Station 5: Bones, Muscles, and Neurovasculature of the thoracic wall

Question 1

How many of each vertebrae are there?

Answer 1

C1-7
T1-12
L1-5
S1-5 (fused)
C4(3-5) (fused)

Question 2

What do you call excessive anterior concavity of the spine?

Answer 2

Kyphosis

Question 3

Which structures form the vertebral arch?

Answer 3

The vertebral arch is the posterior portion of a thoracic vertebrae.

Consists of:
A pair of pedicles, a pair of lamina

Supports 7 processes:
4 Articular processes (2 superior L&R, and 2 inferior L&R)
2 Transverse processes (L&R have the costal facets)
1 Spinous process (attachment for muscles and ligaments)

Question 4

What constitutes the borders of the intervertebral foramina?

Answer 4

Inferior vertebral notch (superiorly)
Superior articular process (inferiorly),
the body of the vertebrae (anteriorly)
The lamina (posteriorly)

Question 5

What passes through the intervertebral foramina?

Answer 5

Spinal nerve root, dorsal root ganglion,
Spinal artery, segmental artery
Recurrent meningeal nerves
Transforaminal ligments

Question 6

What is a Zygapophysial joint? What type of joint?

Answer 6

Synovial joint

Zygapophysial articular surfaces are covered with hyaline cartilage

Joint adjacent vertebrae together via inferior/superior articular processes

Question 7

Name the ‘parts’ of a typical rib, and their function

Answer 7

Head: Articulates with vertebral bodies

Neck

Tubercule: Articulates with transverse processes of the vertebrae

Angle: A point just lateral to the tubercule where the shaft of the rib bends forward

Costal groove: lodges the intercostal V, A & Ns

Question 8

What are the names of the joints that join the rib to the vertebrae, what are the articulations?

Answer 8

Costovertebral: between the head of the rib and the articular process of the body of the vertebrae

Costotransverse: between the tubercule of the rib and the articular surface of the tranasverse process of the vertebrae (part of the vertebral arch)

Question 9

Costotransverse Joint: which articulations? WHat type of joint?

Answer 9

Tubercule of the rib with the articular surface of the transverse process of the vertebrae (part of the vertebral arch).

= Synovial Plane

Question 10

Costovertebral Joint: Which articulation? What type of joint?

Answer 10

Head of the rib with the articular process of the vertebral body

= Synovial Plane

Question 11

What are the bones, and important components of, the sternum? Joints, types of joints, etc

Answer 11

Manubrium (superiorly).
Houses the jugular notch on its superior edge.
Houses articulation of the first costal cartilage (of 1st rib)

Manubriosternal Joint: Symphisis (secondary cartilagenous) joint.
Articulation point of the 2nd costal cartilage (of 2nd rib)

Sternal bone - houses articulations with 3-7 costal cartilages

Xiphoid process
= a cartilagenous process which ossifies later in life, joined to the sternum via fibrous joint

Question 12

Which ribs articulate anteriorly with the sternum, and which part of the sternum do they articulate with?

Answer 12

1-7

1: to the manubrium
2: to the manubriosternal joint

3-7 to the sternum

Question 13

Which ribs articulate with the superior rib’s costal cartilage, instead of the sternum?

Answer 13

Ribs 8-10

Question 14

What are the floating ribs? WHere do they attach?

Answer 14

11 & 12.

Attached only to thoracic vertebrae

Question 15

What are the three layers of the intercostal muscles?

Answer 15

External (hands in pockets), Internal (opposite to externals), and innermost intercostals (more vertical arrangement of fibres)

Question 16

Between which muscle layers are the intercostal aa, vv and nn present?

Answer 16

Between internal and innermost intercostals

Question 17

Where do the posterior intercostal arteries arise from?

Answer 17

The 1st and 2nd posterior IC aa arise from the supreme intercostal artery, which is a branch of the costocervical trunk the SUBCLAVIAN artery

The lower 9 posterior IC aa arise from the posterior of the descending thoracic aorta

Question 18

Describe the drainage of the posterior IC vv

Answer 18

On the LEFT:
The top few left PIC vv drain into the left superior intercostal vein, which drains directly into the brachiocephalic vein (may also communicate w/ accessory hemiazygos v).

The middle left PIC vv drain into the accessory hemiazygos v, which drains into the azygos v. (sometimes the accessory hemiazygos drains into the hemiazygos v)

The lower left PIC xx drain into the hemiazygos v which drains into the azygos vein.

On the RIGHT:
The top few right PIC vv drain into the right superior intercostal vein, which drains into the azygos vein

The remainder of the R PIC vv drain into the azygos.

The azygos then drains directly into the SVC

Question 19

Origins of the anterior intercostal arteries?

Answer 19

From the internal thoracic artery, which arises from the subclavian artery near its origin

Question 20

Where do the anterior intercostal vv drain?

Answer 20

Into the internal thoracic vein, then into the brachiocephalic vein

Question 21

A spinal nerve forms from the union of which 2 structures? The spinal nerve then
almost immediately splits into which 2 structures? Of these 4 structures, which
corresponds to an intercostal nerve in the thorax?

Answer 21

Spinal nerves are formed by the union of a ventral and dorsal root. The ventral and dorsal roots arise from the ventral and dorsal lateral horns in the spinal cord. The spinal nerve then splits into Ventral and Dorsal Rami.

Ventral Rami = Intercostal nerves (T1-T5)

Before splitting, the spinal nerve gives off, and receives, white and grey ramus communicantes, respectfully. White ramus communicantes carry efferents to the sympathetic chain, and grey ones contain both afferent and efferents, but house afferent nerve fibers heading back to the spinal cord.