scapula
innervation: accessory nerve (CN XI)
action: complex movements of the scapula and neck

Arterial: Thoracodorsal artery

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31
Q

Latissimus Dorsi

A

origin: spinous processes of T7-T12 and thoracolumbar fascia; posterior third of the iliac crest; 9th-12th ribs, inferior angle of the scapula
insertion: floor of the bicipital groove of the humerus
innervation: thoracodorsal nerve

arterial supply: thoracodorsal artery (a branch of the subscapular artery)

action: adduction, internal rotation and extension of the shoulder joint

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32
Q

Aortic Arch: Gross anatomy

A

Layers: adventitia, media and intima

Origin: T4 plane continuation of the ascending aorta

Course: posterior and to the left in the superior mediastinum

Termination: continuation as the descending aorta pass the level T4

Branches: brachiocephalic trunk, Left common carotid artery, left subclavian artery

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33
Q

Aortic arch: Relations

A

Superior: Large vessels of the superior mediastinum

Inferior: recurrent laryngeal (which one), ligament arteriosum, the bifurcation of the pulmonary trunk

Anterior: thymus or thymic reminant, fat

Posterior: trachea, oesophagus, thoric duct crosses from right to left

Lateral: right superior vena cava, terminination of the azygos, right upper lobe left: left upper lobe lung

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34
Q

Variants of the Aortic arch

A
  • Double arch
  • Bovine arch common origin of the left common carotid and brachiocephalic trunk
  • Left common carotid from the brachiocephalic trunk

Branches directly from the aorta:

  • Thyroid Ima
  • Vertebral artery (most commonly the left)
  • Right subclavian and right common carotid

Right sided arch:

  • Type 1 - mirror
  • Type 2 – absent left subclavian
  • Type 3 – isolated left subclavian
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35
Q

Coronary circulation: Description

A

The coronary arterial circulation is the system that supplies oxygenated blood the myocardium during diastole

Location: wrapped around the surface of the heart, looks like and inverted crown, located beneath the visceral layer of serous peroicardium

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36
Q

Right coronary artery: Gross anatomy

A

Origin: Right coronary cusp

Course: following the right atrioventricular groove around to the posterior aspect of the heart

Termination: Continues as the posterior interventricular artery in right circulation dominant hearts

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37
Q

Right coronary artery: Branches

A
  • Sinoatrial nodal artery
  • Conus artery
  • Sinotubular artery
  • Acute marginal branches
  • Posterior interventricular
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38
Q

Left coronary artery: Branches

A
  • Obtuse marginal
  • Circumflex
  • LAD
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39
Q

Circumflex coronary artery

A

Continues in the left atrioventricular groove around the posterior aspect of the heart gives of the posterior interventricular in left dominant hearts

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40
Q

LAD

A

Follows the anterior interventricular groove

Terminates at the apex may anastomose with the posterior interventricular artery

Branches: Obtuse marginal, septal perforators, diagonal branches

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41
Q

Coronary arteries: Variants

A

Malignant course: artery has aberrant course and passes between the aorta and pulmonary trunk

Non-malignant course: aberrant from the above described course however does not pass between large pulsating vessels

Origin from non-similarly named aortic cusp

Right or left side dominance as described above

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42
Q

Coronary veins

A

The coronary sinus drains in the right atrium its tributaries:

  • Great cardiac vein (follows circumflex and LAD)
  • Middle cardiac vein (Follows the posterior interventricular)
  • Small cardiac vein (follows RCA)

Anterior cardiac veins drain directly into the right ventricle

Smallest cardiac veins drain directly into all four ventricles

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43
Q

Internal thoracic artery

A

The internal thoracic artery (previously called the internal mammary artery) supplies the anterior body wall and its associated structures from the clavicles to the umbilicus.

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44
Q

Internal thoracic artery: Gross anatomy

A

Origin:

First part of the subclavian arteries bilaterally

Course:

  • Enters the thorax through the superior thoracic aperture posterior to the subclavian vein
  • Descends lateral to the lateral border of the sternum
  • Runs between the transversus thoracus muscle posteriorly and the costal cartilages and internal intercostal muscles anteriorly
  • At the sixth-to-seventh costal cartilages the internal thoracic artery bifurcates into two terminal branches - musculophrenic artery and superior epigastric artery.
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45
Q

Internal thoracic artery: Branches

A
  • Superior and inferior anterior intercostal arteries within each intercostal space
  • Pericardiophrenic artery (runs with the phrenic nerve)
  • Perforating branches
  • musculophrenic artery (terminal branch)
  • superior epigastric artery (terminal branch)
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46
Q

