Untitled Quiz

Thorax & Ribs

• The thorax is the region between the neck and the abdomen
• It protects thoracic organs (heart and lungs)
• It provides attachment for the upper extremities (UE)
• Intercostal muscles, diaphragm, and abdominals form rigid yet moveable walls

Thorax - Surface Anatomy

• Includes lines and segmented levels
• Ribs 1-12 and thoracic vertebrae 1-12
• Sternum
• Superior (thoracic outlet) and Inferior apertures

Thorax - Muscles

• Intercostals (external, internal, and innermost)
• Subcostal
• Transversus thoracis

Thorax - Neurovascular Bundles

• VAN (vein, artery, nerve)
• Diaphragm (superior to inferior)

Thorax - Surface Anatomy Detail

• Clavicles
• Suprasternal notch (T2)
• Xiphisternal junction (T9)
• Sternal angle (2nd costal cartilage and T4/T5)
• Xiphoid process (T10)
• Costal margin

Thorax - Axillary Lines

• Anterior
• Mid-axillary
• Posterior

Thorax - Bony Framework

• 12 ribs
• Costal cartilages
• Sternum (manubrium, body, xiphoid process)
• Thoracic vertebrae

Thorax - Types of Ribs

• True ribs (ribs 1-7): Articulate via costal cartilages with the sternum
• False ribs (ribs 8-10): Articulate via costal arches (don't attach directly to sternum)
• Floating ribs (ribs 11-12)

Thorax - Thoracic Apertures

• Superior aperture: Manubrium, Rib 1 and costal cartilage, T1 vertebrae
• Inferior aperture: T12 vertebrae, Ribs 11 and 12

Thorax - Superior Aperture

• Passageway for esophagus, trachea, great vessels & nerves of head/neck, & vessels of upper limbs, Apex of the lung
• Careful when dry needling around neck – may puncture top of lungs*

Thorax - Inferior Aperture

• Diaphragm is pushed upward to the sternum
• Innervation: phrenic nerve (C3, C4, C5)
• Costal margin

Thorax - Intercostal Muscles

• External intercostals ("hands in pockets")
• Internal intercostals ("hands on chest")
• Innermost intercostals

Thorax - Intercostal Spaces

• Muscles: external intercostal, internal intercostal, innermost intercostal
• Neurovascular bundle: intercostal vein, intercostal artery, intercostal nerve
• Intercostal nerve (anterior ramus): medial br, lateral br, anterior cutaneous branch, innermost intercostal, anterior br, lateral cutaneous branch, posterior br

Thorax - Segmented Levels

• Clavicle - C4
• Nipples (male - T4, females - T5)
• Umbilicus - T10
• Inguinal region - L1

Sympathetic Nervous System

• Cardiopulmonary & Abdominopelvic Splanchnics: How sympathetic fibers arrive at internal structures (heart, lungs, organs)
• It goes everywhere: Innervates internal structures + extremities, head
• Short pre-synaptic / long post-synaptic neuron
• Sympathetic chain ganglia: Along vertebral column, entire length
• Spinal cord: T1-L1/2: Cell bodies located

Sympathetic Neurons Presynaptic Cell Bodies

• It originates in spinal cord (T1-L2/3)
• Located more specifically in lateral horns of gray matter of spinal cord
• IML= intermediolateral cell column
• Conus medullaris: L1-L2

Sympathetic Neurons Presynaptic Neuron

• 2-neuron system
• Cell bodies of the first neuron are in the IML of the spinal cord
• The presynaptic neuron is short
• It only travels to the sympathetic chain ganglia on each side of vertebral column

Sympathetic Neurons Postganglionic Neuron

• Long post-synaptic neuron
• Locations: Body wall and limbs
• Functions: vasomotion, sudomotion, pilomotion

Thoracic Apertures

• Superior aperture
• Inferior aperture

Intercostal Muscles

• External intercostals
• Internal intercostals
• Innermost intercostals

Pericardium and the Heart

• Pericardium: sac enclosing the heart and roots of great vessels
• Two layers: fibrous pericardium and serous pericardium
• Function: Keeps heart in position & protects it, facilitates movement, separates from other structures, fuses with the central tendon of diaphragm
• It aids in open-heart surgery without pleural cavity problems

Pericardium - Clinical Correlations

• Pericarditis: Inflammation of the pericardium, causes chest pain
• Pericardial effusion: Fluid build up, compresses heart, causes reduced cardiac output, tachcardia, cardiac tamponade

Heart

• 4 chambers: 2 atria and 2 ventricles
• Venous input: SVC (superior vena cava), IVC (inferior vena cava), Coronary sinus
• Oxygen-poor blood: Venous system to heart via pulmonary arteries
• Oxygen-rich blood: Pulmonary veins, aortic blood, coronary vessels

Valves of the Heart

• Tricuspid valve: Between right atrium and ventricle (3 leaflets, 3 papillary muscles with chordae tendinae)
• Mitral valve: Between left atrium & ventricle (2 leaflets, 2 papillary muscles with chordae tendinae)
• Aortic valve
• Pulmonary valve

Semilunar Valves (Cusps)

• Aortic valve
• Pulmonary valve
• 3 cusps, concave when viewed from above
• No chordae tendinae
• Prevent backflow

Heart and the Great Vessels- Chambers

• 4 chambers, right atrium, left atrium, right ventricle, left ventricle
• Oxygenated blood enters left atrium
• Blood returns to the heart via superior and inferior vena cava
• Oxygenated blood returns to the right atrium via pulmonary veins

Heart and Great Vessels in Situ/Heart and Great Vessels-con't

• SVC
• IVC
• Aorta
• Pulmonary trunk
• Openings, arteries and veins

Heart and the Great Vessels - Veins

• R. Internal jugular vein
• R. Subclavian vein
• R & L Brachiocephalic vein (to SVC)
• L. Internal jugular vein
• L. Subclavian vein

Heart and the Great Vessels - Arteries

• R. Brachiocephalic trunk
• R. Subclavian artery
• L. Common carotid artery
• L. Subclavian artery
• Aorta

Branches from Aorta

• Right common carotid artery
• Right subclavian artery
• Brachiocephalic trunk
• Left common carotid artery
• Left subclavian artery
• Arch of aorta
• Ascending aorta
• Descending (thoracic) aorta

Conducting System of the Heart

• SA node: at the junction of the SVC and the right atrium
• Pacemaker
• Normal rhythm: 70 bpm
• Spreads through muscle of both atria
• Cardiac plexus (both SNS and PNS supply)
• Signal to AV node

Conducting System of the Heart (cont.)

• AV node: located in the interatrial septum near the coronary sinus
• Activated from SA node signal
• Propagates through AV bundle of His
• Divides into right and left bundles, each going to ventricle
• Moderator band in right ventricle to the anterior papillary muscle

Innervation of the Heart

• Sympathetic supply: Cardiopulmonary splanchnics and post-synaptic sympathetics
• Parasympathetic supply: Presynaptic fibers of the vagus nerve and post-synaptic cell bodies in intrinsic ganglia near SA and AV nodes

Clinical Implications

• Related topics, including possible conditions and testing

Thoracic Viscera

• Cardiopulmonary splanchnic nerves exit the ganglia medially instead of laterally, to the central structures