The Axial Skeleton. THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of...
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The Axial Skeleton Slide 2 THE SKELETAL SYSTEM The Axial Skeleton The skeleton consists of Bones (206) Cartilages Joints also called articulations, are the junctions between skeletal elements Ligaments connect bones Divided into axial and appendicular Slide 3 Axial skeleton - forms long axis of body Skull Vertebral column Thoracic cage Appendicular skeleton appendages and what they attach to Upper limbs (arms) Pectoral girdle (shoulder) Lower limbs (legs) Pelvic girdle Slide 4 Axial skeleton Skull Vertebral column Thoracic cage Axial skeleton is shown in green Slide 5 Slide 6 The Skull Cranial bones (or cranium) Enclose the cranial cavity, which supports and protects the brain Attachment sites for some head and neck muscles Facial bones (anterior aspect of skull) Form framework of face Form cavities for sense organs of sight, taste and smell Provides openings for passage of air and food Hold the teeth Anchor the muscles of the face Slide 7 Cranium Vault calvaria = skullcap Forms superior, lateral and posterior aspects of skull, and forehead Base or floor: inferior part Prominent bony ridges divide cranial base into 3 fossae (steps) anterior, middle and posterior Anterior cranial fossa Middle cranial fossa Posterior cranial fossa (looking down on the floor of the skull) Slide 8 Cranial bones Frontal bone Parietal bones (paired) Occipital bone Temporal bones (paired) Sphenoid bone Ethmoid bone Slide 9 Cranial bones parietal frontal temporal parietal occipital _______sphenoid _____ethmoid occipital Slide 10 Temporal bones this is the right temporal bone looking at it from the right side Slide 11 Sphenoid Ethmoid Small cranial bones Slide 12 Sutures Immovable, interlocking joints of flat bones of skull Irregular, saw-toothed appearance Largest 4 skull sutures: where bones articulate with parietal bones Coronal Sagittal Squamous Lambdoid Slide 13 Find: coronal, squamous and lamboid sutures Slide 14 Find: sagittal and lambdoid sutures Slide 15 Cranial cavity houses brain Smaller cavities Housing middle and inner ear Nasal cavity Orbits Sinuses Openings (foramina, canals, fissures) for: Spinal cord Blood vessels Twelve cranial nerves: I-XII Slide 16 Remember, the skull is composed of: 1.Cranial bones (or cranium) and 2.Facial bones (anterior aspect of skull) Form framework of face Form cavities for sense organs of sight, taste and smell Provides openings for passage of air and food Hold the teeth Anchor the muscles of the face Slide 17 Facial bones Mandible Vomer Maxillae (paired) Zygomatics (paired) Nasal (paired) Lacrimal (paired) Palatines (paired) Inferior nasal conchae (paired) Slide 18 Mandible Vomer Maxillae (paired) Zygomatics (paired) Nasal (paired) Lacrimal (paired) Palatines (paired) Inferior nasal conchae (paired) Facial bones: Slide 19 Slide 20 Slide 21 Slide 22 Slide 23 Slide 24 Slide 25 Mandible (lower jaw) Maxilla (there are 2 which fuse, forming the upper jaw) Slide 26 Nasal cavity Of bone and cartilage nasal bone maxilla___________ Slide 27 Orbit Cone-shaped bony cavities holding the eyes, muscles that move the eyes, some fat and tear-producing glands optic nerve passes out through it Slide 28 Paranasal sinuses Air-filled sacs in the bones Paranasal because they cluster around and connect to the nasal cavity Slide 29 Hyoid bone Only bone which does not articulate with any other bone Moveable base for the tongue Points of attachment for neck muscles that raise and lower the larynx during swallowing Slide 30 Skull Vertebral column Thoracic cage Axial skeleton is shown in green Slide 31 The Vertebral Column Fetus and infant: 33 separate bones or vertebrae Adult: 24 vertebrae Inferior 9 have fused forming The sacrum (5) and The coccyx (4) Slide 32 Vertebrae Cervical 7 Thoracic - 12 Lumbar - 5 Sacrum (5 fused) Coccyx (4 fused) Slide 33 Spinal curvatures Cervical and lumbar are concave posteriorly* (lordosis) Thoracic and sacral are convex posteriorly* (kyphosis) Abnormal: Too much of either Scoliosis (more than 10 degrees of lateral curvature) * when viewed from the side Slide 34 Slide 35 Abnormal curvatures Slide 36 Disorders of the axial skeleton Scoliosis (over 10% curvature) Kyphosis Lordosis Vertebral compression fractures Spinal stenosis Slide 37 Non-bony parts Intervertebral discs anulus fibrosis and nucleus pulposus) Anterior longitudinal ligament Posterior longitudinal ligament Ligamentum flavum Slide 38 Anterior longitudinal ligament: wide, strong and attaches to vertebrae as well as discs (prevents hyperextension) Posterior longitudinal ligament: narrow and relatively weak, attaching only to discs * Slide 39 Structure of a typical vertebra Slide 40 Cervical vertebrae (C1-C7) C1 (atlas) C2 (axis) Slide 41 Smallest Lightest Most flexible Triangular vertebral foramen Transverse processes have foramina (transverse foramen) Spinous process bifid (forked) except for C7 Cervical Vertebrae Slide 42 Heart shaped body Additional small costal facets (costal=ribs) Round or oval vertebral foramen Form posterior part of rib cage Thoracic Vertebrae T1-T12 Slide 43 Massive blocklike bodies Short, thick hatchet-shaped spinous processes Limited mobility Lumbar Vertebrae L1-L5 Slide 44 The Sacrum Shapes posterior wall of pelvis Composite bone of 5 fused vertebrae Sacral foramina allow passage of vessels & nerves Coccyx (the tailbone) Slide 45 Remember that the Axial skeleton includes: Skull Vertebral column Thoracic cage Axial skeleton is shown in green Slide 46 The Thoracic Cage Slide 47 Sternum Ribs Manubrium Body Xiphoid process True ribs 1-7 False ribs 8-12 Floating ribs 11,12