BMS100_Vertebral Column and Thoracic.docx

BMS100 – MSK2 THE VERTEBRAL COLUMN AND THORACIC CAVITY Function posture, support body weight, locomotion and protection for spinal cord and spinal roots 5 regions – 33 vertebrae (26 separate bones) Cervical – 7 Thoracic – 12 Lumbar – 5 Sacral – 5 (fuse to make sacrum) Coccygeal – 2-4 vertebrae (fu...

BMS100 – MSK2 THE VERTEBRAL COLUMN AND THORACIC CAVITY Function posture, support body weight, locomotion and protection for spinal cord and spinal roots 5 regions – 33 vertebrae (26 separate bones) Cervical – 7 Thoracic – 12 Lumbar – 5 Sacral – 5 (fuse to make sacrum) Coccygeal – 2-4 vertebrae (fuse to make coccyx) Curvatures Primary curvatures: develop during fetal period; newborn spine is kyphotic (concave anteriorly) Secondary curvatures split the kyphotic spine into two, resulting in: Thoracic kyphosis Sacral kyphosis Secondary curvatures: result from development of spine; includes lordotic curves (concave posteriorly) Cervical lordosis: develops when infants lift up their head Lumbar lordosis: develops when toddlers begin to stand and walk Intervertebral Discs Functions Attachment between vertebrae for support and protection; weight-bearing and shock absorption (25% column height) Composed of: Annulus fibrosus: concentric rings of fibrocartilage that connect adjacent vertebral bodies and secure nucleus Nucleus pulposus: semi-gelatinous mass that acts as shock absorber (made of collagen fibers) No disc between atlas + skull, atlas + dens, sacral and coccygeal segments Degenerative changes to annulus fibrosus can lead to herniation of nucleus pulposus – herniation can impinge on roots of spinal nerve in intervertebral foramen Typical Vertebrae and Characteristics Body: anterior projection; largest bony segment, stacks up on each other for column height and shock absorption Transverse processes: right and left lateral projections; extend in transverse plane, serves as attachment for ribs and muscles Spinous processes: extends posteriorly from vertebrae in sagittal plane, attachment for ribs and muscles Articular processes: extend superiorly (2) and inferiorly (2) from vertebrae; allows vertebrae to form joints with each other Pedicles: right and left; connects body of vertebrae with TVPs Lamina: right and left; connects TVPs with SPs Vertebral foramen: formed by union of body, pedicle, lamina and SP; borders and protects spinal cord Intervertebral foramen: right and left; formed by adjacent pedicles; borders and protects exiting spinal nerves Cervical Vertebrae – C1-C7 Main features: Small body Transverse foramen in transverse process – accommodates vertebral artery (main blood supply in the brain) Bifurcated spinous process Vertebra prominens: name for 7th cervical vertebra; long spinous process palpable from the skin surface Atlas (C1) No body, laminae or pedicles Anterior and posterior arches – on posterior surface of anterior arch there is another articular surface for the odontoid process of the axis (dense axis) Lateral mass – contain articular on the superior and inferior surfaces Superior articular surface – for other occipital condyles of the skull Inferior articular surface – for the axis (C2) Axis (C2) Large odontoid process (dense axis) which is attached to the superior surface of the body = acts as an axis (pivot) and permits rotation Anterior surface of dens contains articular facet that matches up with the facet on the posterior surface of the anterior arch of C1 Thoracic Vertebrae – T1-T12 Main features: Costal facet – demi-facet, semi-facet or hemi-facet; on sides of the vertebral bodies where heads of the ribs articulate Transverse coastal facet: costa facets on the transverse processes; for articulation with tubercles of the ribs *T11 and T12 have no facets on TVPs* Lumbar Vertebrae – L1-L5 Main features: Body is massive and kidney-shaped; vertebrae is convex anteriorly Pedicles are strong, laminae are thick, transverse processes are long and slender No facets for articulation with ribs and no transverse foramina Mammillary process: found at posterior margin of the superior articular process Sacrum and Coccyx Sacrum: five rudimentary vertebrae fused together to form wedge-shaped bone that is concave anteriorly Articulations: Upper border (base) – articulates with 5th lumbar vertebrae Narrow inferior border – articulates with the coccyx Laterally – articulates with two hip bones to form sacroiliac joints Sacral canal: formed by the vertebral foramina Sacral crests: bony ridges on the posterior surface of