Anatomy Test 2: Thoracic Muscles

Front 1

Innermost intercostals

Back 1

Separated for internal by intercostals by neuromuscular bundle.
Located most laterally
Functions in expiration

Front 2

Subcostal muscle

Back 2

Lower thoracic wall
Cross intercostal spaces from one rib to 2nd or 3rd. Same direction and same action as internal intercostals

Front 3

Transversis throacis

Back 3

On the inside of the thoracic wall; start at the xiphoid process and end at the inferior sternal body.(2-6)
Proprioceptive and weak respiratory functions

Front 4

Internal thoracic artery

Back 4

On either side of the sternum run perpendicular to it. They are a branch off the subclavian artery

Front 5

Jobs of the intercostal muscles

Back 5

Primarily to support the intercostal spaces and preven paradoxical movement and isometeric contraction. Secondariliy they can help in forced respiration.

Front 6

Muscles of the thoracic wall

Back 6

2 serratus muscles(posterior inferior and superior, and anterior)
Levatores costarum
Intercostals
Subcostals
Transverse thoracic

Front 7

Thoracoappendicular muscles

Back 7

Attach to the ribcage but act on the upper limbs
pect major, minor and serratus anterior

Front 8

Scalen muscles

Back 8

In the neck that act during forced respiration

Front 9

Nerves of the thoracic wall

Back 9

12 pairs of spinal nerves
Anterior rami T1-11 = intercostal nerves along the intercostal spaces
Rami 12 is the subcostal nerve
Posterior rmai supply the back lateral to the articular processes of the vertbrae

Front 10

4 names for the spinal roots

Back 10

1. Ventral, efferent, motor, anterior
2. Posterior, dorsal, afferent, sensory

Front 11

Typical intercostal nerve characteristics

Back 11

1. 3-6th nerves come from spinal nerves
2. Enter the intercostal spaces by piercing the intercostal membrane
3. They run within the endothoracic fascia
4. At the angle of the rib it starts to run along the intercostal grooves with the VAs
5. It then bifuractes and collateral branches run along the top of the rib below
6. Nerves branch to other muscles and give lateral cutaneous branches at the MAL
6. At the sternum the nerves branch into the anterior cut.s

Front 12

Branches of typical intercostal nerves(3-11)

Back 12

A rami communicans connects the intercostal nerves here with the sympathetic trunk.
1. collateral branches come at the angle and innervate the parietal pleura and the intercostal muscles
2. Lateral cutaneous branches at the MAL and give anterior and posterior nerves
3. Anterior cutaneous branches divide and give a medial and lateral nerve

Front 13

Atypical intercostal nerves

Back 13

1. T1 innervates the brachial plexus and has no cutaneous branches.
2. 1st and 2nd run the internal surfaces of the 1st and 2nd ribs
3. 2nd(3rd) have large cutaneous branches that penetrates serratus anterior, enters axilla and supplies medial and posterior surface of arm.
4. 7-11 after later cutaneous branches, have no costal margin so the anterior cutaneous branch pierces the rectus sheath into the abdominal wall.

Front 14

Vaculature of the thoracic wall

Back 14

1. Thoracic aorta gives the posterior intercostal and subcostal arteries that supply the thoracic wall.
2. Subclavian artery gives the internal thoracic and supreme(highest) intercostal arteries
3. Axillary artery gives the superior and lateral thoracic arteries
4. Anterior and posterior arteries will anastemos to provide a better blood supply to the thoracic wall

Front 15

Posterior intercostal arteries

Back 15

1. 1st and 2nd will arise from the supreme intercostal artery(subclavian branch)
2. 3-11 arise posteriorly from the thoracic aorta and the right ones are longer and cross the vertebrae behind the esophagus
3. A posterior branch from this artery will supply the spinal cord, vertebral column, back muscles and skin on the back
4. Collateral branches will run along the rib below the rib of numbering
5. follows the passage of typical nerves
6. The terminal branches will anastemos

Front 16

Internal thoracic artery

Back 16

1. Arises from the anterior surface of the subclavian arteries
2. Descends posterior to the clavicle and lateral to the sternum and anterior to the transversis thoracis
3. Terminate at the 6 costal cartilage and divides
4. Gives the 6 anterior intercostal arteries

Front 17

Epigastric and musculophrenic arteries

Back 17

1. They are branches off the internal thoracic artery beginning at the 6th costal cartilage.
2. Epigastric supplies the anterior part of the abdominal wall and some of the diaphragm
3. The musculophrenic supplies the 7,8,9 intercostal spaces and the lower pericardium.

Front 18

Anterior intercostal arteries

Back 18

1. Supply the upper 9 intercostal spaces
2. Pass laterally into spaces inferior and superior
3. 1 and 2 lie between the parietal pleura and the internal intercostals
4. 3-6 separated from parietal pleura by transversis thoracis
5. 7-9 derived from the musculophrenic arteries
6. also supply the pects, breasts and skin

Front 19

Veins of the thoracic wall

Back 19

1. Intercostal veins accompany the arteries into the walls
2. Veins do not branch they have tributaries
3. There are 11 posterior intercostal veins and one subcostal
4. Posterior can anastemos with the anterior
5. Posterior drain into vertbral venous plexuses
6. 4-11 anterior intercostal veins end in the hemiazygous/azygous system that drains into the SVC

Front 20

Azygous system

Back 20

1. Returns blood to the Vena Cava
2. A secondary that will return blood from the lower body to the superior vena cava if the lower one is blocked

Front 21

Azygous vein

Back 21

Major tributary to the SVC on the right side of the body

Front 22

Hemiazygous vein

Back 22

Crosses from the left to the right side at T9 and empties into the Azygous

Front 23

Accessory hemiazygous

Back 23

Crosses left to right at T8 and empties blood from the upper left thoracic cavity into the Azygous vein

Front 24

2nd and 3rd intercostal veins

Back 24

1. Unite to form the superior intercostal vein and finally empty into the Azygous.
2. On the right they empty into the brachiocephalic vein

Front 25

Thoracic Duct

Back 25

A lymphatic channel that you will not see while dissecting, begins at the cervical vertbrae and goes down to the lumber. It is the largest lymph vessel in your body and very important in infection.