OSTEOLOGY OF SKULL -TERMINOLOGY-
• Canal: A long passage within bone that transits blood vessels and nerves
• Foramen: A natural opening or perforation through bone that permits transit of blood vessels and nerves (pl. foramina)
• Fossa: A hollow or depressed area on the surface of bone (pl. fossae)
• Notch: A curved depression or indentation
• Pit, groove and fissure: Depressions that serve to increase the extent of surface for the attachment of ligaments and muscles (pit is circular but groove and fissure are linear).
• Ridge, crest or line: A narrow, rough elevation, extending to some distance along the surface
• Spine: A sharp, slender, pointed eminence
• Sulcus: A groove, crevice or furrow present on a bony surface meant for attachment of soft tissues or to house delicate structures (pl. sulci)
• Tubercle: A small, rough prominence
• Tuberosity, protuberance or process: A broad, rough, uneven elevation on bone
QUICK NOTES ON OSTEOLOGY OF SKULL :
1. The cranium consists of eight bones (two paired and four unpaired bones).
(a) Unpaired bones are frontal, occipital, sphenoid and ethmoid.
(b) Paired bones are parietal and temporal.
2. The facial skeleton consists of 14 bones (2 unpaired and 6 paired bones).
(a) Unpaired bones are vomer and mandible.
(b) Paired bones are inferior nasal conchae, lacrimal, maxillae, nasal, palatine and zygomatic bones.
3. Calvarium refers to the skull without the facial bone.
4. Each maxilla has four processes: frontal, zygomatic, alveolar and palatine.
5. The zygomatic bone is also called the cheekbone or the malar bone.
6. The only movable bone of the skull is the mandible.
7. The smallest bone of the face is the lacrimal bone and the largest is the mandible.
8. The hard palate is formed by two bones: the palatine process of maxilla and the horizontal plate of palatine bone.
9. Pterion is the junction of the greater wing of sphenoid, squamous temporal, parietal and frontal bone. It is an important landmark because the anterior division of the middle meningeal artery lies over this and can lead to serious consequences if injured.
10.Submandibular and sublingual fossae are present on the medial surface of the mandible to accommodate the submandibular and sublingual glands, respectively.
11. Mandible has two processes: coronoid and condylar processes. The condylar process articulates with the temporal bone of the cranium which is called the temporomandibular joint.
12. The nasal complex is partly bony and partly cartilaginous.
13. The bone of maxilla is cancellous and that of mandible is cortical.
14. The superior and middle conchae are parts of the ethmoid bone. Inferior concha is a separate bone.
15. Buttresses are structural pillars of bone that protect the facial skeleton by resisting and dissipating external forces. They are vertical and horizontal. Horizontal buttresses are weaker as compared to the vertical buttresses.
MULTIPLE CHOICE QUESTIONS :
1. The study of bones is called
(a) Osteology
(b) Anthropology
(c) Histology
(d) Archaeology
Ans : a
2. Bones of the skull are
(a) Sesamoid bones
(b) Tubular bones
(c) Short bones
(d) Flat bones
Ans : d
3. The number of bones that make up the
skull are
(a) 22
(b) 8
(c) 14
(d) 16
Ans : a
4. Air-filled cavities within bones are called
(a) Sinuses
(b) Ridges
(c) Sulci
(d) Fossae
Ans : a
5. The function of foramen is to
(a) Transit blood vessel
(b) Transit nerves
(c) Help in muscle attachments
(d) Both a and b
Ans : d
6. The orbital cavity houses one of the following
structures:
(a) Eyeball
(b) Tongue
(c) Maxillary sinus
(d) Ear ossicles
Ans : a
7. The bone of the forehead is referred to as the
(a) Frontal bone
(b) Temporal bone
(c) Parietal bone
(d) Occipital bone
Ans : a
8. Infraorbital foramen is located on the
following bone:
(a) Maxilla
(b) Zygoma
(c) Sphenoid bone
(d) Nasal bone
Ans : a
9. The bones of the facial skeleton are united by
(a) Sutures
(b) Cartilage
(c) Muscles
(d) Fissures
Ans : a
10. The bone that provides the prominence
to the cheek is the
(a) Mandible
(b) Zygoma
(c) Maxilla
(d) Coronoid process
Ans : b
11. The movable bone of the face is the
(a) Maxilla
(b) Mandible
(c) Zygoma
(d) Frontal bone
Ans : b
12. Digastric fossa is present in the
(a) Maxilla
(b) Mandible
(c) Zygoma
(d) Orbit
Ans : b
13. The part of the maxilla or mandible that
bears the teeth is called the
(a) Axilla
(b) Alveolus
(c) Coronoid
(d) Ramus
Ans : b
14. Lingula is a lip-like bony projection
overlying the
(a) Infraorbital foramen
(b) Inferior meatus
(c) Mandibular foramen
(d) Nasopalatine foramen
Ans : c
15. The inferior alveolar canal is located in the
(a) Maxilla
(b) Mandible
(c) Zygoma
(d) Orbit
Ans : b