Anatomy - Thorax, Mediustinum, Chest wall & Breast Flashcards
What is the thoracic cage composed of ?
12 thoracic vertebrae
12 pairs of ribs (i.e. 24 ribs)
Cartilage structures
Sternum – 3 parts
Why do we have a bony thoracic cage?
Ventilation – Allows muscles to change the thoracic volume and bring about respiration
Protection – Strong cage to give protection to some vital organs
The sternum is a fused bone made up of 3 parts, what are they ?
Manubrium
Body
Xiphoid process
What is the joint between the manubrium and the body of the sternum called ?
Sternal angle or manubriosternal joint
What are the three rib types?
Explain them
True – Ribs 1-7
Attach directly to sternum via their own costal cartilage
False – Ribs 8-10
Attach to sternum via rib 7’s costal cartilage
Floating – Ribs 11 & 12
Do not attach to the sternum
No costal cartilages – pointed ends
Ribs can be classifies into typical and Atypical explain these
Typical
Head articulates with both same level and above vertebra
i.e. Rib 4 to T3 & T4
Atypical
Head articulates with vertebra of same level only
i.e. Rib 10 to T10
What type of ribs are Ribs 3-9
Typical
What type of ribs are Ribs 1, 2, 10, 11, & 12
Atypical
Which ribs are most commonly fractured?
4-10
Which rib fractures inidcate high energy trauma ?
Ribs 1-3 fracture indicates a high energy trauma – usually sufficient to cause other internal injuries.
The vertebral colum is formed of 33 bones, these can be divided into different categories depending on region and function what are they?
7 Cervical vertebrae (C1-C7)
12 Thoracic vertebrae (T1-T12)
5 Lumbar vertebrae (L1-L5)
5 (usually all fused) Sacral vertebrae (S1-S5)
4 (some fused) Coccygeal vertebrae (Co1-Co4)
Explain the structure of a typical thoracic verterbrae
On each side a typical thoracic vertebra has:
2 costal demi-facets (superior and inferior) on the vertebral body for articulation with the head of rib.
A facet on the transverse process for articulation with the tubercle of rib.
What and where is the thoracic inlet ?
Boundary – Manubrium, rib 1, and T1.
Allows passage for all vital structures of the chest, upper limb, head, and neck.
Important to know clinically as any damage or inflammation here can compress important structures as there is very little space.
What tumour can press on structures in the thoracic inlet ?
Pancoast Tumour - Cancerous tumour at the apex of the lung.
Can press on structures in the thoracic inlet, causing them to be damaged.
e.g. Horner syndrome – compression of sympathetic trunk
Partial paralysis and paraesthesia in arm – brachial plexus compressed
What is this known as ?
Barrel chest
What is this known as ?
Pectus excavatum
What is this known as ?
Pectus Carunatum
The thorax can be divided into which compartments?
Right pleural cavity
Left pleural cavity
Mediastinum
What can the mediastinum be devided into ?
The mediastinum is divided into Superior and Inferior mediastinum.
Divided by an invisible section from the Sternal angle to the intervertebral disc between T4 and T5.
The inferior mediastinum is further subdivided into:
Anterior mediastinum
Middle mediastinum – Pericardium
Posterior mediastinum
What contents lie within the superior mediustinum ?
Thymus
Trachea
Oesophagus
Thoracic duct
Aortic arch (and associated branches)
Superior vena cava (and associated convergent veins)
Vagus nerve
Phrenic nerve
Recurrent laryngeal nerve
Sympathetic trunk
Lymphatics
Muscles
Where does the mediastinum divide into superior and inferior?
Between T4 and T5
What structures lie within the superior anterior mediastinum ?
Thymus extends from Superior mediastinum
In children – Thymus
In adults – Adipose tissue
Internal thoracic vessels
Lymph nodes – Main important structure
What lies within the inferior middle mediustinum ?
Main content of the middle mediastinum is the heart in the pericardium.
Also contains the beginnings at least of the associated vessels:
Ascending aorta
Superior vena cava
Pulmonary trunk
Also other structures including:
Main/primary bronchi after bifurcation of trachea – structures which go to the hila of the lungs.
Phrenic nerve
Cardiac plexus
Vagus nerve
What lies within the inferior posterior mediustinum ?
Posterior mediastinum contains lots of major vessels and structures, most of which will go to pierce its inferior border – the diaphragm.
Contents:
Descending aorta and its branches
Azygos venous network
Thoracic duct (ascending)
Oesophagus
Sympathetic trunk
Nerves:
Oesophageal plexus
Vagus nerve branches
Which major arteries supply the thorax?
Thoracic Aorta:
Post. 3-11
Also Subcostal A. under Rib 12
Left Subclavian A.:
Internal Thoracic A.
Ant. 1-6
Musculophrenic
Ant. 7-9
Costocervical Trunk
Supreme Intercostal A.
Post. 1 & 2
Does anastomose with Post. 3
What is some venous drainage within the thorax
-Posterior intercostal vein
- Accessory azygos vein
- Azygos vein
- Hemi-azygoz vein
The lymph drainage depends on where in the body its from..
where does the thoracic duct drain?
