Thorax Cardiovascular

Question 1

Surface projection of sternum

Answer 1

Description:
• Flat bone with three parts: manubrium, body, and xiphoid process
• Characteristic features include jugular notch and sternal angle (angle of Louis)
• Articulates with upper seven costal cartilages and clavicles

Also known as:
• Sternum also known as the “breastbone”

Comment:
• Provides attachment for pectoralis major muscle

Question 2

Cephalic v.

Answer 2

Cephalic v.
Drainage:
• Skin and subcutaneous structures of lateral and dorsal hand, forearm, and arm

Course:
• Ascends from dorsum of hand to anterolateral forearm and arm
• Passes into deltopectoral triangle

Question 3

Pectoralis major m.

Answer 3

Action:
• Adduction of arm
• Medial rotation of arm
• Clavicular head: flexion of arm
• Sternocostal head: extension of arm (from flexed position)

Innervation:
• Lateral pectoral nerve (C5-7)
• Medial pectoral nerve (C8-T1)

Question 4

Pectoralis minor m.

Answer 4

Action:
• Stabilizes scapula (holds it against thoracic wall)
• Protraction (abduction) of scapula (assists serratus anterior)
• Lateral rotation of scapula (e.g., depresses the acromion)

Innervation:
• Medial and lateral pectoral nerves

Comment:
• Pectoralis major and minor muscles also known as “pecs”
• Pectoralis minor active during forced inspiration

Question 5

Sternum

Answer 5

Description:
• Flat bone with three parts: manubrium, body, and xiphoid process
• Characteristic features include jugular notch and sternal angle (angle of Louis)
• Articulates with costal cartilages of true ribs (1-7), combined costal cartilages of false ribs (8-10), and clavicles

Also known as:
• “Breastbone”

Comment:
• Floating ribs (ribs 11-12): not attached to sternum
• Provides for attachment of sternocleidomastoid, pectoralis major, sternohyoid, and sternothyroid muscles

Question 6

Costal cartilages

Answer 6

Description:
• Attaches rib to sternum
• True ribs (ribs 1-7): attached directly to sternum by costal cartilages
• False ribs (ribs 8-10): attach indirectly to sternum via a shared costal cartilage
• Costal margin created by costal cartilages of ribs 7-10

Question 7

Internal thoracic a.

Answer 7

Course:
• Descends adjacent to sternum within thoracic cavity

Distribution:
• Intercostal spaces
• Breast
• Pericardium
• Diaphragm
• Anterior abdominal wall

Branches:
• Anterior intercostal
• Pericardiacophrenic
• Superior epigastric
• Musculophrenic

Also known as:
• Internal mammary artery

Question 8

Internal thoracic v.

Answer 8

Drainage:
• Anterior thoracic wall, including breast
• Anterior abdominal wall
• Diaphragm
• Pericardium

Tributaries:
• Musculophrenic
• Superior epigastric
• Pericardiacophrenic
• Anterior intercostal

Course:
• Ascends posterior to costal cartilages, just lateral to sternum

Also known as:
• Internal mammary vein

Comment:
• Formed by union of superior epigastric and musculophrenic veins

Question 9

Thyroid gland

Answer 9

Description:
• Bilobed endocrine gland
• Normally composed of left and right lateral lobes connected across midline by isthmus of gland

Function:
• Follicular cells: synthesize and secrete thyroid hormones T3 (triiodothyronine) and T4 (thyroxine)
• Parafollicular cells: synthesize and secrete calcitonin

Comment:
• Lobes lie lateral to trachea and larynx
• Enlarged thyroid gland known as a goiter, typically due to insufficient dietary iodine

Question 10

Parietal pleura

Answer 10

Description:
• Thin, serous membrane
• Lines pulmonary cavity
• Fused to internal walls of thoracic cavity and lateral surface of mediastinum
• Continuous with visceral pleura at root of lung
• Regions include mediastinal, cervical, diaphragmatic, and costal

Comment:
• Pleural cavity created by narrow space between parietal and visceral layers of pleura
• Thorax has three subdivisions: mediastinum and right and left pulmonary cavities
• Costal and peripheral diaphragmatic pleura innervated by intercostal nerves

Question 11

Right lung

Answer 11

Description:
• Three lobes: upper (or superior), middle, and lower (or inferior), separated by two fissures - oblique and horizontal
• Medial surface has hilum with airway and pulmonary vessels
• Surface of lung covered with visceral pleura

Function:
• Primary organ of respiration

Question 12

Visceral pleura

Answer 12

Description:
• Thin, serous membrane
• Fused to surface of lung
• Continuous with parietal pleura at root of lung
• Separated from parietal pleura by pleural cavity

Comment:
• Thoracic cavity divided into midline mediastinum and right and left pulmonary cavities

Question 13

Phrenic nerve

Answer 13

Contributions:
• Ventral rami of C3-5 spinal nerves

Motor:
• Diaphragm

General sensation:
• Parietal layer of pleura and peritoneum over central diaphragm
• Mediastinal pleura
• Parietal pericardium

