Question

1. how do compact bone and spongy bone differ structurally and in location from each other?

2. what are two main divisions of skeletal and desribe how they differ?

Answer 1

1.

Compact/Cortical bone	Spongy/ cancellous bone
Structure: Compact bones are hard boned tissue made up of osteon. Osteons have mineral matrix and osteocytes that are involved in bone homeostasis. The osteons are linked together by canaliculi. There is no bone marrow in the compact bone. Long bone surrounds the central cavity that has yellow bone marrow made up of fats. Yellow bone marrow is seen as bones age. The lamellae of the bone are composed of compact matrix and surround regular Havershian canal. Havershian canals contain lymphatic vessels, blood vessel and nerves.	Structure: These bones are soft and spongy and made up of thread like trabaculae plates. The trabaculae provides rigidity to the bone. They contain osteocytes, osteoclasts, and osteoblasts. The center of spongy bone houses the red bone marrow containing red blood cells. There is however no bone marrow cavity Interlocking networks form the bone lamellae. These networks give the spongy nature to the bone.
Location: They form the outermost layer of long bones. Thus, they form the shaft of the long bone.	Location: They form the epiphysis or ends of long bones. They form the innermost layer of the bone.

2. The two division of the skeleton is axial skeleton and appendicular skeleton.

Axial skeleton	Appendicular skeleton
There are 80 bones in axial skeleton in humans.	There are 126 bones of the appendicular skeleton in humans.
It connects the skull (cranial bones), middle ear ossicles, hyoid bone, rib cage, sternum and the spinal column. Thus, it makes up the central axis of the body.	It connects the feet, legs, pelvic, tibia, femur, hands, arms, scapula, clavicle, humerus, radius, ulna and also the shoulder girdle. Appendicular skeleton links the appendages of the axial skeleton.
It protects the brain and spinal cord.	The appendages such as hands, arms, pelvic girdle are used for locomotion. It protects internal organs such as heart, lungs, liver etc.
Central nervous system is housed by axial skeleton.	Appendicular skeleton mostly houses the peripheral nervous system.
Common carotid artery and vertebral artery supplies the skull.	Pelvic girdle receives blood supply from common iliac artery. Upper extremities receive blood supply from the branch of brachiocephalic artery. Femoral artery supplied the lower extremities.