THE THORAX THORACIC WALL

Transcription

1 THE THORAX THORACIC WALL BREAST

2 THE THORAX THORACIC WALL BREAST

3 THORACIC WALL THE THORAX

4 THE THORAX THE THORAX - BONES & JOINTS 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 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.

5 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 10 th ribs) floa;ng (vertebral, free) ribs (11th, 12th, and some>mes 10th ribs)

6 THE RIBS THE THORAX - BONES & JOINTS 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.

7 THE RIBS Typical ribs (3rd 9th) have the following components: Head Neck Tubercle Body 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.

8 THE RIBS 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 THORAX - BONES & JOINTS 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.

9 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.

10 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

11 THE THORACIC VERTEBRAE THE THORAX - BONES & JOINTS Characteris>c features of thoracic vertebrae include: Bilateral costal facets (demifacets) on the vertebral bodies, usually occurring 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.

12 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.

13 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

14 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

15 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.

16 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.

17 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

18 JOINTS OF THORACIC WALL THE THORAX - BONES & JOINTS

19 JOINTS OF THORACIC WALL THE THORAX - BONES & JOINTS

20 THE THORACIC APERTURES THE THORAX - BONES & JOINTS

21 THE THORACIC APERTURES THE THORAX - BONES & JOINTS While the thoracic cage provides a complete wall peripherally, it is open superiorly and inferiorly. 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.

22 THE THORACIC APERTURES THE THORAX - BONES & JOINTS 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.

23 THE THORACIC APERTURES 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.

24 THE THORACIC APERTURES THE THORAX - BONES & JOINTS Inferiorly the cavity of the thorax is separated from the abdominal contents by a fibromuscular sheet called the diaphragm. The floor of the thoracic cavity (thoracic diaphragm) is deeply invaginated inferiorly (i.e., is pushed upward) by viscera of the abdominal cavity.

25 THE THORACIC APERTURES THE THORAX - BONES & JOINTS 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.

26 MUSCLES OF THORACIC WALL THE MUSCLES OF THE THORAX

27 THE THORAX MUSCLES OF THE PECTORAL REGION: Pectoralis major Subclavius Pectoralis minor Lateral and medial pectoral nerves Nerve to subclavius Medial pectoral nerve THE MUSCLES OF THE THORAX 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.

28 THE THORAX 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. 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.

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

30 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 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.

31 THE MUSCLES THE MUSCLES OF THE THORAX The external intercostal muscles are con>nuous inferiorly with the external oblique muscles in the anterolateral abdominal wall. 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

32 THE MUSCLES 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 transversus thoracis muscles consist of four or five slips that radiate superolaterally from the posterior aspect of 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.

33 NERVES OF THE THORACIC WALL THE RESPIRATORY SYSTEM The 12 pairs of thoracic spinal nerves supply the thoracic wall. 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 of the intercostal spaces.

34 NERVES OF THE THORACIC WALL THE RESPIRATORY SYSTEM 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.

35 NERVES OF THE THORACIC WALL THE RESPIRATORY SYSTEM 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 of the intercostal space Muscular branches that supply the intercostal, subcostal, transversus thoracis, levatores costarum, and serratus posterior muscles

36 ARTERIES OF THORACIC WALL THE RESPIRATORY SYSTEM 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 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.

37 VEINS OF THORACIC WALL THE RESPIRATORY SYSTEM 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/hemiazygos 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.

38 THE BREASTS THE RESPIRATORY SYSTEM

39 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.

40 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 overlying skin, especially by substan>al skin ligaments, the suspensory ligaments of Cooper.

41 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 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 or remains in the nursing mother. The areolae contain numerous sebaceous glands, which enlarge during pregnancy and secrete an oily substance

42 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: follicles;mula;ng hormone (FSH) and luteinizing hormone (LH) - on the glandular >ssue.

43 VASCULATURE OF BREASTS THE 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 venous drainage of the breast is mainly to the axillary vein, but there is some drainage to the internal thoracic vein.

44 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.

45 VASCULATURE OF BREASTS From the subareolar lympha;c plexus: THE BREASTS 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 opposite breast. lymph from the inferior quadrants may pass deeply to abdominal lymph nodes (subdiaphragma>c inferior phrenic lymph nodes).

46 VASCULATURE OF BREASTS THE 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. 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.

47 VASCULATURE OF BREASTS THE 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.

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