Axial Skeleton Anatomy PDF

The Axial Skeleton Objectives Identify the bones of the axial skeleton and specify their functions. Identify the bones of the cranium and face. Describe the differences between adult, child, and infant skulls. Identify and describe the curvatures of the spi...

The Axial Skeleton Objectives Identify the bones of the axial skeleton and specify their functions. Identify the bones of the cranium and face. Describe the differences between adult, child, and infant skulls. Identify and describe the curvatures of the spinal column. Identify the vertebral regions and give characteristics of each. Explain the articulations between the thoracic vertebrae, the ribs, and sternum. Skeletal system includes both: Axial skeleton – 80 Bones Skull – 28 bones 8 cranial bones: frontal, parietal (2) occipital, temporal (2), sphenoid, ethmoid 14 facial bones: nasal (2), maxillae (2), zygomatic (2), palatine (2), vomer, inferior nasal conchae (2), lacrimal (2), mandible Auditory ossicles (6 bones) 1 hyoid bone Vertebral column- 24 vertebrae, sacrum, cocyx Thoracic cage – 24 ribs and sternum Appendicular skeleton – 126 bones Pectoral and pelvic girdles – 6 bones Upper and lower limbs – 120 bones Total of 206 bones The Axial Skeleton The skull Consists of the cranium and the bones of the face The cranium encloses cranial cavity or cranial vault Facial bones surround and protect the entrances to the respiratory and digestive tracts Lab Experience Locate the following axial skeleton landmarks on the plastic and natural bone specimens in the lab. DO NOT use your pen or pencil to point, use the supplied pipe cleaners 40  List of Cranial Bones and Landmarks Region View Bone Bone Landmarks Cranium Frontal Frontal Supraorbital foramen Nasal Sphenoid Superior orbital fissure Inferior orbital fissure Optic foramen (canal) Ethmoid Perpendicular plate Superior nasal concha Middle nasal concha Inferior nasal concha Lacrimal Zygomatic Mandible Body Ramus Alveolar processes Angle Mental foramen Cranium Lateral Maxilla Infraorbital foramen Mandible Coronoid process Condylar process/Articular surface Mandibular notch Body Ramus Mental foramen Zygomatic Temporal process Temporal Zygomatic process Styloid process Mastoid process External auditory (acoustic) meatus Sphenoid Greater wing Other Bones Nasal, Lacrimal, Occipital, Frontal Other Landmarks Coronal suture, Squamous suture, Lambdoid suture, Sagittal suture (superior view) 41 Region View Bone Bone Landmarks Cranial Floor Superior Frontal Frontal sinus (not always visible) w/ calvaria removed Ethmoid Cribiform plate Olfactory foramina Crista galli Sphenoid Sella turcica (Pituitary fossa) Greater wing Lesser wing Temporal Pterous portion Occipital Foramen magnum Cranium Inferior Maxilla Palatine process (hard palate) w/ mandible removed Palatine Horizontal plate (hard palate) Vomer Sphenoid Temporal Mastoid process Styloid process Mandibular process Occipital External occipital protuberance Foramen magnum Occipital condyles Orbit Frontal Orbital Bones Frontal, Maxilla, Zygomatic, Lacrimal, Ethmoid, Sphenoid, Palatine Nasal Cavity Frontal Ethmoid Middle nasal concha, Perpindicular plate Boney septum Vomer Inferior nasal concha Nasal Sinuses Frontal Bones w/ sinuses Frontal sinus, Sphenoidal sinus, Ethmoidal sinus, Maxillary sinus Sutures Coronal - Between Frontal & Parietal Sagittal - Between Parietals Lambdoidal - Between Parietals & Occipital Squamous - Between Parietals & Temporals Fetal Skull Anterior (frontal) fontanel Posterior (occipital) fontanel Sphenoidal (anterolateral) fontanel Mastoid (posterolateral) fontanel 42  Vertebral Column Divisions Cervical (7) Thoracic (12) Lumbar (5) Sacral (5 fused into 1 bone) & Coccygeal (3-5 fused into 1 bone) Curves Each region has its own curve Primary Curves – Thoracic and sacral form “C” shape in infant Secondary Curves – Cervical develops when supporting head, lumbar develops when supporting body weight while sitting Bony Landmarks Typical Vertebrae Body Pedicle Lamina Vertebral arch Spinous process Transverse processes Superior articular process and facet Inferior articular process and facet Vertebral foramen Intervertebral notch – forms Intervertebral foramen when 2 vertebrae articulate Regional Differences Cervical Smallest C1 also called Atlas, C2 also called Axis form atlantoaxial joint C1 mostly a bony ring, C2 contains the Dens or Odontoid process Allows for turning head as in saying No C2 – C6 contain bifid spinous processes C7 has a large spinous process called vertebra prominens Thoracic Medium sized Downward projecting spinous processes Presence of facets for rib articulations Lumbar Largest Blunt projections Sacrum Base Median sacral crest Apex Auricular surface Sacral foramina Ala or wing Sacral canal Sacral hiatus Coccyx 43  Thoracic Cage Sternum Manibrium Jugular notch Body Clavicular notch Xiphoid process Ribs 12 pair (in both male and female!) True ribs (vertebrosternal) – Ribs 1 – 7 False ribs (vertebrochondral) –Ribs 8-12 *Ribs 11 & 12 are floating ribs (false ribs, but not vertebrochondral) 44