3.1 Skeleton: skull Flashcards
How is the skull organized?
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
parts of the cranial fossae
* fossae = basin like depression in bone
anterior, middle and posterior
” steps down from anterior”
what bones can be found in the anterior cranial fossa
- frontal bone, ethmoid bone and sphenoid bone
*sphenoid bone is central
what bones can be found in the middle cranial fossa
sphanoid, 2 temporal bones and parietal bone
what bones can be found in the posterior cranial fossa
primarily occipital bone
- small amount of sphenoid occupies posterior
- also temporal and parietal
what are the bones in the cranium
frontal bone (1)
parietal bones (2)
Occipital bone (1)
Temporal bones (2)
sphenoid (1)
Ethmoid (1)
what facial bones are found in the skull?
mandible (1)
maxillary bones (2)
zygomatic bones (2)
nasal bones (2)
lacrimal bones(2)
palatine bones (2)
inferior nasal chonchae (2)
vomer (1)
describe the frontal bone
Anterior portion of the cranium
*makes up forehead
- Superior wall of orbits (supraorbital margin)
- occupies most of the anterior cranial fossa
describe the parietal bones
- 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
describe the features of occipital bone
- 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)
describe the main regions of the temportal gone
- 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)
- Petrous region: mastoid process and styloid process
(styloid = pillar,
- Tympanic region: external acoustic meatus (canal for ear from external to middle)
(tympanic relates to ear drum)
*contributes to cheek bones
what are the openings of the temporal bone?
*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
describe the structure of the sphenoid bone
* 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)
what are the passageways int eh Sphenoid Bone
- 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
describe the Ethmoid Bones
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)
what is the mandible
lower jaw
largest, strongest bone in face
- contains sockets for lower teeth
Temporomandicular joint: only freely movable skull joint
parts of mandible
*condyle and angle
describe the maxillary bones
- 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)
describe Zygomatic bones
zygomatic arch (cheekbones)
- inferolateral margins of orbits
dsecribe nasal bones and lacrimal bones
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)
describe the Palatine bones
- L shaped
forms: posterior 1/3 of hard palate, posterolateral walls of nasal cavity, very small part of orbits
Describe the inferior nasal conchae
-forms part of lateral walls of ansal cavity
*helps to inc turbulence in the nasal cavity
Ossicles
what are the 3 regions of the eat
Bones of middle ear
regions: external ear, middle eat and labyrinth (internal ear)
Describe the Hyoid bone, where is it located?
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
What are the Paranasal Sinuses?
What are their function?
* 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
What are the major sutues of the cranium?
* 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
how does fetal skull compare to adult skull
- 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
fontanels of the fetal skull
