Unit 3 - Thorax

Thorax

• From base of neck (thoracic inlet) to diaphragm muscle

• Protects heart and lungs

• Site for attachment of muscles for:

  • Upper limb

  • Back

  • Respiration

Abdomen

• From diaphragm muscle to pelvic inlet

• Contains major viscera of digestive system

• No bony structure; musculature holds viscera in place

Describe the borders of the thorax

Superior border: thoracic inlet or superior thoracic
aperture

• kidney-shaped opening formed by T1
  vertebra, 1st pair ribs & sup. margin of
  manubrium

• includes:
  • apex of lungs
  • common carotid artery
  • internal jugular vein
  • subclavian artery & vein
  • esophagus & trachea
  • brachial plexus
  • (clavicles close, but not part of it)

Inferior boarder: wide opening formed by T12
vertebra, 12th pair ribs, & costal arch

Anterior boarder: sternum, ribs & costal cartilages

Posterior boarder: thoracic vertebrae & ribs

Define and describe the borders of the three thoracic spaces

mediastinum and two pleural cavities

Mediastinum:

• in center and for the heart

• region of the thoracic cavity between the pulmonary
  cavities

Left and Right pleural cavities:

• envelope the lungs

explain this image

Thoracic Osteology (part 1)

12 thoracic vertebrae

• Sternum

• ManubriumBody
  • Xiphoid process
  • Jugular notch
  • Sternal angle

Compare and contrast true ribs, false ribs and floating ribs

12 ribs & their costal cartilages

• True ribs (vertebral costal) attach to the
  sternum —→ ribs 1-7

• False ribs (vertebral chondral) attach to the
  cartilage ——→ ribs 8-10

• Floating ribs (free) no anterior attachment ——→ ribs 11-12

Identify the bony features of an individual rib (Neck and Head)

Head

• has two facets separated by the crest of head

• has 2 facets - 1 that articulates with T7 and another that articulates with T8

• is posterior and medial b/c it articulates w/ verterbra

Neck

• narrowing after the head, contains the tubercle, with a facet
  that articulates to the transverse process of the vertebra
  

R6 articulates w/ T5

Identify the bony features of an individual rib (Body)

Body

• is the rest of the rib

• Has the costal angle, which is a the sharpest curve (site of attachment for
  iliocostalis) and is lateral to rib’s tubercle

• has the costal groove, is an indentation on costal angle where the spinal nerve and vessels passes
  

Identify the individual components of the intercostal spaces and understand their positions relative to each other

• Between the ribs are intercostal spaces
  named for the superior rib

• Inside are 2 nerves and sets of blood vessels:

  • Main intercostal nerve, artery and vein are found in the
    costal groove of the superior rib

  • Collateral branches are found just above the inferior rib

• Space below the 12th rib is the subcostal space

Costal groove is on inferior aspect of rib, which gives notch space for vein, artery, and nerve

Thoracic muscles & fascia

Thoracic wall is covered by muscles that belong to upper limb or move vertebral
column: (People Study To Learn Efficiently)

• Pectoral muscles

• Serratus anterior

• Trapezius

• Latissimus dorsi

• Erector spinae

Thoracic muscles concerned exclusively w/ ribs for respiration: (DILS)

• Diaphragm

• Intercostals

• Levator costarum

• Serratus posterior
  

***Any muscle w/ attachment to ribs has potential to assist respiration under stress

Identify the three layers of intercostal muscles

External

• most superficial

• oblique with inferior edge/border = medial and Superior edge/border = lat.

