THE THORAX THORACIC WALL BREAST THE THORAX THORACIC WALL BREAST - - PowerPoint PPT Presentation

THORACIC WALL BREAST

THE THORAX

THE THORAX

• THORACIC WALL
• BREAST

THE THORAX

THORACIC WALL

THE THORAX The part of the body between the neck and abdomen. The thoracic cage (rib cage), with the horizontal bars formed by ribs and costal car;lages, is also supported by the ver>cal sternum (breastbone) and thoracic vertebrae

THE THORAX - BONES & JOINTS

The thoracic skeleton includes:

• 12 pairs of ribs and associated costal car>lages,
• 12 thoracic vertebrae and the intervertebral (IV) discs interposed

between them,

• and the sternum.

THE RIBS Ribs are curved, flat bones that form most of the thoracic cage

THE THORAX - BONES & JOINTS

There are three types of ribs that can be classified as typical or atypical:

• true (vertebrosternal) ribs (1st–7th ribs)
• false (vertebrochondral) ribs (8th, 9th, and usually 10th ribs)
• floa;ng (vertebral, free) ribs (11th, 12th, and some>mes 10th ribs)

THE RIBS There are three types of ribs that can be classified as typical or atypical:

• true (vertebrosternal) ribs (1st–7th ribs):

they aWach directly to the sternum through their own costal car>lages.

• false (vertebrochondral) ribs (8th, 9th, and usually 10th ribs):

their car>lages are connected to the car>lage of the rib above them; thus their connec>on with the sternum is indirect.

• floa;ng (vertebral, free) ribs (11th, 12th, and some;mes 10th ribs):

the rudimentary car>lages of these ribs do not connect even indirectly with the sternum; instead they end in the posterior abdominal musculature.

THE THORAX - BONES & JOINTS

THE RIBS

THE THORAX - BONES & JOINTS

Typical ribs (3rd–9th) have the following components:

• Head: has two facets, one for ar>cula>on with the numerically

corresponding vertebra and one facet for the vertebra superior to it.

• Neck: connects the head of the rib with the body at the

level of the tubercle.

• Tubercle: ar>culates with the corresponding transverse process of

the vertebra,

• Body (sha[): thin, flat, and curved.

Typical ribs (3rd–9th) have the following components:

• Head
• Neck
• Tubercle
• Body

THE RIBS

THE THORAX - BONES & JOINTS

ATYPICAL RIBS (1st, 2nd, and 10th–12th) are dissimilar:

• the 1st rib is the broadest (i.e., its body is widest and nearly

horizontal), shortest, and most sharply curved

• the 1st rib has a single facet on its head for ar>cula>on with the T1

vertebra only

• the 1st rib has two transversely directed grooves crossing its

superior surface for the subclavian vessels

• the 1st rib has the grooves separated by a scalene tubercle and

ridge, to which the anterior scalene muscle is aWached.

THE RIBS

THE THORAX - BONES & JOINTS

Atypical ribs (1st, 2nd, and 10th–12th) are dissimilar:

• the 2nd rib is has a thinner, less curved body
• has two facets for ar>cula>on with the bodies of the T1 and T2

vertebrae Atypical ribs (1st, 2nd, and 10th–12th) are dissimilar:

• The 10th–12th ribs, like the 1st rib, have only one facet on

their heads and ar;culate with a single vertebra. Atypical ribs (1st, 2nd, and 10th–12th) are dissimilar:

• The 11th and 12th ribs are short and have no neck or

tubercle.

THE COSTAL CARTILAGES

THE THORAX - BONES & JOINTS

Costal car;lages prolong the ribs anteriorly and contribute to the elas>city of the thoracic wall, providing a flexible aWachment for their anterior ends (>ps). Intercostal spaces separate the ribs and their costal car>lages from one another

THE THORACIC VERTEBRAE

THE THORAX - BONES & JOINTS

Characteris>c features of thoracic vertebrae include:

• Bilateral costal facets (demifacets) on the vertebral bodies, usually
• ccurring in inferior and superior pairs, for ar>cula>on with the

heads of ribs.

• Costal facets on the transverse processes for ar>cula>on with the

tubercles of ribs, except for the inferior two or three thoracic vertebrae.

• Long, inferiorly slan>ng spinous processes.

THE THORACIC VERTEBRAE

THE THORAX - BONES & JOINTS

Superior and inferior costal facets occur as bilaterally paired, planar surfaces on the superior and inferior posterolateral margins of the bodies of typical thoracic vertebrae (T2–T9). Atypical thoracic vertebrae:

• The superior costal facets of vertebra T1 are not demifacets because

there are no demifacets on the C7 vertebra above, and rib 1 ar;culates only with vertebra T1. T1 has a typical inferior costal facet.

