BMS MSK Lecture 2 Fall 2023 PDF

BMS Anatomy Lecture 2 The Vertebral Column and Thoracic Cage Presented By: Dr. K. Lumsden ; [email protected] (Toronto Campus) Dr. M. Doroudi; [email protected] (Boucher Campus Moore's Clinically Oriented Anatomy, by Arthur F. Dalley II PhD FAAA (Author), Anne M. R. Agur BSc (OT) MSc PhD FAAA (Autho...

BMS Anatomy Lecture 2 The Vertebral Column and Thoracic Cage Presented By: Dr. K. Lumsden ; [email protected] (Toronto Campus) Dr. M. Doroudi; [email protected] (Boucher Campus Moore's Clinically Oriented Anatomy, by Arthur F. Dalley II PhD FAAA (Author), Anne M. R. Agur BSc (OT) MSc PhD FAAA (Author), 9th ed. Chapter 2: Pages 248 – 301 Chapter 4: Pages 718 – 733 The Vertebral Column One of the components of the axial skeleton Function: Posture, support body weight, locomotion and protection for the spinal cord and spinal roots – We have 33 vertebrae in the 5 regions (alternate 32-34 as individual finding) or 26 separate bones – There are 5 regions: – – – – – Cervical - 7 vertebrae Thoracic - 12 vertebrae Lumbar - 5 vertebrae Sacral - 5 vertebrae – The 5 sacral vertebrae fuse to make the sacrum Coccygeal - 2-4 vertebrae – The 2-4 coccygeal vertebrae fuse to make the coccyx The Vertebral Column Primary (1º) curvatures develop during the fetal period; newborn spine is kyphotic, which is concave anteriorly Secondary (2º) curvatures result from development of spine in first few years of life Lordotic curves are concave posteriorly Cervical lordosis develops when infants begin to hold their heads up Lumbar lordosis develops when toddlers begin standing & walking The development of secondary lordotic curvatures will separate the spine two kyphotic curvatures: creating the alternating pattern shown in the lateral view 3 Typical Vertebra v Analyzing the structure of a typical vertebra, one can easily find that it is made up of two major parts, i.e. , the vertebral body anteriorly and the vertebral arch posteriorly. When the vertebra is dismantled these parts may be recognized: Ø 1) body, 2) vertebral arch, 3) & 4) articular processes, 5) & 6) transverse processes, 7) spinous process, 8) & 9) pedicles, 10) & 11) laminae. Ø Between the body and the vertebral arch there is an opening known as the vertebral foramen which houses the spinal cord Ø In addition, the foramen that is formed between pedicles of the adjacent vertebrae is called intervertebral foramen (this protects exiting spinal nerves) 4 General Vertebral Anatomy: IMPORTANT VERTEBRAL FEATURES: FEATURE DESCRIPTION BODY ANTERIOR PROJECTION; LARGEST BONY SEGMENT, STACKS UP ON EACH OTHER FOR COLUMN HEIGHT AND SHOCK ABSORPTION TRANSVERSE PROCESSES X2 RIGHT AND LEFT (LATERAL PROJECTIONS) EXTEND OUT FROM VERTEBRA IN TRANSVERSE PLANE, SERVES AS ATTACHMENT FOR RIBS AND MUSCLES SPINOUS PROCESSES EXTENDS POSTERIORLY FROM VERTEBRAE IN SAGITTAL PLANE, SERVES AS ATTACHMENT FOR RIBS AND MUSCLES ARTICULAR PROCESSES X4 EXTEND SUPERIORLY AND INFERIORLY FROM VERTEBRAE (2 SUPERIOR, 2 INFERIOR FOR EVERY SEGMENT); ALLOWS VERTEBRAE TO FORM JOINTS WITH EACH OTHER PEDICLES RIGHT AND LEFT = CONNECTS BODY OF VERTEBRAE WITH TVPS LAMINA RIGHT AND LEFT = CONNECTS TVPS OF VERTEBRAE WITH SPS VERTEBRAL FORAMEN FORMED BY UNION OF: BODY, PEDICLE, LAMINA AND SP; BORDERS/ PROTECTS THE SPINAL CORD INTERVERTEBRAL FORAMEN RIGHT AND LEFT = FORMED BY ADJACENT PEDICLES; BORDERS/PROTECTS EXITING SPINAL NERVES 5 Review of a Typical Vertebra Organization of Spinal Nerves: There are 31 pairs of spinal nerves exiting off spinal cord and enter periphery by passing through intervertebral foramen Vertebral Canal Aka spinal canal Protects spinal cord Intervertebral Foramen Protects spinal nerves as they exit from cord 40 r Vertebrae in different regions Cervical Vertebrae There are 7 vertebrae in the cervical region forming a lordotic curvature. The main common features of the typical cervical vertebrae are as follows: Small body Transverse foramen in transverse process Bifurcated spinous process Atlas & Axis These two vertebrae have some special features that make them different from a typical cervical vertebra. Atlas (C1): no body no laminae No pedicles. Additional Features: Anterior and posterior arches. On the posterior surface of the anterior arch there is another articular surface for the odontoid process of axis (Dens of axis). Lateral mass on either side of the vertebrae that contain articular surfaces on the superior and inferior surfaces Superior articular surface: for othe occipital condyles of the skull Inferior articular surface for the axis (C2) respectively. On the posterior surface of the anterior arch there is another articular surface for the odontoid process of axis (Dens axis). 