Bony Thorax pt. 2

Question 1

Large branch off of the Subclavian Artery.
-Runs on either side of the sternum (downwards)
-Used in CABG

Answer 1

Internal Thoracic Artery (AKA the Internal Mammary Artery)

Question 2

Lie in the intercostal spaces and are numbered like the IC spaces are.
-Innervate the intercostal muscles (motor) and supply general sensation to the bony thorax (sensory)
-11 pairs

Answer 2

Intercostal Nerves

Question 3

Spinal Cord → dorsal & ventral roots → spinal nerve → splits into DPR and VPR
VPR becomes the Intercostal nerve

Answer 3

Intercostal Nerves

Question 4

Preganglionic Sympathetic Fibers (B fibers - white Rami Communicantes) → Sympathetic Chain Ganglion (runs entire spinal cord from top to bottom) → Postganglionic Sympathetics (C fibers -Gray Rami Communicantes) → Spinal Nerve

Answer 4

SNS Innervation

Question 5

Has a Lateral Cutaneous Branch that supplies general sensation to the side of the thorax, and ends in the Anterior Cutaneous Branch that supplies general sensation to the Anterior Thorax

Answer 5

Intercostal Nerve

Question 6

2 nerves lying below the 12th ribs in the subcostal area
-Derived from T12
-Help to innervate the Abdominal Muscles (Ex: External Abdominal Oblique)
-Have subcostal arteries and veins running with them

Answer 6

Subcostal Nerves

Question 7

Come off of the Aorta
-11 pairs, lie in the intercostal space
-1 and 2 arise from the Costocervical trunk
-the remaining ones all come off of the Descending Aorta

Answer 7

Posterior Intercostal Arteries

Question 8

Come from the Costocervical Trunk, a branch of the Subclavian Artery
Subclavian Artery → Costocervical Trunk → Ascending Branch (cervical) and Descending Branch (costal) → _________

Answer 8

1st and 2nd Posterior Intercostal Arteries

Question 9

-11 pairs, lie in the intercostal space
-Shorter, get to Anterior Axillary Fold and then connect with the Posterior Intercostal Arteries coming around from the back
-Bottom 2 pairs may be missing

Answer 9

Anterior Intercostal Arteries

Question 10

Arise from the Internal Thoracic Artery (Branch of the Subclavian Artery)

Answer 10

Upper 6 pairs of Anterior Intercostal Arteries

Question 11

Artery that travels down to the Costal Margin where it bifurcates.
-One branch continues on down (Superior Epigastric Artery)
-Other branch continues with the Costal Margin and is called the Musculophrenic Branch.
-Gives off 6 Anterior Intercostal Arteries

Answer 11

Internal Thoracic Artery

Question 12

Gives off an additional 3-5 pairs of Anterior Intercostal Arteries

Answer 12

Musculophrenic Branch of the Internal Thoracic Artery

Question 13

-Costocervical trunk: splits into ascending and descending portions
-Internal Thoracic Artery: gives off Anterior Intercostal Arteries
-Thyrocervical Trunk: supplies thyroid gland and neck
-Vertebral Artery: runs in transverse foramina all the way up to the skull
-Dorsal Scapular Artery: Comes off of the Subclavian in 60% of people. In the remaining 40%, it comes off of the Transverse Cervical Artery (branch of the Thyrocervical Trunk)

Answer 13

Subclavian Artery Branches

Question 14

-Inferior Thyroid Artery
-Transverse Cervical Artery (transverse the neck - gives off Dorsal Scapular Artery in 40% of people)
-Suprascapular Artery (runs over suprascapular notch)

Answer 14

Thyrocervical Trunk

Question 15

Anterior: run with the anterior intercostal arteries, 11 pairs
Posterior: run with the posterior intercostal arteries, 11 pairs
-Most superior: VAN

Answer 15

Intercostal Veins

Question 16

The most superficial of the intercostal muscles.
-Fibers pass downward and forward
-Begin at the spine, wrap around, and end at about the Anterior Axillary Fold
-Attach to the sternum via a continuation of fascia that makes a sleeve called the External Intercostal Membrane
-Facilitate inhalation. Lift up the ribcage and allow it to expand, expanding the lungs to take in air.

Answer 16

External Intercostal Muscles

Question 17

-Fibers pass downward and backwards, at right angles to the fibers of the external intercostals
-Contraction = compresses rib cage. Used in forceful exhaling (exercise, COPD, asthma, etc)
-Begin at the sternum (running straight up and down), and begin to tilt as they move over, and end at the Posterior Axillary Fold
-Attach to the vertebrae via Internal Intercostal Membrane

Answer 17

Internal Intercostal Muscles

Question 18

-Deepest layer of intercostal muscles
-Fibers run in the same direction (Down and around and towards the back) as the Internal Intercostals
-Begin at the sternum and end at the Paravertebral Line (break apart laterally, reform, and then end at the paravertebral line)
-Facilitate forced exhalation
-Continue on and attach to vertebrae by continuation of fascia making a sleeve called the Innermost Intercostal Membrane

Answer 18

Innermost Intercostal Muscles

Question 19

Does 75-80% of the WOB (with help from the intercostal muscles)
-Main muscle of breathing
-Located in the lower thorax, between the thorax and abdomen. Covers up the Inferior Thoracic Outlet.
-Supports the lungs and heart
-Has sternal, costal, and vertebral portions that serve as attachments to keep it in place

Answer 19

Diaphragm

Question 20

-Muscles on the side run in a circular pattern
-In the center is a white part called the Central Tendon: attachment point for all the muscles
-All the muscles of the diaphragm pull on the central tendon to flatten in out, increasing thoracic volume, so pressure in the airway goes down, and air comes in.