Internal thoracic artery: Supply

A
  • The internal thoracic artery supplies the anterior body wall from clavicle to umbilicus including the sternum and the breasts.
  • Via the pericardiophrenic artery it supplies the mediastinum, thymus, phrenic nerves and pericardium.
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47
Q

Internal thoracic artery: Variants

A
  • anomalous origin in 20%
    • second part (uncommon; ~7%) and third part (rare; ~1%) of subclavian artery
    • terminal trifurcation (~12.5%) with an additional xiphoid branch
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48
Q

Left subclavian artery

A

Subclavian artery is a large artery that supplies the arm, neck, anterior thorax, posterior circulation of the brain

Function: Deliver oxygenated blood

Location:

Beneath the clavicles bilaterally

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49
Q

Left subclavian artery: Gross anatomy

A

Origin: the third branch on the aortic arch (normal configuration)

Course: Ascends through the superior thoracic aperture, posterior to the brachiocephalic veins, between the anterior and middle scalene muscles

Divided into 3 parts:

1st part from origin to the medial edge of scalenus anterior

2nd part to the lateral edge of scalenus anterior

3rd part to the lateral border of the first rib

Termination: continues as the axillary artery

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50
Q

Left subclavian artery: Branches

A

1st part:

  • Vertebral
  • Internal thoracic
  • Thyrocervical trunk

2nd part:

  • Costocervical trunk
  • Dorsal scapular

3rd part:

  • None
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51
Q

Left subclavian artery: Variants

A
  • Origin variants
  • Aberrant right subclavian (between trachea and oesophagus)
  • Order of branches may vary
  • Origin of vertebral artery from the aorta
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52
Q

Azygous vein

A

function as an alternate venous return pathway in the setting of IVC occlusion

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53
Q

Azygous vein: Gross anatomy

A

Origin: Formed by the union of the right ascending lumbar veins and right subcostal veins at the level T12-L2

Course: Ascending in the retroperitoneal space of the abdomen, enters the chest through the aortic hiatus (however may pierce the crus), it continues to ascend in the posterior mediastinum

Termination: Arches over the right main bronchus to drain in to the superior vena cava.

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54
Q

Azygous vein: Tributaries

A
  • Hemiazygos vein
  • Accessory hemiazygos vein
  • Right superior intercostal vein
  • Posterior right intercostal veins
  • Right superior phrenic vein
  • Tracheal veins
  • Oesophageal veins
  • Pericardial veins
  • Vertebral venous plexus
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55
Q

Hemiazygous vein: Gross anatomy

A

Origin: Formed by the union of the left ascending lumbar veins and left subcostal veins

Course: Also through the aortic hiatus

Termination: Crosses the midline at T8-T9 to drain in the azygos vein

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56
Q

Hemiazygous: Tributaries

A
  • Left posterior intercostal veins
  • Left superior phrenic vein
  • Left renal vein (sometimes)
  • ICV sometimes
  • The left superior intrercostal vein drains directly into the SVC
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57
Q

Hemiazygous/azygous Variants

A
  • Azygos continuation of the svc
  • Azygos lobe and fissure
  • Hemiazygos continuation of the SVC
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58
Q

Blood supply to lungs

A

The lungs have dual arterial supply and venous drainage.

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59
Q

Pulmonary arteries

A

Transport deoxygenated blood to the lungs, Receive all of the arterial output of the right ventricle

Origin: Pulmonary trunk bifurcation at the level of the transthoracic plane

Course: Enters the hilum and divides into lobar, then segmental, then subsegmental arteries, then intralobular arteries, they follow the bronchi

Termination: Capillary beds of the alveoli

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60
Q

Bronchial arteries

A

Supply 1% of the blood to lung, only high-pressure oxygenated supply to the lungs

There are usually two on the left:

  • Superior left bronchial artery (arises from the arch)
  • Inferior left bronchial artery (arises from the desending aorta)

There is usually one on the right arising from a posterior intercostal artery (intercostalbronchial trunk)

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61
Q

Pulmonary veins

A

drain oxygenated blood from the lungs to the left atrium. Typically 2 drain each lung:

  • Right superior – Right upper and middle lobes
  • Right inferior – Right lower lobe
  • Left superior – Left upper lobe
  • Left inferior – Left lower lobe
  • The pulmonary veins course in the intersegemental septa and do not course with the bronchi like the pulmonary arteries do.
62
Q

Bronchial veins

A
  • Bronchial veins – drain the bronchi and hilar structures and the middle portion of the oesophagus.
  • Divisible into deep and superficial bronchial veins:
    • Deep bronchial veins – Drain the deep structures of the lung into the left atrium or pulmonary veins
    • Superficial bronchial veins – drain the hilum and plura. On the right they drain into the azygos, on the left they drain into the accessory hemiazygos vein.
63
Q

SVC: Description

A

The superior vena cava (SVC) is a large valveless venous channel formed by the union of the brachiocephalic veins. It receives blood from the upper half of the body (except the heart) and returns it to the right atrium.

