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PIMA BIO130
CHP8 Skeletal; Hyoid, Vertebrae, & Thoracic Bones and Their Markings
Question | Answer |
---|---|
Hyoid | U-shaped bone in the neck between the mandible and upper part of the larynx; distinction as the only bone in the body that does not articulate with any other bone; suspended by ligaments from the styloid processes of the temporal bones |
Vertebral Column | Not actually column- a flexible, segmented curved rod, forms axis of body; head balanced above, ribs and viscera suspended in front, and lower extremities attached below; encloses the spinal cord |
General features of Vertebral Column | Anterior part of each vertebra (except the first two cervical) consists of the body; posterior part of the vertebrae consists of the neutral arch, which in turn consists of two pedicles, two laminae, and seven processes projecting from the laminae |
Body | Main part; flat, round mass located anteriorly; supporting or weight bearing part of the vertebra |
Pedicles | Short projections extending posteriorly from the body |
Lamina | Posterior part of the vertebra to which the pedicles join and from which processes project |
Neural arch | Formed by the pedicles and laminae; protects the spinal cord posteriorly; congenital absence of one or more neural arches is known as spina bifida (the cord may protrude right through the skin) |
Spinous process | Sharp process projecting through inferiorly from laminae in the midline |
Transverse processes | Right and left lateral projections from laminae |
Superior articulating processes | Project upward from laminae; have smooth superior articular facets |
inferior articulating processes | Project downward from laminae; articulate with the superior articulating processes of vertebrae below; have smooth inferior articular facets |
Spinal foramen | hole in the center of the vertebra formed by union of the body, pedicles, and laminae; spinal foramina, when vertebrae are superimposed on one another, form the spinal cavity that houses the spinal cord |
Intervertebral foramina | Opening between the vertebrae through which teh spinal nerves emerge |
Cervical Vertebrae | 1-7 vertebrae; the foramen in ea transverse process for transmission of the vertebral artery, vein, & plexus of nerves; short bifurcated spinous process except on 7th vertebrae, it is xtra long & palpable; body=small, foramina= lrg & triangular |
Atlas | 1st cervical vertebrae; lacks body & spinous process; superior articulating processes are concave ovals that act as rockerlike cradles for condyles of occipital bone; named atlas because it supports the head as Atlas supported the world in Greek mythology |
Axis (epistropheus) | 2nd cervical vertebra, so named because the atlas rotates about this bone in rotating movements of the head; the dens, or odontoid process, is a peglike projection extending upward from the body of the axis that forms a pivot for rotation of the atlas |
Thoracic vertebrae | 12 pairs of ribs attached to vertebrae; stronger, w/ more massive bodies than cervical vertebrae; no transverse foramina; 2 sets facets for artiulations w/ the corresponding rib; 1 on body, 2nd on transverse process; upper T have long spinous process |
Lumbar vertebrae | Strong, massive; superior articulating processes directed medially instead of upward; inferior articulating processes, laterally instead of downward; short, blunt spinous processes |
Sacrum | Five separate vertebrae until about 25 years of age; then fused to form one wedge-shaped bone |
Sacral promontory | Protuberance from the anterior, upper border of the sacrum into the pelvis; of obstetrical importance because its size limits the anteroposterior diameter of the pelvic inlet |
Coccyx | four or five separate vertebrae in a child but fused into one as an adult |
Curves | Cruves have great structural importance. They increase carrying strength of vertebral column, make balance possible in upright position (if straight, wt of viscera pull body forward), absorb jolts from walking, & protect column fr fracture |
Primary curves (Thoracic curve & Sacral curve) | Column curves at birth from the head to the sacrum with the convexity posteriorly; after the child stands, the convexity persists only in the thoracic and sacral regions, which are therefore called primary curves |
Secondary curves (Cervical curve & Lumbar curve) | Concavities in the cervical and lumbar regions; the cervical concavity results from the infant's attempts to hod the head erect (2-4 months); the lumbar concavity, from balancing efforts in learning to walk (10-18months) |
Sternum | Breastbone; flat dagger-shaped bone; the sternum, ribs, and thoracic vertebrae together form a bony cage known as the thorax |
Body (re: sternum) | Main central part of bone |
Manubrium (re: sternum) | Flaring upper part |
Xiphoid process (re: sternum) | Projection of cartilage at the lower border of the bone |
True ribs | Upper seven pairs; fasten to the sternum by costal cartilages |
False ribs | These ribs do not attach to the sternum directly; the upper three pairs of false ribs attach by means of the costal cartilage of the seventh ribs |
Floating ribs | The last two pairs of false ribs that do not attach to the sternum at all |
Head (re: ribs) | projection at the posterior end of a rib; articulates with the corresponding thoracic vertebrae & one above, except the last three pairs, which join the corresponding vertebrae only |
Neck (re: ribs) | Constricted portion just below the head |
Tubercle (re: ribs) | Small knob just below the neck; articulates with the transverse process of the corresponding thoracic vertebra; missing in the lowest three ribs |
Body or shaft (re: ribs) | Main part of a rib |
Costal cartilage (re: ribs) | Cartilage at the sternal end of true ribs; attaches ribs (except floating ribs) to the sternum |