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Home , Costotransverse ligament, Sternal angle, Sternum, Thoracic inlet

Osteology of BY ATIBA, P.M ANA 202 GROSS OF THORAX • It is a flat . • It consists of three parts: manubrium, body, and • The length is 164.6 ± 19.96mm and 123.3 ±11.8mm for male and female respectively Keith et al., (2010) Clinical Oriented (Osunwoke et al., Anatomy

29/01/20192009). Osteology of Thorax 2 Sterni Manubri • The notches:  Jugular notch (palpable, T3 level).  Clavicular notch. • The first costal is attached to the side of the manubrium Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 3 Mesosternum • The manubrium articulates with the body of the sternum at the . • Sternal angle (at T4-T5 level), 5cm below Jugular notch. • The angle is reference point of 2nd . Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 4 Mesosternum • The manubriosternal junction is usually fibrocartilaginous, but it may become ossified. • The body of the sternum is notched each side to receive costal 2 to 7. Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 5 Metasternum • The xiphosternal is usually fibrocartilaginous, but become ossified. It is at the apex of the infrasternal angle and is usually at the level of thoracic

10 or 11. Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 6 Xiphoid Process The xiphoid process is a small and variable piece of hyaline cartilage that contains a bony core. It lies in the epigastric fossa, or "pit of the stomach."

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 7 • They are elongated yet flattened that curve inferior and anterior from the . • There are 12 pairs Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 8 RIBS • True ribs • False ribs • Floating ribs

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 9 Ribs- Typical • Ribs 3 to 9 are examples of typical ribs. • Each has  a head,  , and  shaft.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 10 Head of Typical Ribs The head presents two articular surface: one for the corresponding vertebral body and one for the vertebra immediately superior.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 11 NECK The junction of the neck and shaft is marked by a tubercle, which articulates with the transverse process of the corresponding vertebra.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 12 BODY The shaft, which is curved and twisted, presents an angle posteriorly, which indicates the lateral extent of the erector spinae and is the weakest part of the rib. Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 13 BODY The curvature of the rib is such that a person lying on his back is supported by the spinous processes and the angles of the ribs.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 14 BODY The concave, inner surface of the shaft is marked inferiorly by the costal groove, which gives attachment to the internal intercostal muscle and shelter to the intercostal , , and . Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 15 BODY The ribs ossify from a primary centre for the shaft and secondary centres for the head and tubercle.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 16 ATYPICAL RIBS The first rib. • It is short and forms part of the . • The head articulates with the T1 vertebra, and the neck lies behind the apex of the . Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 17 The first rib The flat upper surface faces superiorly and may present a groove for the and the lower trunk of the brachial plexus, anterior to which is the tubercle for the scalenus anterior muscle.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 18 The first rib Further anteriorly is a shallow groove for the . The first rib is difficult to palpate in vivo, but the first can be identified immediately below Keith et al., (2010) Clinical Oriented Anatomy the .

29/01/2019 Osteology of Thorax 19 Second Rib The second rib, which is much longer than the first, is curved but not twisted. It articulates with T1 and 2 vertebral bodies and presents a tuberosity for the serratus anterior muscle. Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 20 Ribs 10 to 12 Rib 10 usually articulates with the tenth thoracic vertebrae, only. Rib 11, which articulates only with the T11 vertebrae, has an indistinct tubercle, angle, and costal groove. Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 21 Ribs 10 to 12 Rib 12, which articulates with the T12 vertebra, is small, slender, and variable in length. The differences in length have to be kept in mind in surgical approaches to the kidney. Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 22 Ribs 10 to 12 The costal cartilages are comprised of hyaline cartilage, which later may become ossified.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 23 Ribs 10 to 12 They fit into depressions in the anterior ends of the ribs, and the upper seven or eight articulate with the sternum.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 24 Ribs 10 to 12 The costal cartilages impart resiliency to the chest wall. They often become partly ossified later in life.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 25 Thoracic Vertebrae The thoracic spine is the second segment of the , located between the cervical and lumbar vertebral segments. It consists of twelve vertebrae, which are separated by intervertebral discs. www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 26 Thoracic Vertebrae Along with the sternum and ribs, the thoracic spine forms part of the thoracic cage. This bony structure helps protect the internal viscera – such as the , and oesophagus. www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 27 Characteristic Features Vertebral body is heart shaped. Presence of demi- facets on the sides of each vertebral body – these articulate with the heads of the ribs.

