Parietal Bone, Occipital Bone, Frontal Bone & Temporal Bone

parietal bone

form a large part of the roof and sides of vault of skull

Outer surface of parietal bone

is convex and smooth, inner surface is concave and depicts vascular markings

occipital bone

occupies posterior and inferior parts of the skull,

Occipital

It is concave forwards and encloses the largest foramen of skull, foramen magnum, through which cranial cavity communicates with the vertebral canal

Squamous part, Basilar part & Condylar or lateral part

Occipital bone is divided into three parts

squamous part

Comprises two surfaces, three angles and four borders

basiocciput

The basilar part of occipital bone is called

frontal bone

forms the forehead, most of the roof of orbit, and most of the floor of anterior cranial fossa

temporal bone

situated at the sides and base of skull

inner or cerebral surface

It is concave and shows grooves for the middle meningeal vessels

mastoid part

forms posterior part of temporal bone

outer surface

give attachment to occipitalis muscle

lateral surface

gives attachment to sternocleido-mastoid, splenius capitis, and longissimus capitis

deep sigmoid sulcus

inner surface is marked by a

petrous part

(Latin rock) triangular in shape

base

fused with squamous and mastoid parts

apex

is irregular and forms posterolateral boundary of foramen lacerum

posterior surface

Internal acoustic meats is present here

tympanic part

It is a curved plate of bone below squamous part and in front of mastoid process

external acoustic meatus

Its anterior wall, floor and lower part of posterior wall are formed by tympanic part

styloid process

(Greek pillar form) long pointed process directed downwards, forwards and medially between parotid gland and internal jugular vein