10 Atlas & Axis These two vertebrae have some special features that make them different from a typical cervical vertebra. The only exceptional feature of the axis is possessing a large odontoid process (dens axis) which is attached to the superior surface of the body. This process acts as an axis (pivot) and permits the rotation of the atlas on the axis bone. Anterior surface of dens contains an articular facet which matches up with the facet on the posterior surface of the anterior arch of C1 (atlas) Together these surfaces form the “medial Atlantoaxial joint” The lateral atlantoaxial joint is formed between the superior articular facet of the axis and the inferior articular facet on the lateral mass of the atlas 11 What is Vertebra Prominens? Vertebra prominens is the proper name for the 7th cervical vertebra. The most distinctive characteristic of this vertebra is the existence of a long and prominent spinous process which is palpable from the skin surface, hence the name. Typical Thoracic Vertebrae vThe thoracic part of the vertebral column forms a kyphotic curvature and is made up of twelve vertebrae vThoracic vertebrae have the following main characteristics: Ø Costal facet are present on the sides of the bodies where the heads of the ribs articulate (demi-facet or semi-facet or hemi-fact), Ø Costal facets on the transverse processes (called transverse costal facet) for articulation with the tubercles of the ribs.(T11 and T12 have no facets on the transverse processes.) 14 The Thoracic Cage T1 Thoracic cage components: 12 thoracic vertebrae + intervertebral discs 12 pairs of ribs + costal cartilages Sternum T12 Functions: 1. 2. 3. 4. Attachment for upper limbs Attachments for many muscles of upper limbs, neck, abdomen, back, and muscles of respiration Functions to protect the thoracic and abdominal organs Attachment for mammary glands of breast tissue which are located in the subcutaneous tissues of 15 anterolateral chest wall Thoracic Cage Classification of rib attachments to the cage: 1. TRUE ribs (1-7) – direct attachment to the sternum 2. FALSE ribs (8-10) – indirect attachment to the sternum 1. 3. They attach / fuse to the costal cartilage of rib 7 to form indirect attachment FREE / FLOATING (11 and 12) – no attachment to the sternum The spaces between the ribs on each side of the thoracic cage called intercostal spaces, are filled by the intercostal muscles and carry the intercostal nerve and vessels. Typical rib A typical rib is a long , twisted, flat bone having a superior border and an inferior border. The inferior border overhangs and forms the costal groove, which accommodates the intercostal vessels and nerve. A rib has a head, neck , tubercle, shaft and angle. Ø The head has two semi-facets for articulation with the numerically corresponding vertebral body and that of the vertebra immediately above. (separated by inter-articular crest). Ø The neck is a constricted portion situated between the head and the tubercle. Ø The tubercle is a prominence on the outer surface of the rib at the junction of the neck with the shaft. It consists of an articular and a non-articular portion. The articular portion has a facet for articulation with the transverse process of the numerically corresponding vertebra. The non-articular portion gives attachment to the ligaments. Ø The shaft or body is thin and flattened and twisted on its long axis. Its inferior border has the costal groove. Ø The angle is where the shaft of the rib bends sharply forward. Ø The anterior end of each rib is attached to the corresponding costal cartilage. Review of a Typical Rib Atypical Ribs The first rib is atypical. This rib is flattened and wider than the rest of the ribs. It has a tubercle on the inner (medial) border ,known as the scalene tubercle, for the insertion of the anterior scalene muscle. This rib neither has an angle nor a costal groove and its head only bears one articular surface for the body of T1 (similar to 11th and 12th ribs). The body of the second rib is has similar characteristics to typical ribs, except it the costal groove. - 10th rib: has only a single articular facet on its head. - 11th and 12th ribs: have only a single articular facet on the head. They have no neck or tubercle. The 11th rib has a slight angle and shallow costal groove but the 12th