Thoracic Wall

What is the inferior thoracic aperture (inlet) and boundaries?

Is a passageway for structures to enter/exit thorax and abdomen Boundaries: Posterior: T12 vertebra Lateral: Ribs 11-12 and costal cartilages 7-10 Anterior: xiphisternal joint - Although the thoracic diaphragm closes most of the aperture, the inferior thoracic aperture serves as a passageway for structures from the thoracic cavity to the abdominal cavity including the esophagus, inferior vena cava, and the thoracic aorta

Internal thoracic veins terminate in _____________ veins

brachiocephalic

The first left and right posterior intercostal veins drain directly to the ______________ veins. The LT and RT posterior intercostal veins are called the left and right ____________ _________ veins

brachiocephalic supreme intercostal

A tubercle is located at the junction between the neck and the body of the rib. The smooth articular part articulates with the vertebral transverse process making the ___________ ________.

costotransverse joint

The Innermost intercostal m.m. are active during __________. Same fiber direction as internal intercostals. Best seen from within the body cavity.

expiration

The __________ vein begins as the ascending left lumbar v. and left subcostal v. This vein will ascend and then crosses the midline at T8 vertebra to drain into the _______ vein

hemiazygos azygos

Which parts of the azygos venous system terminate in the superior vena cava?

terminates at T4 where is dumps into SVC

True or false: No anterior intercostal arteries in spaces 10-11 because there are no costal cartilages linking up to sternum.

true

Blood supply to the intercostal spaces is from what 3 areas?

- aorta - subclavian artery - axillary artery ***refer to reference table in notes packet

What are the 3 categories of the ribs?

1. Vertebrocostal - "true" ribs, (ribs 1-7) attach directly to the sternum via individual costal cartilages 2. Vertebrochondral - "false" ribs, (ribs 8-10), attach indirectly to the sternum via shared costal cartilages. These ribs articulate with the costal cartilages superior to them. 3. Vertebral - "free" or "floating" ribs, (ribs 11-12), do not attach to the sternum and end in the posterior abdominal musculature

Within the intercostal space are 3 layers of overlapping muscle. What are the muscle layers from superficial to deep?

1. external intercostal 2. internal intercostal 3. innermost intercostal

The breasts extend from the ___-___ ribs, and are the most prominent superficial structures in the anterior thoracic wall. They consist of mammary glands and fibrous connective tissue along with blood vessels, lymphatics, and nerves all embedded within a fatty matrix.

2nd-6th

What is the function of the thoracic cage?

Assists in respiration and protects thoracic viscera as well as some abdominal organs. Intercostal spaces separate ribs and cartilages from each element and are where nerves, vessels, and intercostal muscles are housed.

___________ ______________ lines internal surface of thoracic wall. Additionally, it separates parietal pleura from thoracic wall

Endothoracic fascia

As the ribs are elevated during inspiration, the intrathoracic volume increases and pressure changes drawing air into the lungs. The diaphragm, some intercostal muscles, and other muscles relax during expiration, decreasing intrathoracic volume. The elastic tissue of the lungs is also relaxed, allowing it to recoil and expel most of the air.

FYI

The accessory hemiazygos vein is variable. Additionally, If present, will drain posterior intercostal spaces 4-7. •It will empty into either •the azygos vein, •hemiazygos vein, or •left superior intercostal vein

FYI

slide 67: Local anesthesia of an intercostal space is produced by injecting a local anesthetic agent near the intercostal nerves between the paravertebral line and the area requiring anesthesia. This procedure (intercostal nerve block) involves infiltration of the anesthetic about the intercostal nerve trunk and its collateral branches. Be aware of the good neighbor policy of nerves and make sure a sufficient area is anesthetized- usually two or more intercostal nerves must be anesthetized.

FYI

How are sweat glands in the skin overlying the body of the sternum innervated (describe the pathway)?

Intercostal nerves are ventral rami of mixed spinal nerves T1-T11. Rami communicantes connect each intercostal nerve to the ipsilateral sympathetic trunk. Presynaptic sympathetic fibers (GVE) exit each ventral ramus via the white ramus communicans and pass to a ganglion of the sympathetic trunk. These fibers can then synapse at that ganglion, or travel superiorly or inferiorly along the sympathetic trunk to synapse within another sympathetic ganglion. Postsynaptic fibers exit the ganglia of the sympathetic trunk via gray rami communicantes to join the ventral ramus of the nearest spinal nerve to distribute GVE fibers to blood vessels, sweat glands, and smooth muscle of the body wall and limbs. Intercostobrachial nerve(s) 2nd, + sometimes 3rd intercostal nerve provide lateral cutaneous branch which joins medially with the brachial plexus T3-T6 typical intercostal n.n. --> anterior and lateral cutaneous nerves supply this area

The ____________ _________ house several important structures including three overlapping muscle layers, an intercostal nerve, an anterior intercostal artery, a posterior intercostal artery, and collateral arterial branches. The anterior and posterior intercostal arteries anastomose, as do their collateral branches.