64
Q

SVC: Gross anatomy

A

Origin: Lower border of the first right costal cartilage

Course: Descends vertically behind the second and third intercostal spaces to drain into the right atrium at the level of the third costal cartilage.

Its lower half is covered by the fibrous pericardium, which it pierces at the level of the second costal cartilage.

65
Q

SVC: Tributaries

A
  • azygos vein
  • small veins draining the pericardium and other mediastinal structures
66
Q

SVC: Relations

A
  • left lateral: aortic arch, trachea
  • right lateral: pleura, right upper lobe, right phrenic nerve
  • anteriorly: thymus, manubrium
  • posteriorly: azygos vein
  • superiorly: brachiocephalic veins, superior thoracic aperture
  • inferiorly: pericardium, right atrium
67
Q

SVC: Variants

A

brachiocephalic veins: drain into the right atrium separately

SVC duplication

left sided SVC

68
Q

Chest wall venous drainage

A

The venous drainage of the thorax is the vascular system that returns deoxygenated blood from the thorax to the heart

69
Q

Anterior intercostal veins

A

Couse inferior aspect of each rib

Drains: internal thoracic and musculophrenic veins

70
Q

Posterior intercostal veins

A

Origin: intercostal spaces

Course: Inferior to the posterior aspect of each rib (4 to 11)

Termination: drain into azygos system

71
Q

Supreme intercostal vein

A

Origin: 1st intercostal space

Termination: drains into the brachiocephalic veins

72
Q

Superior intercostal veins

A

Origin 2nd and 3rd intercostal veins join to form the superior intercostal vein

Termination: drains into the ayzogos and brachiocephalic (right and left)

73
Q

Chest wall venous drainge: Variants

A

Superior intercostal may also drain the 4th intercostal space

Posterior intercostal veins may be drained by different elements of the azygos system

74
Q

Phrenic N: Description

A

The phrenic nerves are mixed sensory/motor nerves that course through the neck and thorax to innervate the diaphragm

75
Q

Phrenic N: Gross anatomy

A

Origin: ventral rami of C3, C4 and C5

Course: Passes on the anterior surface of scalenus anterior, over the dome of the apical pleura, entering the superior thoracic aperture posterior to the subclavian veins

Left:

Descends lateral to the left subclavian artery, passes anterior to the hilum, pierces the diaphragm directly to enter the abdominal cavity.

Right:

Descends with the superior and inferior vena cava. Enters the abdomen with the inferior vena cava through the caval hiatus at level T8

Within the abdomen the both divide in the anterior, lateral and posterior branches. Coursing out in a radial pattern.

Supply:

Sole motor supply to each hemidiaphragm, sensation to the central tendon

  • Diaphragm
  • Mediastinal pleura
  • Pericardium
  • Central diaphragmatic pleura
76
Q

Phrenic N: Variants

A
  • Course anterior to subclavian vein
  • May pierce the anterior scalene muscle
  • Accessory phrenic nerve
  • Contribution from C2 or C6
  • May supply branch to subclavius
77
Q

Thoracic duct

A

The thoracic duct is the main lymphatic channel for the return of chyle to the venous system.

78
Q

Thoracic duct: Gross anatomy

A
  • Origin: continuation from the cistern chyli
  • Course in the retroperitneum posterior to the great vessels ascending, entering the thoracic cavity via the aortic hiatus at T12, continues to ascend in the posterior mediastinum on the right hand side initially, swapping sides at the level T4, continuing superiorly through the thoracic inlet, anterior to the subclavian artery, anterior to the anterior scalene, draining in the convergence of the left subclavian and internal jugular.
79
Q

Thoracic Duct: Relations

A
  • Anterior: oesophagus, left atrium, carina
  • Posterior: vertebral column, symphathetic chain of ganglion
  • Left lateral: descending aorta, left lung and pleura
  • Right lateral: azygos vein, right lung and pleura
80
Q

Thoracic Duct: Variants

A
  • Variant anatomy in 40% of the population
  • Duplication
  • Aberrant termination
  • Multiple terminal channels

