Anatomy Exam 3, Thoracic Wall and Breast Tissue

Carroll University Path-A Program 2026

Breasts are usually considered what kind of modified glands?

Modified sweat glands (sudiferous glands)

When does the development of breast tissue start?

in the 6th week of embryonic development

When does breast development finish?

After the 5th month of pregnancy

Where is the breast located?

Sternum to tail of the mid axillary line, horizontally between ribs 2-6

What is the function of the lactiferous sinuses?

Storage of milk

How can breast tumors and cancer be diagnosed?

Palpable mass

Mammogram (calcifications)

Dimples, “Peau d’orange”

Nipple deviation, inverted

Unequal breast elevation

Enlarged axillary lymph nodes

If breast cancer spreads, where does it commonly spread to?

Axillary lymph nodes (these nodes account for 75% of the lymphatic drainage for the breast)

How does breast cancer commonly spread to the BBB (blood, brain, bone)?

Through the lymphatic system (lymph to the azygous system)

How does breast cancer commonly spread to the other breast, thorax, and abdomen?

Via the parasternal lymph node, axillary lymph node, and cervical lymph node

What are the types of surigcal treatment available for breast cancer?

Lumpectomy

Mastectomy

What are the two types of mastectomies?

Radical

Simple/modified

What is something to think about in terms of a mastectomy and the costocoracoid membrane?

It contains (VAN), cephalic vein, thoracoacromial artery, and the lateral pectoral nerve

What is something to consider in terms of a mastectomy and the long thoracic nerve?

The long thoracic nerve runs along the medial wall of the axilla. It can be damaged during lymph node removal during a mastectomy. If it is injured, it may cause paralysis of the serratus anterior. If the serratus anterior is damaged, it can cause scapular winging.

What is the superior thoracic aperature/inlet?

“Doorway” between the neck and thorax

What structures pass through the superior opening of the thoracic cavity?

Trachea

Esophagus

Vessels

Nerves

The superior thoracic aperture/inlet is bounded by what structures?

T1 vertebrae

1st pair of ribs

superior border of the manubrium of the sternum

The inferior thoracic aperature/outlet is bounded by what structures?

T12 vertebrae
12th pair of ribs

Xiphisternal joint

What 3 structures pierce the diaphragm?

IVC (T8)

Esophagus (T10)

Aorta (T12)

What is the inferior thoracic aperture?

The lower opening of the thoracic cavity that connects the chest to the abdomen, sealed by the diaphragm.

What is the posterior thoracic wall?

The anatomical boundary at the back of the chest cage, formed by the 12 thoracic vertebrae

What is the anterior thoracic wall?

Musculoskeletal and bony framework that protects vital organs like the heart and lungs, bounded by the sternum and ribs in the front.

The sternum contains what three parts?

Manubrium

Body (gladiolus)

Xiphoid process

The manibrium articulates with:

Clavicle and 1st/2nd costal cartilages

The sternal angle is located on the:

where the manubrium joins the top of the body of the sternum

The sternal angle is also known as the:

Angle of Louis

The body of the sternum articulates with:

Costal cartilages

What is the xiphoid process?

Small, pointed cartilaginous extension at the lowest part of your breastbone (sternum)

The xiphoid process is made out of what kind of cartilages?

Hyaline cartilage

Does the xiphoid process ossify with age?

Yes

Typically completes ossification often between 40-50 years old

The costal cartilages are made out of what kind of cartilage?

Hyaline cartilage

the costal cartilages attach which ribs to the sternum DIRECTLY?

Upper 7 ribs

The costal cartilages attach which ribs to the rib cage?

ribs 8-10

How many pairs of ribs are there?

12

What ribs are considered the “true ribs”?

1-7

The anterior true ribs attach to the:

sternum

The posterior true ribs attach to the:

2 vertebrae (own and the one above)

The 1st rib is attached only to which vertebrae?

T1

Which ribs are considered the “false ribs”?

8-12

Ribs 8-10 anteriorly join the:

costal cartilages of the superior ribs above them

Ribs 8-10 posteriorly join the:

2 vertebrae (rib 8 and 9)

1 vertebrae (rib 10)

Ribs 11-12 are considered what kind of ribs?

Floating ribs

Do ribs 11-12 anteriorly join another structure or are they free floating?

free floating

Ribs 11-12 posteriorly join what structure?

One vertebrae (own)

What are the main structures that can be found on a typical rib?

Superior border

Inferior border

Head

Neck

tubercle

Shaft/body and angle (costal groove)

The superior border of a typical rib is:

Smooth and rounded

The inferior border of a typical rib is:

Rough, has ridges, and is sharp

the head of a typical rib attaches to the:

body of the vertebrae

The tubercle of a typical rib attaches to the:

transverse process of the vertebrae

What are atypical ribs?

