Transcript THORACIC ANATOMY Extramediastinal

THORACIC ANATOMY
Extramediastinal
Boundaries
• Anterior
–
manubrium, sternum and xiphisternum
• Posterior
–
vertebral column and the ribs
• Superior
–
continuous with the neck
• Inferior
–
diaphragm
• Thoracic wall is topographically & developmentally
continuous with the abdominal wall
Skin & Subcutaneous Tissue
Essentially the same as elsewhere in the body
Bones
• Sternum
–
manubrium, body and xiphoid process
– gives rise to and is the area of attachment
of a number of different muscles
• Vertebral column
• Scapula & clavicle
Bones cont…
• Ribs
–
12 pairs
– first seven pairs directly articulate with the sternum
– pairs 8-10 articulate with the rib above and then via 7th rib with
the sternum
– pairs 11&12 are capped with an apex of cartilage but do not
articulate with the sternum
–
atypical: 1st, 11th and 12th
–
remainder are typical
Joints
• Variety of joints
• Ribs
–
articulations between the ribs and the vertebral column:
costovertebral joints
– articulation between the ribs and the sternum: costosternal
joints
• Sternoclavicular joint
–
synovial joint
– medial end of the clavicle and the manubrium
Muscles: Outer Layer
• Consists of: external intercostals, levator costae
and serratus posterior
• External intercostals: corresponds to the external
oblique in the abdomen
• Levator costae: 12 pairs of fan-shaped muscles
• Serratus posterior: superior and inferior
Muscles: Inner Layer
• Consists of: internal intercostals
• Internal intercostals: corresponds with the internal
oblique in the abdomen
Muscles: Innermost Layer
• Consists of : subcostals, innermost intercostals
and tranversus thoracis
• Together referred to as the transversus thoracis
group
• Line the rib cage
–
subcostals: posteriorly
– innermost intercostals: laterally
– transversus thoracis: anteriorly
Intercostal Spaces
• Filled with the muscles of the thoracic wall
–
external/internal/innermost
• Neurovascular bundle lies in the plane between
the internal and innermost layer
–
vein, artery and nerve
– protected by the lower border of the rib above
• Intercostal nerve: anterior ramus of the spinal
nerve
–
segmentally supplies the muscles and skin of the thorax and
the abdominal wall
Intercostal Spaces cont…
• Intercostal arteries: anterior and posterior
–
branches from the descending thoracic aorta and the internal
thoracic artery for all intercostal spaces except for the first two
– supplied by the superior intercostal artery
• Intercostal veins: more complex
–
–
each space has one posterior and two anterior veins
complex drainage pattern
Contents: Lungs
• Surfaces: inferior, mediastinal & costal
• Hilum
–
area on the mediastinal surface where structures running to
and from the lung enter and leave
– different between the right and the left lung
Contents: Lungs cont…
• Structure of the alveolar tree
–
multiple divisions from the trachea to the respiratory
bronchioles
– 20-25 divisions in total
• Relationship of the alveolar tree to vascular supply
–
pulmonary artery divides alongside the bronchi however, it does
not supply it
– ultimately ramifies around the walls of
the alveoli and feeds it with deoxygenated
blood
– branches of the pulmonary vein drain
the area
Contents: Diaphragm
• Separates the thoracic and abdominal cavities
• Arises from within the costal margin: directly from
the ribs and via two large crura
• Relationships
right dome to the level of 4th ICS on expiration
– left dome to the level of the 5th rib
– central tendon level with the xiphisternal joint (T8)
–
• Openings
–
three: aortic, oesophageal and caval
Contents: Diaphragm cont…
• Nerve supply
–
sole muscular supply is
from the phrenic nerve
(C4, 5 & 6)