Thoracic Wall Anatomy PDF

 Faculty of Physical Therapy ❑Course Title: Anatomy III ❑Course Code: FM 201 ❑Department: Anatomy and embryology ❑Lecture Title: Thoracic wall ❑Lecturer Name : Pr.Dr. Morsy Abdelfattah Morsy ❑ Objectives: By the end of this lecture the student will be able to...

 Faculty of Physical Therapy ❑Course Title: Anatomy III ❑Course Code: FM 201 ❑Department: Anatomy and embryology ❑Lecture Title: Thoracic wall ❑Lecturer Name : Pr.Dr. Morsy Abdelfattah Morsy ❑ Objectives: By the end of this lecture the student will be able to: ❖Define the function of thoracic wall ❖Describe the structures of the thoracic wall. ❖Identify the thoracic vertebra. ❖Describes the ribs, sternum and muscles of the thoracic wall. ❖Identify the diaphragm. ❑ THORAX: The region of the body between the neck and abdomen. It communicates above with the neck and separated below from the abdomen by the diaphragm. THORACIC WALL ❑Function of thorax Walls: 1-They protect the lungs and heart. 2-They gives attachment for muscles of thorax ,upper limb, abdomen and back. ❑Structure of the thoracic wall: 1.Sternum and costal cartilages (front). 2.Ribs and intercostal spaces (on either side). 3.Vertebral column (behind). ❑ Thoracic wall: It is composed of skeletal elements and muscles. It extends between the superior thoracic aperture bordered by vertebra TI, rib I, and the manubrium of sternum; and the inferior thoracic aperture bordered by vertebra TXII, rib XII, the end of rib XI, the costal margin, and the xiphoid process of sternum. ❖Skeletal framework: The skeletal elements of the thoracic wall consist of thoracic vertebrae, intervertebral discs, ribs, and sternum. 1- Thoracic vertebrae There are twelve thoracic vertebrae, each of which is characterized by articulations with ribs. The thoracic vertebrae are divided into typical (2nd to 8th ) and atypical (1st,9th,10th,11th and 12th). The typical thoracic vertebra has a heart-shaped vertebral body, and a long spinous process The vertebral foramen is circular, and the laminae are broad and overlap with those of the vertebra below.  The superior articular processes are flat, with their articular surfaces facing posteriorly, while the inferior articular processes project from the laminae and their articular facets face anteriorly. The transverse processes are club shaped and project posterolaterally. ❑ Articulation with ribs The typical thoracic vertebra has three sites on each side for articulation with ribs: two demifacets (Partial facets) are located on the superior and inferior aspects of the body for articulation with corresponding sites on the heads of adjacent ribs. An oval facet (transverse costal facet) at the end of the transverse process articulates with the tubercle of its own rib. ❖ Atypical thoracic vertebrae the superior costal facets on the body of vertebra TI are complete and articulate with a single facet on the head of its own rib. The vertebra TX articulates only with its own rib and therefore lacks inferior demifacets on the body but has circular facet on transverse process. vertebrae TXI and TXII articulate only with the heads of their own ribs-they lack transverse costal facets and have only a single complete facet on each side of their bodies. 2- Ribs: There are twelve pairs of ribs, each terminating anteriorly in a costal cartilage. All ribs articulate with the vertebral column. The ribs are divided into true and false. The costal cartilages of the upper seven ribs, known as true ribs, articulate directly with the sternum. The remaining five pairs of ribs are false ribs. The costal cartilages of ribs VIII to X articulate anteriorly with the costal cartilages of the ribs above. The ribs XI and XII have no anterior connection with other ribs or with the sternum and are called floating ribs.  Also, the ribs are divided into typical(3rd to 9th ) and atypical (1st,2nd,10th,11th,12th) The typical rib consists of a curved shaft with anterior and posterior ends. The anterior end is continuous with its costal cartilage. The posterior end articulates with the vertebral column and is characterized by a head, neck, and tubercle. The head is expanded and typically presents two articular surfaces separated by a crest. The neck is a short flat region of bone that separates the head from the tubercle. The tubercle projects posteriorly from the junction of the neck with the shaft and consists of two regions, an articular part and a non-articular part.  