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29/01/2019 Osteology of Thorax 28 Characteristic Features Presence of costal facets on the transverse processes – these articulate with the tubercles of the ribs. They are present on T1-T10 only.

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29/01/2019 Osteology of Thorax 29 Characteristic Features The spinous processes are long and slant inferiorly. This offers increased protection to the , preventing an object such as a knife entering the . www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 30 Superior and Inferior Costal Facets The superior and inferior costal facets are located on the sides of each vertebral body. They consist of cartilage lined depressions, which articulate with the heads of the ribs. www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 31 Superior and Inferior Costal Facets The superior facet articulates with the head of the adjacent rib, and the inferior facet articulates with the head of the rib below.

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29/01/2019 Osteology of Thorax 32 Superior and Inferior Costal Facets In the majority of the vertebrae (T2- T9) these facets are demi-facets. There are some atypical vertebrae that possess whole facets.

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29/01/2019 Osteology of Thorax 33 Atypical Vertebrae The atypical thoracic vertebrae display variation in the size, location and number of their superior and inferior costal facets.

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29/01/2019 Osteology of Thorax 34 Atypical Vertebrae T1 – Superior facet is not a demifacet, as this is the only vertebrae to articulate with the 1st rib. T10 – A single pair of whole facets is present which articulate with the 10th rib. These facets are located across both the vertebral body and the pedicle.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 35 Atypical Vertebrae T11 and T12 – Each have a single pair of entire costal facets, which are located on the pedicles.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 36 The joints of the thoracic spine can be divided into two groups – those that are present throughout the vertebral column, and those unique to the thoracic spine.

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29/01/2019 Osteology of Thorax 37 Present throughout Vertebral Column There are two types of joints present throughout the vertebral column: Between vertebral bodies – adjacent vertebral bodies are joined by intervertebral discs, made of fibrocartilage. This is a type of , known as a .

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29/01/2019 Osteology of Thorax 38 Present throughout Vertebral Column Between vertebral arches – formed by the articulation of superior and inferior from adjacent vertebrae. It is a synovial type joint.

Keith et al., (2010) Clinical Oriented Anatomy

29/01/2019 Osteology of Thorax 39 Unique to Thoracic Spine The articulations between the vertebrae and the ribs are unique to the thoracic spine. For each rib, there are two separate articulations – costovertebral and costotransverse. www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 40 Unique to Thoracic Spine Each costovertebral joint consists of the head of the rib articulating with: Superior costal facet of the corresponding vertebra Inferior costal facet of the superior vertebra separating the two vertebrae www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 41 Unique to Thoracic Spine Within this joint, the intra-articular of head of rib attaches the rib head to the intervertebral disc. Only slight gliding movements can occur at these joints, due to the close articulation of their components. www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 42 Unique to Thoracic Spine The costotransverse joints are formed by the articulation of transverse processes of a thoracic vertebra and the tubercle of the adjacent rib. They are present in all vertebrae except T11 and T12. www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 43 The thoracic spine is strengthened by the presence of numerous ligaments.

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29/01/2019 Osteology of Thorax 44 Ligament Present Throughout Vertebral Column Anterior and posterior longitudinal ligaments: Long ligaments that run the length of the vertebral column, covering the vertebral bodies and intervertebral discs. Ligamentum flavum: Connects the laminae of adjacent vertebrae. www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 45 Present Throughout Vertebral Column : Connects the spinous processes of adjacent vertebrae. : Connects the tips of adjacent spinous processes.

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29/01/2019 Osteology of Thorax 46 Unique to Thoracic Spine A number of small ligaments also support the : Radiate ligament of head of rib – Fans outwards from the head of the rib to the bodies of the two vertebrae and intervertebral disc. www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 47 Unique to Thoracic Spine Costotransverse ligament – Connects the neck of the rib and the transverse process. Lateral costotransverse ligament – Extends from the transverse process to the tubercle of the rib. Superior costotransverse ligament – Passes from the upper border of the neck of the rib to the transverse process of the vertebra superior to it. www.teachmeanatomy.com

29/01/2019 Osteology of Thorax 48 Clinical Relevance: Thoracic : Kyphosis is an excessive curvature of the thoracic spine, causing the back to appear “hunched”. It may occur for a number of reasons early in life. These include poor posture, abnormally wedge-shaped shaped vertebrae (Scheuermann’s kyphosis), and fusing of vertebrae during development.

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29/01/2019 Osteology of Thorax 49