Skeletal System Flashcards
Why is the skeletal system important?
Provides a strong framework for the protection and support of the remainder of the systems, organs, and tissues.
How are bird bones different from the bones of other animals?
They are evolved to enhance the ability of the birds to fly.
What modifications have been made that allow the birds to fly?
- Pneumatic bones where the air sacs are connected with cavities in some of the long bones.
- Fusion of some vertebral sections to provide rigidity.
- Sternum provides a large surface area for strong attachment of the main muscles used for flight.
- Significant reduction in the size of the head.
- Long neck.
What does a long neck allow for?
- Protection of delicate tissues of the brain from too much jarring when landing. Neck acts as a shock absorber.
- The bird can reach food located on the ground. Rigid body makes this difficult.
- Allows the bird to adjust its center of gravity when changing from walking/perching to flying.
What is the tail of a bird called and why?
- Pygostyle.
- It is a short section of fused vertebrae.
How many pairs of ribs do birds have?
7.
How many pairs of ribs reach the sternum?
2-3, depends*.
*Sometimes the seventh pair does not reach the sternum.
What are the 2 segments in the third through sixth pair of ribs?
- Sternal segment.
- Vertebral segment.
How have the ribs been modified to strengthen them?
The inclusion of a uncinate process.
What is the uncinate process?
A rearward projection of bone, with the process projecting over the outer surface of the next rib through a connection by a ligament.
*Strengthens the thoracic cavity
Which rib pairs have uncinate processes?
Second through fifth.
How many separate bones are in the vertebral column of birds?
39 bones divided into 5 sections.
How many bones are in the cervical section?
13.
How many bones are in the thoracic section?
7.
What do all thoracic vertebrae except the last one have?
Large ventral process for the attachment of muscles.
How many bones are in the lumbar and sacral sections COMBINED?
14.
Which lumbar vertebrae are fused?
Second through fifth.
How many bones are in the coccygeal section?
5.
What bones are difficult to separate?
T7, All of L, All of S, and C1 because of their fusion for strength.
What is the atlas?
The first bone in the cervical vertebrae.
How is the atlas described?
- Ring-like.
- Small.
- Has a deep cavity for articulating with a condyle (projection) at the base of the skull.
What is the atlas/epistropheus?
The second bone in the cervical vertebrae.
How is the axis described?
- Short.
- Projects cranially into the atlas.
- Possesses the dens, a small process that allows for articulation with the occipital condyle.
What motion does the axis allow for?
The head to turn on the neck or side-to-side.
What is the shape of the sternum/breastbone?
Quadrilateral, curved plate.
*Processes project from each angle.
What is the metasternum/caudal medial projection/keel bone?
The longest sternum projection that carries the sternal crest that runs from front to back on the ventral surface.
What muscles are attached to the keel bone?
- Subcontractors.
- Pectoralis.
What are the two regions of the skull?
- Conical facial region.
- Rounded cranium.
What does the conical facial region possess?
2 large orbitals, where the eyes would be.
What two bones separate the orbitals?
- Ethmoid.
- Sphenoid.
*Form the septum.
Why does the cranium’s external appearance suggest that the brain is larger than it actually is?
Due to being formed by 2 layers of dense bone separated by a layer of very spongy bone.
What does the spongy bone contain?
Pockets of air derived from eustachian tubes that connect the inner ear to upper respiratory tract.
Where are the eardrums located?
In large, hemispherical cavities at the rear of the skull called tympanic cavities.
How does the spinal cord directly connect with the brain?
Through an opening at the base of the cranium.
How do the carotid arteries and jugular veins enter the skull?
Through openings in each lateral part of the occipital bone.
Where do the optic nerves enter the cranial cavity?
One common opening.
Where is the hyoid bone found?
Beneath the skull, floating bone.
What does the hyoid bone form the framework for?
The tongue.
What are the 3 major sections of the tongue?
- Entoglossal.
- Basi-hyal.
3.
Where is the entoglossal found?
Within the tongue.
How is the entoglossal connected to the basi-hyal?
Through a moveable joint.
What type of animals have similar forelimbs to birds?
Theropod dinosaurs.
What types of limbs do birds have?
Pentadactyl limbs modified for the purpose of specialized feeding and flight.
What are the two parts of the wing skeleton divided into?
- Shoulder girdle.
- Wing.
What are the 3 parts of the shoulder girdle?
- Scapula.
- Clavicle.
- Coracoid.
What are the 3 parts of the wing?
- Upper arm or humerus.
- Forearm or radius and ulna.
- The hand or manus (carpus, metacarpus, digits).
How is the scapula described?
- Narrow.
- Thin.
- Slightly curved.
What is located at the cranial end of the scapula-coracoid cavity?
The head of the humerus.
What is the strongest bone of the shoulder girdle?
The coracoid.
What does the medial end of the coracoid have?
A flattened articular surface that fits into the sternum and a foramen for the connection of the clavicular air sac.