rib has no angle or costal groove. Review of an Atypical Rib Sternum The sternum is a flat bone that may be divided into three parts : The manubrium :is the upper part of the sternum that articulates with the clavicles and the first and upper part of the second costal cartilages on each side. The suprasternal notch , also known as the jugular notch is the large, visible dip where the clavicle AND first rib joins the sternum. The body of the sternum articulates above with the manubrium. Below , it articulates with the xiphoid process. On each side are notches for articulation with the lower part of the second costal cartilage and the attachment of ribs 3 – 6 via their costal cartilages. The sternal angle (Angle of Louis): is the angle formed by the junction of the manubrium and the body of the sternum in the form of a cartilaginous joint ( Later becomes bony and the manubrium and body fuse at this angle). This is also called the manubriosternal joint. The sternal angle is a palpable clinical landmark. It marks the approximate level of the 2nd pair of costal cartilages and the level of the intervertebral disc between T4 and T5. The xiphoid process is the lowest and smallest part of the sternum. The xiphi-sternal joint is demarcated by transverse ridge, attachment for rib 7 costal cartilage. Lumbar vertebrae The lumbar part of the vertebral column is convex anteriorly and consists of five vertebrae. ØThe body is massive and kidney-shaped. ØThe pedicles are strong. ØThe laminae are thick. ØThe transverse processes are long and slender. ØThe mammillary process is found at the posterior margin of the superior articular processes. ØThe lumbar vertebrae have no facets for articulation with ribs and no foramina in the transverse processes (Obviously!). Regional Characteristics: Lumbar Vertebrae (L1-L5) (spinal nerve) (spinal cord) 23 Sacrum & Coccyx consists of five rudimentary vertebrae fused together to form a wedge-shaped bone , which is concave anteriorly. The upper border , or base , of the bone articulates with the 5th lumbar vertebra. The narrow inferior border articulates with the coccyx. Laterally the sacrum articulates with the two hip bones to form the sacroiliac joints (in auricular surfaces). The vertebral foramina are present and form the sacral canal. On the posterior surface of the sacrum, the spinous, articular, and transverse processes of the sacral vertebrae fuse together and form boney ridges known as sacral crests. There are 4 pairs of posterior sacral foramina. The anterior surface of the sacrum is concave and has four foramina on each side. On the sides of the first sacral vertebra there are two triangular flat surfaces, called sacral Ala. The coccyx consists of four vertebrae fused together to form a small triangular bone, which articulates at its base with the apex of the sacrum. REGIONAL DIFFERENCES: C1 C4 T2 L2 Use this slide to identify/label the specific and unique regional characteristics for each vertebral area. 26 REGIONAL DIFFERENCES: C2 C7 T6 L3 Use this slide to identify/label the specific and unique regional characteristics for each vertebral area. 27 Vertebral Column Between most of the vertebrae there are intervertebral discs, which separate the vertebrae and make up ¼ of the length of our vertebral column (3/4 of the length is formed by the vertebrae) Intervertebral Discs: Functions: strong attachment between vertebrae for support and protection weight bearing, shock absorption Make up approximately 25% of column height L2 L3 Composed of: Annulus fibrosus = concentric rings of fibrocartilage that connect adjacent vertebral bodies and secure nucleus in position Nucleus pulposus = semi-gelatinous mass that acts as shock absorber “L2/3 Disc” Discs are named after the vertebral segments they connect No discs between atlas and skull or atlas and dens, sacral segments, and coccygeal segments 29 Video Tutorials of the Trunk Osteology 1. http://youtu.be/PhELIXP5rNE (Spinal Column) 2. http://youtu.be/Zwni5IwAtRk (A Typical Vertebra) 3. http://youtu.be/gMThzKsiwuw (The Typical Cervical Vertebra) 4. http://youtu.be/668WI946OBg (The Typical Thoracic Vertebra) 5. http://youtu.be/ebYFDTbtfUI (The Atypical Cervical Vertebra) 6. http://youtu.be/h_HQDWNkNRQ (The Sacrum & Coccyx) 7. https://youtu.be/-hz7Z0ENfS4 (The Lumbar Vertebra) 8. https://youtu.be/2Xx9TiOTAWQ OR http://youtu.be/ibC3CBc36dw (The Atypical Thoracic Vertebra) 9. https://youtu.be/tScASG8Zl04 (All Trunk bones, Vertebral Column, Ribs, and Thoracic Cage in one video)