Internal

• oblique with inferior edge/border = lat and Superior edge/border = med
  

Innermost

• most deep

• vertical ( meaning superior/inferior ) and NO oblique

• helps in respiration
  

Additional muscles with only respiration functions

• Serratus posterior

  • serrated like blade

• Levator costarum

  • pulls ribs up for respiration

Diaphragm’s Origin, Insertion, Action,

Origin:

• Xiphoid process

• Lower costal cartilages

• Upper Lumbar vertebrae

• Medial and lateral arcuate ligaments

Insertion:

• Central tendon of diaphragm

Action:

• Expands thorax during inspiration

More about the diaphragm

it is on the inferior aspect of the thorax

• this helps increase vertical space in thorax to allow air to enter

When flat = contracted

when in upside down U-shape = relaxed, which decreases V. space to expel air

REQUIRED FOR LIFE OR DEATH OCCURS

What does being on ventilator do to your diaphragm

it makes the diaphragm atrophy due to no usage of it, to the point when your off the ventilator it will make it hard to breathe

Thorax— 10 visceral contents

• Heart

• Esophagus

• Pulmonary artery

• Pulmonary veins

• Aortic arch

• Descending thoracic aorta

• Superior vena cava

• Inferior vena cava

• Lungs

• Trachea

Compare and contrast serous and fibrous membranes

Most thoracic and abdominal organs are surrounded by a serous membrane and many have fibrous membrane

Serous membrane:

• Double-sided and Fluid-filled membrane that allows for movement

• reduces friction w/ lubricating fluids
  

Fibrous membrane:

• exterior (superficial) to the serous membrane

• contains movement

Fibrous pericardium

Main function: prevent overfilling of the heart

Location (black outline):

• Superiorly to the large vessels exiting the heart

• Inferiorly to the diaphragm

Compare and contrast the general locations and functions of the conducting and respiratory portions of the respiratory tract

List, in order, the respiratory structures that air passes through during inhalation and exhalation.

IN 10 steps

Inhalation:

1. air passes via Nasal cavity

2. air goes down pharynx

3. air goes down larynx

4. air goes down trachea

5. air goes to primary bronchi

6. air goes to secondary bronchi

7. air goes to tertiary bronchi

8. air goes to terminal bronchioles

9. air goes to respiratory bronchioles

10. air goes to alveolar duct

11. air goes to alveolar sacs (bunch of grapes)

12. air goes to alveoli (single grape)

****exhalation is the reverse of the inhalation***

Describe the gross anatomical features of the trachea, including its positioning with respect to the esophagus

Trachea

• made of hyaline cartilage b/c it provides flexibility to stretch without breaking

• there is cilia for moving food

• anterior to the esophagus

Explain the parietal and visceral pleurae and pleura cavity concept

parietal pleura

• most superficial and congruent/inseparable to rib cage (and wall)

Pleural cavity

• fluid filled in btw V and P pleurae

Visceral pleura

• inner lining visceral membrane

The purpose:

• pleural cavity’s fluid acts like glue (surface tension) b/c when parietal pleura moves due to inspiration so does the pleural cavity and visceral pleura and the lungs

• this allows increasing of thoracic cavity to allow air to enter

Collasped lung

something enters pleural cavity and lung recoils —> NO air can enter

Parts of the Left lung

Red = left superior lobe

Green = oblique fissure

Blue = Left inferior lobe

Parts of the Right lung

bigger than left and has more lobes b/c heart is placed more to the left

Red = Right superior lobe

Black = Horizontal fissure

Orange = Right middle lobe

Green = Oblique fissure

Blue = Right inferior lobe

Hilum

seen in sagittal view

• Pulmonary vein

• pulmonary artery

• left main bronchus

For posterior

• it is darker lavitity: blood moves down b/c of gravity

Identify and describe the gross anatomic features of the bronchial tree (e.g., bronchi, bronchioles, alveolar ducts, alveolar sacs and alveoli).

bronchi:

• have cartilage b/c the trachea splits into bronchi

bronchioles:

• have smooth muscles in their walls for constriction and dilation

alveolar ducts

• extend from respiratory bronchioles and their walls are lined w/ alveoli

alveolar sacs

• clusters of alveoli @ ends of alveolar ducts

alveoli

• very small sacs

Capillaries

• surround alveoli

Identify the esophagus and describe its location relative to other body structures.

• Long stretchy tube

• Food moves by peristalsis

• Passes through diaphragm hiatus

• Ends at gastro-esophageal
  sphincter

• posterior to trachea

Parietal vs Visceral

Parietal: body wall

Visceral: organ wall

• Pink = exhaled lung size

• grey = inhale expansion