The shaft is generally thin and flat with internal and external surfaces. It has superior margin is smooth and rounded, and inferior margin is sharp. The shaft bends forward just laterally to the tubercle at a site termed the angle. The inferior margin of the internal surface is marked by a distinct costal groove. ❑ Distinct features of a typical ribs: ❑ Rib I: Is flat and has broad superior and inferior surfaces. The head articulates only with the body of vertebra TI and therefore has only one articular surface. The tubercle has a facet for articulation with the transverse process. At the superior surface of the rib there is scalene tubercle, which separates two smooth grooves. ❑ Rib II: Is like rib I, is flat but twice as long. It articulates with the vertebral column in a way typical of most ribs. ❑ Rib X ,The head of rib X has a single facet for articulation with its own vertebra. ❑ Ribs XI and XII, articulate only with the bodies of their own vertebrae and have no tubercles or necks. Both ribs are short, have little curve, and are pointed anteriorly. 3-Sternum: The adult sternum consists of three elements: 1-manubrium of sternum, 2- body of sternum, 3- xiphoid process. ❑ Manubrium of sternum: The superior surface of the manubrium has the jugular notch (suprasternal notch), in the midline. On either side of this notch is a large oval fossa for articulation with the clavicle. Immediately inferior to this fossa, on each lateral surface of the manubrium, is a facet for the attachment of the first costal cartilage. At the lower end of the lateral border is a demifacets for articulation with the upper half of the anterior end of the second costal cartilage. ❑ Body of the sternum: It is flat and has anterior and posterior surfaces. Its anterior surface is marked by transverse ridges. The lateral margins of the body of the sternum have articular facets for costal cartilages Its inferior end is attached to the xiphoid process. ❑ Xiphoid process It is the smallest part of the sternum. Its shape is variable: it may be wide, thin, pointed, bifid, curved, or perforated. On each side of its upper lateral margin is a demifacet for articulation with the inferior end of the seventh costal cartilage. ❑Intercostal spaces: They lie between adjacent ribs and are filled by intercostal muscles. Intercostal nerves and major arteries and veins lie in the costal groove along the inferior margin of the superior rib and pass in the plane between the inner two layers of muscles.  In each space, the vein is the most superior structure then the artery is inferior to the vein, and the nerve is inferior to the artery and often not protected by the groove. Small collateral branches of the major intercostal nerves and vessels are often present superior to the inferior rib below. ❑ Muscles of the thoracic wall: 1-External intercostal muscles: 11 pairs ❖ Origin: They extend from the inferior edges of the ribs above ❖ Insertion: They attached to the superior surfaces of the ribs below ❖ Action: Most active during inspiration; supports intercostal space; moves ribs superiorly ❖ Nerve supply: Intercostal nerves. 2-Internal intercostal muscles: 11 pairs ❖ Origin: Lateral edge of costal groove of rib above ❖ Insertion: Superior surface of rib below deep to the attachment of the related external intercostals ❖ Action: Most active during expiration; supports intercostal space; moves ribs inferiorly ❖ Nerve supply: Intercostal nerves. 3-Innermost intercostal muscles: ❖Origin: Inner edge of costal groove of rib above ❖Insertion: Internal aspect of superior surface of rib below ❖Action: Acts with internal intercostals muscles ❖Nerve supply: Intercostal nerves. 