Comment:
• Supplies all motor innervation to diaphragm (hint: remember C3, 4, 5 “keeps the diaphragm alive”)

Question 14

Thymus Gland

Answer 14

Description:
• Large, bilobed gland in children
• Atrophies during adolescence
• Remnant in adults consists primarily of fibrous and adipose tissue

Function:
• Secretes thymopoietin and thymosins that stimulate and promote differentiation, growth and maturation of T-lymphocytes
• Site for maturation and differentiation of T-lymphocytes (primarily in young individuals)

Question 15

Fibrous pericardium

Answer 15

Description:
• Forms fibrous sac enclosing heart
• External to serous pericardium
• Fused to diaphragm
• In contact with parietal (mediastinal) pleura

Question 16

Left lung

Answer 16

Description:
• Two lobes: upper (or superior) and lower (or inferior), separated by oblique fissure
• Medial surface has hilum with airway and pulmonary vessels
• Surface of lung covered with visceral pleura

Function:
• Primary organ of respiration

Question 17

Axillary v.

Answer 17

Drainage:
• Pectoral, shoulder, and scapular regions

Course:
• Passes through axilla with axillary artery surrounded by cords and branches of brachial plexus

Termination:
• Continues as subclavian vein at lateral border of rib 1

Comment:
• Single, large, deep vein that accompanies axillary artery
• Axillary vein formed by continuation of basilic vein, with contribution of paired brachial veins

Question 18

Right brachiocephalic v.

Answer 18

Drainage:
• Head and neck (right side)
• Upper limb (right)

Tributaries:
• Internal jugular
• Subclavian

Course:
• Descends vertically from junction of internal jugular and subclavian veins
• Posterior to right sternoclavicular junction
• Does not cross midline

Also known as:
• Right innominate vein (Latin: innominatus = nameless)

Comment:
• Lacks valves

Question 19

Superior vena cava

Answer 19

Drainage:
• Head
• Upper limbs
• Posterior thoracic walls
• Mediastinal structures

Tributaries:
• Formed by union of right and left brachiocephalic veins
• Arch of azygos vein

Course:
• Descends in mediastinum from level of right 1st costal cartilage

Termination:
• Right atrium

Question 20

Pulmonary a.

Answer 20

Course:
• Left: laterally, inferior to arch of aorta and anterior to left main bronchus
• Right: laterally, posterior to ascending aorta and superior vena cava
• Through root and hilum of respective lungs

Distribution:
• Lung

Branches:
• Lobar arteries to lung lobes

Comment:
• Conveys oxygen-poor blood to lung

Question 21

Right auricle

Answer 21

Description:
• Small, conical, pouch-like extension of right atrium
• Thin, rough wall (pectinate muscles)

Question 22

Right atrium

Answer 22

Description:
• One of four heart chambers
• Thin, smooth, posterior wall
• Thin, rough anterior wall (pectinate muscles)
• Receives superior and inferior venae cavae and coronary sinus
• Internal features include interatrial septum, fossa ovalis, and crista terminalis

Comment:
• Forms right surface of heart
• Separated from right ventricle by atrioventricular (tricuspid) valve

Question 23

Ascending aorta

Answer 23

Origin:
• Left ventricle (aortic vestibule)

Distribution:
• Heart (via coronary arteries)

Branches:
• Right and left coronary arteries
• Continues as arch of aorta

Comment:
• Has aortic valve at origin
• Large arteries do not by themselves supply structures, but do so through their branches

Question 24

Arch of aorta

Answer 24

Course:
• Arches diagonally and posteriorly to the left

Distribution:
• Head, including brain
• Neck
• Upper extremities

Branches:
• Brachiocephalic trunk 
• Left common carotid 
• Left subclavian 
• Continues as descending (thoracic) aorta 

Comment:
• Ligamentum arteriosum attached to concave surface of arch
• Large arteries do not by themselves supply structures, but do so through their branches

Question 25

Left brachiocephalic v.

Answer 25

Drainage:
• Head and neck (left side)
• Upper limb (left)

Course:
• Descends obliquely to the right from junction of internal jugular and subclavian veins
• Posterior to manubrium
• Crosses midline

Termination:
• Superior vena cava

Also known as:
• Left innominate vein (Latin: innominatus = nameless)

Comment:
• Lacks valves

Question 26

Subclavian v.

Answer 26

Drainage:
• Upper limb
• Superficial back and neck

Course:
• Begins at lateral border of rib 1
• Arches over rib 1 to enter thoracic cavity

Termination:
• Joins internal jugular vein posterior to sternum to form brachiocephalic vein

Comment:
• Lies anterior to anterior scalene muscle
• Access point to large veins for insertion of electrical leads for heart pacemaker or tubes to administer chemotherapeutic agents to cancer patients

Question 27

Pulmonary trunk

Answer 27

Origin:
• Right ventricle

Course:
• Ascends within pericardium
• Initially anterior to ascending aorta and then to its left and slightly posterior

Distribution:
• Lungs

Branches:
• Right pulmonary artery
• Left pulmonary artery

Comment:
• Conveys oxygen-poor blood from right ventricle of heart
• Has pulmonary (semilunar) valve at its origin
• Large arteries do not by themselves supply structures, but do so through their branches

Question 28

Internal jugular v.