Intercostal spaces

_________ _________ give rise to 15-20 buds that develop into lobules (alveoli) of the mammary gland, which in turn constitute the functional substance (parenchyma) of the gland. The _________ __________ drain the glandular lobules. The ducts converge at the nipple and open independently.

Lactiferous ducts

Also branching from the axillary artery is the ________ ________ artery which anastomoses with internal thoracic artery, supplies serratus anterior m. and pectoralis major m., and in females sends off an external mammary branch to supply the breasts

Lateral thoracic

The ________ ________ __________ vein is formed by the union of posterior intercostal veins 2-3. It empties directly into left brachiocephalic vein and can drain the accessory hemiazygos v.

Left superior intercostal

Milk is produced where? Once the milk has been produced, where does it enter? Milk is then routed to a dilated duct where milk accumulates. What is the name of this area?

Lobules of mammary gland Lactiferous ducts; Drain 15-20 lobules each. Lactiferous sinuses

_________ ________ are modified sweat glands, and are rudimentary and functionless in men.

Mammary glands

____________ GVE fibers leave ganglia of the sympathetic trunk via gray rami to join the ventral ramus of the nearest spinal nerve to take to body wall.

Postsynaptic

__________ GVE fibers leave each ventral ramus via a white ramus & pass to a ganglion of the sympathetic trunk

Presynaptic

The ___________ _________ is a potential space between pectoral fascia and deep surface of breast. It permits movement or breast along pectoral fascial surface.

Retromammary space

_________ _______ _________ vein is formed by the union of posterior intercostal veins 2-4. It empties into azygos vein.

Right superior intercostal

What is the Superior thoracic aperture (inlet) and boundaries?

Serves as a passageway for structures communicating between the neck and thoracic cavity, including the trachea, esophagus, nerves, and vessels supplying and draining the head, neck, and upper limbs Boundaries: Posterior: T1 vertebra Lateral: first ribs and costal cartilage Anterior: superior border of manubrium

The 12th intercostal nerve is also atypical, it is a _________ n., which is the ventral ramus of T12.

Subcostal

Branching from the axillary artery is the ________ __________ artery which supplies the anterior intercostal spaces 1-2 by anastomosing with internal thoracic artery, as well as supplying the serratus anterior muscle.

Superior thoracic

What are the 2 thoracic apertures?

Superior thoracic aperture Inferior thoracic aperture

_________ __________ are condensations of fibrous connective tissue within the skin that act to firmly attach the breasts to the dermis, and also help support the lobules of the mammary glands. They are particularly well-developed superiorly.

Suspensory ligaments

The Manubrium of the sternum occurs at the level of the vertebral bodies of ___-____. On either side a _____________ joint is present where the clavicles articulate with the manubrium.

T3-T4 sternoclavicular

Define nerve block

The term block indicates that the nerve endings in the skin and the transmission of impulses via the sensory nerves carrying information about pain are interrupted (blocked) prior to reaching the spinal cord and brain.

What boundaries define the thorax?

The thorax is located between the neck and the abdomen, and contains the primary organs of the respiratory and cardiovascular systems. The thoracic wall includes the thoracic cage and its muscles, as well as the skin, subcutaneous fascia, mammary glands, and muscles overlying the anterolateral aspect. The thorax is floored by the thoracic diaphragm.

If the anterior portion of the thoracic cage is removed, you would find these muscles. ___________ _________ arise at the posterior aspect of the sternum and insert on costal cartilages 2-6. Usually, three to four muscles occur and are reduced in size. Likely assist with forced expiration.

Transversus thoracis (sternocostalis)

What is the paravertebral line?

a vertical line corresponding to the tips of the transverse processes of the vertebrae

The 1st intercostal N is an atypical intercostal nerve because it lacks _____________/_________ __________ branches

anterior/lateral cutaneous

Azygos vein is formed by what 2 veins?

ascending right lumbar v. and right subcostal vein

Posterior intercostal veins 2-11 and subcostal veins drain to the ________ venous system

azygos (means "lacking pair")

The Intercostobrachial nerves 2nd, + sometimes 3rd intercostal nerve have a Lateral cutaneous branch which joins medially with the ________ ________

brachial plexus

The posterior intercostal a.a. give off ________ _________.

collateral branches

The head has two facets. One articulates with the numerically corresponding vertebra and the other articulates to the vertebra superior to it. This forms what joint?

