sinuses

Paranasal sinuses
are air cavities located in the maxillae and frontal, sphenoid, and ethmoid bones . As the name paranasal suggests, they open into the nasal cavities and are lined with ciliated epithelium continuous with the mucosa of the nasal cavities. We are aware of our sinuses only when they become “stuffed up,” which means that the mucus they produce cannot drain into the nasal cavities. This may happen during upper respiratory infections such

as colds, or with allergies such as hay fever. These sinuses, however, do have functions: They make the skull lighter in weight, because air is lighter than bone, and they provide resonance for the voice, meaning more air to vibrate and thus deepen the pitch of the voice. The mastoid sinusesare air cavities in the mastoid process of each temporal bone; they open into the middle ear. Before the availability of antibiotics, middle ear infections often caused mastoiditis, infection of these sinuses. Within each middle ear cavity are three auditory bones: the malleus, incus, and stapes. As part of the hearing process , these bones transmit vibrations from the eardrum to the receptors in the inner ear 
VERTEBRAL COLUMN The vertebral column(spinal column or backbone) is made of individual bones called vertebrae. The names
of vertebrae indicate their location along the length of the spinal column. There are 7 cervical vertebrae, 12 thoracic, 5 lumbar, 5 sacral fused into 1 sacrum, and 4 to 5 small coccygeal vertebrae fused into 1 coccyx . The seven cervical vertebrae are those within the neck. The first vertebra is called the atlas, which articulates with the occipital bone to support the skull and forms a pivot joint with the odontoid process of the axis, the second cervical vertebra. This pivot joint allows us to turn our heads from side to side. The remaining five cervical vertebrae do not have individual names. The thoracic vertebrae articulate (form joints) with the ribs on the posterior side of the trunk. The lumbar vertebrae, the largest and strongest bones of the spine, are found in the small of the back. The sacrum permits the articulation of the two hip bones: the sacroiliac joints. The coccyx is the remnant of tail vertebrae, and some muscles of the perineum (pelvic floor) are anchored to it.

Summary;Sutures

 —Sutures: these are immovable joints that connect bones of the skull in the adult.There are four major sutures of the skull.—The lambdoidal suture separates the occipital bone from the parietal bones.Coronal suture attaches the frontal bone to the parietal bones on both sides.—The occipital, parietal, and frontal bones constitutes the calvaria.—The sagital suture extends from the lambdoidal to the coronal suture, between the parietal bones.—Squamosal suture marks the boundary between the temporal bone and the parietal bone on that side.



References

•Bloom, M.D., and D.W. Fawcett (1975) A Textbook of Histology, W.B. Saunders

•Campbell, N.A., J.B. Reece, L.G. Mitchell, and M.R. Taylor (2003) Biology: Concepts and Connections, Benjamin/Cummings

•Hoar, W.S. (1983) General and Comparative Physiology, Prentice-Hall

•Snell, R.S.(2003) Clinical Neuroanatomy for Medical Students. Lippincott Williams &Wilkins

•Rosenzweig, M.R., S.M. Breedlove, and A.L. Leiman (2002) Biological Psychology: An Introduction to Behavioural, Cognitive and Clinical Neuroscience. Sinauer Associates