Continues on the right to terminate in the right internal jugular vein

81
Q

Breast: Description

A

Bilateral prominences of the anterior thorax

Function: Lactation

82
Q

Breast: Gross anatomy

A
  • Mixed fatty and glandular tissue comprise the bulk of the breast
  • Structural support via fibrous tissue known as the ligaments of Cooper
  • Typically divided into 5 sections, four quadrants centered on the nipple and an axillary tail
  • Glandular tissue is comprised of lobules draining into lactiferous ducts converging on the areola to drain to the nipple
  • Lactiferous lobules are modified apocrine glands, typically 14-18, draining to the nipple areola complex
83
Q

Breast: Neurovasculature

A

Arterial supply:

  • Performing branches from the internal thorax and intercostal arteries
  • Thoracoacromial artery
  • Lateral thoracic arteries

Venous drainage:

  • Axillary vein
  • Internal thoracic vein
  • Posterior intercostal veins

Innervation:

Thoracic intercostal nerve T3-T5

Supraclavicular nerves

Lymphatic drainage:

Initially into Sappy’s plexus (subareolar plexus) then into one of three routes (AIR):

  • Axillary pathway – runs from the inferior edge of the pec major to the pectoral group of axillary nodes
  • Internal mammary pathway – passes through pec major, connect may cross the medial plane to the contralateral breast
  • Retromammary pathway – from the posterior portion of the breast

75% of lymph from the breast is drained via the axillary nodes

84
Q

Breast: Variants

A
  • Hypoplasia
  • Amastia
  • Amazia
  • Polythelia
  • Polymastia
85
Q

Lymphatic drainage of the breast: Description

A

The lymphatic drainage of the breast originates from the breast lobules and flows into a subareolar plexus, called Sappy’s plexus. From this plexus, lymphatic drainage takes place through three main routes:

86
Q

Lymphatic drainage of the breast: Pathways

A

Axiallary or lateral pathway:

Receives 75% of the lymph this pathway runs around the inferior edge of the pectoralis major and reaches the pectoral group of axillary nodes.

Internal mammary pathway:

Originates from both the medial and lateral halves of the breast and passes through the pec. Major. Connections may lead across the median plane and hence to the contralateral breast

Retromammary pathway:

Drains the posterior portion of the breast

87
Q

Lymphatic drainage of the breast: Variants

A

Lymphatics may reach the sheath of the rectus abdominus and the sub peritoneal and subhepatic plexuses.

88
Q

Left ventricle

A

The left ventricle is one of four heart chambers. It receives oxygenated blood from the left atrium and pumps it into the systemic circulation via the aorta.

89
Q

Left ventricle: Gross anatomy

A
  • The left ventricle is conical in shape
  • anteroinferiorly projecting apex
  • longer with thicker walls than the right ventricle
  • separated from the right ventricle by the interventricular septum,
  • Internally, there are smooth inflow and outflow tracts and the remainder of the left ventricle (mainly apical) is lined by fine trabeculae carnae.
90
Q

Left ventricle: Neurovasculature

A

Arterial supply:

  • left anterior descending artery: supplies the free wall and most of the papillary muscles
  • left circumflex artery: supplies the free wall

Venous drainage:

  • great cardiac vein, middle cardiac vein and posterior vein of the left ventricle: drain into the coronary sinus
  • tiny myocardial thebesian veins drain directly into the right ventricle

Innervation:

  • Superior and inferior cardiac plexi
  • Conduction system of the heart

Lymphatics:

Lymphatics system of the heart draining into the tracheobronchial, para-aortic nodes and superior phrenic nodes.

91
Q

Left ventricle: Variants

A

double-inlet ventricle: inflow from both the right and left atria

parachute valve: mitral valve chordae tendineae inserting into a single papillary muscle

92
Q

RIght atrium: Description

A

The right atrium (RA) is one of the four chambers of the human heart.

Function: the first chamber to receive deoxygenated blood returning from the body, pre-loads the right ventricle with increase it efficiency (Frank Starling law)

93
Q

Right atrium: Gross anatomy

A

The right atrium receives deoxygenated blood from the superior vena cava (SVC), the inferior vena cava (IVC), the coronary sinus (covered by the thebesian valve), and the thebesian veins.

Grossly ellipsoid in shape except for the atrial appendage.

The right atrium is separated from the left atrium by the interatrial septum. Which has an indentiation in it called the fossa ovalis (was previously the foramen ovalis prior to birth)

The right atrium leads into the right ventricle through the tricuspid valve.

