Axial Skeleton 1 Flashcards
Skull - Most of the bones are fused together by immovable joints called
sutures
Main function of skull
Its main function is to protect the brain (cranial cavity)
the skull’s surface markings serve
as muscle attachment sites and passageways for blood vessels and nerves
In addition to the cranial cavity, some skull bones form the
orbits and nasal cavity
Some skull bones also contain
smaller cavities (e.g., paranasal sinuses, middle and inner ear structures)
2 bone groups of the skull
Cranial Bones (8) - Form the cranial cavity (protects the brain)
Facial Bones (14) - Form the face
All Cranial Bones
Frontal bone
Parietal bones (2) - one left one right
Temporal bones (2) - one left one right
Occipital bone
Sphenoid bone
Ethmoid bone
Frontal Bone Forms
The forehead
The anterior portion of the cranial cavity
Part of each orbit
Frontal bone landmarks
Supraorbital margin (the ridge that separates the forehead from the superior part of the orbit
Supraorbital foramen (towards the midline from the supraorbital)
Artery & nerve
Parietal Bones (2) Form
Form:
The top and upper part of the sides of the head
Most of the superolateral portion of the cranial cavity
Temporal Bones (2) form
Form:
The lower part of the sides of the head (“temples”)
Most of the inferolateral portion of the cranial cavity
Temporal Bones features
Features:
Styloid process
Mastoid process
Stylomastoid foramen - CN VII
Carotid foramen - Internal carotid artery
Jugular foramen - Internal jugular vein, CN IX, CN X, CN XI
Temporal Bones (2) outside features
Features:
Zygomatic process - Zygomatic bone
Mandibular fossa -Mandible
External auditory meatus
Internal auditory meatus - CN VII, CN VIII
Parts of the ear
Tympanic membrane
“Eardrum”
Middle ear
Cavity in the temporal bone
Inner ear
Cavity in the temporal bone
Oval window
Opening in a bony partition between middle/inner ears
3 small bones of middle ear
Malleus (“hammer”) - physically attatched tympanic membrane
Incus (“anvil”)
Stapes (“stirrup”) - Attached to a membrane covering the oval window
How do our ears work?
Sounds come in through the outer ear and vibrate the tympanic membrane, these vibrations are sent to the “Auditory ossicles”
(Smallest bones in the body)
then to the cochlea
Auditory (Eustachian) tube
Connects the middle ear to the nasopharynx (throat)
Assists with pressure equalization in the middle ear
Route for pathogens into the middle ear (infection)
Occipital Bone form
Forms:
The back of the head
The posteroinferior portion of the cranial cavity
Occipital Bone landmarks
External occipital protuberance- Muscle attachments (back of head in line with tops of ear lobes)
Superior nuchal line - Muscle attachments (ridges lateral from EOP)
Inferior nuchal line - Muscle attachments
Occipital condyles -
First cervical vertebra (C1)
Foramen magnum - Medulla oblongata, CN XI, vertebral arteries
Sphenoid Bone forms
Forms:
The middle part of the inferior portion of the cranial cavity
Part of each orbit
Part of the nasal cavity
“Sphenoid” = “wedge” (Greek)
The “keystone” to the cranial floor since it articulates with all of the other cranial bones
Sphenoid landmarks
body
sphenoid sinus
sella turcica - Pituitary gland
Sphenoid wings
Greater wing (2)
Lesser wing (2)
Pterygoid process (4) - muscle attachments
Two openings of the back of the orbit of the Sphenoid bone
Optic foramen - CN II
Superior orbital fissure - CN III, CN IV, CN V, CN VI
2 Greater wing openings of the Sphenoid bone
Foramen rotundum (2) (anterior)
Foramen Ovale (2) (interior)
Ethmoid Bone forms
Forms:
Part of the anteroinferior portion of the cranial floor
Part of each orbit
Part of the border of the nasal cavity
“Ethmoid” = “sieve-like” (Greek)
Sponge-like in appearance with lots of small cavities
Ethmoid Bone - landmarks
Cribriform plate
Olfactory foramina - CN I - opening - smell reseptors
crista galli - supior projection
Ethmoid Bone - landmarks (inferior to Cribriform plate)
Perpendicular plate - Part of the nasal septum
Lateral mass (2) - Wall of the nasal cavity
Ethmoidal sinuses -
Landmarks mideal to each lateral mass
Superior nasal concha
Middle nasal concha
-creates turbulance as air enters to become moist and warm
-These conchae increase the surface area of the nasal mucous membranes, which act to warm and moisten the air
Facial Bones
Nasal bones (2)
Lacrimal bones (2)
Zygomatic bones (2)
Maxillae (2)
Palatine bones (2)
Vomer
Inferior nasal conchae (2)
Mandible
Zygomatic bones and Temporal meet how?
the temporal process and zyomatic process meet together to create the “zygomatic arch”
the temporal process is part of the zyomatic bone and vice versa
Palatine bones forms
posterior Part of the hard palate
maxillae bones forms
contains Infraorbital foramen
Artery & nerve
Each bone forms part of the hard palate and contains a maxillary sinus
Vomer is where
inferior to the parapedicular plate of the ethmoid bone (Part of the nasal septum)
Inferior nasal conchae (2) is where
lateral walls of nasel cavity inferior to the middle nasal cavity of the ethmoid bone
Mandible landmarks
Mandibular foramen (2) - Entry to the mandibular canal, which carries arteries and nerves to the teeth
Ramus - superior to the skull
Angle - between ramus and body
Body - lower teeth
Condylar process (2)
Temporal bone
Temporomandibular joint
Coronoid process (2)
both processes are connected by Mandibular notch (2)
Bones that form each orbit (eye sockect)
Roof
Frontal bone
Sphenoid bone
Lateral wall
Zygomatic bone
Sphenoid bone
Medial wall
Maxilla
Lacrimal bone
Ethmoid bone
Sphenoid bone
Floor
Maxilla
Zygomatic bone
Sphenoid bone
Nasal Septum
Separates the nasal cavity into left and right sides
Composed of cartilage (anteriorly) and bone (posteriorly) - Ethmoid bone (perpendicular plate) and vomer
Paranasal Sinuses
Cavities within certain bones lined with mucous membranes that are continuous with the nasal cavity
Function to decrease the weight of the skull and increase the surface area of the nasal mucosa (moisten/clean inhaled air)
Bones that have sinuses include the frontal bone, sphenoid bone, ethmoid bone, and maxillae
Each bone in the sinus have sinus what are they called?
same but with sinus at the end
Hyoid Bone
Located in the anterior neck between the mandible and larynx
Does not articulate with any other bone!
Provides attachment sites for muscles of the tongue, pharynx, and anterior neck
Assists in tongue movements and swallowing