Where does the right thoracic duct drain?
Thoracic duct
Left head, neck, thorax, and arm + all pelvis and lower limbs
Right lymphatic duct
Right head, neck, thorax, and arm
What are the muscle layers of the intercostal muscle ?
External, Internal, and Innermost
Where do the neurovascular structures lie between the ribs?
Why is this important?
Neurovascular structures:Intercostal artery, Intercostal vein, and Intercostal nerve.
located in the costal groove in the undersurface of each rib
When inserting a chest drain.
Where does the Caval opening – Inferior Vena Cava pass through diaphram ?
T8
Where does the Oesophageal hiatus – Oesophagus, vagus nerve pass through the diraphram ?
The esophagus passes through the muscular part of the diaphragm, just to the left of midline, approximately at vertebral level T0
▪ The vagus nerves pass through the diaphragm with the esophagus.
Where does the Aortic hiatus – Descending aorta (thoracic to abdominal), thoracic duct, azygos system, sympathetic trunk, other nerves pass through the diaphram ?
T12
What is the neuromuscular supply to the Diaphram - arterial, venous and nerve?
Arterial supply:
Pericardiacophrenic and musculophrenic a.
Superior phrenic a.
Branches of intercostal a.
Inferior phrenic a. – Largest supply
Venous drainage:
Brachiocephalic veins
Azygos system
Inferior vena cava
Nerve supply:
Phrenic nerve (C3, C4, C5)
Aside from the breast, there is very little between the thorax and exterior of the body.
What are th emuscles within the chest wall ?
Pectoralis Major
Pectoralis Minor
Serratus Anterior
What structures lie at the sternal angle? Think RATPLANT
R – Rib 2
A – Aortic arch
T – Tracheal bifurcation (Carina)
P – Pulmonary trunk
L – Ligamentum arteriosum
A – Azygos vein drains into SVC
N – Nerves (cardiac plexus, loop of recurrent laryngeal etc.)
T – Thoracic duct (right-to-left movement before exiting thoracic inlet)
Point to myself where these structures are
Anterior axillary fold
Posterior axillary fold
Axillary fossa/Axilla
Jugular notch
Pectoralis major and other muscles
What is the safe trangle ?
Where is it located ?
The ‘Safe Triangle’ is an important area to note for where chest drains could be inserted safely.
Anterior: Lateral border of pectoralis major muscle.
Posterior: Lateral border of latissimus dorsi muscle.
Inferior: 5th intercostal space
What is the arterial and venous supply to the breast ?
Arterial supply:
Medially: Internal thoracic artery
Laterally: Branches of axillary artery
Perforating chest wall: 2nd-4th intercostal arteries
Venous drainage:
Parallels arterial supply – Internal thoracic, intercostal, and axillary vein branches.
What are mammary glands?
The mammary gland is a specialised sweat gland.
Consists of a series of ducts and secretory lobules.
These converge on the nipple as 15-20 independent lactiferous ducts.
he structure of the breast lies over chest wall.
It is separated by a loose connective tissue layer called the submammary/retromammary space.
What does this provide ?
This provides a degree of movement for the breast independent of underlying structures
The nipple is surrounded by a pigmented area of the skin known as the what ?
Areola
Considering breast lymphatics, where do the deep vessels drain to ?
The deep vessels can drain to several nodes depending on location:
Medial breast
Parasternal nodes
Anastomoses (connections) exist in the channels to cross to the opposite breast or nodes.
Lateral breast
Axillary nodes – receive >75% of lymph from the breast
Anterior (pectoral), posterior (subscapular), lateral (humeral/brachial), central and apical (subclavicular)
Changes in the breast could indicate signs of disease in the breast tissue.
What could this include ?
These include (but are not limited to):
Pain
Lump – whether hard, firm, or soft
Skin changes
Dimpling – Highly suggestive of cancer
Visible lump
Peau d’orange (appearance of orange peel)
Redness
Ulceration
Vascular signs
Nipple changes
Inversion or change of shape
Eczema/rash involving nipple
Nipple discharge
Explain parts of a breast examination
This should be performed with the patient sitting comfortably, pressing hands on hips (A) , lifting arms in the air (B) , and pressing hands on top of the head. Palpation: the patient should sit on an examination couch as shown in (C) , with the backrest at about 45 degrees and rolled slightly to the contralateral side. The arm on the side to be examined should be elevated and the head rested on the pillow. The effect of these manoeuvres is to spread the breast over a greater area of the chest wall. The flat of the right hand is used to palpate the breast circumferentially by quadrants (D–F) . The central part of the breast and the axillary tail must also be palpated. If there is a history of nipple discharge, the areola is pressed in different areas (F) to identify the duct from which it emanates and therefore the segment involved. Finally, the axillary lymph nodes are palpated as shown in (G) and (H) . The right axilla is palpated with the left hand (G) and the left axilla is palpated with the right hand (H). It is important to relax the axillary muscles by supporting the weight of the patient’s arm as shown. The fingers of the examining hand are firmly held in a curve, pressed high into the apex of the axilla against the chest wall and drawn downwards. The hand will then ‘ride over’ any enlarged axillary nodes.