The crista terminalis is a muscular ridge on the anterior aspect of the chamber.

The atrium is lined by pectinate muscles to the left of this crest, and these extend into the right atrial appendage.

94
Q

Right atrium: Neurovasculature

A

Blood supply:

arterial supply is primarily from the right coronary artery (RCA) and several of it’s branches:

conus artery (first branch off RCA in 55%, otherwise arises off left circumflex artery)

sinoatrial node artery (usually second branch off RCA in 60%)

acute marginal branches

Venous drainage:

variable veins drain the atrial wall

tiny myocardial thebesian veins drain directly into the right ventricle

Nerve supply:

The right atrium is the location of the sinoatrial node, the heart’s pacemaker. It is located subepicardially in the terminal groove, near the junction of the SVC and right atrium.

Although the sinoatrial node can generate conduction rhythms spontaneously, it is regulated by the vagus nerve (CN X) and the cardiac sympathetic plexus.

95
Q

Right atrium: Variant

A

Eustachian valve of the IVC

96
Q

Oesophagus: Description

A

The oesophagus is a muscular tube that connect the pharynx to the stomach

Function: convey food bolus to the stomach

97
Q

Oesophagus: Gross anatomy

A

~23-37cm in length

Divided into segments:

  • Cervical – hypopharynx to superior thoracic aperture
  • Thoracic – Sup. Thoracic aperture to the oesophageal hiatus
  • Intraabdominal – diaphragm to cardia of the stomach

Course: through the superior thoracic inlet, running in the posterior mediastinum behind the trachea, passes through the diaphragm through the oesophageal hiatus at level T10

Termination: joins the cardia via the lower oesophageal sphincter

98
Q

Oesophagus: Relations

A

Anterior: trachea, carina, heart

Posterior: vertebral bodies from C4 to T11

Lateral: Ascending laryngeal nerve in the tracheooesophageal groove

99
Q

Oesophagus: Neurovasculature

A

Arterial supply:

  • Inferior thyroid
  • Direct branches of the desending aorta
  • Braches from the left gastric

Venous drainage:

  • Superior: Inferior thyroid plexus
  • Middle: Azygos system
  • Inferior: via the left gastric to portal vein

Innervation:

Oesophageal plexus supplied by the vagus and sympathetic chain of ganglions

Lymphatics:

  • Deep cervical
  • Posterior mediastinal
  • Coeliac
100
Q

Oesophagus: Variants

A
  • Oesophageal bronchus
  • Oesophageal atresia
  • Tracheo-oesophageal fistula
  • Duplication cyst
  • Fenestrated oesophagus
101
Q

Cervical relations of oesophagus

A

Anterior: trachea, cricoid cartilage, the isthmus of the thyroid

Posterior: bodies and disc of vertebra C4 – C7

Lateral: Trachea oesophageal grooves, right and left recurrent laryngeal nerves, the carotid spaces

Superior: Cricopharygeus, oropharynx

Inferior: Thoracic oesophagus

102
Q

Thoracic oesophageal relations

A

Anterior: Trachea, left recurrent laryngeal nerve, pericardium

Posterior: Thoracic vertebral bodies, thoracic duct, azygos veins, descending aorta

Lateral: Right – Pleura, terminal part of the azygos vein, Left – Left subclavian artery, aortic arch, thoracic duct, pleura

Superior: Cervical oesophagus

Inferior: Diaphragm, oesophageal hiatus, the abdominal component of the oesophagus

103
Q

Abdominal oesophageal relations

A

Anterior: Left vagus nerve, posterior surface of the heart

Posterior: Right vagus nerve, left crus of the diaphragm

Lateral: Left – fundus of the stomach, spleen, Right - coeliac axis

Superior: Thoracic oesophagus

Inferior: Cardia of the heart

104
Q

Pericardium: Description

A

The pericardium is a sac like covering of the heart and the root of the great vessels

Function: Reduce friction between the heart and surrounding tissue to allow for cardiac movement

105
Q

Pericardium: Gross anatomy

A

Fibrous outer sac is referred to as the fibrous pericardium, it is fused to:

  • central tendon of the diaphragm
  • sternum via the superior and inferior sternopericardial ligaments
  • roots of the great vessels
  • pre-tracheal fascia

The serous inner sac is divided into 2 layers between which there is 15-50mls of pericardial fluid. The outer layer of parietal serous pericardium is fused to the fibrous pericardium, the inner layer is adherent to the surface of the heart and origins of the great vessels

106
Q

Pericardium: Recesses/sinuses

A

Sinuses:

