66
GRANT’S DISSECTOR
3. Use an illustration and your dissected specimen to
review the origin, course, and branches of the posterior
intercostal artery and intercostal nerve.
4. Consult a dermatome chart and compare the der-
matome pattern to the distribution of the intercostal
nerves.
[G 348; L 162; N 159; R 205; C 10]
REMOVAL OF THE ANTERIOR
THORACIC WALL
Dissection Overview
To view the contents of the thoracic cavity, the anterior tho-
racic wall must be removed. The goal of this dissection is to
remove the thoracic wall with the
costal pleura
attached to
its inner surface. The structures to be removed include the
12. The anterior end of the intercostal space is sup-
plied by
anterior intercostal branches
of the
internal thoracic artery
. The internal thoracic
artery runs a vertical course just lateral to the
border of the sternum and crosses the deep sur-
faces of the costal cartilages.
[G 24; L 167, 168;
N 183; R 208; C 148]
Dissection Follow-up
1. Replace the internal and external intercostal muscles in
their correct anatomical positions.
2. Review the muscles that lie in the intercostal space.
Review their actions. Understand how they assist res-
piration by elevating and depressing the ribs.
Body of 4th thoracic vertebra
Spinal cord
Spinal
ganglion
Anterior ramus
(intercostal nerve)
4th thoracic
spinal nerve
Posterior ramus
Anterior branch
Posterior branch
Anterior cutaneous branches of
4th intercostal nerve:
Lateral branch
Medial branch
Sternum
Lung
Transversus thoracis
muscle
External intercostal
membrane
External intercostal
muscle
Internal intercostal
muscle
Innermost intercostal
muscle
Parietal pleura
Lateral cutaneous branches
of 4th intercostal nerve:
Posterior cutaneous branches of
posterior ramus of 4th thoracic nerve:
Lateral branch
Medial branch
FIGURE 3.6
Course and distribution of the fourth thoracic spinal nerve.
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