Anatomy: Head & Upper Limb

The human cranium:

-22 bones interconnected through immobile sutures -cranial cavity: the upper (domed) part the base of the skull

Sphenoid bone

-butterfly shaped, unpaired bone -location: anterior to the basilar portion of the occipital bone, middle part of the neurocranium -pneumatized bone: sphenoidal sinuses -participates in formation of: nasal cavity orbits middle portion endocranium -the body contains a depression (sella turcica: home of the pituitary gland)

Zygomatic bone:

-irregular paired bone -forms the face's lateral prominences -part of the orbit inferior and lateral rims

Palatine bone

-irregular paired bones -alongside the maxillae, forms the hard palate -location: btwn maxilla and the pterygoid process of the sphenoid -fuse together on the midline

Mandible

-lg bone forming the chain and jaw line -unpaired -not an actual part of the skull -articulates with the temporal bone through the temporo-mandibular joint -holds lower teeth

Maxillae

-lg paired bones: the upper jaw -pneumatized bones--> maxillary sinuses -hold upper teeth -involved in formation of orbit nasal cavity palate

Temporal bone

-paired flat bones located on the sides of the cranium -houses structures of the ears -pneumatized bone

Parietal bone:

-paired quadrilateral bone -forms the roof and sides of the cranium -composed of: 2 surfaces 4 angles 4 margins

Ethmoid bone:

-small, unpaired bone, irregular shape -separates the nasal from the cranial cavity -pneumatized bone -superior projection- crust galli -sieve-like structure on each side of the ridge allows passage of small olfactory fibers to the olfactory bulb--> cribriform plate -forms a small portion of the orbit -articulates with the frontal and with sphenoid bone

Fontanels:

-soft membranous gaps btwn the cranial bones of the calvaria--> present until age 2 -allow the rapidly growing brain to expand -craniosynostosis is a pathological process leading to complete ossification prematurely 6 fontanels: -posterior fontanel -anterior fontanel -posterolateral (mastoid) -anterolateral (sphenoid)

Cranial sutures

-synarthroses -developed after birth over the course of 2 years -flexible in infancy and early childhood coronal suture sagittal suture lambdoid suture squamous suture

Frontal Bone:

-the forehead and superior rim of the orbit -pneumatized bone -superior to each orbital rim (supraciliary arch, supraorbital notch) -glabells: a small depression btwn the 2 arches -partially forms the medial rim of the orbit -laterally, the frontal bone extends with the frontal process

Occipital bone

-trapezoidal curved bone -main bone of the occiput -overlies the occipital lobes -4 parts squamous basilar 2 lateral parts -contains a lg opening though which the spinal cord passes: foramen magnum

Eight bones form the cranial portion of the skull. Which of the bones exists singularly?

frontal

Fontanels closure:

posterior fontanel- 1st to close sphenoid fontanel- 2nd to close mastoid fontanel- 3rd to close anterior fontanel- last to close

Bones of the skull are connected by synarthrosis. Which of them runs between each temporal bone and parietal bone?

squamosal

Eight bones form the cranial portion of the skull. Which of them surrounds the external acoustic meatus?

temporal