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Home , Sternal angle, Sternum, Thoracic cavity

Lab 4

FUNCTIONAL HUMAN LAB #4

THORACIC OSTEOLOGY:

BREASTPLATE:

Manubrium The between the Manubrium and the is called the manubrialsternal joint. This point is also a surface landmark called the (which can be easily palpated). This is clinically Sternum important because it is located at the level of the second . Once the sternal angle has been palpated, the intercostal spaces may be identified.

RIBS:

Head

Neck 1-7 are true ribs (have direct connection to the sternum); 8-12 Tubercle are false ribs (no direct connection to the sternum); 11-12 are also floating ribs (have no anterior connection at all). Each rib articulates Angle with the thoracic vertebre in two places. The head of the rib articulates with the body of a vertebre and the tubercle of the rib articulates with Costal groove the tranverse process of a vertebre. There are costal facets present at these articulation points. Sternal end

Costal chondrial joint

THORACIC MUSCULATURE:

Pectoralis major Medial attachment: consists of three heads (clavicular, sternal and Proximal end of clavical, body of sternum and the middle few ribs abdominal); only identify for now, we will discuss the function of this muscle in the Lateral attachment: upper extremity lab Lateral of interturbicular (bicipital) groove

Function: Flexion of the arm at (clavicular head); horizontal adduction (sternal head); flexion of arm at shoulder from a hyperextended position (abdominal head); horizontal adduction and internal rotation (all three heads)

Pectoralis minor Superior attachment: Acts primarily as a scapular stabilizer Corocoid process of the

Inferior attachment: 3rd - 5th ribs near their costal

Function: depress scapula

Serratus Anterior Medial attachment: consists of three heads (clavicular, sternal and Medial border of Scapula abdominal); only identify for now, we will discuss the function of this muscle in the Lateral attachment: upper extremity lab Ribs 1 – 8 (or 9) at the (approx.) anterior axillary line

Function: protract scapula

1 Lab 4

External Intercostals Superior attachment: Outermost layer of muscle between the ribs; Inferior border of rib fibers run medially from superior to inferior; muscle does not cover the costal cartilages Inferior attachment: (exists as a transparent membrane only) Superior border of rib of adjacent rib

Function: elevate ribs (inspiration)

Internal intercostals Superior attachment: Middle layer of muscle between the ribs; fibers Inferior border of rib run laterally from superior to inferior; separated from the innermost intercostals by Inferior attachment: the intercostal vasculature Superior border of rib of adjacent rib

Function: elevate ribs (inspiration)

Innermost Intercostals Superior attachment: Innermost layer of muscle between the ribs; Inferior border of rib fibers run laterally from superior to inferior; separated from the internal intercostals by the Inferior attachment: intercostal vasculature Superior border of rib of adjacent rib

Function: elevate ribs (inspiration)

Subcostals Superior attachment: Located beneath the ribcage Inferior border of rib

Inferior attachment: Superior border of rib (spans 2 ribs); best developed in ribs 6 – 12

Function: depress ribs (expiration)

Tranversus thoracis Medial attachment: Located beneath the ribcage; has a “christmas Posterior lateral side of distal end of body of sternum tree” shape Lateral attachment: Internal inferior border of costal cartilages of 2nd - 6th ribs

Function: depress ribs (expiration)

2 Lab 4

After dissecting the , the parietal pleura is seen. Before puncturing the pleura, the are still inflated due to the adhesion between the parietal and visceral pleural layers. This is important to note since this adhesion is the way the lungs are able to expand. The lungs themselves have no ability to expand on their own; the ribcage expands and the lungs (through this adhesion) are forced to expand as well. The parietal pleura lines the , ribs and diaphram and fills the gap in the superior thoracic aperture (circle formed by the Manubrium, first ribs and first thoracic vertebre). Once the parietal pleura is punctured, the lungs collapse. This same thing would happen if anything entered the space between the parietal and visceral pleural layers (e.g., air, blood, water, etc.).

The lungs are (or should be) free everywhere except at the root. At the root, the parietal and visceral pleural layers meet and form the pulmonary ligament. This is the only communication between the and the mediastinum. Note that the phrenic and accompanying vessels (pericardiocophrenic a. & v.) pass anterior to the root of the lungs.

In between the two pleural cavities is the area called the Mediastinum which is bordered by:

Anteriorly – plate (Manubrium, Sternum and Xiphoid process)

Posteriorly – Thoracic vertebre

Laterally – Pleural cavities

Superiorly – Superior thoracic aperture

Inferiorly – Diaphram and contains:

Heart gland Primary bronchi Phrenic N. Vagus N. Thoracic duct Inferior Vena Cava Azygos v. Sympathetic Chain Pulmonary a. Pulmonary v. Pericardial cavity nodes Fat

HEART:

Blood flow:

Start at the Left Ventricle (apex) > Aortic Valve > Aorta > Body > Superior or

Inferior Vena Cava > Right Atrium > Tricuspid Valve > Right Ventricle >

Pulmonic Valve > Pulmonary Trunk > Pulmonary a. > Lungs > Pulmonary v. >

Left Atrium > Bicuspid Valve > Start Over

This represents the total blood circulation which consists of Systemic blood flow (from left ventricle to right ventricle) and Pulmonic blood flow (from right ventricle back to left ventricle). The heart has its own Coronary blood flow which is slightly different. When blood leaves the left ventricle and goes through the Aortic valve, some of it is taken back to the heart via the Right and Left Coronary a. This blood supplies the heart muscle and is drained through Coronary v. which combine to form the Coronary sinus. The Coronary sinus drains directly into the interior of the Right Atrium next to the Inferior Vena Cava. In this way, the blood that supplies the heart is turned over faster than the blood that goes to the rest of the body.

When the parietal is opened, the major vessels entering and leaving the heart can be palpated. This can be done by feeling around in the Oblique and Tranverse pericardial sinuses. Note which vessels can be palpated in each sinus.

When the heart is dissected, be sure to palpate the Fossa Ovalis which is the remains of the opening between the right and left atria present in fetal circulation.

3 Lab 4

LUNGS: once removed identify the following:

Apex

Superior Lobe

Inferior Lobe

Middle Lobe (on right only)

Pulmonary ligament

Root of lung

Openings of the lungs (pulmonary a., pulmonary v. and bronchial) – the bronchial openings will be have the thickest vessel walls (due to the presence of ); the arterial walls will be the next thickest; and the veinous walls will be the thinnest. Locationally, the will be superior and anterior, the bronchials will be superior and posterior and the will be inferior (this is only for general location; vessels must be further assessed to be sure of type)

With the lungs removed, it is now possible to see the vagus passing posterior to the root of the lungs. Also note the pleural recesses. The lungs partially fill this space as they expand.

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