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MD1S2: Anatomy 202 > Thoracic Wall > Flashcards

Thoracic Wall Flashcards

1
Q

What is the thorax?

A

Region of the body between the neck and abdomen
Enclosed by the bony framework of the thoracic cage

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2
Q

Which structures form the thoracic cage?

A

Anteriorly: Sternum and costal cartilage
Laterally: Ribs and intercostal spaces
Posteriorly: Vertebral column

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3
Q

What structures form the superior margin of the thorax?

A

Anteriorly: Superior border of manubrium sterni
Laterally: Medial border of the 1st ribs and their costal cartilages
Posteriorly: 1st thoracic vertebra

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4
Q

What structures occupy the superior margin of the thorax?

A

Midline structures passing between the neck and thorax (e.g. esophagus and trachea)
Suprapleural membrane on either side of the midline structures

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5
Q

What is the suprapleural membrane?

A

Tent shaped dense fascial sheet that covers the apex of each lung
It is an extension of the endothoracic fascia
Extends approximately an inch superior to the superior thoracic aperture

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6
Q

What are the attachment points of the suprapleural membrane?

A

Laterally to the internal border of the first rib & costal cartilage
At its apex to the transverse process of C7 vertebra
Medially to the fascia covering the structures passing through the superior thoracic aperture

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7
Q

What structures form the inferior margin of the thorax?

A

Anterior: Xiphisternal joint
Lateral: Curving costal margin
Posterior: 12th thoracic vertebra

The opening is closed by the diaphragm

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8
Q

What is the purpose of the thoracic cage?

A

Protects the lungs, heart and large vessels
Provides attachment to the muscles of the thorax, upper limbs, abdomen and back

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9
Q

How is the thoracic cage divided?

A

Mediastinum in the middle
Pleura and lungs laterally

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10
Q

What are the thoracic cutaneous nerves?

A

Anterior wall:
1. Above sternal angle: Supraclavicular nerve
2. Below sternal angle: Segmental innervation by anterior and lateral cutaneous branches of the intercostal nerves

Posterior wall: Segmental innervation by posterior rami of thoracic spinal nerves

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11
Q

What does an intercostal space contain?

A

Intercostal muscles
Intercostal neurovascular bundle
Lymphatics

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12
Q

What are the muscles of the intercostal spaces?

A

Superficial to deep:
1. External Intercostals
2. Internal Intercostals
3. Innermost Intercostals

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13
Q

Which nerves supply the intercostal muscles?

A

Corresponding intercostal nerves

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14
Q

What are the actions of the intercostal muscles?

A

Pull the ribs nearer to each other
Strengthen tissue of the space

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15
Q

How can external intercostal muscles be differentiated from other intercostal muscles?

A

Outermost muscle layer
Fibers directed downward and forward

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16
Q

What is the origin and insertion of the external intercostal muscles?

A

Origin: Lower border of rib above
Insertion: Upper border of rib below

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17
Q

What happens to the external intercostal muscles on the anterior surface?

A

External intercostals are deficient anteriorly and are replaced by the external/anterior intercostal membrane

18
Q

How can internal intercostal muscles be differentiated from other intercostal muscles?

A

Intermediate muscle layer
Fibers directed downwards and backwards

19
Q

What is the origin and insertion of the internal intercostal muscles?

A

Origin: from subcostal groove of the rib above
Insertion: upper border of rib below

20
Q

What happens to the internal intercostal muscles on the posterior surface?

A

Deficient posteriorly & replaced by internal/posterior intercostal membrane

21
Q

How can innermost intercostal muscles be differentiated from other intercostal muscles?

A

It is the deepest intercostal muscle layer

22
Q

What are the features of the innermost intercostal muscle?

A

Incomplete layer, divided into three portions
Fibers cross more than one intercostal space
Related externally to intercostal nerve and vessels, and internally to endothoracic fascia

23
Q

What is the endothoracic fascia?

