Chapter 7 - Axial Skeleton

Chapter 7 - Axial Skeleton - KIN 216 Applied Human Anatomy...

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Unformatted text preview: KIN 216 Applied Human Anatomy Chapter 7 Axial Skeleton Skeleton, in general Bones, cartilages, joints (articulations), ligaments 206 bones Axial skeleton 80 bones Skull Vertebral column Thoracic cage Upper and lower limbs Pectoral and pelvic regions Appendicular skeleton (next chapter) Bone Markings KNOW Table 7.1, p. 147 Points to remember Tuberosity is large, but not as large as trochanter (which is only on femur) Tubercle is smaller than tuberosity Spine is usually pointed, not just a ridge (like crest or line) Sinus has mucous membrane Fossa and facet very similar difficult to tell other than memorizing location Skull Most complex bony structure Cranial bones (cranium) Vault (aka calvaria) = superior, lateral, posterior, forehead Base (aka floor) = inferior Facial bones (anterior surface) Mostly flat bones held together by sutures (type of articulation) Longest sutures (4) connect cranial bones (1-coronal, 2-sagittal, 3-squamous, 4-lambdoid) Other sutures are named for bones they connect Skull (2) Cranial cavity = brain occupies Smaller cavities Middle ear Inner ear Nasal Orbits Paranasal sinuses Spinal cord Major blood vessels Cranial nerves 85 openings (foramina, canals, fissures) Cranial Bones Eight large bones form shell Paired: parietal (2) and temporal (2) Unpaired: frontal, occipital, sphenoid, ethmoid Supraorbital margin Glabella = smooth part of forehead between eyebrow arches Frontal bone Frontal Parietal Squamous suture Coronal suture Ethmoid Sphenoid Occipital Temporal Cranial Bones (2) Parietal bones 4 major sutures formed where parietal bones meet with other cranial bones Coronal suture = parietal bones meet frontal bone Squamous suture = parietal bones meet temporal bones (inferiorly and laterally) Sagittal suture = parietal bones meet superiorly Lambdoid suture = parietal bones meet occipital bone posteriorly Sagittal suture Sutural bone Lambdoid suture Occipital bone Parietal bone Cranial Bones (3) Sutural bones Occur within sutures (esp. lambdoid) Irregular and NOT all people have them Posterior Base has foramen magnum (hole through which inferior part of brain connects to spinal cord) Occipital condyles = articulate with 1st vertebra Occipital bone Zygomatic process Occipital Condyles Foramen Magnum Mastoid process Styloid process Cranial Bones (4) Temporal bones Located inferior to parietal bones 4 major regions Squamous = has zygomatic process Tympanic = surrounds external acoustic meatus and has styloid process Mastoid = has mastoid process Petrous = projects medially looks like bony wedge between occipital bone and sphenoid bone; holds cavities of middle ear and inner ear Cranial Bones (5) Sphenoid bone Articulates with every other cranial bone Difficult to view complex shape and location Central body and 3 pairs of processes Greater wings Lesser wings 5 key openings Cranial Bones (6) Ethmoid bone Deepest bone, betw. nasal and sphenoid Cribriform plates (roof of nasal cavities) Hyoid Bone Lies inferior to the mandible No direct articulation with any other bone Acts as a movable base for the tongue NOT part of the skull but associated Facial Bones 14 bones 2-Unpaired (mandible , vomer) 6-Paired (maxillae, zygomatics, nasals, lacrimals, palatines, and inferior nasal conchae) Lower jawbone (body and rami) Mandible Facial Bones (2) Maxillary bones (maxillae) Upper jaw articulate with all other facial bones except mandible (house upper teeth) Palatine processes (hard palate) Zygomatic processes Facial Bones (3) Zygomatic bones (Cheekbones ) Nasal bones (Bridge of nose) Lacrimal bones (medial orbital walls) Palatine bones (posterior to maxillae) Form posterior part of hard palate Vomer (skinny, plow-shaped in nasal cavity inferior part of nasal septum) Inferior nasal conchae (nasal cavity) Facial Bones (Anterior View) Nasal Lacrimal Zygomatic Maxilla Mandible Ethmoid bone Inferior Nasal Concha Vomer Special Parts of the Skull Nasal cavity (could say there are 7 bones...) Bone and cartilage Roof is ethmoid bone (1), floor is palatine processes of maxillae (2) and horizontal plates of palatine bones (3) Lateral walls nasal bones (4), all conchae (5), maxillae (6), and plate of palatine