• T10 has only one bilateral pair of (whole) costal facets, located

partly on its body and partly on its pedicle.

• T11 and T12 also have only a single pair of (whole) costal facets,

located on their pedicles.

THE STERNUM

THE THORAX - BONES & JOINTS

The sternum is the flat, elongated bone that forms the middle of the anterior part of the thoracic cage. The sternum consists of three parts:

• manubrium,
• body, and
• xiphoid process

THE STERNUM

THE THORAX - BONES & JOINTS

The easily palpated concave center of the superior border of the manubrium is the jugular notch (suprasternal notch). The jugular notch lies at the level of the inferior border of the body of T2 vertebra and the space between the 1st and 2nd thoracic spinous processes. The manubrium and body of the sternum lie in slightly different planes superior and inferior to their junc>on, the manubriosternal joint; hence, their junc>on forms a projec>ng sternal angle (of Louis). Inferolateral to the clavicular notch, the costal car>lage of the 1st rib is >ghtly aWached to the lateral border of the manubrium –

• the synchondrosis of the first rib

THE STERNUM

THE THORAX - BONES & JOINTS

The body of the sternum, is longer, narrower, and thinner than the manubrium, and is located at the level of the T5–T9 vertebrae The xiphoid process, the smallest and most variable part of the sternum, is thin and elongated. Its inferior end lies at the level of T10 vertebra.

THE STERNUM

THE THORAX - BONES & JOINTS

The xiphisternal joint is a midline marker for the superior limit of the liver, the central tendon of the diaphragm, and the inferior border of the heart.

JOINTS OF THORACIC WALL

THE THORAX - BONES & JOINTS

• Intervertebral (of vertebrae T1–T12)
• Costovertebral (joints of head of rib)
• Costochondral
• Interchondral
• Sternocostal
• Sternoclavicular
• Manubriosternal
• Xiphisternal

JOINTS OF THORACIC WALL

THE THORAX - BONES & JOINTS

JOINTS OF THORACIC WALL

THE THORAX - BONES & JOINTS

THE THORAX - BONES & JOINTS

THE THORACIC APERTURES

THE THORAX - BONES & JOINTS

While the thoracic cage provides a complete wall peripherally, it is

• pen superiorly and inferiorly.

THE THORACIC APERTURES The much smaller superior opening (aperture) is a passageway that allows communica>on with the neck and upper limbs. The larger inferior opening provides the ring-like origin of the diaphragm, which completely occludes the opening.

THE THORACIC APERTURES The SUPERIOR THORACIC APERTURE is bounded:

• Posteriorly, by vertebra T1, the body of which protrudes

anteriorly into the opening.

• Laterally, by the 1st pair of ribs and their costal car>lages.
• Anteriorly, by the superior border of the manubrium.

THE THORAX - BONES & JOINTS

THE THORACIC INLET Space-occupying tumours in this loca>on may compress adjacent structures, leading to the clinical condi>on called thoracic outlet syndrome.

THE THORAX - BONES & JOINTS

THE THORACIC APERTURES

Inferiorly the cavity of the thorax is separated from the abdominal contents by a fibromuscular sheet called the diaphragm.

THE THORAX - BONES & JOINTS

THE THORACIC APERTURES The floor of the thoracic cavity (thoracic diaphragm) is deeply invaginated inferiorly (i.e., is pushed upward) by viscera of the abdominal cavity.

The INFERIOR THORACIC APERTURE is bounded as follows:

• Posteriorly, by the 12th thoracic vertebra, the body of which

protrudes anteriorly into the opening.

• Posterolaterally, by the 11th and 12th pairs of ribs.
• Anterolaterally, by the joined costal car>lages of ribs 7–10, forming

the costal margins.

• Anteriorly, by the xiphisternal joint.

THE THORAX - BONES & JOINTS

THE THORACIC APERTURES

THE MUSCLES OF THE THORAX

MUSCLES OF THORACIC WALL

THE MUSCLES OF THE THORAX

MUSCLES OF THE PECTORAL REGION:

• Pectoralis major
• Subclavius
• Pectoralis minor

THE THORAX

• Lateral and medial pectoral nerves
• Medial pectoral nerve
• Nerve to subclavius

The pectoralis major muscle is the largest and most superficial of the pectoral region muscles. The subclavius and pectoralis minor muscles underlie pectoralis major:

• subclavius is small and passes laterally from the anterior and

medial part of rib I to the inferior surface of the clavicle;

• pectoralis minor passes from the anterior surfaces of ribs III to V to

the coracoid process of the scapula.

