Bones and Joints of the Ribs

What are the spaces within the thoracic cavity?

- Central compartment, mediastinum, which houses the thoracic viscera (except for the lungs) like the hearts and the structures transporting the air, blood and food. - Right and left pulmonary cavities which house the lungs. *majority of the thoracic cavity is occupied by the lungs and its constituents.

Why is the xiphoid process an important landmark in the median plane?

- Its junction with the sternal body at the xiphisternal joint indicates the inferior limit of the central part of the thoracic cavity; this joint is also the site of the infrasternal angle (subcostal angle) formed by the right and left costal margins. -It is a mid-line marker for the superior limit of the liver, the central tendon of the diaphragm, and the inferior border of the heart.

Describe the jugular notch

-Aka the suprasternal notch -Easily palpated concave center of the superior border on either side of which there is an oval articular surface for clavicle.

What are characteristic features of typical thoracic vertebrae?

-Bilateral costal facets (demifacets) on the vertebral bodies, usually occurring in inferior and superior pairs, for articulation with the heads of ribs. -Costal facets on the transverse processes for articulation with the tubercles of ribs, except for the inferior two or three thoracic vertebrae. -Long inferiorly slanting spinous processes.

Describe the body of the sternum

-Longer, narrower and thinner than the manubrium. -Located at the level of the T5-T9 vertebrae. -It is the fusion of 4 sternabrae that fuse from a synchondroses to synostosis between puberty and 25 yrs. These synostoses cause three visible transverse ridges on the body of the sternum. -Alongside are costal notches for articulation with costal cartilage, which cause the width of the body to vary.Costal notches for continuous connections with ribs 3-7.

What is the inferior thoracic aperture bounded by?

-Posteriorly by the 12th thoracic vertebra, the body of which protrudes anteriorly into the opening. -Posterolaterlly by the 11th and 12th pair of ribs. -Anterolaterally by the joined costal cartilages of ribs 7-10, forming the costal margins. -Anteriorly, by the xiphisternal joint.

What is the superior thoracic aperture bounded by?

-Posteriorly by vertebra T1 the body of which protrudes anteriorly into the opening. -Laterally by the 1st pair of ribs and their costal cartilages. -Anteriorly by the superior border of the manubrium

What are the functions of the thoracic Cage?

-Protects vital thoracic and abdominal organs (most air or fluid filled) from external forces. -Resist the negative (sub-atmospheric) internal pressures generated by the elastic recoil of the lungs and inspiratory movements. -Provide attachment for and support weight of the upper limbs. - provide the anchoring attachment (origin) of many of the muscles that move and maintain the position of the upper limbs relative to the trunk as well as provide the attachments for muscles of the abdomen, neck, back and respiration.

Ligaments of joints of head of ribs

-The crest of the head of the rib attaches to the IV disc by and intra-articular ligament of head of rib within the joint, dividing the enclosed space into two synovial cavities. -The fibrous layer of the joint capsule is strongest anteriorly where it forms a radiate ligament of head of rib that fans out from the anterior margin of the head of the rib to the sides of the bodies of tho vertebrae an the IV disc between them. The heads of the ribs connect so cloelsy to the vertebral bodies that only slight gliding movements occur at the demifacets. However even slight movement at the joints of the heads of ribs may produce a large excursion of the distal (sternal or anterior) end of a rib. *heads of 1st, 11th and 12th ribs (sometimes 10th) articulate only with vertebral body of same number.

Where do the costal cartilages attach on the sternum?

-The first 7 costal cartilages attach directly and independently to the sternum. These costal cartilages belong to the first 7 true vertebrosternal ribs. -The 8th, 9th 10 articulate with the costal cartilages just superior to them, forming a continuous articulated, cartilaginous costal margin.

What curvatures do the ribs have?

1. Edge curvature 2. Flat surface curvature 3. Torsion curvature

Expansion of the ribs is made possible how?

1. Mobility of the costo-vertebral joints 2. Elasticity of the costal cartilages which permit twisting 3. to a slight extent by increased kyphosis of the thoracic column

What are the three types of rib?

1. True (vertebrosternal) ribs 2. False (vertebrochondral) ribs 3. Floating (vertebral, free) ribs

Please describe the 10th-12th ribs

10th-12th ribs, like the 1st rib have only 1 facet on their heads and articulate with a single vertebra. 11th and 12th ribs are short and have no neck or tubercle.

Which are the floating (vertebral, free) ribs?

11th, 12th and sometimes 10th rib. The rudimentary cartilages of these ribs do not connect even indirectly with the sternum. Instead they end on the posterior abdominal musculature.

Which are the atypical ribs?

1st, 2nd and 10th-12th rib are dissimilar.

sternocostal joint

1st: primary cartilaginous joint (synchondrosis). Articulation oft 1st costal cartilage with manubrium of sternum. 2nd-7th synovial plane joint. articulation of the 2nd-7th pairs of costal cartilage with sternum. Ligaments are anterior and posterior radiate sternocostal; intra-articular. Articular cavities often absent, fibrocartilage covers articular surfaces.