bones Each conchae forms roof over air passageway called meatus (superior, middle, inferior) Nasal septum divides (vomer and ethmoid, plus cartilage) Walls of nasal cavity covered with mucous membrane Sphenoid (7) Special Parts of the Skull (2) Orbits Cone-shaped and hold the eyes 7 bones form each orbit (frontal, sphenoid, zygomatic, maxilla, palatine, lacrimal, ethmoid) Found in many skull bones (frontal, ethmoid, sphenoid, maxillae) Paranasal sinuses (para = near) Vertebral Column 26 bones Main support of body axis Surrounds and protects spinal cord Attachments for ribs and muscles of neck and back Originally 33 bones (vertebrae) in fetus, some fuse to form sacrum and coccyx Vertebrae separated by intervertebral discs Anterior and posterior longitudinal ligaments Ligamentum flavum Vertebral Column (2) Intervertebral Discs Nucleus pulposes (inner sphere) Acts like rubber ball (absorb compression) Contain nucleus pulposes, resist tension Anulus fibrosus (outer collar; concentric rings) Discs serve as shock absorbers, thickest in lumbar region (25% of height of column); flatten during the day Herniated discs (rupture of anulus fibrosus followed by bulging of nucleus pulposes) Intervertebral Discs Nucleus Pulposus Anulus Fibrosus Regions and Curvatures Smallest Largest Structure of Vertebrae Body (centrum) anterior Vertebral arch posterior 2 pedicles (project from vertebral body) 2 laminae (posterior portion of arch) Vertebral foramen formed by body and vertebral arch 7 processes from each vertebral arch Spinous process (median and posterior) 2 transverse processes (each pedicle-lamina junction) 2 superior articular processes 2 inferior articular processes General Structure of Vertebrae Lamina Transeverse Process Superior Articular Process Pedicle Spinous Process Vertebral Arch Vertebral foramen Body Regional Vertebral Characteristics Cervical vertebrae Smallest and lightest Body wider laterally than anteroposterior Spinous process is short, split at tip Large vertebral foramen Transverse foramen C1 is atlas ("yes") No spinous process or body Has dens process C2 is axis ("no") (no disc betw. C1 & C2) Regional Vertebral Characteristics (2) Thoracic vertebrae All articulate with ribs Heart-shaped vertebral body with 2 facets (demifacets) Long spinous process points inferiorly Circular vertebral foramen Transverse costal facets Regional Vertebral Characteristics (3) Lumbar vertebrae Receives most stress Large bodies Shorter and thicker laminae and pedicles Spinous processes short, flat, hatchet-shaped and face posteriorly Triangular vertebral foramen Regional Vertebral Characteristics (4) Sacrum Sacral promontory bulges anteriorly and superiorly, into pelvic cavity Ala = wing (alae form sacroiliac joints) Median sacral crest = midline, represents fused spinous processes Sacral canal = vertebral canal Coccyx Thoracic Cage Formed by thoracic vertebrae, ribs, sternum, and costal cartilages Protects organs Supports shoulder girdles, upper limbs Intercostal muscles breathing Sternum Aka breastbone Flat bone, ~15 cm long (about 7 inches) 3 sections Manubrium = superior Body = middle, bulk of sternum Xiphoid process = inferior, tongue-shaped Jugular notch (superior border of manubrium) Sternal angle (horizontal ridge where manubrium meets body) Xiphisternal joint (body and xiphoid meet) 3 important landmarks Manubrium 7 True Ribs Sternum Body Xiphoid Process 5 False Ribs Costal Cartilage Ribs 12 pairs, all attach to thoracic vertebrae posteriorly 7 superior pairs are true ribs 5 inferior pairs are false ribs Shaft = most of rib Superior border is smooth; inferior has costal groove Head = articulates with vertebral bodies via 2 facets Disorders of Axial Skeleton Spinal curvatures Scoliosis lateral curvature of > 10 degrees, often in thoracic region Kyphosis hunchback (exaggerated thoracic curvature) Lordosis accented lumbar curvature Narrowing of vertebral canal in lumbar region (often caused by arthritis or bone spurs) Right and left halves do not join medially, leaves opening between mouth and nasal cavity Stenosis Cleft palate ...
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This note was uploaded on 03/19/2008 for the course KIN 216 taught by Professor Pfeifer during the Spring '08 term at Michigan State University.

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