Question

What is a Skeleton? Briefly list out the bones of the skull and explain each in 1 or 2 sentences.

Answer 1

Skeleton:

• The bony and cartilaginous framework which supports the soft tissues and gives a definite form to the body is called the skeleton.
• The functions of the bone are:
  • (a) to give support to the weight of the body.
  • (b) to give protection to the underlying soft parts.
  • (c) to give a definite shape to the body.
  • (d) to provide space for muscular attachment and
  • (e) to help in lever action for locomotion.
• The bones of the skeleton are divisible according to their shape and appearance into four classes: short. long flat and irregular.

Skull:

• For descriptive purposes the skull may be divided into
  • (a) a cranial part or cranium, which forms the brain-box and
  • (b) a facial part, the bones of which are situated below the front portion of the cranium.
• The cranial part is constituted by the following bones:
  • Frontal, Parietal, Occipital, Ethmoid, Sphenoid, Temporal, Inferior nasal conchae, Nasal bones, Lachrymal bones and Vomer.
• Frontal:
  • It forms the region of the forehead or the front of the cranial region.
• Parietal:
  • Two in number.
  • Each one is irregularly quadrilateral in shape.
  • They form the side walls and roof of the brainbox.
  • Occipital. It forms the posterior and the inferior part of the cranium.
• Ethmoid:
  • It is placed at the anterior part of the base of the cranium, and is cuboidal in shape.
  • It forms the lateral walls and roof of the nasal cavity, the medial walls of the orbit and the septum of the nose.
• Sphenoid:
  • In shape it resembles a flying bat.
  • It is placed in front of the temporal bones and the basal portion of the occipital bone, at the base of the skull.
  • It consists of a centrally placed body and two wings-greater and lesser.
• Temporal:
  • Two in number.
  • They are placed at the base and sides of the skull.
  • A temporal bone has five parts-the squamous, petrous, mastoid, tympanic parts and the styloid process.
• Inferior Nasal Conchae:
  • Two in number
  • . Each forms a curved lamina and is placed horizontally in the lateral walls of the nasal cavity.
• Nasal bones:
  • Two in number.
  • These are small bones placed side by side immediately below the frontal, forming the bridge of the nose.
• Lachrymal:
  • Two in number.
  • They are placed near the front parts of the medial orbital walls.
• Vomer:
  • It is a thin bony plate, composed of two fused laminae and is quadrilateral in shape.
  • It is situated in the lower part of the septum of the nose.

 

• The cranial part is constituted by the following bones:
  • Maxilla and Mandible.
• Maxilla:
  • Two in number.
  • They form the whole of the upper jaw.
  • Each is placed below the orbit forming the floor of the orbit, and also forms the roof of the mouth and the floor and the lateral wall of the nasal cavity.
  • Each maxilla has a body and four processes--frontal, alveolar, zygomatic and palatine.
  • Zygomatic - Two in number. Each being situated in the upper and lateral parts of the face, makes prominence of the cheek.
  • Palatine - Two in number. It is placed between the max illa and the pterygoid process of the sphenoid bone at the posterior aspect of the nasal cavity. Each palatine bone consists of a perpendicular plate, a horizontal plate and three processes, namely, the tubercle, orbital and sphenoidal.
• Mandible:
  • It forms the lower jaw and is the largest and strongest bone of the face.
  • The bone consists of a curved horizontal body and two broad ramii.
  • Each ramus ends above in two processes-the coronoid and condyloid, being separated by a notch called the mandibular notch.

The skull as a whole may be looked at from above (norma verticalis), from front (norma frontalis), from back (norma occipitalis), from below (norma basalis), and from the side (norma lateralis).

Skull:

• The bones that form the head is called the Skull.
• The skull is made up of cranial bones (bones that surround and protect the brain) and facial bones (bones that form the eye sockets, nose, cheeks, jaw, and other parts of the face).
• An opening at the base of the skull is where the spinal cord connects to the brain.