  • Oblique sinus – formed behind the left atrium bounded by the origins of the superior and inferior vena cava and the pulmonary veins
  • Transverse sinus – between the aorta and pulmonary trunk and the atria posteriorly

Recesses:

  • Pulmonic venous recess right and left
  • Pulmonary recess right and left
  • Superior and inferior aortic recess
  • Postcaval recess
107
Q

Pericardium: Neurovasculature

A

Arterial supply:

Pericardiophrenic and musculophrenic arteries branches of the internal thoracic

Venous drainage:

Pericardiophrenic and musculophrenic veins into brachiocephalic and internal thoracic veins

Innervation:

  • Superior and inferior cardiac plexus supplied by the vagus and the sympathetic chain of ganglion
  • Phrenic nerves
108
Q

Pericardium: Relations

A
  • Inferior: central tendon of the diaphragm
  • Anterior: Sternum and costal cartilages (3-7), lung and plura (thymus in children)
  • Lateral: pleural and lung, phrenic nerves,
  • Medial: heart and origin of the great vessels
109
Q

Pericardium: Variants

A
  • Agenesis of the pericardium
  • Pericardial cysts
110
Q

Pleura: Description

A

The pleura are serous membrane sacs that contain the lungs

Function: reduce friction between the lungs and the thoracic walls

111
Q

Pleura: Gross anatomy

A

Divided into the parietal and visceral pleural with 15-50ml of pleural fluid between them

The visceral pleura invaginates the fissures of the lungs

The parietal pleura is named after the surface it covers:

  • Cervical
  • Costal
  • Diaphragmatic
  • Mediastinal
112
Q

Pleura: Lines of reflection

A
  • 2nd rib – both descend midline
  • 4th rib – the left deviates for the heart
  • 6th rib – the right and left deviate for the heart
  • 8th rib – Right and left both pass the mid clavicular line
  • 10th rib – right and left pass the midaxillary line
  • 12th rib – right and left travel posteriorly around the chest wall
113
Q

Pleura: Neurovasculature

A

Blood supply:

Visceral pleura:

Bronchial and pulmonary arteries

Parietal pleura:

Internal thoracic, intercostal and phrenic

Venous drainage:

Bronchial and pulmonary veins

Lymphatics:

Perihilar nodes

Innervation:

The parietal pleural is innervated by the phrenic nerves and the intercostal nerves (mediastinal and costal parts respectively)

114
Q

Pleura: Relations

A

Anterior: Anterior thorax

Posterior: posterior thorax and thoracic vertebra

Lateral: rib intercostal muscles etc

Inferior the diaphragm

Superior the superior thoracic aperture

115
Q

Pleura: Variants

A
  • Azygos lobe
  • Agenesis
  • Superior and inferior accessory fissures of the right lung
  • Left horizontal fissure
116
Q

Segmental anatomy of lungs: Description

A

The segmental anatomy of the lung describes the division of the lung into segments based the the supply of segmental bronchi.

117
Q

Segmental anatomy of lungs: Gross anatomy

A

The trachea divides at the carina (T4) forming the right and left main stem bronchi. These further divide into lobar bronchi. Which then in turn divide into segmental bronchi. The lung supplied by each segmental bronchi is defined as a lung segment.

In general each lung has 10 segments, giving 20 in total

Each segment is an independent anatomically functional unit. This allows for discrete surgical resection.

118
Q

Right lung segments

A

Upper lobe:

  • Apical (B1)
  • Posterior (B2)
  • Anterior (B3)

Middle lobe:

  • Lateral (B4)
  • Medial (B5)

Lower lobe:

  • Superior (B6)
  • Medial (B7)
  • Anterior (B8)
  • Lateral (B9)
  • Posterior (B10)
119
Q

Left lung segments

A

Upper lobe:

  • Apicoposterior (B1/2)
  • Superior lingular (B4)
  • Inferior lingular (B5)
  • Anterior (B3)

Lower lobe:

  • Anteriomedial (B7/B8)
  • Lateral (B9)
  • Posterior (B10)
  • Superior (B6)
120
Q

Segmental lung anatomy: Variants

A
  • Azygos lobe
  • tracheal broncus
  • cardiac bronchus
  • oesophageal bronchus
121
Q

Thymus: Description

A

The thymus is a T-cell producing lymphoid organ in the anterior mediastinum that plays a role in the development of the immune system, particular the maturation of T-cells. It typically has a retrosternal location and hence can mimic retrosternal pathology.