Answer 20

Diaphragm

Question 21

At full expiration, the Right Hemidiaphragm comes up as high as the ____ ICS.

Answer 21

4th ICS

Question 22

A longitudinal muscle that runs up and curves around
-Runs from the body of the 4th Lumbar Vertebra, runs all the way up to the Diaphragm, and then makes a curvature on top of a column.

Answer 22

Right Diaphragmatic Crus

Question 23

A muscle that originates on the 3rd Lumbar Vertebra, runs up and joins with the Right Diaphragmatic Crus.

Answer 23

Left Diaphragmatic Crus

Question 24

These form an opening in the Diaphragm called the Aortic Hiatus (also called the Median Diaphragmatic Aperture) at T12
-When the thoracic aorta passes through the aortic hiatus, it is now called the Abdominal Aorta

Answer 24

Right and Left Diaphragmatic Crus

Question 25

Ligamentous structure arching around the Psoas Major
-L1-L2

Answer 25

Medial Arcuate Ligaments

Question 26

Ligamentous structure arching over the Quadratus Lumborum Muscle
-L1 - 12th rib

Answer 26

Lateral Arcuate Ligaments

Question 27

Fits loosely around the diaphragm.
-T10
-Occurs as the esophagus passes through the thorax into the abdomen
-Site of hiatal hernia
-slightly to the right of the aortic hiatus and more anterior

Answer 27

Esophageal Hiatus (T10)

Question 28

Stomach herniates, at least partially, through the Esophageal Hiatus, an opening into the thorax
-Pain is relieved with standing as gravity pulls the esophagus down. Laying down at night causes the hernia to worsen, causing pain

Answer 28

Esophageal/Hiatal Hernia

Question 29

An opening in the diaphragm that allows the IVC to pass through
-T8-T9
-further to the right and more anterior than the aortic hiatus and the esophageal hiatus

Answer 29

Caval Hiatus

Question 30

Crosses anteriorly to the anterior scalene m., passes down through the superior thoracic aperture, runs anterior to the mainstem bronchi, and runs on either side of the heart, through the pericardium, and ends in the diaphragm
-C3, C4, C5 VPR

Answer 30

Phrenic Nerve

Question 31

Diaphragm moves to the 4th rib on the right and the 4th ICS on the left

Answer 31

Exhalation

Question 32

Diaphragm flattens and descends to the 6th ICS on the right and the 7th rib on the left

Answer 32

Inhalation

Question 33

-Muscle that lies on the Posterior surface of the Anterior Thoracic Wall
-originates from the side of the sternum and inserts on ribs 2-6
-Used with forceful exhalation. Closes up IC rib spaces, reducing the volume in the thorax to force air out.

Answer 33

Transverse Thoracis muscle

Question 34

Muscles that run from transverse processes (origin) of vertebrae to ribs (insertion)
-Lift up ribs to increase volume and space between the ribs
-Inhalation

Answer 34

Levatores Costarum muscles

Question 35

-Very thin muscle
-Runs from Ligamentum Nuchae to the upper ribs
-Contracts to lift up the rib cage, increasing space between the ribs, helping you to inhale

Answer 35

Serratus Posterior Superior Muscles

Question 36

-Very thin muscles
-Originates from lower thoracic and upper lumbar vertebrae and insert on lower ribs
-Contract to close intercostal spaces, reducing the volume in your chest, helping you to forcefully exhale

Answer 36

Serratus Posterior Inferior Muscles

Question 37

Muscles that runs from the transverse cervical vertebrae to the ribcage.
-Contract to lift the ribcage up
-Increase space between the ribs to help you inhale

Answer 37

Scalenes (anterior, middle, and posterior)

Question 38

Powerful muscle for breathing.
-Runs from the Mastoid Process to the ribcage/clavicle
-Contracts to lift the ribcage up and increase the volume in the chest, decreasing the pressure, allowing air to be sucked in for inhalation

Answer 38

Sternocleidomastoid Muscle

Question 39

Very small muscles
-Modified Innermost Intercostal Muscles
-Found in the Posterior thorax, running across ribs 10-12
-Used with forceful exhalation. Contract to close rib spaces, allowing you to forcefully exhale

Answer 39

Subcostales Muscles

Question 40

-Rectus Abdominis
-Eternal Abdominal Oblique
-Internal Abdominal Oblique
-Transversus Abdominis
-When these muscles contract, they increase intra-abdominal pressure, which pushes the diaphragm up, compressing the chest, making the pressure in chest go up, pushing air out.
-Compress the abdomen
-Forceful exhalation (think squeezing a balloon)

Answer 40

Abdominal Wall Muscles

Question 41

An active process. Requires muscle contraction.
-Diaphragm, External Intercostals, SCM, etc

Answer 41

Inhalation

Question 42

A passive process that requires muscle relaxation (unless you’re exercising or have disease)
-Involves surface tension that is created in the airways. Helps them to partially collapse so that you breathe out.
-Lungs rebound off of the chest wall/diaphragm after reaching the maximal point of inspiration. Due to resistance, they passively exhale.
-Trouble breathing is more active and requires muscles for forceful exhalation

Answer 42

Exhalation