thorax Flashcards
thoracic cage
bony framework of the chest
structure of the thoracic cage
thoracic vertebrae posteriorly (12), ribs laterally, sternum, and costal cartilages anteriorly
function of the thoracic cage
a bony cage that protects the thoracic viscera, supports the shoulder girdle and upper limb, provides attachments for upper limb muscles
-houses the intercostal muscles that elevate and depress the thorax during respiration
thorax key elemtns
-barrel shape
-somite development
-vasculature and innervation
axial skeleton
forms the long axis of the body
supports the head, neck, and trunk, protects the brain, spinal cord and thoracic regions
axial skeleton 3 main regions
skull
vertebral column
and thoracic cage
what are the vertebral regions (5 regions)
-cervical: 7 vertebrae of the trunk
-thoracic: 12 vertebrae of thorax
-lumbar: 5 vertebrae of lower back
-sacrum: 5 fused vertebral segments; articulate with hip bones
-coccyx: 4 fused segments
vertebrae
-vertebral body
hold weight
vertebrae
-vertebral arch
(dorsal); muscle and ligament attachment
vertebrae
-vertebral foramen
location of the spinal cord
vertebrae
pedicle and lamina:
bony rami; connect processes to vertebral body
vertebrae
spinus process and transverse process (2 transverse)
allow connections to other vertebra and muscles
vertebrae
intervertebral foramen
where spinal nerve rami exit
sternum
anteriorly located
-has 3 sections: manubrium, body, xiphoid processd
sternum:
manubrium
superior section
-articulates with the medial ends of the clavicles and ribs 1 and 2
sternum
body
middle portion
sides are notched at articulations for the costal cartilages of ribs 2-7
sternum
xiphoid process
inferior end of sternum
plate of hyaline cartilage
fully ossifies around age 40
three anatomical landmarks of sternum
-jugular notch: suprasternal notch, location of jugular veins
-sternal angle: lies anterior to arch of aorta, marks the start and end of aortic arch. anterior to corina (bifurcation of trachea). corresponds to IV disc between T4 and T5 vertebra, marks inferior boundary of superior mediastinum- gives volume
-xiphisternal joint: deep to this joint, heart lines on the diaphragm.
how many ribs are present
24 total, 12 pairs on each side
true ribs
superior 7 pairs; attach directly to the sternum by coastal cartilage
floating ribs
inferior 5 pairs (8-12); attach to the sternum either indirectly or not at all
floating ribs
ribs 11-12; have no anterior attachments, embedded in the muscles of the lateral body wall
head of rib
articulates with the vertebral bodies by two facets
tubercule
articulates with the transverse process of the thoracic vertebra of the same number
shaft
bulk of the rib
costal groove
located on the inferior border, houses the intercostal nerve and vessels
synovial joints with ribs
there are two synovial joints at each rib articulation, gives ability to elevate and depress ribs
intercostal space
separate ribs and are occupied by muscles, vessels, and nerves
thoracic apertures
openings
thoracic inlet and thoracic outlet
thoracic inlet
passage of trachea, esophagus vessels, and nerves. thoracic cavity communicates with the neck and upper limb.
-narrow, provides major blood supply to the head and limb (superior)
boundaries of thoracic inlet
-posterior: T1 vertebra
-lateral: 1st ribs and costal cartilages
-anterior: superior border of manubrium
thoracic outlet
more spacious than thoracic inlet; allows passage of IVC , esophagus and aorta, inferior and wider. diaphragm is located within
boundaries of thoracic outlet
-posterior: T12 vertebra
-lateral: 11th and 12th ribs and cartilages, costal margin
-anterior: xiphersternal joint
intercostal space
separate the ribs, remnants of somites.
-occupied by muscles blood vessels and nerves. they travel in the costal groove on the inferior surface of a rib, between the internal and innermost intercostal muscles
innervation of thoracic body wall
ventral rami (intercostal nerves); innervate lateral ato anterior
arterial supply of the thoracic body wall
carry oxygenated blood to the body, wrap around from the dorsal side to the anterioir side
1. anteriorly via the internal thoracic and anterior intercostal arteries off the subclavian arteries
2. subclavian artery
3. posterior intercostal and subcostal arteries via the thoracic aorta
-inferior vena cava:
offset to the right side of the thorax, drains into the right side of the heart. on thh back wall
right side venous drainage of thorax
-intercostal veins drain into the azygos vein which joins the superior vena cava
left side venous drainage of the thorax
intercostal vein drain into the accessory hemiazygos and hemiazygos veins that drain into the azygous vein which drains into the SVC
-hemiazygos veins cross over vertebral body, underneath the aorta to reach azygous veins
nerves of the thorax
12 pairs of thoracic spinal nerves
-anterior rami of T1-T11L form intercostal nerves on right and left sides
-anterior rami of T12 nerves: subcostal nerves
posterior rami of thoracic spinal nerves: supply the bones, joints, deep back muscles, and skin of the back and thoracic region
diaphragm
the most important muscle of respiration
-flattens as it contracts, increases the volume of thoracic cavity
-runs in a transverse direction