122
Q

Thymus: Gross anatomy

A

It is relatively large in infancy

Grows considerably immediately after birth

maximal weight in adolescence between 12 and 19 years then gradually involuting with age with progressive fatty replacement of the cellular components.

Consist of two lateral lobes touching in the midline, situated partly in the thorax, partly in the neck.

The gland extends from as high as the lower border of the thyroid gland to the fourth costal cartilage downwards.

123
Q

Thymus: Relations

A

Anteriorly: sternum, origins of the inferior strap muscles

Posteriorly: pericardium, aortic arch, great vessels, left brachiocephalic vein, trachea

Laterally: pleura, pretracheal fascia

124
Q

Thymus: Neurovasculature

A

Arterial:

Inferior thyroid and internal thoracic arteries

Venous:

left brachiocephalic, internal thoracic and inferior thyroid veins

Lymphatic drainage:

parasternal, brachiocephalic and tracheobronchial lymph nodes

Innervation:

  • Vagus
125
Q

Thymus: Variants

A
  • variable location: ectopic and/or accessory thymic tissue may be located anywhere along the path of descent of the thymopharyngeal ducts. e.g. retrocaval, cervical, posterior mediastinal
  • variable shape: e.g. unilobed, trilobed, X-shaped, inverted V-shaped
126
Q

Trachea: Description

A

The trachea is the primary trunk of the conductive airways

Function: transmission of gas between the larynx and the main bronchi

Location: Visceral space of the neck and posterior mediastinum

127
Q

Trachea: Gross anatomy

A

Made up of posteriorly incomplete cartilage rings with interspaced annular ligaments

Enveloped by the trachealis muscle which is particularly prominent posteriorly

Lined with ciliated epithelium

Divided into: cervical and thoracic trachea

Origin: continuation of the airway distal to the cricoid cartilage (C6)

Termination: bifurcates at the carina level L4

128
Q

Trachea: Neurovasculature

A

Arterial supply:

  • Inferior thyroid arteries
  • Bronchial arteries

Venous drainage:

  • Inferior thyroid veins
  • Azygos system

Lymphatics:

  • Drainage into deep cervical, peri and para-tracheal nodes of the mediastinum

Innervation:

  • Vagus and sympathetic trunk
129
Q

Trachea: Relations

A
  • Posterior: oesophagus and recurrent laryngeal nerve
  • Anterior: Thyroid strap muscle, jugular notch, manubrium, great vessels of the superior mediastinum
  • Lateral: Sternocleidomastoid, brachiocephalic veins and arteries
  • Superior: larynx
  • Inferior: Sub-carinal lymph nodes, main bronchi
130
Q

Trachea: Variants

A
  • Trachea oesophageal fistula
  • Tracheal atresia
  • Pig bronchus
  • Lunate trachea
  • Tracheal diverticulum
131
Q

Bronchial tree: Description

A

Branching tree of airways beginning at the carina.

The lumen diameter decreases with each branching.

Airways down to the level of the bronchioles contain c-shaped rings of hyaline cartilage to maintain the patency of the lumen.

Function: transmission of gas between the trachea and the respiratory airways of the lungs

132
Q

Branches of the Bronchial tree

A

Right side:

  • Right main bronchus
  • Bronchus intermedius
  • Right Upper lobe bronchus
  • Right middle lobe bronchus
  • Right lower lobe bronchus

Left side:

  • Left main bronchus
  • Left upper lobe bronchus
  • Left lower lobe bronchus

Further branches:

  • Segmental bronchi
  • 20 to 25 generations of bronchioles
  • Terminal bronchioles
133
Q

Bronchial tree: Vasculature

A

Arterial supply:

  • Bronchial arteries
  • Branches of the descending aorta

Venous drainage:

  • Bronchial veins draining into the azygos system

Lymphatic drainage:

  • Hilar nodes
134
Q

Bronchial Tree: Variants

A
  • Bronchial cyst
  • Pig bronchus
  • Oesophageal branch
  • Azygos bronchus
  • Cardiac bronchus
135
Q

Superior mediastinum: Description

A

Superior mediastinum is an artificially divided wedge-shaped compartment of the mediastinum located between the thoracic plane inferiorly and the thoracic inlet superiorly. The inferior mediastinum, comprising of the anterior, middle and posterior parts, lies inferiorly.

