Thoracic wall & inlet

What does the Thoracic skeleton consist of?

* Thoracic vertebrae posteriorly
* Ribs laterally
* Sternum & costal cartilages anteriorly

What secures the ribs to the sternum?

Costal cartilages

What does the Thoracic skeleton provide attachment for?

Muscles of the back & chest that support the shoulder girdle (scapula & clavicle) & movement of the limbs

What is Costochondritis?

Inflammation & irritation of the Costochondral joint that leads to localized chest pain & treated with NSAIDS

What is the normal shape/construction of the Thoracic vertebrae?

2 costal facets, one at the superior edge & one at the inferior head where they receive the heads of the ribs

Which Thoracic vertebrae bear costal facets that articulate with the tubercles of the ribs?

T1 - T10

How do the ribs course?

Oblique, inferior direction from thoracic vertebral articulation to their

What are the Typical ribs?

Ribs 2-10

What is the head & neck of the ribs?

Forms costovertebral joints by articulating with the costal demifacets of adjacent thoracic vertebral bodies & intervertebral discs

What is the tubercle of the ribs?

Articulates with the costal facets of adjacent thoracic vertebral transverse processes (not 11 & 12)

What is the shaft of the ribs?

Long portion of the rib with a smooth superior border & sharp, thin inferior border possessing a costal groove that has intercostal veins, arteries, & nerves

What does the distal end of the shaft articulate with?

Costal cartilage that forms costochondral

What is the most common portion of a rib to fracture that is the weakest point?

Anterior to the angle

What can a fracture of the rib puncture?

Parietal pleura which can cause a pneumothorax

Which ribs are atypical?

1, 11, & 12

Why is Rib 1 atypical?

It is not palpable because it lies deep to the clavicle

What is on the upper surface of Rib 1?

Scalene tubercle for inferior attachment of the anterior scalene muscle

What is on the anterior surface of the scalene tubercle on Rib 1?

Groove for the Subclavian vein

What is on the posterior surface of the scalene tubercle on Rib 1?

Groove for the Subclavian artery

Why are Ribs 11 & 12 atypical & also termed the floating ribs?

They don’t articulate with the sternum

What does the Manubrium contain?

Jugular notch at T2 that is flanked on each side w/ a synovial sternoclavicular joint that provides attachment between upper limbs & axial skeleton

Which joint between the costal cartilages & the sternum are cartilaginous?

1st sternochondral joint with rib 1

What does the upper half of rib 2 attach to?

Body of the sternum at the manubriosternal joint aka the sternal angle

What is the Xiphoid process?

Located at T9, articulates with the sternal body, & has attachment for the linea alba

What is significant about rib 2’s articulation with the sternum at the sternal angle?

Palpation of the sternal angle permits bilateral identification of rib 2 & all lower ribs

What does the Sternal angle mark?

* Level of T4 & T5 in an axial plane
* Start & end of aortic arch
* Tracheal bifurcation into r/l primary bronchi
* Azygous vein & its course over the r. primary bronchus to the SVC
* Border between superior & middle mediastinum
* Thoracic lymphatic duct transitions from r/l side of the thoracic cavity

What are the Superficial thoracic muscles?

Originate on the thoracic skeleton & inserts on the upper limb therefore prod. motion of the upper limb

Which muscles are in the Superficial thoracic muscles group?

* Pectoralis major muscle
* Pectoralis minor muscle
* Seratus anterior muscle
* Subclavius muscle

What are the Deep thoracic muscles?

Located within the intercostal spaces & are primarily responsible for changing the volume of the thoracic cavity during respiration

Which muscles are in the Deep thoracic muscles group?

* External intercostal muscles
* Internal intercostal muscles

What does the Pectoralis major muscle attach to?

Sternum, clavicle, & costal margins & laterally to the intertubercular groove of the humerus

What is the function of the Pectoralis major muscle?

Prime flexor, ADDuctor, & medial rotator of the humerus

What does the Pectoralis minor muscle attach to?

Anteriorly on the thoracic skeleton to ribs 3 & 5 & superiorly to the coracoid process of the scapula

What is the function of the Pectoralis minor muscle?

Stabilizes the scapula against the thoracic wall

What does the Serratus anterior attach to?

Ribs 1 & 8 along the midaxillary line & courses posteriorly to the medial margin of the scapula

What is the function of the Serratus anterior muscle?

Primary protractor of the scapula as well as a stabilizer of the scapula against the thoracic wall

What does the Subclavius attach to?

Clavicle & rib 1

What is the function of the Subclavius muscle?

Moves the clavicle inferiorly

What acts as accessory respiratory muscles by helping to expand the thoracic cavity when inspiration is deep & forceful?

Superficial thoracic muscles

Which muscle fills the intercostal spaces posteriorly from the tubercles of the ribs to the costochondral joint anteriorly?

External intercostal muscles

The external intercostal muscle continues from the costochondral joint to the sternum as what?

External intercostal membrane

What is the function of the External intercostal muscles?

Move ribs superiorly & most active during __inspiration__

What does the Internal costal muscles fill?

Intercostal spaces anteriorly from the sternum to the angle of the ribs posteriorly

The internal intercostal muscle continues from the angle of the ribs to the vertebral column as the what?

Internal intercostal membrane

What is the function of the Internal intercostal muscles?

Moves the ribs inferiorly & most active during __expiration__

What are the groups of Intercostal (deep) muscles?

* Transverse thoracis muscles
* Innermost intercostal muscles
* Subcostal muscles

What is the function of Intercostal (deep) muscles?

Aids in depressing the ribs & facilitates expiration

What is the significance of the Thoracic inlet?

Important anatomic landmark that serves as the central conducting pathway for vital structures extending from neck to chest & vice versa

What is the Thoracic inlet?

1st rib developing from T1 costal processes & joining the manubrium + T1 vertebral body & manubrium = 1st rib forming the opening

What is another name for the Thoracic inlet?

Superior thoracic cage or Superior thoracic aperture

What is Thoracic outlet syndrome?

A neurogenic syndrome where the subclavian vessels and/or brachial plexus are compressed as they exit thorax via the space between the 1st rib, clavicle, & scalene muscle. Symptoms include pain & paresthesia of the arm, hand, or finger

What is a treatment of Thoracic outlet syndrome?

Resection of the 1st rib & scalenectomy

Where are the Intercostal nerves derived from?

Ventral rami of the 1st 11 thoracic spinal nerves

What do the Intercostal nerves give rise to?

Anterior & lateral cutaneous branches (sensory) & muscular branches (motor)

What is the arterial supply to the Thoracic wall?

* Superior/supreme intercostal arteries
* Internal thoracic artery
* Anterior intercostal arteries
* Anterior perforating arteries
* Musculophrenic artery
* Superior epigastric artery
* Posterior intercostal arteries
* Subcostal artery

What provides venous drainage of the Thoracic wall?

* Internal thoracic vein
* Anterior intercostal veins
* Posterior intercostal veins

What is the Internal thoracic vein?

Accompanies internal thoracic artery along internal surface of the rib cage lateral to the sternum, draining into the brachiocephalic vein

What are the Anterior intercostal veins?

Accompanies the anterior intercostal arteries between the internal & innermost intercostal muscles & are tributaries to the musculophrenic & internal thoracic veins which are tributaries of the brachiocephalic veins

What are the Posterior intercostal veins?

Accompanies the posterior intercostal arteries between the internal & innermost intercostal muscles.

The upper two posterior intercostal veins of the Posterior intercostal veins drains into where?

Brachiocephalic veins

What are the 9 lowest spaces of the Posterior intercostal veins?

Tributaries of the azygous system which drains into the SVC