Anatomy of the Thoracic Wall Flashcards
What is the purpose of the Thorax?
- 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
What makes up the Thoracic Cage?
- Sternum
- 12 Pairs of Ribs
- Costal Cartilages
- 12 Thoracic Vertebrae and their Intervertebral disks
What makes up the Thoracic Wall?
- Thoracic Cage
- Skin and subcutaneous tissue
- Thoracic muscles and fascia
- Intercostal Muscles - 3 layers
- Mammary Glands/Breast Tissue
Describe the movements permitted by the Thoracic Vertebrae
Some rotation due to arcuate arangement of articular facets, but no flexion
What is the purpose of Costal Cartilage?
Provides Mobility and Elasticity
What are the True Ribs?
Ribs 1-7 which attach to the Sternum directly through their own Costal Cartilage
What are False Ribs?
Ribs 8-10 which attach to the Sternum indirectly through Costal Cartilage of Rib 7
What are Floating Ribs
Ribs 11-12 which don’t articulate with Sternum
Describe the structure of a typical Rib
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.
Which Ribs are classified as ‘typical’?
Ribs 2-9
Describe the structure of the First Rib
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.
Describe the structure of the 11th and 12th Ribs
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
Describe the structure of the Sternum
Made up of 3 parts:
* Manubrium
* Body
* Xiphoid Process
What is the sternal angle?
Joint between Manubrium and Sternal Body
What occurs at the level of the Sternal Angle?
- 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
What useful surface feature can be found at the Xiphosternum?
T6 Dermatome
Name the Joint that occurs between a Vertebra and a Rib
Costovertebral Joint
Name the Joint that occurs between the Tubercle of the Rib and the Transverse Process of its corresponding Vertebrae
Costotransverse Joint
Describe Costotransverse Joints 1-7
Have curved facets allowing for rotatory movement
Describe Costotransverse Joints 8-10
Have flat facets allowing for gliding movement
Describe the Costochondral Joint
All ribs articulate anteriorly with a costal cartilage via a primary cartilagenous joint
Name the Joint that occurs between the Costal Cartilage and the Sternum
Sternocostal Joint
What is unique about the Costochondral Joint of Ribs 9 and 10
It is fibrous, whilst all others are synovial
Describe the Thoracic Inlet
- 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
What structures pass through the Thoracic Inlet?
- Vessels that supply and drain the head and neck
- Trachea
- Oesophagus
- Vagus Nerve and Recurrent Laryngeal Nerve
- Phrenic Nerve
What Structures lie on the 1st Rib?
- Subclavian Vein
- Subclavian Artery
- Inferior Trunk of Brachial Plexus
Describe the Thoracic Outlet
Bound by T12 vertebra, 11th and 12th Ribs, Costal Cartilage of Ribs 7-10 and Xiphoid Process. Closed incompletely by diaphragm.
What is affected by Thoracic Outlet Syndrome?
Thoracic Inlet
What is the cause of Thoracic Outlet Syndrome?
Structures lying in the Thoracic Inlet may be compressed by Muscles, Narrow Bony Passages or Pathology
What are some symptoms of Thoracic Outlet Syndrome?
- 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
Describe the Breast
- Consists of Mammary Glands, Skin and Connective Tissue
- Modified Sweat Gland
- Similar structure in males and prepubertal females
- Surface features include Areola and Nipple
What is the importance of ‘Milk Lines’
Locations along which supernumery nipples may occur - present in 1:500 people
Describe the Areola
- Contains Areolar Glands - Type of Sebaceous Gland
- Montgomery Tubercles are visible portions of Areolar Glands
- Secretions assist in forming a seal during feeding
Describe the location of the Breast in an Adult Female
- Base located between 2nd and 7th Ribs
- From Lateral border of Sternum to Mid-axillary line
- Upper lateral section may extend towards the axilla
Describe the Fascias of the Breast
Superficial and Deep Breast Fascias derived from Superficial Fascia
Describe the Structure of the Breast
- 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
What is the Retromammary Space?
Layer of loose connective tissue between the deep fascia of breast and deep pectoral fascia
Describe the Blood supply of the Breast
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
Describe the Lymphatic Drainage of the Breast
Areola and Lateral Quadrants
* Axillary Lymph Nodes
Medial Quadrants
* Parasternal Lymph Nodes
* Opposite Breast
Inferior Quadrants
* Inferior Phrenic Lymph Nodes
Describe External Intercostal Muscle
- 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
Describe Internal Intercostal Muscle
- 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
Where do Intercostal Neves lie?
In the Costal Groove at Inferior Edge of the Rib
Travels together with the Intercostal Vein and Artery - ordered VAN
What Spinal Nerves form Intercostal Nerves
Anterior Rami of all Thorcic Spinal Nerves exept T1
