Anatomy of the Thoracic Wall

Question 1

What is the purpose of the Thorax?

Answer 1

• Provides protection for underlying structures and organs
• Assists in respiration by resisting negative intra-thoracic pressure
• Provides attachments for muscles
• Haematopoiesis - especially in the sternum
• Connects to the neck, upper limbs and abdomen

Question 2

What makes up the Thoracic Cage?

Answer 2

• Sternum
• 12 Pairs of Ribs
• Costal Cartilages
• 12 Thoracic Vertebrae and their Intervertebral disks

Question 3

What makes up the Thoracic Wall?

Answer 3

• Thoracic Cage
• Skin and subcutaneous tissue
• Thoracic muscles and fascia
• Intercostal Muscles - 3 layers
• Mammary Glands/Breast Tissue

Question 4

Describe the movements permitted by the Thoracic Vertebrae

Answer 4

Some rotation due to arcuate arangement of articular facets, but no flexion

Question 5

What is the purpose of Costal Cartilage?

Answer 5

Provides Mobility and Elasticity

Question 6

What are the True Ribs?

Answer 6

Ribs 1-7 which attach to the Sternum directly through their own Costal Cartilage

Question 7

What are False Ribs?

Answer 7

Ribs 8-10 which attach to the Sternum indirectly through Costal Cartilage of Rib 7

Question 8

What are Floating Ribs

Answer 8

Ribs 11-12 which don’t articulate with Sternum

Question 9

Describe the structure of a typical Rib

Answer 9

Consists of a Head with two articular facets divided by a Ridge, a neck, a tubercle with an articular surface, the angle - the sharpest curve of the rib, vulnerable to breakage, and the shaft. A Costal Groove is present on the inner inferior border of the rib and covers the intercostal nerves and vessels.

Question 10

Which Ribs are classified as ‘typical’?

Answer 10

Ribs 2-9

Question 11

Describe the structure of the First Rib

Answer 11

Head has only one articular facet, articulates with T1 only. Scalene tubercle present on superior surface divides the groove for the subclavian vein and groove for subclavian artery and inferior trunk (C8 and T1) of the brachial plexus.

Question 12

Describe the structure of the 11th and 12th Ribs

Answer 12

Head has only one articular facet, articulate only with corresponding vertebrae. No Tubercle as they do not articulate with transverse precesses. Are not attached to Sternum

Question 13

Describe the structure of the Sternum

Answer 13

Made up of 3 parts:
* Manubrium
* Body
* Xiphoid Process

Question 14

What is the sternal angle?

Answer 14

Joint between Manubrium and Sternal Body

Question 15

What occurs at the level of the Sternal Angle?

Answer 15

• 2nd Costal Cartilage joins Sternum
• Intervertebral disk between T4 and T5 vertebrae
• Beginning and End of Aortic Arch
• Bifurcation of the Trachea (Carina)
• Superior limit of the Pulmonary Trunk
• Azygos Vein opening to the Superior Vena Cava
• Ligamentum Ateriosum

Question 16

What useful surface feature can be found at the Xiphosternum?

Answer 16

T6 Dermatome

Question 17

Name the Joint that occurs between a Vertebra and a Rib

Answer 17

Costovertebral Joint

Question 18

Name the Joint that occurs between the Tubercle of the Rib and the Transverse Process of its corresponding Vertebrae

Answer 18

Costotransverse Joint

Question 19

Describe Costotransverse Joints 1-7

Answer 19

Have curved facets allowing for rotatory movement

Question 20

Describe Costotransverse Joints 8-10

Answer 20

Have flat facets allowing for gliding movement

Question 21

Describe the Costochondral Joint

Answer 21

All ribs articulate anteriorly with a costal cartilage via a primary cartilagenous joint

Question 22

Name the Joint that occurs between the Costal Cartilage and the Sternum

Answer 22

Sternocostal Joint

Question 23

What is unique about the Costochondral Joint of Ribs 9 and 10

Answer 23

It is fibrous, whilst all others are synovial

Question 24

Describe the Thoracic Inlet

Answer 24

• Bound by T1 Vertebra, 1st Rib and Costochondral Joint and Manubrium
• Slopes antero-inferiorly to the level of T2-3
• Apex of Lung extends 2-3cm above the anterior part of 1st Rib and Clavicle

Question 25

What structures pass through the Thoracic Inlet?