4-Subcostales: ❖Origin: Internal surface (near angle) of lower ribs ❖Insertion: Internal surface of second or third rib below ❖Action: May depress ribs ❖Nerve supply: Related inter-costal nerves 5-Transversus thoracis: ❖Origin: Inferior aspect of deep surface of body of sternum, xiphoid process and costal cartilages ribs IV-VII ❖Insertion: Lower margins and internal surfaces of costal cartilages of second to sixth ribs ❖Action: Depresses costal cartilages ❖Nerve supply: Related inter-costal nerves ❑ Innervation of the thoracic wall: ❖ Intercostal nerves Innervation of the thoracic wall is mainly by the intercostal nerves, which are the anterior rami of spinal nerves T1 to T11 and lie in the intercostal spaces between adjacent ribs. The anterior ramus of spinal nerve T12 (the subcostal nerve) is inferior to rib XII. The typical intercostal nerve passes laterally around the thoracic wall in an intercostal space. Its largest branches is the lateral cutaneous branch, which pierces the lateral thoracic wall and divides into an anterior and a posterior branches that innervate the overlying skin. The intercostal nerves end as anterior cutaneous branches, which emerge either parasternally, between adjacent costal cartilages, or laterally to the midline, on the anterior abdominal wall, to supply the skin. ❑ Diaphragm: The diaphragm is a thin musculotendinous structure that fills the inferior thoracic aperture and separates the thoracic cavity from the abdominal cavity. It is attached peripherally to the xiphoid process of the sternum; the costal margin of the thoracic wall; the ends of ribs XI and XII; ligaments that span across structures of the posterior abdominal wall; and vertebrae of the lumbar region. From these peripheral attachments, muscle fibers converge to join the central tendon. The pericardium is attached to the middle part of the central tendon. ❑ Major openings of the diaphragm: 1. IVC 2. Aortic 3. Esophageal ❑ Innervation The diaphragm is innervated by the phrenic nerves (C3 to C5), which penetrate the diaphragm and innervate it from its abdominal surface. Contraction of the domes of the diaphragm flattens the diaphragm, so increasing thoracic volume. Movements of the diaphragm are essential for normal breathing. ❑ Movements of the thoracic wall and diaphragm during breathing. The functions of the thoracic wall and the diaphragm is altering the volume of the thorax and move air in and out of the lungs. During breathing, the dimensions of the thorax change in the vertical, lateral, and anteroposterior directions. Elevation and depression of the diaphragm alter the vertical dimensions of the thorax. Changes in the anteroposterior and lateral dimensions result from elevation and depression of the ribs. when the ribs are elevated, they move the sternum upward and forward. When the ribs are depressed, the sternum moves downward and backward. This 'pump handle' movement. When the shafts are elevated, the middles of the shafts move laterally. This 'bucket handle' movement.  MCQ: Q1:Which of the followings are present in the back of the thoracic wall? a. Ribs b. Sternum and costal cartilages c. Thoracic vertebrae d. External intercostal muscles Q2:Which one of the followings is considered as insertion of the diaphragm? a. Xiphoid process b. Lumber vertebrae c. Costal cartilages d. Central tendon Q3: Which of the following is considered as the anterior rami of intercostal nerves? a. C8-T9 b. C8-T10 c. T1-T11 d. T1-T12 Q4:Which one of the following is present at the upper end of the sternum? a. Sternal notch b. Xiphoid process c. Body of the sternum d. Sternal angle Q5: Regarding external intercostal muscles which one of the following is true ? a. They extend from medial edge of costal groove of rib above b. They attached to the internal aspect of superior surface of rib below c. Most active during expiration d. Its nerve supply is intercostal nerve.  References 1-Gray H, Anatomy of the Human Body. 20th ed. New York: Bartleby 2000. 2-Gray, s anatomy for students by Richard Drake and A. Wayne Vogel, 2019. 3-Snell R. " Clinical Anatomy by Regions ' 8th ed. Lippincott Williams and Wilkins, Philadelphia, 2008. 4-Agur A. & Dalley A. " Atlas of Anatomy" Lippincott Williams and Wilkins, Philadelphia, 2005  References 1-Gray H, Anatomy of the Human Body. 20th ed. New York: Bartleby 2000. 2-Gray, s anatomy for students by Richard Drake and A. Wayne Vogel, 2019. 3-Snell R. " Clinical Anatomy by Regions ' 8th ed. Lippincott Williams and Wilkins, Philadelphia, 2008. 4-Agur A. & Dalley A. " Atlas of Anatomy" Lippincott Williams and Wilkins, Philadelphia, 2005 Thanks, with the best wishes. Pr.Dr/Morsy Abdelfattah.