The sternum consists of what specific parts? What is the sternal angle and what is it's clinical relevance?
Manubrium (between 1st and 2nd costals) latin handle/ blade of sword
Body of Sternum
**Manubrium is the widest and thickest part of the sternum-
Very important: the manubrium and the body of the first rib lie in different planes superior and inferior to their junction, forming a Sternal Angle (of Louis)this is easy to palpate and locate the approximate location of the 2nd rib !!!
What is clinically relevavent regarding the sternal angle (or angle of Louie)?
**The sternal angle (also know as the angle of Louie) is between the manubrium and the body of the sternum and it is clinically relevant because you can PALPATE the angle and definitively locate and mark the 2ND RIB for a procedure. It also marks about T4/T5 vertebrae
Clinical: What is pectus excavatum? What are the 3 causes?**
Don't Miss easy clinical questions.
It is an anterior chest wall deformity characterized by a concave depression.Caused by:
1.) Intrauterine pressure on the chest wall during development
2.) Abnormal diaphragm positioning causing a posterior retraction
3.) Abnormal Connective Tissue production
Clinical: What is Pectus Carinatum? What are the 4 causes?
Pt will present with a protrusion of the sternum and costal cartilages
1.)Abnormal anterior cartilage growth
2.)Abnormal Sternal growth
3.)CT tissue disorders
4.)Associated conditions like scoliosis and congenital heart disease
Clinical: What is Flail Chest?
Flail chest describes an unstable chest wall usually due to multiple rib fractures from a trauma.
The trauma or impact breaks the ribs at both the proximal and distal points creating an uncoupled or loose flaps that exhibit paradoxical movement (inward on inspiration and outward on expiration)
-Very painful injury and impairs ventilation, affecting oxygenation of blood.
Treatment fixes the loose segments with hooks or wires so it cannot move.
The inferior end of the xiphoid process marks what level of vertebrae?
The xiphoid process is and important landmark clinically why?
First: It's junction with the sternal body at the xiphisternal joint tells you where the inferior limit of the central part of the thoracic cavity projected onto the anterior body wall (This is where the infrasternal angle or subcostal angle is formed by the right and left costal margins--look at above picture--The RED triangle indicates where the left and right costal margins are located
It is a midline marker for the superior limit of the liver, the central tendon of the diaphragm and inferior border of the heart.
Clinical: What is Thoracic Outlet Syndrome (TOS)?
What nerves and arteries can be involved?
This refers to the clinician's thoracic outlet: the arteries and T1 spinal nerves that emerge from the thorax through this superior aperature to enter the lower neck and limbs.
TOS: these emerging structures are affected by obstructions of the superior thoracic aperature--can be compression of these structures--
Typically manifestations of TOS involve the upper limb
Ulnar N. Median N. and Subclavian vessels can be involved in TOS
What are the three types of ribs?
True, Fales and Floating
What is characteristic of a true rib? Which ribs are true?
True (vertebrocostal) ribs (1st-7th ribs) are attached directly to the sternum through their OWN costal cartilage
What is characteristic of a false rib? Which ribs are false?
False (vertebrochondral) ribs(8th, 9th, and usually the 10th)- their cartilages are connected to the cartilage of the rib above them; so their connection with the sternum is indirect.
What is characteristic of your floating ribs?
Floating (vertebral, free) ribs
(11th, 12th and sometimes the 10th ribs) have rudimentary cartilages that do not connect even indirectly with the sternum; instead they end in the posterior abdominal musculature.
What is unique about your 1st rib? (It's an atypical rib)
1st: broadest shortest most sharply curved-has a single facet on its head for articulation with T1 vertebra and two transvers grooves crossing its superior surface for the subclavian vessels.
Which ribs are atypical?
1st, 2nd, 10th-12th ribs
Typical ribs #s?
3-9th Ribs are TYPICAL.
What is unique regarding your 2nd rib?
