Common Bone Features: Holes and Depressed Areas

1. Common Bone Features: Holes and Depressed Areas • _________ _________: A hole in bone. • Usually allow the passage of nerve or blood vessel or may exist simply to lighten structure (pelvis) • ______________: A depressed or sunken area on the surface of a bone. • Usually occupied by muscles or tendons.

2. The Skeleton • ______________ Skeleton = Bones of head and trunk • skull, hyoid bone, vertebrae, ribs, sternum • _______________ Skeleton = Bones of limbs and appendages • thoracic and pelvic limbs • ______________ Skeleton = bones formed in the soft organs.

3. Skull • Consists of 37 or 38 separate bones joined by immovable fibrous joints called ____________. • exception: the ______________ is freely movable at is connected to the rest of the skull by a synovial joint. • Skull bones are divided into 3 regions: • Bones of the ____________ • Bones of the ____________ • Bones of the ____________ • Within each region, there are external (visible) and internal (hidden within the skull) bones

4. Bones of the Cranium • Cranium-portion of skull that surrounds the brain. • External Bones of Cranium: • Frontal Bones (2) • Interparietal Bones (2) • Occipital Bone (1) • Parietal Bones (2) • Temporal Bones (2) • Internal Bones of Cranium: • Ethmoid Bone (1) • Sphenoid Bone (1)

5. Occipital Bone • Single bone that forms the caudoventralportion or _________ of skull, most caudal skull bone. • Importance: • Is where spinal cord exits skull • _______________ magnum • Skull bone that articulates with first cervical vertebrae (atlas). • _____________ condyles are articular surfaces on either side of foramen magnum that come together with the atlas to form the atlantooccipital joint

6. Interparietal Bones • Bone(s) located on dorsal __________ between occipital and parietal bones • Clearly visible in young animals, may fuse together in older animals.

7. Parietal Bones • Two bones that form the dorsolateral walls of the cranium • Well developed in dogs, cats and humans, but relatively small in horses and cattle.

8. Temporal Bones • Two bones located ventral to the parietal bones • Importance: • Form walls of the cranium • Contain middle and inner ear structures • Form the temporomandibular joints with the ___________ (Lower jaw)

9. Frontal Bones • Forms ______________ region of skull and a portion of the eye’s orbit. • Located rostral to parietal bone. • Frontal sinus is contained within frontal bone. • ____________ are extension of frontal bone.

10. Internal (hidden) Bones of the Cranium • Sphenoid Bone • Forms____________ portion of the cranium and contains the pituitary fossa, which houses the ____________ gland. • Contains the sphenoidal sinus in most animals.

11. INTERNAL (hidden) BONES OF THE CRANIUM • Ethmoid Bone • Located rostral to sphenoid bone. • Contains _____________ plate which has branches of olfactory nerve passing through. • Horses and humans also have ethmoidal sinus in the ethmoid bone.

12. Bones of the Ear (Ossicles) • Hidden in the middle ear from the outside in: • ____________-hammer • ____________-anvil • ____________-stirrup • Function is to transmit vibrations from the tympanic membrane (eardrum) to cochlea where vibrations are changed into nerve impulses.