Anatomy of thoracic cage Flashcards
The 4 key components of anatomy of thoracic cage
Vertebrae, intervertebral discs, ribs, costal cartilages
Function of thoracic cage
Protect viscera, large area for muscle attachment, pectoral girdle for pec major, arm attached via sternoclavicular joint
How many pairs of ribs
12
True Ribs; number and features
1-7. Rib, CC, Sternum
False ribs; number and features
8-10. Rib, CC, CC joined together
Floating ribs; number and features
11-12. No CC
Typical rib; numbers
3-9
Atypical ribs: numbers
1,2,10,11,12
Features of a typical rib
Head with 2 facets, neck, tubercle with one facet, shaft, costal cartilage, costal groove for intercostal vein, artery and nerve
Features of an atypical rib
Head with one facet, neck, tubercle with one facet, shaft, costal groove for intercostal vein, artery and nerve
Features of thoracic vertebrae
Heart shaped body with 2 demifacets, 2 transverse processes with one facet on each, inferior-pointing spinous process, spinal canal
Name the joints of the thoracic wall.
Intervertebral, costovertebral, costotransverse, interchondral, costochondral, sternocostal, sternoclavicular
Features of Pectoralis Major
Origin/proximal attachment: clavicle, sternum, costal cartilages. Insertion/distal attachment: humerus. Function: adduction and medial rotation of humerus; adduction, flexion and internal rotation of shoulder joint. Innervation: Medial and lateral pectoral nerves.
Features of pectoralis minor
Origin/proximal attachment: 3rd-5th rib. Insertion/distal attachment: coracoid process of scapula. Function: Stabilises scapula; draws scapula inferiorly, anteriorly and medially; elevates ribs during exercise and excessive breathing. Innervation: Lateral Pectoral nerve.
Name the types of intercostal muscles, and their directions and features
External (anterior inferior), internal (posterior, inferior), innermost intercostal muscles. Supplied by intercostal artery, vein and nerve.
How are the intercostal muscles involved in breathing?
External crosses over internal intercostal muscles so can lift ribs during inspiration and crush during expiration
Serratus Anterior
Origin/proximal attachment: 1st-8th rib, sometimes 9th. Insertion/proximal attachment: medial border of scapula. Function: protract scapula, holds scapula flat against thoracic cage. Innervation: Long thoracic nerve.
Arterial supply of thoracic cage
Segmental arterial blood supply. Aorta heads down in front of vertebrae and at each vertebral level branches into a posterior intercostal artery in costal groove. Subclavian artery branches into anterior intercostal artery in costal grooves at each vertebral level. These arteries are right behind the sternum.
