Human Anatomy & Phy 1 (Chapter 7: Skeletal System)

Skeletal System

The body system that consists of the bones and their associated skeletal cartilage.

How many bones does the human body have?

206 bones

What are the basic parts of the skeleton?

• Skull

• Vertebral column

• Thoracic cage

• Pectoral girdle (clavical & scapula)

• Upper limb

• Pelvic girdle (ilium, ishium, pubis)

• Lower limb

What are the 2 structural divisions of the skeleton?

• Axial

• Appendicular

Skeleton Structural Divisions: Axial

Axial skeleton forms the longitudinal axis of the body

• Consists of the bones of the skull, vertebral column, and the thoracic cage.

The bones of the axial skeleton are structured largely for protection, as they encase body cavities and protect the underlying organs.

Skeleton Structural Divisions: Appendicular

• Consists of the bones of the upper and lower limbs, pectoral and pelvic girdles

• These bones are structured largely for motion and act primarily as levers and supportive structures to which muscles attach.

Bone Markings

• Bones have a number of surface features: depressions, openings, and projections (collectively known as bone markings)

→ Depressions allow blood vessels and nerves to travel along the bone or provide a place where two bones can articulate (form a joint)

→ Openings enclose delicate structures and allow them to travel through bones

→ Projections provide sites to which ligaments and tendons attach or where bones articulate

What are the 2 groups of bones that consists of the skull?

• Cranial bones (cranium and encase the brain)

• Facial bones ( form the framework for the face)

Both groups also contribute to the bony structures that house the special sensory organs

Skull: 8 Cranial Bones

• Four single bones:

→ Frontal, Occipital, Ethmoid, and Sphenoid Bones

• 2 paired bones

→ Temporal and parietal bones

Skull: 14 facial bones

• Include the paired maxillary, zygomatic, nasal, lacrimal, palatine, inferior nasal conchal bones, as well as the unpaired mandible and vomer.

• With the exception of the mandible, all skull bones are united in adults by immovable joints called sutures.

Sutures

A fibrous joint, structurally and a synarthrosis functionally that is found between the bones of the skull.