HUMAN SKULL - AN OVERVIEW

HUMAN SKULL:

The bones of the skull are grouped into two different catagories
1-Cranial bones
2-facial bones
Cranial bones are 8 and facial bones are 14 in number. Cranial bones form the cranial cavity which encloses and protect the brain

CRANIAL BONES

1-Frontal bone
2-Parietal bones 2
3-Occipetal bone
4-Temporal bones
5-Sphenoid bone
6- Ethmoid bone

FRONTAL BONE:

It forms the forehead. It is single. It is common to cranial and facial bones but we include it in cranial bones. In a child there is right and left frontal bones which are join togeather by suture. At the age of 6 these two equal bones join to form a single bone

PARIETAL BONE:

The two parietal bones form the roof of the cranial cavity. They are largest
TEMPORAL BONES:
The two parietal bones present at ear region. Temporal bone consist of EXTERNAL ACOUSTIC MEATUS(ear opening).

OCCIPETAL BONE:

It forms base and back of the cranium. There is large aparture present in it called foramen magnum( Through which spinal cord communicates with the brane. Joint between the skull and vertebral column is known as ATLANTO-OCCIPETAL joint

SPHENOID BONE:

It is complex butterfly shaped bone forms the base of the cranium. It articulates with every cranial bone and held them togeather. There is a depression present in it called SELLA TURCICA (In which pituitary gland is present)

ETHMOID BONE:

It is single. It forms the superior nasal septum

FACIAL BONES:

There are 14 facial bones. Shape of face changes dramatically during the first two year after birth. Growth of face stops at age of 16
1-NASAL 2
2-MAXILLAE 2
3-MANDIBLE 1
4-ZYGOMATIC 2
5-LACRIMAL 2
6-VOMER 1
7-PALATINE 2
8-INFERIOR NASAL CONCNAE 2

Mendible is the lower jaw and maxillae is the upper jaw. Both jaw has teeths.

MAXILLAE:

The paired maxillae unite to forms the upper jaw. it articulate with every facial bone except mendible

ZYGOMATIC:

They are also known as cheek bones

LACRIMAL:

They are smallest facial bones

MANDIBLE:

It is single. It is largest and stronger facial bone. Except auditory osscles mendible is the only moveable skull bone

UNIQUE FEATURES:

SUTURES:

A suture is an immovable joint in the adult skull. These are joints between skull bones only

FONTANELS:

The skull of newly formed embroy consist of cartilage or mesenchyma. Gradually ossification occurs and bone replaces most of the cartilage or mesenchyma. At birth, mesenchyma filled spaces are present in skull called fontanels or commonly known as soft spots. At fontanels at time of birth ossification not occur.

HYOID BONE:

It is u shaped bone present below the tongue and upper to larynx. It is the only bone in the body that don't articulate or don't form joint with other bone