Lab 9: Thorax Flashcards
breast
- nipples and areola may become swollen and exude a small amount of secretion immediately after birth for both sexes
- breast activity rapidly subsides after and becomes like subcutaneous tissue until puberty
- for females breasts increase in size and the glandular tissue becomes surrounded with fatty superficial fascia at puberty
- breast is rudimentary in males
- blood supply of the breast derives from the internal and lateral thoracic arteries
female breast
- mammary gland
- structurally similar to apocrine sweat gland
pectoralis major
- breast rests on the fascia covering the pectoralis major and a bit of serratus anterior
- anterior portion of thorax
axillary tail
- extension of adipose tissue of the breast
- runs upward and lateral into the axilla (armpit)
- lymphatic drainage of the breast is primarily into nodes at the end of the axillary tail
nipple
- surrounded by pigmented ring of skin -> areola
- areola has a number of small elevations -> areolar gland (montgomery tubercles) -> lubricate the nipple during lactation (milk secretion)
- nipple is pierced by 15-20 lactiferous ducts
- lactiferous ducts enlarge immediately below the areola to form -> lactiferous sinuses -> constitute milk reservoirs during lactation
- lactiferous ducts drains a glandular lobe which is comprised of a number of smaller lobules
- each lobule has a number of simple secretory sacs -> alveoli
- glandular lobes are surrounded by adipose tissue and are supported from the skin and the deep fascia overlying the pectoralis major muscle by a series of suspensory ligaments (coopers ligaments) -> form fibrous septa within the breast
- clavy pectoral fascia -> suspensory ligaments -> pectoralis major
lactiferous sinuses
- constitute milk reservoirs during lactation
- stores milk after its produced
thoracic skeleton
- 12 thoracic vertebrae
- 12 pairs of ribs
- sternum: manubrium, sternal body, xiphoid process
- costal cartilages (ribs articulate with sternum)
- surrounds the thoracic cavity posteriorly, laterally, and anteriorly
sternum
- forms a skeletal brace in the midline anteriorly
- 3 separate components that are united by fibrocartilaginous joints: manubrium, sternal body and xiphoid process
sternum: manubrium
- upper most element of sternum
- superior border has a depression known as the jugular notch -> lies at the level of the intervertebral disc between T1-T2
- superolateral corners have concave facets that articulate with the clavicles
- below each clavicular facet is a facet that articulates with the costal cartilage of the first rib
- inferior border joins the sternal body at the junction of the 2nd rib
- manubriosternal joint has a slight anterior angle (sternal angle) that can be felt as a ridge just under the skin
- sternal angle lies at the level of vertebra T5
sternum: sternal body
- middle element of sternum
- made up of 4 segments (sternebrae) that fuse between puberty and age 20
- junctions can be palpated as slight transverse ridges on the front of the bone
- 2nd-7th costal cartilage articulate with the sternal body
sternum: xiphoid procress
- inferior, tongue shaped portion of the sternum
- articulates with the body of the sternum at the level of vertebra T10
Ribs and costal cartilage
- 12 ribs on each side
- articulate posteriorly by synovial joints with the vertebrae
- ribs 1-10- articulate anteriorly with the sternum by rods of hyaline cartilage -> costal cartilage
- costochondral junction/joint- where the rib becomes cartilage
- ribs 1-7- (true ribs) articulate directly with the sternum by their own costal cartilages
- ribs 8-10- (false ribs)- articulate with the sternum indirectly by connecting with the 7th costal cartilage
- ribs 11-12- (floating ribs) short and do not reach the sternum -> distal ends terminate in the musculature of the body wall
respiratory movement of the thoracic skeleton
- heads of ribs 2-9 articulate by synovial joints with two adjacent vertebral bodies (its own and one above) across the intervertebral disk
- tubercles of ribs 1-10 articulate by synovial joints with the transverse process of the vertebra
- synovial joints permit free movement of the costal cage during forced inspiration and expiration
- ribs are elevated during inspiration -> Expands the anteroposterior dimension of the thoracic cavity in a movement analogous to the motion of a bucket handle
- increase in thoracic volume creates a partial vacuum -> filled by air rushing into the lungs
muscles of the back
- 4 hypaxial muscles that attach to thoracic vertebrae and/or ribs:
- trapezius
- latissimus dorsi
- rhomboideus
- quadratus lumborum
- 3 epaxial muscles attach to thoracic vertebrae:
- erector spinae
- semispinalis
- multifidus
muscles of upper limb
one muscle attaches to the sternum
- pectoralis major
- there are also 2 costoscapular muscles: a sternocostal muscle, 3 intercostal muscles and the abdominal diaphragm
costoscapular muscles
- 2 muscles run from the rib cage into the scapula
- both protract the scapula (pull forward)
- one rotates the scapula upward and the other downward
- pectoralis major
- serratus anterior
costoscapular muscles: pectoralis minor
- arises from the anterior surface of ribs 3-5
- inserts onto the coracoid process of the scapula
- protracts (pull forward) and rotates the scapula so the glenoid fossa faces inferiorly
- deep to pectoralis major
- innervated by medial pectoral nerve (branch of brachial plexus)
costoscapular muscles: serratus anterior
