The Thorax

Front 1

Thorax (Thorax Cavity)

Back 1

1) surrounded by ribs, sternum, and 12 thoracic vertebrae
a) thoracic diaphragm forms inferior boundary
2) rib cage provides protection for the heart & lungs and is part of mechanism for respiration

Front 2

Rib movements during respiration

Back 2

1) during inspiration, upper ribs are elevated, lower ribs are fixed in position, and the thoracic diaphragm contracts, causing top of diaphragm dome to move inferiorly (downward)
a) increase internal volume of thorax
b) decreases air pressure in thoracic cavity and thus draws air into lungs
2) elevation of ribs creates "bucket-handle" effect - ribs swing upward & away from body
a) articulations between vertebrae & rib provide for superior rotation of rib
b) increases both anterior-posterior and lateral dimensions of thorax

Front 3

Muscles Of Respiration
x 4
1) Thoracic Diaphragm

Back 3

contraction shortens muscle & resuces superior curve; resulting downward movement of diaphragm serves to increase internal thoracic volume

Front 4

Muscles Of Respiration
x 4
2) Sternocleidomastoid &
Scalene Muscles

Back 4

(anterior, posterior middle) - raise upper rib cage during forced inspiration

Front 5

Muscles Of Respiration
x 4
3) Quadratus Lumborum

Back 5

a) spans between posterior iliac crest and rib 12
b) anchors lower rib cage - resists upward pull on rib 12; elevate next lower rib

Front 6

Muscles Of Respiration
x 4
4) Intercostal Muscle

Back 6

maintain integrity of thoracic wall; elevate next lower rib

Front 7

Intercostal Muscles

Back 7

- fill intercostal spaces between adjacent ribs
1) external intercostal muscle - fibers run down & medially; elevate ribs during inspiration
2) Internal Intercostal Muscle - fibers run down & laterally (at right angle to external intercostal muscle); depress (lower) ribs during expiration
3) Innermost intercostal Muscle - fibers run down & laterally (same as internal intercostal)
a) intercostal artery, vein, & nerve run between internal & innermost intercostal layers

Front 8

Thoracic Diaphragm

1 of 2

Back 8

Origin - inferior sternum & xiphoid process, margin of rib cage (ribs 7-12), L1 - L3 vertebrae
Insert - fibers converge into aponeurotic central tendon; located at top of dome
Innerv - right & left phrenic nerves (from C3-C5 spinal nerves, via cervical plexus)

Front 9

Thoracic Diaphragm

2 of 2

Back 9

10 thoracic diaphragm seperates thoracic & abdominal cavities
a) dome-shaped muscle - top at level of rib 5 (on right side) or rib 6 (on left side) during normal expiration (approximate level of nipple in males)
b) during normal inspiration, moves approximately one rib lower
2) opening in diaphragm:
a) aortic hiatus - passage for aorta against vertebral column; at T12 vertebral level
b) esophageal hiatus - passage for esophagus & vagus nerves; at T10 level
c) caval hiatus - passage for inferior vena cava; at T8 level, within central tendon

Front 10

Blood Vessels of Thoracic Wall
x 3
1) Thoracic Aorta

Back 10

1) Descends along left side of vertebral column in upper thorax, then moves to mid-line before passing through diaphragm
a) posterior intercoastal arteries - one pair to each intercostal space;
1) artery runs in costal groove (along inferior margin of each rib), with intercostal vein & intercostal nerve
2) intercostal artery, vein, nerve run between internal intercostal & innermost intercostal muscle layers

Front 11

Blood Vessels of Thoracic Wall
x 3
2) Internal Thoracic Artery

Back 11

1) from subclavian artery
a) descends against anterior thoracic wall, along lateral border of sternum
b) gives off anterior intercostal artery to each intercostal space - anastomoses with posterior intercostal artery
2) At inferior end of sternum, internal thoracic artery divides into:
a) musculophrenic artry - follows medial edge of rib cage to supply remaining intercostal spaces
b) superior epigastric artery - runs inferiorly, deep to (supplies) rectus abdominis muscle
1) anastomoses with inferior epigastric artery (from external iliac artery)

Front 12

Blood Vessels of Thoracic Wall
x 3
3) Azygos Vein

Back 12

- receives drainage from posterior intercostal veins in each intercostal space
a) runs superiorly up right side of posterior thoracic wal
b) empties into posterior side of superior vena cava

Front 13

Nerves of the Thoracic Cavity
x4
1) Phrenic Nerves

Back 13

run inferiorly through thoracic cavity, on either side of heart - motor to thoracic diaphragm

Front 14

Nerves of the Thoracic Cavity
x4
2) Vagus Nerve CN X

Back 14

a) right & left vagus nerves enter thorax via base of neck
b) pass posterior to heart, then follow esophagus through diaphragm into abdominal cavity
c) in thorax, give off preganglionic parasympathetic fibers to heart & lungs
1) preganglionic axons synapse onto postganglionic neurons in terminal ganglia (located within walls of organs)

Front 15

Nerves of the Thoracic Cavity
x4
3) Thoracic Sympathetic Trunk

Back 15

a) interconnected chain ganglia running along either side of vertebral column
b) receives white rami communicantes (preganglionic sympathetic fibers) from T1-L2 spinal nerves
c) provides gray rami communicantes (postganglionic sympathetic fibers) to all spinal nerves
d) gives off greater Splanchnic Nerve (preganglionic sympathetic fibers)
1) passes inferiorly through diaphragm into abdominal cavity
2) synapses in collateral ganglia at base of major abdominal aorta arterial branches
3) postganglionic sympathetic fibers distribute with blood vessels to abdominal organs

