Thorax Flashcards
Mediastinum
Cavity in the median sagittal position of the thorax.
Contains: Heart Oesophagus Trachea Major Systemic blood vessels Phrenic nerves
Function of the thorax
Protection:
- Thoracic wall protects vital organs: heart, lungs, great vessels
- Protects some viscera organs
Breathing:
- The pleural cavity contains the lungs and the cavity extends beyond the first rib
- The thoracic wall acts as mechanical support and well as the diaphragm which curves up to the 6th rib.
Conduit:
- Allows a passage for structures to connect from one region to another
- Connects organs in the thorax to other parts of the body
Sternum
Composed of :
Manubrium, Main body and Xiphoid process.
Forms a sternal angle that is can be seen in surface anatomy- a bump
Allows attachment of true ribs: 1-7
Manubrium
Superior section of the sternum.
Superior surface contains a jugular notch.
Attached to main body through a manubriosternal joint.
Allows attachment for the first rib and the upper end of rib 2 through the demifacet.
Contains oval fossa for the attachment of the clavicle.
Main body of the sternum.
Inferior to the manubrium inferior to the xiphoid process.
At the lateral superior border contains demifacet for the attachment of the second rib.
Contains articular facets for the attachments for ribs 3-6.
The lateral inferior border contains a demifacet for rib 7.
The anterior surface contains many transverse ridges
Xiphoid process
The inferior sections of the sternum.
The anterior lateral margin contains:
A demifacet for the articulation of the costal cartilage of the inferior end of the 7th rib.
Describe a typical rib
Includes ribs 3-9, 10
Contains: Head, neck, angle, costal cartilage and costal groove, tubercle.
Head: Contains two articular surfaces separated by a crest.
Tubercle: Contains non-articular and articular regions. Articular region articulates with the transverse process of the vertebrae.
Non-articular forms attachments to the vertebrae by a ligament.
Costal groove: Section where nerves and blood vessels run.
Costal margin: Anterior end of the rib which articulates with the sternum or other ribs.
True rib
Ribs that articulate with the sternum:
Ribs 1-7
False rib
RIbs that articulate with other ribs:
Ribs 8-10
Floating ribs
Ribs that do not articulate to the sternum or other ribs:
Ribs 11-12
Articular facet of ribs
The superior articular facet at the posterior end attaches to the inferior costal facet of the vertebrae above its associated one.
The inferior articular facet attaches to the superior costal facet of its associated vertebrae.
Typical thoracic vertebrae
Includes ribs 2, 3-8 and 9 sometimes
Contains:
- Heart shaped vertebral body.
- Lamina which overlaps with the vertebrae below.
- Superior articular process and inferior articular process.
- Costal facet:
Superior articulates with the inferior end of its own rib.
Inferior articulates with the superior end of the rib below. - Transverse process: Allows attachment of tubercle, contains facets for the articulation with the tubercle.
Spinous process: Inferior pointing
The atypical thoracic vertebrae
T 1, 10-12 and sometimes 9
1- Contains complete costal facet which allows rib 1 to only attach to T1 and not T2 as well
10- Single costal facet.
11+12- Single costal facet and no costal facet on the transverse process.
Costotransverse
Synovial joint between the tubercle and transverse process of a vertebrae.
Costochondral
Joint between a rib and costal cartilage between ribs.
Sternocostal
Joint between the costal cartilage from the rib and the sternum
Costovertebral
Joint between a rib and a vertebrae:
Between the articular facets of the head of the rib and the costal facets of the vertebrae.
Costotransverse
Joint between the tubercle of the rib and the transverse process of the vertebrae.
Sternoclavicular
Joint between the sternum and clavicle.
Inferior thoracic aperture.
Bottom of the thoracic cage:
Border:
- Body of T12, posteriorly
- Xiphoid process, anteriorly
- Rib 12 and distal rib 11, posteriolaterally
- Costal cartilage of ribs 7-10, anteriolaterally
Superior thoracic aperture
Superior opening of the thoracic cage.
Borders:
- Body of T1, posteriorly
- Manubrium, anteriorly
- Rib 1 on each side at the medial margin. This is angled anteriorly.
Describe some of the paediatric variations in the thoracic wall
- Ribs are more horizontal,
- Xiphoid process may protrude
- More circular cavity which causes less expansion laterally when breathing.
Origin and insertion of the pectoralis major
Insertion:
Lateral lip of the intertubercular sulcus of the humerus.
Origins:
Medial half of the clavicle
Anterior surface of the sternum and costal cartilages 1-7
Innervation of the pectoralis major
Medial and lateral pectoral nerves.
Function of the pectoralis major
Medial rotation of the arms.
Flexion of the humerus at the shoulder.
Adduction.
Origin and insertion of the pectoralis minor.
Origin:
Ribs 3-5
Insertion:
Coracoid process of the scapula.
Innervation of the pectoralis minor
Medial pectoral nerve
Function of the pectoralis minor
Stabilises the scapula
Pulls the tip of the shoulder inferiorly
Describe the glands of the breast.
Mammary glands, secretory glands:
Drains into lactiferous ducts and out the lactiferous sinus
Bloody supply of the breast
Branches of the internal thoracic artery.
2-4th intercostal arteries supply the anteromedial part of the breast.
Innervation of the breast.
- Anterior and lateral cutaneous branches of the second to sixth intercostal nerves.
- The nipple is innervated by the fourth intercostal nerve.
Lymphatic vessels of the breast.
25% of lymph drains into the parasternal lymphatic vessel.
75% drains into the axillary region.
Innervation and function of the external intercostal muscle
Innervation:
Intercostal nerves originating from T1- T11
Function:
Moves ribs superiorly
Runs in the Inferior/ anterior direction
Innervation and function of the internal intercostal muscle
Innervation:
Intercostal nerves arising from T1-T11
Function:
Moves ribs inferiorly, allows forced exhalation
Runs in the inferior/ posterior direction
Innervation and function of the innermost intercostal muscle
Innervation:
Intercostal nerves arising from T1-T11
Function:
Moves ribs inferiorly
Runs in the inferior/ posterior direction
Blood supply of the intercostal muscles
Arterial:
Anterior and posterior intercostal arteries.
Vein:
Internal thoracic veins
Serratus anterior
Most superficial muscle in the thoracic wall.
Sits on the lateral surfaces of ribs 1-9
Origin and insertion of the serratus anterior
Origin:
Ribs 1-9
Insertion:
Medial border of the scapula
Function of the serratus anterior
Protracts the scapula
Innervation of the serratus anterior
Long thoracic nerve:
branched from the brachial plexus
Scalene tubercle
Located on the first rib: Separates two grooves.
The anterior groove is where the subclavian vein sits
The posterior groove is where the subclavian artery sits.