136
Q

Superior mediatstinum: Boundaries

A
  • superiorly: thoracic inlet
  • inferiorly: thoracic plane
  • laterally: mediastinal pleura
  • anteriorly: manubrium of the sternum
  • posteriorly: bodies of upper four thoracic vertebrae
137
Q

Superior mediastinum: Contents

A

muscles: origin of sternohyoid, sternothyroid and lower end of longus colli muscles

arteries: aortic arch and great vessels

veins: right and left brachiocephalic veins, left superior intercostal vein, upper half of superior vena cava

nerves: phrenic, vagus and cardiac nerves; cardiac plexus; left recurrent laryngeal nerve

lymph nodes: brachiocephalic; tracheobronchial; paratracheal

Organs:

  • trachea
  • oesophagus
  • thoracic duct
  • thymus
138
Q

T5 level: Description

A

The T5 level is also known as the transthoracic plane or plane of Ludwig. It is a horizontal plane at the level of the inferior endplate of L4.

Divides the superior and inferior mediastinum

139
Q

T5 level transection

A
  • Carina
  • Pulmonary trunk bifurcates
  • Thoracic duct crosses from right to left at this level
  • Azygos vein drains into the superior vena cava
  • Inferior concavity of the aortic arch
  • Ligamentum venosum
  • Termination of the pre-tracheal and pre-vertebral fascia
  • Cardiac plexus
  • Recurrent laryngeal loops under the arch
  • Superior vena cava
  • Sternal angle
  • Ribs 2 – 4
  • Internal and external intercostal muscles
  • Internal thoracic artery
  • Lungs
  • Muscles of the thorax and arms
  • Humerus
140
Q

Superior thoracic apeture: Description

A

The superior thoracic aperture is the superior opening into the thorax

Function: Allow the passage of a large number of structure into and out of the thorax

Location: Encircled by the first rib, the T1 vertebrae and the manubrium

141
Q

Thoracic inlet: Organs

A
  • Lung apices
  • Trachea
  • Oesophagus
  • Thymus
  • Sometimes the thyroid
142
Q

Thoracic inlet: Vasculature

A
  • Brachiocephalic veins
  • Internal thoracic arteries
  • Brachiocephalic truck
  • The left common carotid artery
  • The left subclavian artery

Lymphatics:

  • Cervical lymph nodes
  • Thoracic duct
143
Q

Thoracic inlet: Nerves

A
  • Vagus nerves
  • Phrenic nerves
  • Ascending laryngeal nerves
  • The sympathethetic chain of ganglion
144
Q

Thoracic inlet: Muscles

A
  • Part of sternocleidomastoid
  • Sternohyoid
  • Sternothyroid
145
Q

Thoracic inlet: Variants

A
  • Right common carotid and subclavian can pass through
  • Thyroid IMA artery can pass through
  • Thyroid can extend through
  • Cervical ribs
146
Q

Intercostal space:Description

A

The intercostal spaces are the space between the ribs. There are 11 spaces on each side and they are numbered according to the rib which is the superior border of the space.

147
Q

Intercostal space: Gross anatomy

A

The intercostal spaces contain three layers of muscle:

  • External
  • Internal
  • Innermost

The neurovascular bundle is found between the internal and innermost layers.

148
Q

Intercostal spaces: Muscles

A

The external intercostal muscle fibres run down and medial

The internal intercostal muscle fibres run down and lateral

The deepest layer of muscle in the intercostal space is made up of three muscles which are collectively known as the tranversus thoracis group. This group includes the:

  • subcostal muscles posteriorly
  • the innermost intercostals laterally
  • the transversus thoracis / sternocostalis muscles anteriorly.
149
Q

Intercostal spaces: Neurovascular bundle

A

The neuromuscular bundles are found between the middle and innermost layers, protected by the costal groove of the superior rib of each intercostal space. They are ordered vein, artery, nerve from superior to inferior (mnemonic VAN). The collateral neurovascular bundle runs at the lower edge of the space, just above the inferior rib and the order is reversed, i.e. nerve, artery, vein from superior to inferior.

150
Q

Intercostal spaces: Neurovasculature

A

Blood supply:

Arterial supply:

Single large posterior intercostal artery and 2 smaller anterior intercostal arteries.

In the first and second intercostal spaces a large posterior artery arises from the superior intercostal artery (a branch from the costocervical trunk).

The arteries in the remaining spaces branch directly from the descending thoracic aorta.

The anterior intercostal arteries arise from the internal thoracic and musculophrenic (below 6th interspace).

Venous drainage:

Posterior veins drain into the azygos or hemiazygos veins. Anterior veins drain into the internal thoracic or musculophrenic veins.

Innervation:

Each intercostal space is supplied segmentally by muscular branches of anterior rami of spinal nerves T1-T11.

Anatomy (11 decks)

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