Which are the typical ribs?

3-9

Costotransverse Joints ligaments

A costotransverse ligament passing from the neck of the rib to the transverse process and a lateral costotransverse ligament passing from the the tubercles of the rib to the tip of the transverse processes strengthen the anterior and posterior aspects of the joint respectively. A superior costo-tranvserse ligament is a broad band that joins the crest of the neck of the rib to the transverse process superior to it. The superior constotransverse ligament may be divided into a strong anterior costotansverse ligament and a weak posterior costotransverse ligament. *11th and 12th ribs do not articulate with transverse process of vertebrae of the same number.

What is the purpose of the sternum?

Affords protection for mediastinal viscera in general and much of the heart in particular.

Where are the subcostal spaces widest?

Anterolaterally. The spaces widen further with inspiration and on contra-lateral extension and or lateral flexion of the thoracic vertebral column.

Describe the neck of the rib

Connects the head of the rib with the body at the level of the tubercle.

What are the ribs in general?

Curved flat bones that form most of the thoracic cage. Remarkably light in weight yet highly resilient. Each rib has a spongy interior containing bone marrow (hematopoietic tissue) which forms blood cells.

Please describe the 2nd rib

Has a thinner, less curved body and is substantially longer than the 1st rib. Its head has two facets for articulation with the bodies of T1 and T2 vertebrae. its main atypical feature is a rough area on its upper surface, the tuberosity for serratus anteriorm from which part of that muscles originates.

What components do the typical ribs have?

Head, neck, tubercle, and body

synchondrosis of first rib

Inferolateral to the clavicular notch the costal cartilage of the 1st rib is tightly attached to the lateral border of the manubrium, known as synchondrosis (primary cartilaginous joint) of the first rib.

What occupies the intercostal space?

Intercostal muscles, and membranes, two sets (main and collateral) of intercostal blood vessels and nerves, identified by the same number assigned to the space.

What is the size of an adult superior thoracic aperture?

It measures approximately 6.5 cm anteroposteriorly and 11 cm transversely. Slightly larger than 2 inches x 4 inches. Because of the obliquity of the 1st pair of ribs, the aperture slopes antero-inferiorly.

manubriosternal joint

Joint between the manubrium and body of sternum *synchondroses in adolescents and young adults, synostosis in adults. The manubrium and body of the sternum lie in slightly different planes superior and inferior to their junction; hence their junction forms a projecting sternal angle (which is open posteriorly) (of Louis) which is a landmark for rib 2.

Describe the tubercle of the rib

Located at the junction of the neck and body; a smooth articular part articulates with the corresponding transverse process of the vertebra and a rough non-articular part that provides attachment for the costotransverse ligament.

What are the main parts of the sternum?

Manubrium, body, xiphoid process. In adolescents and young adults the three parts are connected together by cartilaginous joints (synchondroses) that ossify during middle to late adulthood.

What is the thorax?

Part of the body between the neck and abdomen

costochondral joint

Primary cartilaginous joint between distal end of rib and lateral end of costal cartilage. The ligaments are cartilage and bone bound by periosteum. No movement occurs at this joint; costal cartilage provides flexibility.

Describe the manubrium

Roughly a trapezoidal bone. It is the widest and thicket of the three parts of the sternum. The easily palpated concave center of the superior border of the manubrium

What is the inferior thoracic aperture?

Significantly larger than the superior thoracic aperture, it provides a ring like origin of the diaphragm which completely occludes the opening. Excursions of the diaphragm primarily control the volume internal pressure of the thoracic cavity providing the bases for tidal respiration (air exchange).

Clavicular notch

Small notches on the manubrium where the medial ends of the clavicles articulate which are much larger than the relatively small clavicular notches. The medial ends of the clavicles and the clavicular notch form the sternoclavicular joint.

What is the intercostal space and how are they named?

Space between the ribs that separate the ribs and costal cartilages from one another. They are named according to the rib forming the superior border of the space. e.g. the 4th intercostal space lies between rib 4 and 5. There are 11 intercostal spaces and 11 intercostal nerves.

Thoracic skeleton includes

Sternum 12 pairs of ribs and associated costal cartilage 12 thoracic vertebrae and the intervertebral discs interposed between them.

What components make up the chest?

Superior part of the trunk that is broadest superiorly owing to the presence of the pectoral girdle with much of its girth accounted for by the pectoral and scapular musculature and, in adult females the breasts.

Costovertebral Joints

Synovial plane joints of heads of ribs and costotransverse joints.

Which thoracic vertebrae are atypical?

T1, T10, T11, T12

Describe the costal facets on T10

T10 has only one bilateral pair of who costal facets located partly on its body and partly on its pedicle. No inferior demifacets.

Describe the costal facets on T11 and T12

T11 and T12 also only have a single pair of (whole) costal facets, located on their pedicles.

Which are the true (vertebrosternal) ribs?

The 1st-7th ribs. They attach directly to the sternum through their own costal cartilages.