-arises from the upper 1-8 ribs by series of fingerlike digitations
-inserts ventrally onto the medial border of the scapula
-travels in between the scapula and the ribcage -> inserts medially
-protracts (pull forward) and rotates the scapula so that the glenoid fossa faces superiorly
-running in the space between ribs and scapula -> anterior to scapula
-from anterior to posterior-
ribs -> serratus anterior -> subscapular muscle -> scapula
-innervated by long thoracic nerve (ventral rami C5-C7)
sternocostal muscle: transversus thoracis
- transversus thoracis
- arises from the posterior surface of the sternal body and xiphoid
- inserts into the backs of costal cartilages 2-6
- draws the ribs downward in forced expiration
- weak muscle
- helps with forced expiration
- connects sternum to ribs
- innervated by intercostal nerves
intercostal muscles
- 3 layers of thin muscles run in the intercostal space between successive ribs
- between the middle and innermost layers is the neurovascular plane
- run in between ribs
- intercostal nerve, artery, and vein run in this plane
- 3 muscle layers differ in the extent to which they fill the intercostal space
- fibers of the external layer are orientated differently from those of the inner two -> helps strengthen the thoracic wall
- all three layers are innervated by intercostal nerves
- external intercostal: occupies the space between the tubercle of the rib and the edge of the costochondral junction -> its fibers are directed downward and forward
- internal intercostal: occupies the space between the angle of the rib and the edge of the costosternal junction -> fibers are directed downward and backward
- innermost intercostal: lies deep to the neurovascular plane -> fibers are directed downward and backward
abdominal diaphragm
- thoracic and abdominal cavities are separated by a muscular diaphragm
- principal force behind respiration
- dome-shaped muscle that is convex upward
- fibers originate peripherally from the back of the xiphoid process, internal surfaces of ribs 9-12, costal cartilages 6-8, the epimysium over the quadratus lumborum and psoas major muscles, and the bodies of L1-L3 -> all attached to tendon
- enclosed all the way around except for openings for the aorta, esophagus, and inferior vena cava
- left and right crus attach to aorta
- these fibers converge upon a thin, crescent shaped central tendon
- this tendon has 3 parts known as leaves
- left and right leaves are below the lungs
- middle leaf is below and fused to the lower surface of the fibrous pericardium around the heart
- also has 3 major orifices that permit the passage of structures between the thorax and abdomen (respectively from front to back):
- vena caval foramen- through the middle leaf and the central tendon, for the inferior vena cava -> lies at the level of vertebra T8
- esophageal hiatus- through posterior muscular fibers, for the esophagus -> lies at the level of vertebra T10
- aortic hiatus- (behind the diaphragm for the descending aorta) -> lies at the level pf vertebra T12
- abdominal diaphragm is innervated by phrenic nerve (C3, C4, C5) -> travels inferiorly to the left and right sides of the heart (pericardium) and branch out along diaphragm
thoracic cavity
- ribs and abdominal diaphragm enclose the thoracic cavity
- contains the trachea and lungs, the heart and some very large blood vessels, the esophagus as well as nerves and lymphatic channels
coelom
- in the embryo a large blood vessel (heart tube), the trachea and its lung buds, and the gut tube develop in the front of the primordial vertebral column and behind a membranous sac -> this is the coelom
- coelom extends throughout the thorax and abdomen
- as the heart tube grows in size into the heart and as the lung buds increase in size into the lungs -> the tissues of the coelomic sac are pushed inward -> forming septa that subdivide the original single coelomic cavity into 3 separate cavities
pericardial cavity
-middle cavity into which the heart grows
pleural cavities
-2 lateral cavities into which the lungs grow
parietal and visceral layer of pericardial and pleural cavities
- sacs of the pericardial and pleural cavities are composed of serous membrane
- part of the membrane lies against the outer thoracic wall -> forms the parietal layer of the sac
- part of the membrane is adherent to the organ (heart of lung) -> forms the visceral layer of the sac
- space between the parietal and visceral layers contain serous fluid -> permits free movement of the heart and lungs, and their adherent visceral membranes, against the parietal membrane and thoracic wall
- some of the fibrous connective tissue from the septa around the pericardial cavity adheres to the outside of its parietal layer -> forms fibrous pericardium
mediastinum
- structures that occupy the space between the lungs form a partition between them
- largest structure here is the heart
- entering the top of the pericardial sac on the right is the superior vena cava
- to the left and right of the superior vena cava is the aortic arch -> emerges from the pericardial sac
- brachiocephalic trunk, left common carotid artery, and left subclavian artery come off the aortic arch
- pulmonary arties are below the superior vena cava and aortic arch -> they emerge by the pulmonary trunk from the heart and run into the lungs
- trachea is behind the superior vena cava and aorta -> left and right bronchi bifurcate from the traches behind pulmonary arteries at about the level of sternal angle (posterior)