Answer 25

* Vessels that supply and drain the head and neck * Trachea * Oesophagus * Vagus Nerve and Recurrent Laryngeal Nerve * Phrenic Nerve

Question 26

What Structures lie on the 1st Rib?

Answer 26

* Subclavian Vein * Subclavian Artery * Inferior Trunk of Brachial Plexus

Question 27

Describe the Thoracic Outlet

Answer 27

Bound by **T12 vertebra**, **11th and 12th Ribs**, **Costal Cartilage of Ribs 7-10** and **Xiphoid Process**. Closed incompletely by **diaphragm**.

Question 28

What is affected by Thoracic Outlet Syndrome?

Answer 28

Thoracic Inlet

Question 29

What is the cause of Thoracic Outlet Syndrome?

Answer 29

Structures lying in the Thoracic Inlet may be compressed by Muscles, Narrow Bony Passages or Pathology

Question 30

What are some symptoms of Thoracic Outlet Syndrome?

Answer 30

* Pain and parathaesia in upper limb * Weakening grip * Discolouration/ swelling in hand/ limb * Throbbing lump near clavicle * Upper limb fatigue * Cold hands * Raynaud’s phenomenon * Pallor in hand/ fingers * Weakness/ absence of pulses in upper limb

Question 31

Describe the Breast

Answer 31

* Consists of Mammary Glands, Skin and Connective Tissue * Modified Sweat Gland * Similar structure in males and prepubertal females * Surface features include Areola and Nipple

Question 32

What is the importance of 'Milk Lines'

Answer 32

Locations along which **supernumery nipples** may occur - present in **1:500** people

Question 33

Describe the Areola

Answer 33

* Contains Areolar Glands - Type of Sebaceous Gland * Montgomery Tubercles are visible portions of Areolar Glands * Secretions assist in forming a seal during feeding

Question 34

Describe the location of the Breast in an Adult Female

Answer 34

* Base located between 2nd and 7th Ribs * From Lateral border of Sternum to Mid-axillary line * Upper lateral section may extend towards the axilla

Question 35

Describe the Fascias of the Breast

Answer 35

Superficial and Deep Breast Fascias derived from Superficial Fascia

Question 36

Describe the Structure of the Breast

Answer 36

* 15-25 lobes made up of lobules and ducts * Surrounded by fat and connective tissue network * Suspensory Ligaments formed from connective tissue - Cooper's ligaments

Question 37

What is the Retromammary Space?

Answer 37

Layer of **loose connective tissue** between the **deep fascia of breast** and **deep pectoral fascia**

Question 38

Describe the Blood supply of the Breast

Answer 38

Internal Thorcic Artery * Mammary Branches * Anterior Intercostal Arteries Axillary Artery * Lateral Thoracic Artery * Thoracoacromial Artery Venous drainage follows the arteries * Axillary Vein * Internal Thoracic Vein

Question 39

Describe the Lymphatic Drainage of the Breast

Answer 39

Areola and Lateral Quadrants * Axillary Lymph Nodes Medial Quadrants * Parasternal Lymph Nodes * Opposite Breast Inferior Quadrants * Inferior Phrenic Lymph Nodes

Question 40

Describe External Intercostal Muscle

Answer 40

* Extend from the inferior edge of the rib above, to superior edge of the rib below * Anteriorly, muscle fibres are replaced by external intercostal membrane * Raise ribs in forced inspiration, * Prevent indrawing during inspiration

Question 41

Describe Internal Intercostal Muscle

Answer 41

* Extend from the lateral edge of costal groove of the rib above, to superior edge of the rib below * Posteriorly, muscle fibres are replaced by internal intercostal membrane * Prevent indrawing during inspiration * Aids elastic recoil by moving ribs inferiorly in expiration

Question 42

Where do Intercostal Neves lie?

Answer 42

In the Costal Groove at Inferior Edge of the Rib Travels together with the Intercostal Vein and Artery - ordered VAN

Question 43

What Spinal Nerves form Intercostal Nerves

Answer 43

Anterior Rami of all Thorcic Spinal Nerves exept T1