Gray's Anatomy: Conceptual Overview

Question 1

Functions of the Thorax

Answer 1

Breathing, Protection of Vital Organs, Conduit

Question 2

What does the Superior Thoracic Aperture consist of?

Answer 2

Body of vertebra T1 posteriorly, medial margin of rib I on each side, and manubrium anteriorly

Question 3

Skeletal elements of the inferior thoracic aperture?

Answer 3

body of vertebra TXII posteriorly, rib XII and the distal end of rib XI posterolaterally; distal cartilaginous ends of ribs VII to X which untie to form costal margin anterolaterally, and xiphoid process anteriorly

Question 4

Parietal vs Visceral Pleura

Answer 4

Parietal: lines walls of cavity. Visceral: pleura reflected from mediastinum at the roots and onto the surfaces of lungs

Question 5

What separates the mediastinum into superior and inferior parts?

Answer 5

Horizontal plane passing through sternal angle and the intervertebral disc b/t vertebrae TIV and TV

Question 6

What constitutes the middle mediastinum?

Answer 6

The pericardium and the heart

Question 7

Where does the superior aspect of each pleural cavity extend?

Answer 7

Approx 2-3 cm above rib I and costal cartilage into the neck

Question 8

What separates the thorax from the abdomen?

Answer 8

Diaphragm

Question 9

Blood Supply to the Breast

Answer 9

Mammary artery, intercostal (perforators), thoracodorsal, thoracoacromial, lateral thoracic artery

Question 10

Horizontal plane passing thru disc that separates T4 & T5 is significant plane bc:

Answer 10

1. passes thru sternal angle anteriorly, marking position of anterior articulation of costal cartilage of rib II w/ sternum.
2. Separates superior from inferior mediastinum
3. marks where arch of aorta begins and ends
4. passes thru site where SVC penetrates pericardium to enter heart
5. Level at which trachea bifurcates into R & L main bronchi
6. Marks superior limit of pulmonary trunk

Question 11

Venous Shunts from L to R

Answer 11

L brachiocephalic vein: crosses midline immediately posterior to manubrium, delivers blood from L side of head and neck, L upper limb, and part of left thoracic wall into SVC.
Hemiazygos and accessory hemiazygos veins: drain post and lat parts of L thoracic wall, flow into azygos vein on R side, which connects with SVC

Question 12

Innervation of the Diaphragm

Answer 12

Two phrenic nerves that originate one on each side as branches of cervical plexus in neck. Arise from anterior rami of nerves C3, C4, C5. Spinal cord injuries below level of origin of phrenic nerve don’t affect movement of diaphragm. They pass vertically thru neck to superior thoracic aperture & mediastinum to supply motor innervation to entire diaphragm.