- esophagus is behind trachea -> runs through the abdominal diaphragm
- aortic arch runs upward and then curves back over the left bronchus of trachea -> then it descends through the thorax as the descending aorta between the vertebral column and esophagus -> descending aorta runs through the abdominal diaphragm
- also contains the main lymphatic channel of thorax -> thoracic duct, the phrenic nerve and vagus nerves, and the azygos and hemiaxygos veins -> run along either side of vertebral column
superior vena cava
-drain the left and right brachiocephalic veins
respiratory apparatus
- consists of the oral and nasal cavities in the head: the pharynx, larynx, and trachea
- in the neck: trachea, bronchial tree, and lungs within the thorax
trachea
- 4-5 inches long
- diameter is 1 inch
- begins immediately below the cricoid cartilage
- tracheal lumen is kept open by series of C-shaped tracheal cartilages
- tracheal cartilages partially surround it except on the posterior aspect
- cartilages are connected by fibroelastic tissue and smooth muscle fibers
- at the level of sternal angle -> trachea divides into left and right bronchial trees
bronchial tree
- at the level of sternal angle -> trachea divides into left and right bronchial trees
- last cartilaginous ring of the trachea has a projection that runs in the sagittal plane through its center -> separates the left and right bronchi
- keel-like ridge at the orifices of the primary bronchi -> carina
- bronchial tree has 3 levels of division:
- bronchus: primary bronchus, secondary (lobular) bronchus, tertiary (segmental) bronchus
- bronchiole: bronchiole, terminal (respiratory) bronchiole
- alveolar portion: alveolar duct, alveolar sac, alveolus
bronchial tree: bronchus
- trachea bifurcates into the left and right primary bronchi
- right primary bronchus is about 1 inch long
- left is longer by about 1 inch bc the entrance (hilum) of left lung is pushed laterally by the heart
- once primary bronchus enters the lung -> divides into secondary (lobar) bronchi (3 in right lung, 2 in left)
- 3 lobar bronchi in the right lung bc it has 3 lobes
- there are 2 lobar bronchi in the left lung bc it has only 2 lobes
- lobar bronchi divide into tertiary (segmental) bronchi
- segmental bronchus serves 1 bronchopulmonary segment of the lung -> each lung has 10 segmental (tertiary) bronchi
- segmental bronchi divide into bronchioles
bronchial tree: bronchioles
- not supported by cartilage
- segmental bronchi divide into bronchioles
- bronchioles differ from bronchi bc they lack cartilaginous rings
- bronchioles divide into even smaller terminal respiratory bronchioles
- respiratory bronchioles branch into a number of alveolar ducts
bronchial tree: alveolar portion
- respiratory bronchioles branch into a number of alveolar ducts
- they enter into alveolar sacs that bud numerous microscopic alveoli
- gas exchange takes place in alveoli
- alveolar ducts -> alveolar sacs -> alveoli
- alveoli have capillary beds for gas exchange
- at the ends of terminal bronchioles
lungs
- fill most of the thoracic cavity
- each composed of a mass of spongy tissue -> the alveoli (respiratory portion)
- each also contain a branching network of tubes -> bronchi and bronchioles (conducting portion)
- lung is covered by visceral pleura which is separated from the parietal pleura that lines the thoracic wall by an intrapleural space with a slightly lower pressure than that of the atmosphere
- this space also contains serous fluid that facilitates movement of the lungs during inspiration and expiration
- the top (apex) of lung is somewhat pointed
- bottom (base) of lung is concave bc it rests upon the dome-shaped abdominal diaphragm
- bc the heart takes up more space on the left side of the thoracic cavity -> left lung differs slightly in its gross appearance from the right lung
- both lungs have 10 bronchopulmonary segments -> these blocks of lung tissue receive air supply from a separate bronchus and its blood supply from a separate branch of lobar artery
right lung
- has 3 lobes separated by 2 fissures
- uppermost is the superior lobe
- below is the middle lobe
- lowermost is the inferior lobe
- horizontal fissure separates the superior and middle lobes
- the oblique fissure separates the inferior lobe from the superior and middle lobes
left lung
- has 2 lobes separated by one fissure
- uppermost is the superior lobe
- separated from the inferior lobe by the oblique fissure
- left lung has no middle lobe
- it has concavity -> the cardiac notch -> where the heart fits
- below the cardiac notch the anterior aspect of the superior lobe has a tongue-like protrusion -> lingula
heart
- large part of mediastinum
- 4 chamber muscular pump
- takes deoxygenated blood from body and pumps it into lungs -> then pumps oxygenated blood from lungs into body
- provides blood to its own cardiac muscle via a separate network of vessels
- size of clenched fist
- cone shaped
- located in center of chest
- mass is to the left of the midline
- lies closer to the front than the back of the thorax
upper margin of the heart
- on the left side of the upper margin -> located on the lower border of the left 2nd costal cartilage
- one finger breadth from the edge of the sternum
- (2nd costal cartilage articulates with the sternum at sternal angle)
- right side of upper margin -> on the upper border of the right 3rd costal cartilage
- one finger breadth from the edge of the sternum