The Axial Skeleton ï‚ the skull ï‚ the vertebral column...
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The Axial Skeleton the skull the vertebral column the thoracic cage the cranium Surround and protect the brain Curvature is structurally strong in resisting impact forces the facial bones protect the front of the head Give our faces their individual shape Protect and orient the eyes Allow chewing of food Sutures are irregularly shaped, interlocking, and immovable joints Bound by strong, tiny fibers Permit a very small amount of movement which contributes to the compliance (ability to change size and shape in response to force) and elasticity Only exception to sutures in the skull is the mandible which is a hinge joint Infants have large heads in comparison to their bodies/represents1/4 th of body height Adult skull accounts for 1/8 th of total body height French for little fountain because the babys pulse can be felt through the soft spots Openings connected only by pockets of fibrous membranes where bones join together Allows compression of the skull during birth Enables brain growth during late pregnancy and early infancy Ossify to bone by 22 to 24 months frontal bone forms the forehead, forms part of the orbits parietal bones (2) form the majority of the top and sides of the skull temporal bones (2) surround the ears occipital bones (2) forms the base and lower back portion of the skull ethmoid bone forms part of the nasal septum, forms part of the orbits sphenoid bone butterfly shaped, centrally located with the skull, supports the base of the brain, forms part of the orbits, connected to all the other bones of the skull maxillary bones (2) form the upper jaw, house the upper teeth, connects to all bones of the face except the mandible, forms part of the orbits palatine bones (2) forms the posterior part of the hard palate zygomatic bones (2) cheekbones, forms much of the sides of the orbits lacrimal bones (2) surround the tear ducts, forms part of the orbits nasal bones (2) forms the bridge of the nose vomer comprises most of the bony nasal septum inferior concha bones (2) forms the sides of the nasal cavity mandible lower jawbone, largest facial bone; only moveable facial bone External Auditory meatus Styloid Process regions of the spine Cervical C1- C7 Thoracic T1 T12 Lumbar L1 L5 Sacrum 5 fused bones Coccyx 4 fused bones curves of the spine Primary spinal curves (present at birth) * thoracic curve (anteriorly concave), present at birth * sacral curve (anteriorly concave), present at birth Secondary spinal curves (develop after birth as baby raises head, sits and stands) * cervical curve (posteriorly concave) raises head * lumbar curve (posteriorly concave) begins to stand and walk Develop due to genetic or congenital abnormalities or when the spine is habitually subjected to asymmetrical forces. Lordosis exaggeration of the lumbar curve Kyphosis accentuation of the thoracic curve Scoliosis any lateral deviation of the spine vertebral body thick, disc-shaped portion that bears weight and forms the anterior portion of the vertebra vertebral arch round projection of bone on the posterior aspect of the vertebra vertebral foramen opening in vertebra where the spinal cord passes through transverse processes bony projections on the lateral sides of the vertebral arch spinous process bony projection that extends posteriorly superior and inferior articular processes indentations or facets where a vertebra articulates, or joins, with the vertebra immediately above or below (facet joints) Composed of fibrocartilage located between vertebrae shock absorbers allow flexibility Account for of he height of the spine 1. Support the shoulder girdle and upper limbs 2. Protect the viscera in the thoracic and upper abdominal cavities 3. Play a role in breathing 3 fused bones 1. Manubrium 2. Body 3. Xiphoid process 12 pair of ribs that attach posteriorly to the Thoracic Vertebrae and then curve downward and forward toward the anterior body surface. The ribs increase in length from 1 to 7 and then decrease in length from 8 to 12. True Ribs: upper 7 that are attached to the sternum by costal cartilage False Ribs: remaining 5; either attach indirectly to the sternum or lack sternal attachment entirely Floating Ribs: pairs 11 & 12; have no anterior attachment; their costal cartilages lie embedded in the muscles of the lateral body wall Appendicular Skeleton Supports the upper limbs Attachment for several muscles that move the upper limbs Braces the freely movable scapulae, helping to hold the shoulder in place. Provides attachment for muscles of the upper limbs, chest, and back. Triangular bones located on either side of the upper back. A spine divides the posterior surface of each scapula into unequal portions. The spine leads to 2 processes: 1. Acromium process that forms the tip of the shoulder; articulates with the clavicle 2. Coracoid process that curves anteriorly and inferiorly to the clavicle Between the process is a depression called the glenoid cavity that articulates with the head of the humerus (arm bone) Humerus: Ulna: Radius: Carpus: 8 bones in 2 rows Metacarpals: Palm, 1 to 5 from thumb to little finger Phalanges: Fingers, 14 bones 1. Attaches the lower limbs to the axial skeleton 2. Supports the visceral organs of the pelvic cavity 3. Formed by the 2 coxal bones that articulate anteriorly at the symphysis pubis and posteriorly with the sacrum 4. The 3 bones fuse in the region of a cup- shaped cavity called the acetabulum, which receives the rounded head of the femur 3 fused bones: 1. Ilium Largest and uppermost portion that forms the prominance of the hip (iliac crest); joins the sacrum to form the sacroiliac joint 2. Ischium lowest portion; L-shaped; ischial tuberosity points posteriorly and downward and supports the weight of the body when sitting; ischial spine near the junction of the ilium and ischium 3. Pubis anterior portion forms the joint called the symphysis pubis; joins with the ischium to form the largest foramen in the skeleton, the obturator foramen 1. False Pelvis: portion superior to the pelvic brim 2. True Pelvis: region inferior to the pelvic brim that is almost entirely surrounded by bone and forms a deep bowl containing the pelvic organs 3. Pelvic Inlet: pelvic brim; widest dimension is along the frontal plane 4. Pelvic Outlet: inferior margin of the true pelvis; bounded anteriorly by the pubic arch, laterally by the ischia, and posteriorly by the sacrum; since both the coccyx and the ischial spines protrude into the outlet, a sharply angled coccyx or large spines can cause problems during childbirth CharacteristicFemaleMale General Structure & Functional Modifications Tilted forward, modified for childbearing; cavity of the true pelvis is broad, shallow, and has a greater capacity Tilted backward; adapted for support of a strong body; cavity of the true pelvis is narrow and deep Bone Thickness Less; bones lighter, thinner and smoother Greater; bones heavier and thicker, and markings are more prominent AcetabulumSmaller; farther apartLarger; closer together Pubic angle/archBroader (over 90 o ), more rounded Angle is more acute (less than 90 o ) MaleFemale 1. Carry the entire weight of the erect body 2. Subjected to exceptional forces when jumping and running 3. Thicker and stronger than comparable bones of the upper limbs Longest bone in the body Located on the medial side Non weight bearing bone Located laterally Knee Cap Foot A segmented structure can only hold up weight if it is arched. The foot has 3 arches that give when weight is applied to the foot and spring back when the weight is removed: 2 longitudinal 1. Medial 2. Lateral 1 transverse