Answer 28

Drainage:
• Cranial cavity, including brain
• Face
• Neck

Course:
• Formed in jugular foramen of skull
• Descends through neck in carotid sheath
• Enters thorax

Termination:
• Posterior to sternum unites with subclavian vein to form brachiocephalic vein

Comment:
• Enclosed in carotid sheath

Question 29

Left recurrent laryngeal n.

Answer 29

Contributions:
• Branch of vagus nerve (CN X) in thorax

Motor:
• Intrinsic laryngeal muscles, except cricothyroid

Sensory:
• Mucous membranes of trachea and larynx (inferior to vocal fold)

Comment:
• In thorax, left recurrent laryngeal nerve loops inferior to arch of aorta
• In thorax, right recurrent laryngeal nerve loops inferior to right subclavian artery
• Recurrent laryngeal nerves ascend in neck to larynx
• Terminal part (within larynx) is termed inferior laryngeal nerve

Question 30

Ligamentum arteriosum

Answer 30

Ligamentum arteriosum
Origin:
• Left pulmonary artery

Course:
• Ascends to attach to arch of aorta on its concave surface

Comment:
• A fibrous cord
• Remnant of ductus arteriosus in fetus
• Ductus arteriosus shunts blood in fetus from pulmonary artery to aorta, thereby bypassing lungs

Question 31

Right ventricle

Answer 31

Location:
• Heart

Description:
• One of four heart chambers
• Rough, muscular walls (trabeculae carneae)
• Muscle wall thicker than either atrium, and thinner than left ventricle
• Internal features include papillary muscles, chordae tendineae, interventricular septum, and conus arteriosus

Comment:
• Separated from right atrium by atrioventricular (tricuspid) valve
• Separated from pulmonary trunk by pulmonary valve
• Responsible for pumping oxygen-poor blood to lungs

Question 32

Heart

Answer 32

Description:
• Conical, muscular organ with four chambers: two atria and two ventricles

Function:
• Pumps blood to body
• Modified cardiac muscle cells in right atrium secrete the hormone atriopeptin (atrial natriuretic peptide) in response to distension (stretching) of the atrial wall
• Atriopeptin reduces blood volume by causing water loss and sodium excretion into urine (with less blood volume, blood pressure is reduced)

Question 33

Left Ventricle

Answer 33

Description:
• One of four heart chambers
• Thick, muscular walls
• Internal features include papillary muscles, chordae tendineae, trabeculae carneae, interventricular septum, and aortic vestibule

Comment:
• Separated from left atrium by left atrioventricular (bicuspid or mitral) valve
• Separated from aorta by aortic valve
• Walls twice as thick as right ventricle
• Forms apex of heart
• Responsible for pumping oxygen-rich blood to body (except lungs)

Question 34

Apex of Heart

Answer 34

Location:
• Heart (inferolateral point)

Description:
• Blunt tip of left ventricle

Comment:
• Surface projection at left 5th intercostal space in mid-clavicular line

Question 35

Left common carotid a.

Answer 35

Course:
• Exits thorax and ascends in neck

Branches:
• Internal and external carotid arteries (at level of C4 vertebra)

Comment:
• Has no branches before terminal branches
• Enclosed in carotid sheath
• Carotid sheath is a fascial sleeve which contains common and internal carotid arteries, internal jugular vein, vagus nerve (CN X), and lymphatic channels
• Large arteries do not by themselves supply structures, but do so through their branches

Question 36

Left main bronchus

Answer 36

Description:
• Formed at bifurcation of trachea
• Longer, more narrow, and less vertical than right main bronchus
• Component of root and hilum of left lung

Comment:
• Foreign bodies that enter trachea tend to pass to right main bronchus

Question 37

Right main bronchus

Answer 37

Description:
• Formed at bifurcation of trachea
• Shorter, wider, and more vertical than left main bronchus
• Component of root and hilum of right lung

Also known as:
• Right primary bronchus

Comment:
• Foreign bodies that enter trachea tend to pass to right main bronchus

Question 38

Pulmonary vv.

Answer 38

Drainage:
• Lungs

Course:
• Two veins pass through root of each lung (i.e., four pulmonary veins in total) and directly into left atrium

Comment:
• Pulmonary veins carry oxygen-rich blood

Question 39

Parietal layer of serous pericardium

Answer 39

Description:
• Thin, serous membrane fused to inner surface of fibrous pericardium
• Outer limit of pericardial cavity
• Continuous with visceral layer of serous pericardium

Comment:
• Pericardial cavity created by narrow space between parietal and visceral layers of serous pericardium

Question 40

Inferior vena cava

Answer 40

Drainage:
• Everything inferior to diaphragm, except posterior abdominal wall, which drains into azygos system

Course:
• Ascends from level of L4 vertebral body, through diaphragm, to heart

Termination:
• Right atrium of heart

Comment:
• Largest vein of body