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- The human skeletal structure is categorised into two
- Axial skeleton (Skull, ribcage, & vertebral column)
- Appendicular skeleton (Pectoral girdle, upper limb, pelvic girdle, & lower limb)
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1. Axial skeleton
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- Skull
- Skulls are made up of flat bones joined by sutures (immovable joints).
- Skull is the framework of the face and support the teeth.
- The lower jaw (mandible) is movable and allow mouth opening and closing.
- The cranium protects the brain.
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- Ribcage (Sternum & ribs)
- 12 pairs of ribs articulate with the sternum and thoracic vertebrae.
- Ribs and sternum form a cage to protect the heart and lungs.
- The sternum is a flattened, narrow bone and ribs are curved bones.
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- Vertebral column
- Consist of 33 vertebrae attached to form a strong & flexible column. There are 5 types of vertebrae.
- It protects the spinal cord, support the head, provides a base for back muscle attachment and provides an articulating surface for ribs and pelvic girdle.
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| Characteristics of cervical vertebrae: |
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| Vertebra |
Characteristics and functions |
| Atlas (1) |
- Has large neural canal
- No centrum
- Has two transverse foramina - allow arterioles to pass through brain
- Support the skull
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| Axis (1) |
- Odontoid process extends into ventral part of the neural canal of atlas and acts as pivot to allow the head to move side-to-side
- Has two transverse foramina
- Side-to-side head movement
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| Cervical (7) |
- Broad and short transverse process
- Broad centrum
- Has two transverse foramina
- Support head and neck
- Attachment for neck muscles
- Has a short spinous process
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| Thoracic (12) |
- Has long spinous process which points backwards
- Support rib bones to form the rib cage and provide surface for attachment of muscles to the transverse process and centrum
- Muscle attachment to support head and neck
- Large and thick centrum
- Long transverse process
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| Lumbar (5) |
- The largest and strongest vertebra in the vertebral column
- Large and thick centrum
- Transverse process is long and flat
- Spinous process is short
- The large centrum supports the weight of the lower back
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| Sacrum (5) and caudal (4) |
- Five bones fused together forming a broad
- Coccyx is formed by fusion of four vetebrae bones
- Balances and supports sitting position
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| Types of vertebrae |
Cervical vertebrae |
| Spinous process |
Short |
| Transverse process |
Broad and short |
| Centrum |
Small |
| Transverse foramen |
Has a pair of transverse foramen |
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| Types of vertebrae |
Thoracic vertebrae |
| Spinous process |
Long |
| Transverse process |
Long |
| Centrum |
Medium size |
| Transverse foramen |
Absent |
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| Types of vertebrae |
Lumbar vertebrae |
| Spinous process |
Short |
| Transverse process |
Short |
| Centrum |
Large |
| Transverse foramen |
Absent |
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Joint:
- Movements of human limbs can be done by:
- The presence of joints in which two or more bones meet
- The actions between skeletal muscles and bones
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| Types of joint |
Characteristic |
Examples |
| Immovable joints |
- Bone attached together by fibrous connective tissue
- No movement is allowed
- These joints are categorised as sutures
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Joints in skull & pelvic girdle |
| Slightly movable joints |
- Bone attached together by cartilage
- Movements are limited
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The joint between vertebrae & between ribs and sternum |
| Freely moveable joints |
- Bones joint together with synovial fluid
- Movement in one plane or all planes
- These joints are known as synovial joints
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Hinge joints & ball-and-socket joints |
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- Role of muscles, ligament, tendon and joint in movement.
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- Tendon - Joint muscle to bones.
- Ligament - Joint the bone to bone
- Synovial membrane - secretes the synovial fluid
- Synovial fluid - Lubricate the joint and reduce the friction between bones. It also nourishes the cartilage.
- Cartilage - Absorbs shock and protect the bone.
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| Tendon |
- Characteristics:
- Not elastic
- Strong
- Connective tissue
- Function
- Joins muscle to bones
- Transmits pulling force exerted by contraction of muscles to the bone and pull it up
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| Ligament |
- Characteristics
- Elastic
- Strong
- Connective tissue
- Flexible
- Functions:
- Join bone to bone
- Hold joints together
- Prevent dislocation
- Allow limited movement
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| Muscle |
- Characteristic
- A pair of muscles that work together
- When contracts, the other relaxes
- Examples: Biceps and triceps of the arm
- Functions:
- Exert pulling force onto bone
- Support movement and locomotion
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