Bony Thorax pt. 2 Flashcards
Large branch off of the Subclavian Artery.
-Runs on either side of the sternum (downwards)
-Used in CABG
Internal Thoracic Artery (AKA the Internal Mammary Artery)
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
Intercostal Nerves
Spinal Cord → dorsal & ventral roots → spinal nerve → splits into DPR and VPR
VPR becomes the Intercostal nerve
Intercostal Nerves
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
SNS Innervation
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
Intercostal Nerve
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
Subcostal Nerves
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
Posterior Intercostal Arteries
Come from the Costocervical Trunk, a branch of the Subclavian Artery
Subclavian Artery → Costocervical Trunk → Ascending Branch (cervical) and Descending Branch (costal) → _________
1st and 2nd Posterior Intercostal Arteries
-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
Anterior Intercostal Arteries
Arise from the Internal Thoracic Artery (Branch of the Subclavian Artery)
Upper 6 pairs of Anterior Intercostal Arteries
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
Internal Thoracic Artery
Gives off an additional 3-5 pairs of Anterior Intercostal Arteries
Musculophrenic Branch of the Internal Thoracic Artery
-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)
Subclavian Artery Branches
-Inferior Thyroid Artery
-Transverse Cervical Artery (transverse the neck - gives off Dorsal Scapular Artery in 40% of people)
-Suprascapular Artery (runs over suprascapular notch)
Thyrocervical Trunk
Anterior: run with the anterior intercostal arteries, 11 pairs
Posterior: run with the posterior intercostal arteries, 11 pairs
-Most superior: VAN
Intercostal Veins
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.
External Intercostal Muscles
-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
Internal Intercostal Muscles
-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
Innermost Intercostal Muscles
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
Diaphragm
-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.
Diaphragm
At full expiration, the Right Hemidiaphragm comes up as high as the ____ ICS.
4th ICS
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.
Right Diaphragmatic Crus
A muscle that originates on the 3rd Lumbar Vertebra, runs up and joins with the Right Diaphragmatic Crus.
Left Diaphragmatic Crus
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
Right and Left Diaphragmatic Crus
Ligamentous structure arching around the Psoas Major
-L1-L2
Medial Arcuate Ligaments
Ligamentous structure arching over the Quadratus Lumborum Muscle
-L1 - 12th rib
Lateral Arcuate Ligaments
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
Esophageal Hiatus (T10)
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
Esophageal/Hiatal Hernia
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
Caval Hiatus
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
Phrenic Nerve
Diaphragm moves to the 4th rib on the right and the 4th ICS on the left
Exhalation
Diaphragm flattens and descends to the 6th ICS on the right and the 7th rib on the left
Inhalation
-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.
Transverse Thoracis muscle
Muscles that run from transverse processes (origin) of vertebrae to ribs (insertion)
-Lift up ribs to increase volume and space between the ribs
-Inhalation
Levatores Costarum muscles
-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
Serratus Posterior Superior Muscles
-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
Serratus Posterior Inferior Muscles
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
Scalenes (anterior, middle, and posterior)
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
Sternocleidomastoid Muscle
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
Subcostales Muscles
-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)
Abdominal Wall Muscles
An active process. Requires muscle contraction.
-Diaphragm, External Intercostals, SCM, etc
Inhalation
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
Exhalation