sacrum; spinous, articular and transverse processes fused together 4 pairs of sacral foramina Sacral Ala: two triangular flat surfaces on sides of the first sacral vertebra Coccyx: four vertebrae fused together to form a small triangular bone which articulates at its base with the apex of the sacrum Thoracic Cavity, Sternum and Ribs Components of the thoracic cage: 12 thoracic vertebrae + intervertebral discs 12 pairs of ribs + costal cartilages Sternum Functions: Attachment for upper limbs Attachment for muscles (upper body and respiration muscles) Functions to protect thoracic and abdominal organs Attachment for mammary glands of breast tissue located in subcutaneous tissues of anterolateral chest wall Rib classifications: TRUE ribs (1-7) – direct attachment to sternum FALSE ribs (8-10) – indirect attachment to sternum (fuse to costal cartilage of rib 7) FREE/FLOATING (11 and 12) – no attachment to sternum Intercostal spaces: spaces between ribs on each side of thoracic cage; filled by intercostal muscles and carry nerves/vessels Sternum: flat bone divided into three parts; manubrium, body, and xiphoid process Manubrium: upper part that articulates with the clavicles and first and upper part of the second costal cartilages on each side Suprasternal notch (jugular notch): large, visible dip where clavicle and first rib join the sternum Sternal body: articulates with manubrium and xiphoid process; notches on each side for articulation with the lower part of the second costal cartilage and attachment of ribs 3-6 Sternal angle (manubriosternal joint): formed by junction of manubrium and body of sternum in the form of a cartilaginous joint; marks level of 2nd pair of costal cartilages and level of intervertebral disc between T4/T5 Xiphoid process: lowest/smallest part of sternum Xiphi-sternal joint: demarcated by transverse ridge; attachment for rib 7 costal cartilage Ribs Typical Ribs Costal groove: formed by overhang of the inferior border of the rib; accommodates intercostal vessels and nerve Head: two semi-facets for articulation with corresponding vertebral body and vertebrae immediately above Neck: between head and tubercle Tubercle: prominent on outer surface; consists of an articular and non-articular portion Articular portion facet to articulate with transverse process Non-articular portion attachment to ligaments Angle: where the shaft of the rib bends sharply forward Atypical Ribs 1st rib Flatter and wider Scalene tubercle: tubercle on the inner (medial) border; for insertion of anterior scalene muscle NO angle or costal groove; only one particular surface for the body of C1 2nd rib NO costal groove 10th rib Only a single articular facet on its head 11th and 12th rib Only a single articular facet on its head NO neck or tubercle; 11th has slight angle/costal groove, 12th does not have either JOINTS OF THE VERTEBRAL COLUMN JOINT NAME WHERE AND TYPE OF JOINT LIGAMENTS IMAGE Intervertebral Joints 2 articulations between each vertebra: JOINT 1 JOINT 2 JOINT 1 WHERE: Bodies articulate with each other via intervertebral disc TYPE: Amphiarthrodial – cartilaginous symphysis joint Anterior Longitudinal Ligament (ALL): extends along anterior surfaces of vertebral bodies from occipital bone to sacrum; limits backward bending and supports Posterior Longitudinal Ligament (PLL): within vertebral canal and extends along posterior surfaces of bodies of vertebrae from axis to sacrum; does not attach to body but covers arteries/veins/lymph; low tensile strength = does not limit back bending JOINT 2 – zygapophysial (facet) joints WHERE: articular processes of each vertebra articulate with upper and lower vertebrae articular processes TYPE: Diarthrodial (synovial) – planar joints (slide and glide) *Enveloped by capsules lined by synovial membranes – extended and looser in cervical than in thoracic and lumbar regions Ligamenta Flava: connect laminae of adjacent vertebrae from axis to first segment (vertebra) of the sacrum Elasticity = preserve upright posture and assist in resuming after flexion Supraspinous Ligament: strong fibrous cord connecting apices of spinous processes from C7 to sacrum; continues to the external occipital perturbance as the ligamentum nucha *ligamentum nucha – helps connect vertebral column with cranium Interspinous Ligament: thin/membranous; connects adjoining spinous processes and extend from the root to the apex of each process Intertransverse Ligament: interposed between the transverse processes Craniovertebral Joints Two sets of joints: Atlanto-occipital