Chapter 14, Problem F14.1A

Summary Introduction

To label:

The bones and features in a given figure.

Introduction:

The human skull is part of the axial skeleton. It consists of 22 bones out of which 8 bones form the cranium or the brain box. The other 14 bones are part of the facial skeleton. These eight bones are immovable and are interlocked along the sutures. The facial skeleton contains 2 nasal bones, 2 nasal conchae, a vomer, 2 maxilla, a mandible, 2 zygomatic bones, 2 palatine bones and 2 lacrimal bones. There are many features on bones of the skull such as projections and openings.

Answer to Problem F14.1A

The table below represents the correct names of bones and features in the given figure.

S.no	Bone/ feature
1.	Parietal bone
2.	Frontal bone
3.	Coronal suture
4.	Temporal bone
5.	Perpendicular plate
6.	Infraorbital foramen
7.	Vomer
8.	Mandible
9.	Supra orbital foramen
10.	Nasal bone
11.	Sphenoid bone
12.	Zygomatic bone
13.	Middle nasal concha
14.	Inferior nasal concha
15.	Maxilla
16.	Mental foramen

Explanation of Solution

1. Parietal bone- Just behind the frontal bone on each side is a plate-like bone called parietal bone. It has four margins. They are joined together in the middle by sagittal suture and are joined to frontal bone by coronal suture. Hence, bone 1 which is marked in blue is parietal bone.
2. Frontal bone- It forms the forehead of the skull and protects the nervous tissues of the brain. Shaped like a bowl it has many landmarks such as two sinuses and supraorbital foramen which transmit blood vessels and nerves. Hence bone 2 is frontal bone.
3. Coronal suture- It is one of the four major sutures of the cranium. It is the joint between the frontal bone and two parietal bones. This suture is oblique and runs from one ear to another ear. It is dense and made up of fibrous connective tissue. Hence, feature 3 is a coronal suture.
4. Temporal bone- It forms the lower lateral walls of the cranium. It houses the middle and inner parts of the ear. Many cranial nerves pass through this bone. It forms a temporomandibular joint (TMJ) with the mandible. Hence bone 4 is the temporal bone.
5. Perpendicular plate- It is a part of the nasal septum that forms the palatine bone. Hence feature 5 is a perpendicular plate.
6. Infraorbital foramen-This is an opening located in the maxilla which provides passage to the infraorbital nerve, vein and artery. Hence, feature 6 is correctly named as an infraorbital foramen.
7. Vomer- It is a small bone at the base of the nasal cavity forming the nasal septum. Hence bone 7 is vomer.
8. Mandible-This forms the lower jaw of the skull. It is the only movable joint in the skull. It forms the temporomandibular joint with the temporal bone. Hence bone 8 is the mandible.
9. Supra orbital foramen-This feature is located in the frontal bone and it allows entry of vein, artery and nerves into the orbit. Hence, feature 9 is the supraorbital foramen.
10. Nasal bone-Bridge of the nose is made up of two nasal bones that are fused together. It articulates with the maxilla, ethmoid bone and frontal bone. Hence, bone 10 is the nasal bone.
11. Sphenoid bone- It forms the superior part of the skull that houses and protects the brain. It is a butterfly shaped bone with paired greater and lesser wings and two pterygoid processes. It has a hollow body with two sphenoidal sinuses. Hence, bone 11 is sphenoid bone.
12. Zygomatic bone-It is a cheekbone and it also forms the orbit. It articulates with frontal, sphenoid, temporal and maxilla. Hence the green bone in the figure is zygomatic bone.
13. Middle nasal concha-It is a landmark of ethmoid bone that appears as a free convoluted margin in the nasal cavity. It contains olfactory nerves. Hence, feature 13 is middle nasal concha.
14. Inferior nasal concha-It is located within the nasal cavity. It appears curled in shape and helps in increasing the surface area of the nasal cavity. Hence, part 14 is inferior nasal concha.
15. Maxilla-The upper jaw is made up of maxilla bones. It forms the base of orbits, bed for upper teeth and floor of the nose. Hence, the yellow bone in the figure is maxilla.
16. Mental foramen- It is an important landmark of the mandible which provided passage to many nerve fibers in the area. Hence, feature 16 is mental foramen.