Cranial Bones (Q1,P5)

Question 1

Axial Skeleton

Answer 1

• Formed from 80 named bones
  Consists of skull, vertebral column, and bony thorax

Question 2

Function of Facial Bones

Answer 2

• Form framework of the face
• Form cavities for the sense organs of sight, taste, and smell
• Provide openings for the passage of air and food
• Hold the teeth
• Anchor muscles of the face

Question 3

Cavities of the Skull

Answer 3

Middle and inner ear cavities – in lateral aspect of
cranial base
◦ Nasal cavity – lies in and posterior to the nose
◦ Orbits – house the eyeballs
◦ Air-filled sinuses – occur in several bones around the nasal cavity

Question 4

How many openings does the skull have? What are they called? and what are they for?

Answer 4

• approximately 85 named openings
• Foramina, canals, and fissures
• Provide openings for important structures like the Spinal cord, blood vessels serving the brain, and12 pairs of cranial nerves

Question 5

Bones of the Cranium

Answer 5

formed from eight large bones
Temporal bones (2)
Parietal bones (2)
Frontal bone (1)
Occipital bone (1)
Sphenoid bone (1)
Ethmoid bone (1)

Question 6

Frontal Bone

Answer 6

Forms the forehead and roofs of the orbits
Includes: supraorbital margin, superciliary arches, glabella, frontal eminences, frontal sinuses

Question 7

Sutures of the Cranium

Answer 7

coronal suture
squamous suture
sagittal suture
lambdoid suture

Question 8

Sutural Bones

Answer 8

• Small bones that occur within sutures
• Irregular in shape, size, and location
  Not all people have sutural bones

Question 9

Occipital Bone

Answer 9

Forms the posterior portion of the cranium and cranial base
* Articulates with the temporal bones and parietal bones
* Forms the posterior cranial fossa
* Foramen magnum located at its base – through this opening, the inferior part of the brain (brain stem) connects with the spinal cord.

Question 10

Features of Occipital Bone

Answer 10

Occipital condyles: enables us to nod our head “yes”
External occipital protuberance: external surface of the occipital bone is a knob in the midline

Question 11

Temporal Bones

Answer 11

• Lie inferior to parietal bones
• Form the inferolateral portion of the skull
• Term “temporal” comes from Latin word for time

Question 12

Specific Regions of the temporal bone

Answer 12

Squamosal, tympanic, petrous, and mastoid regions

Question 13

Squamosal Region

Answer 13

• region of temporal bone
• plate-shaped region that abuts the squamous suture
• includes: zygomatic process and mandibular fossa

Question 14

Tympanic Region

Answer 14

• region of temporal bone
• surround the external auditory meatus; external ear canal where sound enters the ear
• has styloid process: projects inferiorly from the tympanic region

Question 15

Mastoid Region

Answer 15

• breast-shaped region located just posterior to the tympanic region
• includes: mastoid process, and mastoid air cells

Question 16

Petrous Region

Answer 16

• projects medially and contributes to the cranial base; bony wedge between the occipital bone posteriorly and sphenoid bone anteriorly.
• includes carotid canal and jugular foramen

Question 17

Ear Ossicles

Answer 17

• bones of the ear
• malleus, incus, stapes

Question 18

Sphenoid Bone

Answer 18

• Spans the width of the cranial floor
• Resembles a butterfly or bat
• Consists of a central body and three pairs of processes:
  ◦ Greater Wings
  ◦ Lesser Wings
  ◦ Pterygoid Processes

Question 19

Sella Turcica

Answer 19

saddle-shaped prominence on the superior surface of the body; seat of the saddle is called the hypophyseal fossa (holds the pituitary gland).

Question 20

Sphenoidal Sinuses

Answer 20

within the sphenoid body are the paired sphenoidal sinuses (paranasal sinuses)

Question 21

Ethmoid Bone

Answer 21

• Lies between nasal and sphenoid bones
• Forms most of the medial bony region between the nasal cavity and orbits

Question 22

Cribriform Plate

Answer 22

• the superior surface of the ethmoid bone is formed by paired, horizontal cribriform plates that contribute to the roof of the nasal cavity and the floor of the anterior cranial fossa; tiny filaments of Cranial Nerve I, the olfactory nerve, pass through these small openings.

Question 23

Superior and Middle Nasal Concha

Answer 23

• part of the ethmoid bone
• extend medially from the the lateral masses and and protrude into the nasal cavity.

Question 24

Crista Galli

Answer 24

• part of ethmoid bone
• between the two cribriform plates, in the midline, is a superior projection called the crista galli (helps to secure the brain within the cranial cavity)

Question 25

Perpendicular Plate

Answer 25

• part of ethmoid bone
• projects inferiorly in the median plane; it forms the superior part of the nasal septum

Question 26

Ethmoid Sinuses

Answer 26

part of the paranasal sinuses