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.

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.

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

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)

Occipital Bone• Single bone that forms the caudoventral portion 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

Interparietal Bones• Bone(s) located on dorsal __________ between occipital

and parietal bones

• Clearly visible in young animals, may fuse together in older animals.

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.

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)

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.

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.

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.

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.