Front 16

Nerves of the Thoracic Cavity
x4
4) Intercostal Nerves

Back 16

- motor to intercostal muscles & sensory to overlying skin
a) contrinuation of T1-T12 spinal nerves
b) intercostal nerves run in costal groove along inferior border of each rib, between internal intercostal & innermost intercostal muscle layers
c) also provide cutaneous innervation to skin via lateral & anterior cutaneous nerves

Front 17

Thoracic Cavity Divided into 3 areas

Back 17

1) two pulmonary cavities - located laterally; contain lungs, bronchi, pulmonary artery & veins
2) mediastinum - located centrally; contains heart & all structures passing into or out of thorax (aorta & branches of aortic arch, branchiocephalic veins & superior vena cava, esophagus, trachea, azygos vein, phrenic & vagus nerves)

Front 18

Pulmonary Cavity

Back 18

space defined by chest wall, diaphtagm (inferior), & mediastinum (medial)
1) internal surfaces lined by parietal pleura (serous membrane) - continues as visceral pleura over surface of lung
a) parietal & visceral pleura connected at hilum (root) of lung (entry.exit site for bronchi, pulmonary artery & veins)
b) pleural cavity = space between parietal & visceral pleura (contains serous fluid only)

Front 19

Lungs

Back 19

1) in life, lungs are soft masses whose size & shape when inflated is determined by shape of pulmonary cavity
2) lobes:
a) left lung - has superior & inferior lobes
b) right lung - has superior, middle, & inferior lobes (right lung is tri-lobes)

Front 20

Respiratory Tract

Back 20

air is brought into the lungs via a series of respiratory structures: nose, nasal cavities, pharynx, larynx, trachea, and bronchi

Front 21

Nasal Cavity

Back 21

- area of skull between nose & nasopharynx
a) superior, middlem and inferior nasal concha - scroll-like evaginations of lateral nasal cavity wall; serve to warm & moisten incoming air
1) only superior concha has olfactory epithelium for sense of smell
b) nasal septum divides into right & left nasal cavities - septum formed by vomer bone (inferior part od septum), perpendicular plate of ethmoid bone (superior part of septum), and septal cartilage (anterior part of septum)
c) nasal cavity & oral cavity (mouth) seperated by hard palate - formed by patine processes of maxilla bone (anterior) & palatine bones (posterior)

Front 22

Pharynx

Back 22

- muscular tube extending downward from nasal & oral cavities; has 3 parts:
a) nasopharynx - posterior continuation of nasal cavity
1) has opening for auditory tube (Eustachian tube) - connects to middle ear cavity
b) oropharynx - posterior continuation of oral cavity
1) soft palate - muscular structure seperating nasopharynx & oropharynx; elevates to close off nasopharynx during swallowing; free, posterior tip of soft palate = uvula
c) laryngopharynx - region around opening to larynx
d) pharynx terminates by dividing into esophagus & larynx

Front 23

Larynx

Back 23

a) cartilaginous structure that marks beginning of respiratory tract proper
1) passageways of respiratory tract (larynx, trachea, bronchi) all contain cartilage in walls - maintain open lumen during changes in air pressure
b) larynx connected to (suspended from) hyoid bone (located superior to larynx)
1) larynx moves upward during swallowing (causes downward bending of epiglottis)
2) larynx & hyoid bone raised by suprahyoid muscles; depressed by infrahyoid muscles
c) functions of larynx:
1) serve as valve in respiratory tract - prevents entrance of foreign material into trachea
2) phonation (production of sound)

Front 24

Major Cartilages of Larynx

x4

Back 24

1)Thyroid Cartilage - V-shaped cartilage that forms laryngeal prominence
a) larger in males (Adam's Apple)
b) anterior end of vocal ligament (vocal cord) attaches to inner, anterior wall of thyroid cartilage
2) Cricoid Cartilage - forms inferior border of larynx
a) thyroid cartilage sits on top of cricoid cartilage - can pivot in anterior-posterior direction
3) Epiglottic Cartilage - at superior end of larynx
a) forms epiglottis - bends downward during swallowing to help divert food laterally away from laryngeal entrance & into esophagus
4) Arytenoid Cartilage - small, paired cartilages; sit on top of posterior cricoid cartilage
a) attachment point for posterior end of vocal ligament (vocal cord)

Front 25

Phonation

Back 25

1) sound produced by moving air, causing vibration of vocal ligaments (vocal cords)
a) elastic ligaments that are attached to inside of thyroid cartilage (anteriorly) & arytenoid cartilages (posteriorly)
b) pivot motions of thyroid cartilage on top of cricoid cartilage increases or decreases stretch (tension) on vocal ligaments and alters sound pitch
2) sound modified & chopped into segments (words) by upper pharynx, tongue, lips
3) muscles of larynx innervated by motor branches from vagus nerve

Front 26

Glottis

Back 26

- lumen (space) between vocal folds
1) changes in width - narrowing during phonation; wide during forced inspiration
2) serves as last line of defense for entry of foreign material into lungs - stimulation of laryngeal walls by material evokes complete closure of glottis & cough reflex

Front 27

Trachea

Back 27

- originates at inferior border of larynx
a) consists of series of semicircular cartilage rings held together by smooth muscle
b) runs down mid-line, anterior to esophagus
c) bifurcates at level of sternal angle into 2 mainstem bronchi

Front 28

Mainstem (Primary) Bronchi

Back 28

- to right & left lung
a) Left lung - has superior & inferior lobar bronchi
b) right lung - has superior, middle, & inferior lobar bronchi
c) lobar bronchi branch into segmental bronchi

Front 29

Segmental (Tertiary) bronchi

Back 29

- supply bronchopulmonary segments
a) bronchopulmonary segment - smallest anatomical (surgical) unit of lung; total of 10 in each lung; each supplied by segmental bronchus & branch of pulmonary artery