3.1 Skeleton: skull

Question 1

How is the skull organized?

Answer 1

Cranial bones

• enclose brain in cranial cavity
• provide attachemnt site for head and neck muscles
• cranial valut (calvaria = superior aspect)
• cranial base (made up of 3 cranial fossae)

Facial bones

• framework of face
• anchor facial muscles & attachment site for teeth
• cavities for special sense organs (orbits for eyes, nasal cav for olofactory)
• openings for air passage

Associated bones

Question 2

parts of the cranial fossae

Answer 2

* fossae = basin like depression in bone

anterior, middle and posterior

” steps down from anterior”

Question 3

what bones can be found in the anterior cranial fossa

Answer 3

• frontal bone, ethmoid bone and sphenoid bone

*sphenoid bone is central

Question 4

what bones can be found in the middle cranial fossa

Answer 4

sphanoid, 2 temporal bones and parietal bone

Question 5

what bones can be found in the posterior cranial fossa

Answer 5

primarily occipital bone

• small amount of sphenoid occupies posterior
• also temporal and parietal

Question 7

what are the bones in the cranium

Answer 7

frontal bone (1)

parietal bones (2)

Occipital bone (1)

Temporal bones (2)

sphenoid (1)

Ethmoid (1)

Question 8

what facial bones are found in the skull?

Answer 8

mandible (1)

maxillary bones (2)

zygomatic bones (2)

nasal bones (2)

lacrimal bones(2)

palatine bones (2)

inferior nasal chonchae (2)

vomer (1)

Question 9

describe the frontal bone

Answer 9

Anterior portion of the cranium

*makes up forehead

• Superior wall of orbits (supraorbital margin)
• occupies most of the anterior cranial fossa

Question 10

describe the parietal bones

Answer 10

• are located at superior and lateral aspects of the calvaria
• fused at midline

*calvaria is the top part of the skull

• sagittal suture is between right and left parietal bones
• lamdboid suture is between the patietal and occipital bones

Question 11

describe the features of occipital bone

Answer 11

• occupies most of posterior wall and posterior cranial fossa
• contains foramen magnum BIG HOLE for passage of spinal cord
• articulates with 1 vertebra via occipital condyles

(articulates = juncture between bones or cartilages in the skeleton of a vertebrate)

(condyles = rounded articulating surface since its occipital bone its the occipital condyle)

• Hypoglossal canal: passage of CN XII (hypoglossal nerve)

Question 12

describe the main regions of the temportal gone

Answer 12

• inferolateral aspects of the skull & parts of cranial floor
  1. Squamous region: zygomatic process and mandibular fossa

(squamus = fish scale bc its thin ans scale like, zyg.. means cross bar, mandicular = jaw)

2. Petrous region: mastoid process and styloid process

(styloid = pillar,

3. Tympanic region: external acoustic meatus (canal for ear from external to middle)

(tympanic relates to ear drum)

*contributes to cheek bones

Question 13

what are the openings of the temporal bone?

Answer 13

*contains middle and internal ear

• Carotid canal: for internal carotid artery (aupplied clood to carotid)
• Stylemastoid foramen: for facial nerve CN VII (hole bwn mastoid and stylo)
• Inernal acoustic Meatus: for facial CN VII and vestibulucochlear CN VIII nerves

** Jugular foramen: for internal jugular nein and CN IX, X, XI

Mastoid air cells; lighten skull

Question 14

describe the structure of the sphenoid bone

Answer 14

* kinda like a bat, in centre/middle so interacts w/ a lot

• greater wings
• lesser wings (more superior and anterior, contribute to anterior cranial fossa)
• pterygoid process: comes out inferiorly and splits into medial and laterla plates

(pterygoid = shaped like wing)

• Sella turcica (contains the hypophyseal fossa)

Question 15

what are the passageways int eh Sphenoid Bone

Answer 15

• Superior orbital Fissure: for nerve that controlls eye movements (CN III, IV, V1 & VI)
• Optic Canal: For optic nerve (CN II) *its more medial
• Foramen rotundum: for trigemental nerve CN v2
• Foramen ovale: for trigmental nerve CN V3

Foramen Spinosum: for middle meningeal artery (supplies blood to mininges

Question 16

describe the Ethmoid Bones

Answer 16

deepest skull bone

• contributes to medial wall of orbits
• superior part of ansal septum, roof of nasal cavities, 2 nasal conchae

Crista galli: attaches dura matter

(tough outer layer of tissue that covers and protects the brain and spinal cord)

Cribfiform plate: for olofactora foramina (CN 1)

Question 17

what is the mandible

Answer 17

lower jaw

largest, strongest bone in face

• contains sockets for lower teeth

Temporomandicular joint: only freely movable skull joint

Question 18

parts of mandible

Answer 18

*condyle and angle

Question 19

describe the maxillary bones

Answer 19

• medially fused to form upper jaw, hard palte (palatine process) & central factial skeleton
• Maxillary bones holds upper teeth in aleolar processes

- has a zygomatic process contriuting to zygomatic arch

(zygomatic bone refers to cheek bone, below and lateral to the orbit)

Question 20

describe Zygomatic bones

Answer 20

zygomatic arch (cheekbones)

• inferolateral margins of orbits

Question 21

dsecribe nasal bones and lacrimal bones

Answer 21

Nasal: form bridge of nose and attach to nose nartilage

Lacrimal bones: forms medial orbital walls

*contain lacrimal fossa houses lacrimal sac

(helps shut tears products in orbital cavity to nasal cavity)

Question 22

describe the Palatine bones

Answer 22

• L shaped
  forms: posterior 1/3 of hard palate, posterolateral walls of nasal cavity, very small part of orbits

Question 23

Describe the inferior nasal conchae

Answer 23

-forms part of lateral walls of ansal cavity

*helps to inc turbulence in the nasal cavity

Question 24

Ossicles

what are the 3 regions of the eat

Answer 24

Bones of middle ear

regions: external ear, middle eat and labyrinth (internal ear)

Question 25

Describe the Hyoid bone, where is it located?

Answer 25

NOT A SKULL BONE - does not directly articulare with another bone (anchored by ligaments) - acts as a movable base for tongue and stie of attachement for muscles of swalling and speech \*ocated at vertebrae level C3

Question 26

What are the Paranasal Sinuses? What are their function?

Answer 26

\* sinus = cavity within a cone, filled w/ air and lined with muscus membranes Function: warm and humifiy inspired air, lighten skull and enhance vocal resonance

Question 27

What are the major sutues of the cranium?

Answer 27

\* type of immovable joint, esp between the bones of the skull (cranial suture) a seam or joining, as in sewing. **Coronal:** between parietal and frontal bones **squamous:** between parietal and temporal bones **Pterion:** etween frontal, parietal, temporal and sphenoid bones \*one of weakest parts of skull, blow can cause damage to minigeal artery -\> cranial bleed **Sagittal suture:** between right and left parietal bones **lambdoid:** between parietal and occipital bones

Question 28

how does fetal skull compare to adult skull

Answer 28

- as more bones than adult - at birth the skull is not comlpete and connected by 4 fontanels (unossified remnants of fibrous membranes) \*Fontanel is at the junction point of sutures

Question 29

fontanels of the fetal skull

Answer 29