1. Thoracic Cage

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Thoracic

cage


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Surface

Anatomy


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Anterior Surface of Thorax

Palpate Sternum (3 parts)

Jugular notch

Sternal Angle (= 2nd

rib) Clavicle

Costal margin

Infrasternal angle

Xiphosternal joint Midclavicular Line

Midaxillary Line


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Posterior Surface of Thorax

Palpate Spinous Process of C7

Scapula (ribs 2-7) Scapular spine

Acromion Process

Inferior Angle of Spine

Inferior Border


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Locating Internal Structures

Heart deep to xiphosternalangle

Pleural Cavities Inferior margin = adjacent

to T12 in Posterior Midline

To Rib 10 at Midaxillary line

To Rib 8 at Midclavicularline

To Xiphosternal jointmedially

Lungs posterior border is 2ribs superior to pleuralcavity (rib 8)


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The Vertebral Column Composed of 26 bones, including

24 individual vertebrae and the

fused vertebrae that form both the sacrum andthe coccyx

The vertebral column has several functions: providing vertical support for the body supporting the weight of the head helping to maintain upright body position

helping to transfer axial skeletal weight to theappendicular skeleton of the lower limbs

housing and protecting the delicate spinal cord andproviding a passageway for spinal nerves connectingto the spinal cord


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The Chest Wall

Rib cage Soft tissues

Muscles

The chest wall is lined by the parietal pleura.

The parietal pleura also covers the mediastinum. The visceral and parietal pleurae are attached by a

thin film of liquid.

There is normally no pleural space.


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Thoracic Wall Dimensional Changes

During Respiration Lateral dimensional changes occur with rib

movements. Elevation of the ribs increases the lateral

dimensions of the thoracic cavity, whiledepression of the ribs decreases the lateraldimensions of the thoracic cavity.


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Muscles that Move the Ribs The scalenes help increase thoracic cavity dimensions by elevating

the first and second ribs during forced inhalation.

The ribs elevate upon contraction of the external intercostals,

thereby increasing the transverse dimensions of the thoracic cavityduring inhalation.

Contraction of the internal intercostals depresses the ribs, but thisonly occurs during forced exhalation.

Normal exhalation requires no active muscular effort.

A small transversus thoracis extends across the inner surface of the

thoracic cage and attaches to ribs 26. It helps depress the ribs. Two posterior thorax muscles also assist with respiration. These

muscles are located deep to the trapezius and latissimus dorsi, butsuperficial to the erector spinae muscles.

The serratus posterior superior elevates ribs 25 during inhalation,and the serratus posterior inferior depresses ribs 812 during

exhalation. In addition, some accessory muscles assist with respiratory

activities.

The pectoralis minor, serratus anterior, and sternocleidomastoidhelp with forced inhalation, while the abdominal muscles (externaland internal obliques, transversus abdominis, and rectus abdominis)

assist in active exhalation.


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Boyles Law The pressure of a gas decreases if the volume of the

container increases, and vice versa.

When the volume of the thoracic cavity increases evenslightly during inhalation, the intrapulmonary pressuredecreases slightly, and air flows into the lungs throughthe conducting airways.

Air flows into the lungs from a region of higherpressure (the atmosphere) into a region of lower

pressure (the intrapulmonary region). When the volume of the thoracic cavity decreases

during exhalation, the intrapulmonary pressureincreases and forces air out of the lungs into theatmosphere.


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Parts and regions of the thorax

Boundaries Superiorjugular notch,

sternoclavicular joint,superior border ofclavicle, acromion,spinous processes ofC7

Inferiorxiphoidprocess, costal arch,12th and 11th ribs,vertebra T12

Regions Thoracic wall Thoracic cavity


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Landmarks Jugular notch corresponds with

The 2th thoracic vertebra inmale, the 3th thoracic vertebrain female

Sternal angle connects 2ndcostal cartilage laterallycorresponds with The lower border of 4th thoracic

vertebra The bifurcation of trachea in the

adult The beginning of aortic arch

which ends posteriorly at the

same level The esophagus is crossed by the

left main bronchus


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Xiphoid processphisternal junction lies

opposite the body of the9th thoracic vertebra

Clavicle Inferior fossa of clavicle

Coracoid process

Ribs and intercostalspaces

Costal arch Infrasternal angle

Xiphocostal angle Papillae


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Thoracic wall

Skin

Superficial fascia Thoracoepigastric v.

Supraclavicular n. Anterior and lateral

cutaneous branchesof intercostal n.

Deep fascia


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Intercostal space

Posterior intercostal v.

Posterior intercostal a.

Intercostal n.


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Internal thoracic vessels

Internal thoracic a.&v Parasternal ln

Endothoracic fascia


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Anatomy of the Breast Location:

Female

Superior border: 2nd rib Inferior border: 6th rib Medial border: Sternum Lateral border: Midaxillary line

Male Fourth Intercostal Space, Midclavicular line

Underlying muscle Pectoralis major and minor Part of serratus anterior, external obliques

Arterial blood supply

Internal thoracic artery

Lateral thoracic artery

Posterior intercostals

Thoracoacromial artery Venous blood supply

Axillary vein

Internal thoracic vein

Intercostal veins

Innervations

Intercostal nerves


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Mammary Glands

Modified sweat glands Function only in lactating

females Role to provide

nourishment and passiveimmunity to the neonate

15 to 25 lobes Lobes made of lobules

Alveoli Alveoli lined by epithelial

cells Secrete milk

Lactiferous ducts open tothe nipple Compound alveolar gland

M Gl d


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Mammary Glands

Mammar Glands


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Mammary Glands

Suspensoryligament Lobes surrounded

by adipose and

connective tissue Areola

Pigmented skinthat surrounds thenipple

1. Thoracic Cage

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