Chapter 7: Axial Skeleton

Chapter 7 Axial Skeleton Appendicular skeleton · skull (and associated bones), the vertebral · pectoral girdle, pelvic girdle, and upper& lower limbs, · 80 bones along the central axis of the body · 126 bones that form/support the upper & lower limbs column, and the thoracic cage clavicles and scapula Functions of the Axial Skeleton · provides supportive framework · protects the brain, spinal column, thoracic organs, abdominal organs · provides extensive surface area for muscle attachment Cranial (skull) Bones · the skull contains 22 bones: 8 form the cranium, and 14 are associated with the face · 8 cranial bones enclose the cranial cavity · cranial cavity: a fluid-filled chamber that supports and protects the brain Cranial Bones are joined by Sutures: - coronal suture - sagittal suture - lambdoid suture - squamous suture Cranial Bones are joined by Sutures: - coronal suture - sagittal suture - lambdoid suture - squamous suture The Orbital Complex “You do not need to name all of the bones that make up the eye, maybe just the amount of bones there are” - Ms. Perry Fontanelles · non-ossified fibrous areas between cranial bones that allow for rapid brain growth in infants and children · The anterior fontanelle is often called the "soft spot"on a newborn · There are 6 Fontanelles: ↳ paired sphenoidal fontanelles ↳ paired mastoid fontanelles ↳ anterior fontanelle ↳ posterior fontanelle Facial Bones Paired Bones: · Maxillae (upper jaw) · Zygomatic bones (cheekbones) · Nasal bones · Palatine bones · Lacrimal bones (tear duct bone) Single Bones: · Mandible The Hyoid Bone · below lower jaw · supports your tongue · swallowing · Speech · not attached to any other bones Bone Markings of the Skull · Sinuses -decrease weight of bone -lined with mucous membranes -resonating chambers in speech production · Foramina and Fissures -openings/passageways -allow entry of muscles, nerves, arteries etc. -foramen = hole, fissure = slit · Canals -groove that vessels sit in Vertebral Column · 26 bones: 24 Vertebrae + 1 Sacrum + 1 coccyx · divided into 5 vertebral regions/curves: ↳ Cervical (7 vertebrae; (C1 - C7) ↳ Thoracic (12 vertebrae; T1 - T12) ↳ Lumbar (5 vertebrae; (L1 - L5) ↳ Sacral ↳ Coccygeal Spinal Curves · allows for transfer of weight through vertebral column · Primary curves (accommodation curves) ↳ forms during fetal development ↳ thoracic and sacral curves · Secondary curves (compensation curves) ↳ forms after birth ↳ cervical and lumbar curves Vertebral Anatomy · Each vertebral bone is composed of 3 general parts: ① Vertebral body ② Vertebral arch ③ Articular processes · Spinous processes: projects posteriorly · Transverse processes: projects laterally Cervical Vertebrae (c1-C7) · smallest · transverse processes are fused to costal processes which both encircle round transverse foramina · C1 & C2: Atlas and Axis - Atlas (C1) ↳ holds up the head ↳ point of contact between vertebrae and skull (articulates with occipital condyles) ↳ largest foramen of all vertebrae (largest hole) ↳ no vertebral body or spinous processes ↳ nodding of the head at the atlantooccipital joint - Axis (C2) ↳ point of contact between atlas and C3 ↳ allows you to move your head left and right at the atlantoaxial joint · C7: Vertebra Prominens ↳ has a large spinous process with a large tubercle on the end Thoracic Vertebrae (T1-T12) · Have costal facets that articulate with the heads of the ribs · Spinous process projects posteriorly and inferiorly · T1-T8 articulate with two ribs and have two costal facets · T9-T11 articulate with only one rib and have one costal facet Lumbar Vertebrae · largest vertebral bodies, withstand the most weight · short, thick, dorsally projecting spinous processes · does not have costal facets (no more ribs) Sacrum and Coccyx · the sacrum has 5 fused sacral vertebrae · the coccyx has 4 fused coccygeal vertebrae · apex = the point · base = wider portion Thoracic Cage · includes the thoracic vertebrae, ribs, costal cartilages, and sternum · Functions: 1. Protects the heart, lungs, thymus, and other structures in the thoracic cavity 2. Attachment point for muscles used in breathing, stability, and movement Ribs · long, curved, flattened bones · originate at the thoracic vertebrae and curve to the anterior (front) · 12 pairs of ribs - True Ribs (vertebrosternal ribs) ↳ ribs 1-7 ↳ Connected to the sternum by individual costal cartilages - False Ribs ↳ ribs 8-12 ↳ vertebrochondral ribs (8-10) ↳ floating ribs (11-12) · typical rib consists of a head, neck, tubercle, and body ↳ the tubercle attaches to transverse process of a vertebrae Sternum · flat bone in the anterior midline of thoracic wall · Consists of 3 parts: ① Manubrium ↳ clavicle attaches here ↳ attachment site for first rib ↳ jugular notch ② Body ↳ costal cartilages of 2-7 ribs ↳ sternal angle -> rib #2 ③ Xiphoid process ↳ diaphragm and rectus abdominis attach Terms to Remember: · costal angle = curvature of body of rib · costal groove = muscle attachments, blood vessels and nerves · costal margin = bottom edge · intercostal space = between ribs space · intercostal muscle = muscles between ribs