Which are the false (vertebrochondral) ribs?

The 8th, 9th and usually 10th rib. Their cartilages are connected to the cartilage of the rib above them; thus their connection with the sternum is indirect.

Please describe the 1st rib

The broadest (i.e. its body is widest and nearly horizontal), shortest and most sharply curved of the seven true ribs. it has a single facet on its head for articulation with T1 vertebra only and two transversely directed grooves crossing its superior surface for the sub-clavian vessels. The grooves are separated by a scalene tubercle and ridge which the anterior scalene muscle is attached.

Joints of heads of ribs

The head of the rib articulates with the superior costal facet of the corresponding (same numbered) vertebra, the inferior costal facet of the vertebra superior to it and the adjacent inter-vertebral disc unites the two vertebrae.

What are the parts of the manubrium?

The jugular notch, the clavicular notches, synchondrosis of the first rib. Manubriosternal joint, notch for articulation for the 2nd rib, at the inferior lateral edge.

xiphisternal joint

The point where the sternal body and xiphoid process articulate. Primary cartilaginous joint (synchondrosis). This joint often fuses and becomes a synostoses in older individuals.

What is the superior thoracic aperture?

The smaller superior opening of the thoracic cage. It allows communication with the neck and upper limbs. Oblique, and kidney shaped.

Please describe the xiphoid process

The smallest and most variable part of the sternum, it is thin and elongated. Its inferior end lies at the level of the T10 vertebra. Although often pointed, the process may be blunt, bifid, curved or deflected to one side or anteriorly. It is cartilaginous in young people but more or less ossified in adults older than age 40.

What is the subcostal space?

The space below the 12th rib. Subcostal nerve is the anterior ramus of spinal nerve T12

Describe the costal facets on the typical thoracic vertebrae.

The superior and inferior costal faces most of which are demifacets occur as bi-laterally paired planar surfaces on the superior and inferior posterolateral margins of the bodies of typical thoracic vertebrae (T2-T9).

Describe the costal facets on T1

The superior costal facets of vertebra T1 is a complete facet since there are no demifacets on the C7 vertebra above and rib 1 articulates only with vertebra T1. T1 has a typical inferior costal demifacet.

Describe the costal cartilage on the anterior ends of the 11th and 12th ribs

They form caps on the ribs and do not reach or attach to any other bone or cartilage.

What is the purpose of the costal cartilage?

They prolong the ribs anteriorly and contribute to the elasticity of the thoracic wall, providing a flexible attachment for their anterior end (tips). The costal cartilage increase in length through the first 7 and then gradually decrease.

Describe the body of the rib

Thin flat and curved, most markedly at the costal angel where the rib turns anterolaterally.The angle also demarcates the lateral limit of attachment of the deep back muscles to the ribs. The concave internal surface of the body has a costal groove parallling the inferior border of the rib which orivides some protection for the intercostal nerve and vessels.

What is the true thoracic wall?

Thoracic cage, the muscles that extend between the ribs as well as the skin, subcutaneous tissue, muscles and fascia covering its anterolateral aspect. The same structures covering its posterior aspect are considered to belong to the back.

What structures pass between the thoracic cavity and the neck through the superior thoracic aperture?

Trachea, esophagus, nerves and vessels that supply and drain the head, neck and upper limbs.

Costotransverse Joints articulation

Tubercle of rib with transverse process of vertebra of same number.

Inter-vertebral joints of vertebrae T1-T2

Type: symphysis (secondary cartilaginous) Articulation: adjacent vertebral bodies bound together by IV disc Ligaments: Anterior and posterior longitudinal Comments: movement mostly limited to small degrees of rotation.

Describe the head of the rib

Wedge shaped and has two facets, which are separated by the crest of the head. One facet for articulation with the numerically corresponding vertebra and one facet for the vertebra superior to it.

Is the inferior thoracic aperture oblique?

Yes, because the posterior thoracic wall is much longer than the anterior wall. It is also irregular in outline, and much more spacious than the anterior thoracic aperture.

Sex differences of the body of the sternum

body is linger males than in females. for sterna of the lame length, that of the male is narrower and slimmer than that of a female.

sternoclavicular joint

sternoclavicular joint: synovial joint, saddle; this joint is divided into two compartments by an articular disc; the articulation is between the sternal end of the clavicle with manubrium and the 1st costal cartilage. The ligaments are the anterior and posterior sternoclavicular; costoclavicular.

interchondral joints

synovial plane joints; between costal cartilages of 6th and 7th, 7th and 8th, and 8th and 9th ribs. their ligaments are interchondral ligaments. Articulation between costal cartilages of 9th and 10 ribs is fibrous.

What is the role of the diaphragm in the thoracic cavity?

the diaphragm separates the thoracic and abdominal cavities almost completely. Structures that pass from the thorax to the abdomen or visa versa pass through the opening that traverse the diaphragm (e.g. the esophagus and inferior vena cava) or pass posterior to it (e.g. the aorta).