Rib 1

Rib 2

Ribs 11-12

Rib 1 has a scalene tubercle that is attached to what muscles?

Anterior and middle scalene

Rib 1 has a subclavian artery and vein groove, which groove is anterior and which is posterior?

Anterior groove is for the vein

Posterior is for the artery

Rib 2 is attached to what muscles?

Serratus anterior (tuberosity)

Posterior scalene

What makes ribs 11-12 atypical?

Single facet on the head

tapered

What joints allow for costal arthology?

Costovertebral joints

Costotransverse joints

The costovertberal joints articulate with:

the head of the rib and adjacent vertebral body

What kind of joint is the costovertebral joint?

Gliding/plane synovial joint

The costotransverse joints can be found on what ribs?

ribs 1-10

the cosotransverse joints articulate with:

the tubercle of rib and transverse process of the vertebrae

What kind of joint is the costotransverse joint?

gliding synovial joint

What is the function of the sternocostal joint?

Provide structural stability to the chest while allowing the rib cage to expand and contract during respiration

The sternocostal joint articulates with:

the sternum and costal cartilages of ribs #1-7

The costal cartilage 1 and the manubrium are what kind of joint?

synchondrosis, a primary cartilaginous joint

Costal cartilages 2-7 and the sternum are a type of:

synovial plane joint

Costalchondral joints articulate with the:

Costal cartilages (lateral end) and the rib (sternal end)

What is the function of the costochondrial joints?

provide a firm yet flexible union that allows the rib cage to expand and twist during breathing, while maintaining the structural rigidity necessary to protect vital organs

What kind of joint is the costalchondrial joint?

synchondrosis

the manubriosternal joint articulates with the:

manubrium and body of the sternum

In adults, the manubriosternal joint is what kind of joint?

Symphysis

In juveniles, the manubriosternal joint is what kind of joint?

Synchondrosis

What is the function of the manubriosternal joint?

Connects the manubrium to the sternal body, forming the sternal angle.

The xiphisternal joint articulates with the:

Body of the sternum and xiphoid process

What kind of joint is the xiphisternal joint?

Synchondrosis

What is the function of the xiphisternal joint?

Connects the lower body of the sternum to the xiphoid process

Guides safe hand placement during CPR to avoid organ damage

Each intercostal space contains the neuromuscular bundle (VAN), which contains what?

Intercostal vein

Intercostal artery

Intercostal nerve

Nerves T1-T6: Will they travel or stay in the same spot?

Stay in their intercostal space

Nerves T7-T9: Will they leave or stay in the same spot?

Leaves the space to enter the body wall

Nerves T10-T11: Will they leave or stay in the same spot?

Pass directly to the body wall, PASS THROUGH

Nerve T12: Will it leave or stay in the same spot?

Travels inferior to the 12th rib and directly into abdominal wall

Nerve T12 is also known as the:

Subcostal nerve

Clinical application: How should a intercostal nerve block be placed?

To cover the incision site, you must inject the intercostal space above and below the incision site. this is due to the dermatome overlap. If this is not done, the patient would be able to feel the incision site.

What is a dermatome?

Area of skin innervated by the spinal nerve

Armpits are which dermatome?

T1

Nipples are which dermatomes?

T4

The xiphoid process is which dermatome?

T6

There is only ___ posterior intercostal artery per space.

one

There are ___ anterior intercostal arteries per space.

two

The posterior portion of the intercostal space drains into which venous system?

Azygous system

The anterior portion of the intercostal space drains into which venous system?

Drains into the internal thoracic vein

What is the innervation of the external and internal intercostal muscles?

intercostal nerve

What is the function of the external intercostal muscles?

Elevate the ribs during inhale

What is the function of the internal intercostal muscles?

either depress or elevate the ribs

What are the 2 parts of the internal intercostal muscles?

Interosseous

Interchondral

What is the function of the interosseous intercostal muscles?

depress the ribs

What is the function of the interchondral muscles?

elevate the ribs

The transversus thoracis is comprised of what 3 muscles?

Sternocostalis

Subcostalis

intermost intercostal

What is the function of the transversus thoracis?

Weakly depress the ribs

The transversus thoracis is innervated by what nerve?

intercostal nerve

What are some additional muscles that are apart of the thoracic wall (4 muscles)?

Levatores costarum

Serratus anterior

Serratus posterior superior

Serratus posterior inferior

What is the function of the levatores costarum?

Elevate ribs

What is the innervation of the levatores costarum?

C8-T11