What is ear ossicles
Branchial arches(III to VII pair of Visceral arches)
These are five pairs,which constitute III to VII pair of visceral arches.These constitute gill racker in fishes but terrestrial animals then form hyoid apparatus in collaboration with hyoid proper.Five pairs of branchial arches are as follows-(a)III pair ceratohyle.
(b)IV pair i.e.,is epihyal.
(c)V pair i.e., is stylohyal.
(d)VI pair i.e., tympanohyal.
(e)VII pair i.e.,thyrohyal.
In man however the skull remain erect at top of vertebral column because of perfectly erect posture of body it is divisible into the large and hollow cranium and the facial region together protects and support some useful organ for vision,taste,smell,hearing and equilibrium.
(1) Cranium(Brain box)
Cranium stabilize the position of brain.In skull of man all eight bones are articulated with each other to form the cranium as follows-
Forms the forehead(Anterior or front part of the top of cranium) and some upper parts(roof) of eye orbit or sockets and nasal cavities.A newborn infant displays a faint structure in midline of frontal,indicating that adult frontal is actually formed of two completely fused frontal.Frontal suture between two frontal disappear by age 6 years.If persists throughout life referred as metopic sutures.
Articulated to and situated just behind frontal.Form the main parts of bulging top and sides of cranium.
Articulated to and situated just behind parietals.Forms posterior (back) and lower (base) parts of cranium.Foramen magnum is a large perforation in this bone.On each side of the foramen,the occipital bears a prominent elevation called occipital condyle.The condyles articulate the skull with first vertebra(atlas).Thus ,human skull is dicondylic.
Form lower parts of right and left sides of cranium,as well as the floor of cranial cavity. These house structures of internal and middle ears and form a part of external auditory meatus. The middle ear of each side encloses the three small ear ossicles-malleus,incus and stapes.The mastoid process with mastoid air cells in adult.
A typically butterfly-shaped bone that forms the middle and anterior parts of base of cranium in front of occipital in the middle and temporals on the sides.It articulates with all skull bones,keeping these firmly together.It also forms part of lateral walls and floors of eye orbits.Sphenoid with sella turcica depression for pituitary body.
A small ,irregular bone in front of sphenoid and behind nasal bones.It fashions the front (anterior) extremity and closer of cranial cavity.It also contributes to the architecture of eye orbits and proximal parts of nasal chambers.
The facial region:
This is the front or anterior part of our skull comprising of 14 bones as follow:
- Inferior nasal conchae(Turbinates) :2(bones)
- Zygomatics(Malars): 2(bones)
Small,oblong bones in middle of upper part of face,forming proximal part of the bridge of our nose.The remaining ,lower part of our nose is formed of cartilage.
Two highly coiled,scroll-like process of ethmoid bone,called conchae project into each nasal cavity from lateral wall of the proximal bony part of concerned nasal chamber. One ethmoidal concha is superior(uppermost). The other one is called middle concha,because it is followed by a thin,separate scroll-like bone which is named inferior nasal concha or turbinate.
A thin,elongated,platelike bone,forming a part of the septum which separates the two nasal cavities.
Small and thin,finger shaped bone,each located in front part of the medial(inner) side of corresponding eye orbit.these form a part of the passage of corresponding tear ducts.
Cheek-bone; form the prominences of our cheeks and parts of the floor and side walls of eye orbits.
L-shaped bone that form the back(Posterior) part of our hard palate (roof of mouth).Also contribute to the framework of nasal cavities and floor of eye orbits.
Large,upper jaw bones that form the major part of our face and upper jaw. Comprise entire front(anterior) part of our hard palate.Also contribute to the architecture of eye orbits and nose.Bear the teeth of upper jaw.
Largest bone of our face,and strogest of all bones of the body.Forms entire lower jaw and bears all lower jaw teeth.Articulated with temporal bones of skull.Only skull bone that moves.