costovertebral joint

The Internal intercostal muscles arise at the inferior border of a rib and insert on the superior border of the rib below. The fibers run upward and forward from origin "hands in back pockets orientation". They are most active during _________. The ________ ________ ___________ replaces the internal intercostal muscles between the ribs posteriorly and medial to the angles of the ribs and extends to the thoracic vertebrae

expiration internal intercostal membrane or (posterior intercostal membrane)

The Subcostal m.m. cross 1-2 intercostal spaces. These m.m. may be active during __________ __________. Fibers run in the same direction as innermost intercostals but are deep to them. The subcostal m.m. have the appearance of crossing over ribs.

forced expiration

The posterior intercostal a.a. run along the _________ border of the rib; whereas, the collateral branches descend to the _________ border of the rib below to dive between the muscle layers.

inferior superior

External intercostal m.m. are active during ______________. These m.m. terminate anteriorly, replaced by external intercostal membrane fiber direction lateral to medial. "hands in pocket direction"

inspiration

Anterior intercostal veins drain to __________ ________ veins

internal thoracic

The _________ ________ artery is a branch off the subclavian artery running lateral to the sternum. This artery sends anterior intercostal branches which anastomose with the posterior intercostal branches.

internal thoracic a.a.

Each lactiferous duct has a dilated portion called the ___________ ______ deep to the circular, pigmented areola. If lactating, the __________ ______ is where small droplets of milk accumulate before compression of the areola by the neonate causes the droplets to be expressed and secreted (not sucked) into the neonate's mouth

lactiferous sinus

Also coming off the posterior intercostal a.a. are the ________ ___________ branches. These branches pierce through the intercostal spaces and give off anterior and posterior cutaneous a.a.

lateral cutaneous

Typical intercostal n.n. at vertebral levels T3-T6 will have an __________ __________ nerve and a __________ _________ nerve.

lateral cutaneous nerve anterior cutaneous nerve

The manubrium and body of the sternum join at the _____________ joint and lie in different planes; thus, their junction forms a projecting sternal angle (of Louis). This is a palpable clinical landmark and it is located opposite the 2nd pair of costal cartilages at the level of the intervertebral disc between ___-_____.

manubriosternal T4-T5

Which thoracic structures are associated with the sternal angle?

manubrium (T3-T4) body of sternum (T5-T9) "angle of Louis"

The internal thoracic artery is going to continue inferiorly and gives off several _________ a.a. This starts at the 7th rib - the 7th, 8th, and 9th intercostal spaces are supplied by this artery.

musculophrenic

The thoracic aorta is to the left of the vertebral bodies. The thoracic aorta gives off _________ ________ arteries at intercostal spaces ___-___.

posterior intercostal 3-11

Breast vasculature and drainage: Arterial blood supply originates from what 3 branches?

subclavian artery axillary artery thoracic aorta

Because there are no more intercostal spaces below the 12th rib, the last pairing of a.a. coming off the thoracic aorta are called the _________ _____. Occurs below the 12th rib. Not technically an intercostal artery.

subcostal artery

After the internal thoracic artery gives off the musculophrenic a.a. it courses inferiorly to form what artery?

superior epigastric artery

Azygos vein reaches the level of T4, then drains to the _________ _______ _____.

superior vena cava

The ________ ________ is a branch from the intercostal (costocervical) trunk which comes off of the subclavian artery. This artery serves Posterior intercostal spaces 1-2.

supreme intercostal or highest intercostal artery

A tumor in the female breast exerts traction on which structure(s), causing nipple retraction?

suspensory ligament - dimpling of skin lactiferous duct - nipple retraction

Intercostal n.n. 7-11 are atypical intercostal n.n. give rise to lateral cutaneous branches, then are no longer present between the ribs, becoming __________ _________ nerves

thoraco-abdominal`

The ___________ joint is formed at the junction between the sternal body and the xiphoid process and is a midline marker for the upper limit of the liver, the central tendon of the diaphragm, and the inferior border of the heart

xiphisternal

Body of sternum is located at what vertebral levels? Xiphoid process at what level?

•At level of T5-T9 bodies - T10

What are the contents of the superficial fascia of thoracic wall?

•Blood vessels •Fat •Lymph tissue •Nerves and sweat glands •Mammary glands***

What is the deep fascia of thoracic wall?

•Fibrous and dense •Forms a loose attachment to superficial fascia •Regionally named for muscle it invests (e.g., pectoralis fascia)

thoracic cage or rib cage is formed by what structures?

•Ribs •Costal cartilages •Intercostal spaces •Sternum •Thoracic vertebrae •Intervertebral discs