Atlanto-axial ATLANTOAXIAL (3) “shaking head no” Lateral atlantoaxial joints x 2 WHERE: between lateral masses of the atlas and superior articular processes of the axis TYPE: synovial gliding Medial atlantoaxial joints WHERE: between odontoid process of axis and ring formed by anterior arch and transverse ligament of the atlas TYPE: synovial pivot *rotation* Anterior Atlantoaxial Ligament (membrane): strong, fixed membrane from lower border of the anterior arch of the atlas (above) to the front of body of axis (below) Posterior Atlantoaxial Ligament: broad, thin membrane attached to lower border of posterior arch of atlas (above) to the upper edges of the laminae of the axis (below) – supplies place of the ligamentum flavum Cruciate ligament of the atlas (3): Transverse ligament of the atlas: thick, strong band arching across the ring of atlas retaining the odontoid process in contact with the anterior arch Superior longitudinal band: attached to basilar part of occipital bone Inferior longitudinal band: fixed to posterior surface of the body of the axis Tectorial membrane: in vertebral canal covering the odontoid process and it’s ligaments; prolongation upward of the posterior longitudinal ligament of the vertebral column Alar ligaments: on either side of upper part of odontoid process, passing obliquely upward and lateral; inserted into the medial sides of the condyles of the occipital bone ATLANTOOCCIPITAL “shaking head yes” WHERE: articulation of the occipital bone with the atlas TYPE: synovial condyloid Flexion and extension (nodding of head) Slight lateral flexion (bending) and rotation Anterior Atlantooccipital Membrane: passes anterior margin of the foramen magnum (above) and upper border of the anterior arch of the atlas (below) Posterior Atlantooccipital Membrane: posterior margin of foramen magnum (above) to upper border of posterior arch of the atlas (below) Articular capsules: surround condyles of occipital bone and connect them with superior articular surface of lateral masses of the atlas; thin and loose Uncovertebral joints (clefts) of Luschka WHERE: between uncinate processes of cervical vertebrae (C3-C7); two lips project upward from superior surface of vertebral body (below) and one from inferior surface of vertebral body (above) TYPE: synovial planar Flexion and extension Limit lateral flexion of cervical spine Costovertebral Joint WHERE: articulation of head of ribs with facets on the sides of the bodies of the thoracic vertebrae and with the intervertebral discs between them TYPE: synovial planar – diarthrodial Radiate ligament of head of rib: connects head of each rib with side of bodies of two vertebrae and intervertebral disc between them Intra-articular ligament of head of rib: situation in joint’s interior; attached one end of the crest separating the two articular facets on the head of the rib to the other end of the intervertebral disc – divides joint into two cavities Costotransverse Joint WHERE: formed between tubercle of rib with articular surface on adjacent transverse process TYPE: diarthrodial joint Superior costotransverse ligament: attached from upper border of neck of rib (below) to transverse process (above) Costotransverse ligament: connects rough surface on back of neck of the rib with anterior surface of the adjacent transverse process Lateral costotransverse ligament: passes obliquely from tip of transverse process to the rough non-articular tubercle of the rib JOINTS OF THE THORACIC CAGE JOINT NAME WHERE AND TYPE OF JOINT LIGAMENTS IMAGE Sternocostal Joint WHERE: articulation of the cartilages of the true ribs with sternum TYPE: slight gliding movements are permitted *except for first rib where cartilage is directly united with sternum = synchondrosis articulation Anterior and posterior radiate sternocostal ligaments: broad and thin membranous bands that radiate from front and back of the sternal ends of the cartilages of the true ribs to the anterior and posterior surfaces of the sternum Costochondral Joints WHERE: lateral end of each costal cartilage is received into a depression in the sternal end of the rib; the two are held together by periosteum TYPE: synarthrosis (structurally) - synchondrosis **Each rib touches 2 vertebral bodies and 1 transverse process Ex. 7th rib forms articulation with bodies of T7 and T6 and the TVP of T7 ***Joint movement Sternocostal + costotransverse + costovertebral = move ribs superior and lateral = bucket handle motion Sternocostal = pulls sternum in superior direction = pump handle motion