THE MUSCLES OF THE THORAX

The muscles of the pectoral region form the anterior wall of the axilla, a region between the upper limb and the neck through which all major structures pass. THE THORAX Nerves, vessels, and lympha>cs that pass between the pectoral region and the axilla pass through the clavipectoral fascia between subclavius and pectoralis minor or pass under the inferior margins of pectoralis major and minor.

THE MUSCLES OF THE THORAX

The true muscles of the thoracic wall are the: serratus posterior, levatores costarum, intercostal, subcostal, and transversus thoracis. THE MUSCLES

THE MUSCLES OF THE THORAX

The levatores costarum muscles are 12 fan-shaped muscles that elevate the ribs, but their role, if any, in normal inspira>on is uncertain. THE MUSCLES The intercostal muscles occupy the intercostal spaces The superficial layer - the external intercostals, the inner layer - the internal intercostals. The deepest fibers - the innermost intercostals. The external intercostal muscles (11 pairs) occupy the intercostal spaces from the tubercles of the ribs posteriorly to the costochondral junc>ons anteriorly.

THE MUSCLES OF THE THORAX

The external intercostal muscles are con>nuous inferiorly with the external oblique muscles in the anterolateral abdominal wall. THE MUSCLES The internal intercostal muscles (11 pairs) run deep to and at right angles to the external intercostals. Between the ribs posteriorly, medial to the angles, the internal intercostals are replaced by the internal intercostal membranes. The inferior internal intercostal muscles are con>nuous with the internal oblique muscles in the anterolateral abdominal wall. The innermost intercostal muscles are similar to the internal intercostals and are essen>ally their deeper parts. The innermost intercostals are separated from the internal intercostals by intercostal nerves and vessels

THE MUSCLES OF THE THORAX

The subcostal muscles are variable in size and shape, usually being well developed only in the lower thoracic wall. THE MUSCLES The transversus thoracis muscles consist of four or five slips that radiate superolaterally from the posterior aspect

• f the inferior sternum.

The external and internal intercostals are ac>ve during inspira;on and expira;on. The role of these muscles in producing movement of the ribs appears to be related mainly to forced respira;on. The primary role of the intercostal muscles in respira>on is to support (increase the tonus or rigidity of) the intercostal space. The diaphragm is the primary muscle of inspira>on.

NERVES OF THE THORACIC WALL The 12 pairs of thoracic spinal nerves supply the thoracic wall.

THE RESPIRATORY SYSTEM

As soon as they leave the IV foramina in which they are formed, the mixed thoracic spinal nerves divide into anterior and posterior (primary) rami or branches The anterior rami of nerves T1–T11 form the intercostal nerves that run along the extent

• f the intercostal spaces.

NERVES OF THE THORACIC WALL Near the angles of the ribs, the nerves pass between the internal intercostal and the innermost intercostal muscles. At this point, the intercostal nerves pass to and then con>nue to course in or just inferior to the costal grooves, running inferior to the intercostal arteries.

THE RESPIRATORY SYSTEM

NERVES OF THE THORACIC WALL The branches of a typical intercostal nerve are:

• Rami communicantes, or communica>ng branches, that connect

each intercostal nerve to the ipsilateral sympathe>c trunk.

• Collateral branches that arise near the angles of the ribs
• Lateral cutaneous branches that arise near the MAL
• Anterior cutaneous branches pierce the muscles and membranes
• f the intercostal space
• Muscular branches that supply the intercostal, subcostal,

transversus thoracis, levatores costarum, and serratus posterior muscles

THE RESPIRATORY SYSTEM

ARTERIES OF THORACIC WALL The arterial supply to the thoracic wall derives from the:

• Thoracic aorta, through the posterior intercostal and subcostal

arteries.

• Subclavian artery, through the internal thoracic and supreme

intercostal arteries.

• Axillary artery, through the superior and lateral thoracic arteries.

THE RESPIRATORY SYSTEM

The intercostal arteries course through the thoracic wall between the ribs. Each intercostal space is supplied by three arteries: a large posterior intercostal artery (and its collateral branch) and a small pair of anterior intercostal arteries.

VEINS OF THORACIC WALL

THE RESPIRATORY SYSTEM

VEINS OF THORACIC WALL There are 11 posterior intercostal veins and one subcostal vein on each side. The posterior intercostal veins anastomose with the anterior intercostal veins (tributaries of internal thoracic veins). Most posterior intercostal veins (4–11) end in the azygos/hemi- azygos venous system, which conveys venous blood to the superior vena cava (SVC). The posterior intercostal veins of the 1st intercostal space usually enter directly into the right and le[ brachiocephalic veins.