A

An extrapleural fascia lining the chest wall

24
Q

What is the location of the endothoracic fascia?

A

Between the muscles and bones of the thoracic wall and parietal pleura
Extends over the cupola (apex) of the pleura as the suprapleural membrane and forms a thin layer between the diaphragm and the pleura

25
Q

Location of the intercostal neurovascular bundle?

A

Lies between the innermost and the internal intercostal muscles
Runs high in the intercostal space near the subcostal groove of the rib above
As the innermost intercostal muscle is not forming a complete layer, the bundle is generally covered on the inside by the endothoracic fascia

26
Q

What is the arrangement of the neurovascular bundle?

A

Top to bottom (VAN):
1. Vein
2. Artery
3. Nerve

27
Q

Number of intercostal nerves?

A

12 pairs

28
Q

What nerves are the intercostal nerves a branch of?

A

The anterior primary rami of the thoracic spinal nerves

29
Q

Distribution of intercostal nerves

A

1-6: Distributed in intercostal spaces
7-11: Supply anterior abdominal wall
Anterior ramus of 12: Runs forward in abdomen as subcostal nerve

30
Q

What do the intercostal nerves supply?

A

Skin
Muscles of the intercostal space and abdomen
Parietal pleura and parietal peritoneum

Intercostal nerves are mixed nerves because they are both sensory and motor nerves

31
Q

What are the branches of the intercostal nerves?

A

CLAMPPR
Collateral branches
Lateral cutaneous
Anterior cutaneous
Muscular branches
Pleural
Peritoneal (7th-11th)
Rami communicantes

32
Q

What are the atypical intercostal nerves?

A

First thoracic nerve
Second thoracic nerve

33
Q

Why is the first thoracic nerve an atypical nerve?

A

Has no anterior cutaneous branch
Joined to the brachial plexus by a large branch that corresponds to the lateral cutaneous branch

34
Q

Why is the second thoracic nerve an atypical nerve?

A

Joined to the medial cutaneous nerve of the arm by brachial plexus by a branch called the intercostobrachial nerve that corresponds to the lateral cutaneous branch

35
Q

How many arteries does each intercostal space contain?

A

One posterior and two anterior intercostal arteries

Each artery gives off branches to the muscles, skin, parietal pleura and breast tissue

36
Q

What is the origin of the posterior intercostal arteries?

A

Upper two: Superior intercostal artery (branch of costocervical truck of the subclavian artery)
Lower nine: Branches of thoracic aorta

Branching and course of intercostal arteries follows intercostal nerves

37
Q

What is the origin of the anterior intercostal arteries?

A

Upper six: Internal thoracic artery
Lower five: Musculophrenic artery

Anterior and posterior intercostal arteries form anastomosis

38
Q

What are the characteristics of intercostal veins?

A

Accompany intercostal arteries and nerves
Each space has posterior & anterior intercostal veins
Eleven posterior intercostal and one subcostal vein
Lie deepest in the costal grooves
Contain valves which direct the blood posteriorly

39
Q

Where do the posterior intercostal veins on the right side drain?

A

First space: Right brachiocephalic vein
All other intercostal spaces: Azygous vein

40
Q

Where do the posterior intercostal veins on the left side drain?

A

Upper three intercostal spaces: Left brachiocephalic vein
Rest of intercostal spaces: Hemiazygos and accessory hemiazygos veins, which drain into the azygos vein

41
Q

Where do the anterior intercostal veins drain?

A

Lower five spaces: Musculophrenic vein (tributary of internal thoracic vein)
Upper six spaces: Internal thoracic vein (which drains into subclavian vein)

42
Q

Where do lymph vessels drain?

A

Anteriorly drain into anterior intercostal nodes that lie along the internal thoracic artery
Posteriorly drain into posterior intercostal nodes that lie in the posterior mediastinum

Deep lymphatics generally follow arteries

MD1S2: Anatomy 202 (33 decks)

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