Structure Week 1

Describe the bones and muscle layers of the chest wall

Bones

• sternum: manubrium, body, xiphoid process

• Ribs (12 pairs)

• Thoracic vertebrae (T1-T12)

Muscle Layers

• Intercostal muscles: external intercostals, internal intercostals, innermost intercostals

• Diaphragm

what are the 3 components of the sternum

• manubrium → The superior portion featuring the jugular (suprasternal) notch and the sternoclavicular joints where it articulates with the clavicles

• body → The middle portion of the sternum articulating with ribs 2 through 7

• xiphoid process → The inferior-most portion, located at the level of T10, which may ossify and fuse with the body in adulthood

what are the 3 components of the manubrium

• Jugular (suprasternal) notch → superior portion of sternum

• Sternoclavicular joint → where sternum articulates with clavicles

• Sternal angle (T4/T5) → critical clinical landmark formed by the junction of the manubrium and the body

what is a subcomponent of the xiphoid process

Xiphisternal joint → The articulation between the xiphoid process and the sternal body

what are the 3 classification of ribs & their locations

• True ribs (1-7) → Attach directly to the sternum through their own costal cartilages

• False ribs (8-10) → Their costal cartilages attach to the cartilage of the rib above, forming the costal margin

• Floating ribs (11-12) → Have no anterior attachment and end in the posterior abdominal musculature

What are the features & landmarks of the ribs

• head → Features superior and inferior articular facets for articulation with two adjacent vertebral bodies

• neck → Articulate with the transverse process of the vertebra of the same number

• tubercules → Articulate with the transverse process of the vertebra of the same number

• angle → The point where the rib turns anterolaterally

• costal groove → Located on the internal surface of the inferior border, it protects the intercostal neurovascular bundle

what does the head of a rib include

Superior/ inferior articular facets

what are the articulations & attachments of the ribs

• Posterior articulations

• Anterior articulations

• Costal cartilage

Posterior articulations

• Costotransverse joint

• Costovertebral joint

Anterior articulations

• Costochondral joint

• Sternochondral joint

• costal cartilage

Thoracic Vertebrae

Thoracic vertebrae

Recognize cervical vs thoracic vs lumbar vertebrae (include numbers)

what are the muscle layers of the chest wall

intercostal muscles

• external intercostals → outermost

• internal intercostals → middle

• innermost intercostals → deepest

diaphragm

describe the primary muscles of respiration

• diaphragm: primary muscle of respiration, separating the thoracic and abdominal cavities

• intercostal muscles: (External, Internal, and Innermost) stabilize the rib cage during the respiratory cycle

what are the innnervations of the primary muscles of respiration

The intercostal muscles are innervated by the intercostal nerves, which are the ventral rami of spinal nerves T1 through T11

functions of intercostal muscles

stabilize intercostal spaces during respiration

what are the borders of the thoracic cavity

• Anterior border: Formed by the sternum and costal cartilages.

• Lateral borders: Formed by the 12 pairs of ribs and intercostal muscles.

• Posterior border: Formed by the 12 thoracic vertebrae and intervertebral discs.

• Inferior border: Formed by the diaphragm

anterior border of thoracic cavity

Formed by the sternum and costal cartilages

lateral borders of thoracic cavities

Formed by the 12 pairs of ribs and intercostal muscles

posterior border of thoracic cavity

Formed by the 12 thoracic vertebrae and intervertebral discs

inferior border of thoracic cavity

Formed by the diaphragm