the human skeleton

The human skeleton

Axial Skeleton

Includes:

1. Skull

2. Vertebral column

3. Ribs

4. Sternum

Appendicular skeletonIncludes:

1. Girdles – Pectoral and Pelvic

2. Limb Bones – Fore limb and

Hind limb

https://askabiologist.asu.edu/sites/default/files/SkeletonViewer/SkeletonViewer.swf

The SkullCranium:

Consists of 8 flat bones joined together by immovable joints called sutures.

Surrounds and protects the brain.

The bones of the cranium: Frontal Bone (1)

2. Parietal Bones (2)

– the “back” of the head

3. Occipital Bone (1)

4. Temporal Bones (2)

Sphenoid Bone (1)

Ethmoid Bone (1)

There is a large opening at the base of the skull called

the FORAMEN MAGNUM through which the spinal

cord passes

On either side of the foramen magnum is a projection or

condyle which articulate with the first vertebra (called the

ATLAS) to give the nodding movement of the head

Facial bones:

15 facial bones.

Irregular bones that include: cheek nasal , temple and

upper and lower jaw bones.

The only movable bone is the lower jaw.

Mandible- Lower Jaw

The upper and lower jaws bear the sockets for the

32 permanent teeth.

The human dental formula is: 2.1.2.3

The vertebrate column The vertebral columns is divided into 5 regions:

Cervical (neck) region

Thoracic region (chest)

Lumbar region (lower back)

Sacral region

Coccyx

Cervical (neck) region

Consisting of 7 vertebrae.

1st vertebra Atlas

2nd vertebra Axis

Thoracic region (chest)

12 vertebrae each of which bears a pair of ribs

Lumbar region (lower back)

The largest vertebrae as they carry the weight of the body

Sacral region

Consist of 5 fused vertebrae forming a bone called the sacrum.

Coccyx

Made up of 4 infused bones

Curves of a spineFour curves:

The cervical and lumbar regions curving FOWARD

The thoracic and sacral regions curve BACKWARD

FUNCTIONS OF VERTEBRAL COLUMN

Supports the skull

Surrounds and protects the spinal cord.

Provides attachment for ribs, girdles, and back muscles

Separate vertebrae and S-shaped curvature provide flexibility

allowing humans to bend backwards, forwards and sideways.

Cartilage discs act as shock absorbers

RIB CAGE Consists of 12 thoracic vertebrae, 12 pairs of ribs and the

sternum or breastbone

Functions of rib cage:

Protection of the heart and lungs

With the help of the diaphragm and the intercostal

muscles they increase. And decrease the volume of the

thoracic cavity thereby allowing inhalation and exhalation

to take place.