THE BREASTS

THE RESPIRATORY SYSTEM

BREASTS The breasts consist of glandular and suppor>ng fibrous ;ssue embedded within a faWy matrix, together with blood vessels, lympha>cs, and nerves.

THE BREASTS

The mammary glands are in the subcutaneous >ssue overlying the pectoralis major and minor muscles. At the greatest prominence of the breast is the nipple, surrounded by a circular pigmented area of skin, the areola The roughly circular body of the female breast rests on a bed of the breast that extends transversely from the lateral border of the sternum to the midaxillary line and ver>cally from the 2nd through 6th ribs.

FEMALE BREASTS Two thirds of the bed are formed by the pectoral fascia overlying the pectoralis major; the other third, by the fascia covering the serratus anterior.

THE BREASTS

Between the breast and the pectoral fascia is a loose subcutaneous >ssue plane or poten>al space –

• the retromammary space.

A small part of the mammary gland may extend along the inferolateral edge of the pectoralis major toward the axillary fossa (armpit), forming an axillary process or tail (of Spence). The mammary glands are firmly aWached to the dermis of the

• verlying skin, especially by substan>al skin ligaments,

the suspensory ligaments of Cooper.

FEMALE BREASTS These condensa>ons of fibrous connec>ve >ssue, par>cularly well developed in the superior part of the gland, help support the lobes and lobules of the mammary gland.

THE BREASTS

The lac;ferous ducts give rise to buds that develop into 15–20 lobules of the mammary gland, which cons>tute the parenchyma (func>onal substance) of the mammary gland. Thus each lobule is drained by a lac;ferous duct. Each duct has a dilated por>on deep to the areola, the lac;ferous sinus, in which a small droplet of milk accumulates

• r remains in the nursing mother.

The areolae contain numerous sebaceous glands, which enlarge during pregnancy and secrete an oily substance

FEMALE BREASTS The nipples are conical or cylindrical prominences in the centers of the areolae.

THE BREASTS

The mammary glands are modified sweat glands; therefore, they have no capsule or sheath. In most women, the breasts enlarge slightly during the menstrual period from increased release of gonadotropic hormones: follicle- s;mula;ng hormone (FSH) and luteinizing hormone (LH) - on the glandular >ssue.

VASCULATURE OF BREASTS The arterial supply of the breast derives from the:

• Medial mammary branches of perfora>ng branches and anterior

intercostal branches of the internal thoracic artery, origina>ng from the subclavian artery.

• Lateral thoracic and thoraco-acromial arteries, branches of the

axillary artery.

• Posterior intercostal arteries, branches of the thoracic aorta in the

2nd, 3rd, and 4th intercostal spaces.

THE BREASTS

The venous drainage of the breast is mainly to the axillary vein, but there is some drainage to the internal thoracic vein.

VASCULATURE OF BREASTS

THE BREASTS

The lympha;c drainage of the breast is important because of its role in the metastasis of cancer cells. Lymph passes from the nipple, areola, and lobules of the gland to the subareolar lympha;c plexus.

VASCULATURE OF BREASTS From the subareolar lympha;c plexus:

• most lymph (>75%), especially from the lateral breast quadrants,

drains to the axillary lymph nodes, ini>ally to the anterior or pectoral nodes for the most part.

• most of the remaining lymph, par>cularly from the medial breast

quadrants, drains to the parasternal lymph nodes or to the

• pposite breast.
• lymph from the inferior quadrants may pass deeply to abdominal

lymph nodes (subdiaphragma>c inferior phrenic lymph nodes).

THE BREASTS

VASCULATURE OF BREASTS Lymph from the axillary nodes drains into clavicular (infraclavicular and supraclavicular) lymph nodes and from them into the subclavian lympha;c trunk, which also drains lymph from the upper limb.

THE BREASTS

Lymph from the parasternal nodes enters the bronchomedias>nal lympha>c trunks, which also drain lymph from the thoracic viscera. The termina>on of the lympha>c trunks varies. These trunks are described as merging with each other and with the jugular lympha;c trunk, draining the head and neck to form a short right lympha;c duct on the right side or entering the termina>on at the thoracic duct on the le[ side.

VASCULATURE OF BREASTS The trunks open independently into the junc>on of the internal jugular and subclavian veins, the right or led venous angles, that form the right and le[ brachiocephalic veins.

THE BREASTS

NERVES OF BREASTS The nerves of the breast derive from anterior and lateral cutaneous branches of the 4th - 6th intercostal nerves.

THE BREASTS

The branches of the intercostal nerves convey:

• sensory fibers from the skin of the breast
• sympathe;c fibers to the blood vessels in the breasts and smooth

muscle in the overlying skin and nipple.