2nd: is thinner, less curved body, much longer than the first rib- It's head has two facets (1st rib has only one for T1)
Most Atypical Feature is a rough area on its upper surface, the tuberosity for serratus anterior, where the muscle originates
What is unique about the 10th-12th ribs?
They are like the first ribthey have only one facet on their headsand articulate with a single vertebrae.
What is atypical about the 11th and 12th ribs?
They are short and have NO neck or tubercle.
What are the components of the typical ribs? (ribs 3-9) KNOW these components
They have a head, neck, tubercle, body (curved at the costal angle) and a costal groove
What is clinically significant regarding the fracture of the first rib?
The short, broad first rib, posteroinferior to the clavical, is rarely fractured because it is protected (it can't be palpated)
When you fracture the first rib, damage can occur to the brachial plexus of nerves and subclavian vessels of the upper limb.
What is clinically significant regarding the middle ribs?
What part of the middle ribs are most commonly fractured?
The middle ribs are most commonly fractured.
Rib fx caused by blows or crushing injuries.
weakest part of rib: just anterior to its angle (although direct violence can damage a rib anywhere)
Damaged ribs can injure internal organs like the LUNG and SPLEEN.
Rib Fx Suck because they are extremely painful because the broken parts move during respiration, coughing, laughing and sneezing
Fractures of the lower ribs can cause what?
Lower rib fxs can tear the diaphragm and result in diaphragmatic hernia (where abdominal contents move into the chest cavity)
Dislocation of Ribs ("slipping rib" syndrome) is what?
The displacement of costal cartilage from the sternum---the dislocation of a sternocostal joint or the displacement of the interchondral joints.
Common in body-contact sports
pressure to nerves, vessels and muscles nearby
If the trauma is severe enough to disslocate a rib, it often injures underlying structures like the liver or diaphagm (causes severe pain)
What is "Rib Separation"?
It refers to the disslocation of costo-chondral junctions between the rib and its costal cartilage.
In separations of the 3rd-10th ribs tearing of the perichondrium and periosteum usually occurs, as a result, the rib can move superiorly overriding the rib above and causing pain.
What is Supernumary Ribs?
Normally we have 12 ribs on each side
We may have extra cervical ribswhich can affect the neurovascular structures exitign the superior thoracic aperature.
Can also have lumbar ribs (less common)
Supernumerary Ribs can affect identification of vertebral levels in diagnositic imaging
Describe Sternal Fractures
Occur in Crush Injuries
Typically Comminuted Fracture (
Sternum broken into many pieces)
Think of persons chest being forced against the steering column during an accident!
Displacement of bone fragments is uncommon due to the deep fascia
What is the most common fracture location on the sternum?
The sternal angle!
What is a Median Sternotomy?
To gain accessto the thoracic cavity for surgical operations in the mediastinum (for coronary artery bypass grafting) the sternum is divided in the median plane and retracted.
What allows this? The flexibility if the ribs and costal cartilages!
This splitting also gives foor access for removing tumors in the superior lobes of the lungs.
After surgery- two halves of the sternum are joined by wire sutures.
What is the purpose of a Sternal Biopsy?
The body of the sternum is often used for bone marrow needle biopsybecause of its breadth and sub-q position (so close to the skin)
The needle pierces the thin cortical boen and enters the vascular spongy bone
Sternal biopsy is commonly used for detection of metastatic cancer and blood dyscrasias (abnormalities)
There are several joints of the chest wall, what is the clinical significance if any of these joints are disturbed?
**During normal respiration the range of movement of these joints is small, but if any of them are distrubed it reduces the mobility of the joint and interferes with respiration
*Clinical: What is Ankylosing Spondylitis?
Chronic inflammatory disease affecting the joints of the axial skeletonLimits spinal range of motion, causes exercise intolerance sometimes
Leads to bone protuberances (extraarticular manifestations)
Tx: Preventitive and supportive
What is the main muscle for inspiration?
It is a dome shaped structure separating thoracic cavity from the abdominal cavity and is attached to the lower ribs and sternum
*You also use the external intercostals, serratus posterior superior and levator costorum for inspiration