Skull: Lesson 1 - Anatomy
What are the primary landmarks of the frontal bone?
-Glabella -Frontal Tuberosity -Suprerciliary Ridge (arch) -Supraorbital Groove -Supraorbital Notch (foramen) -Supraorbital Margin (SOM)
What are the 3 main areas of the cranial floor?
1. Anterior Cranial Fossa 2. Middle 3. Posterior Cranial Fossa
What are the 4 parts of the occipital bone?
1. Squamous Portion 2. Right Occipital Condyle 3. Left Occipital Condyle 4. Foramen Magnum
The cranium reaches adult size and density at age _______.
12 yrs
The cranium develops at _______ years old.
5-6yrs
Coronal Suture:
Between the frontal bone and the parietal bone
Lambdoidal Suture:
Between the occipital bone and the right and left parietal bones
Squamosal Suture:
Between the parietal bone and the temporal bone
Sagittal Suture:
Between the right and left parietal bones
Basillar Portion of the Occipital Bone
Curves anterior and superiorly Articulates with body of the sphenoid
Squamous Portion
Curves posterior & superiorly from the foramen magnum Largest part of the occipital bone
Posterior Cranial Fossa:
Deep depression behind the petrous portions ***hearing
Supraorbital Groove
Depression below the frontal tuberosity and Suprerciliary Ridge (arch)
How many cranial bones are there in total?
Eight (8): -Frontal -Rt. Parietal -Lt. Parietal -Occipital -Ethmoid -Sphenoid -Rt. Temporal -Lt. Temporal
Suprerciliary Ridge (arch)
Eyebrow
Glabella
Flat surface between the 2 superciliary arches
Occipital Bone
Forms the posterior half of the base of the skull and the greater portion of the posterior cranial fossa Articulates with C1 (alatooccipital joint)
Parietal Bones
Forms the posterior portion of cranial roof -Square shaped -Convex external service
How many sutures are there in the cranium?
Four (4): -Coronal -Sagittal -Squamosal -Lambdoidal
How many bones make up the floor of the cranium?
Four (4): -Ethmoid -Sphenoid -Rt. Temporal -Lt. Temporal
How many bones make up the Calvaria (skull cap)?
Four (4): -Frontal -Rt. Parietal -Lt. Parietal -Occipital
Anterior Cranial Fossa:
Frontal lobes of the cerebellum
Pteroin intersection:
Located where the coronal and the sqamosal suture meet ***right and left
Bregma intersection:
Located where the coronal suture and sagittal suture meet
Lambda intersection:
Located where the sagittal suture and the lambdoidal suture meet
Asterion intersection:
Located where the squamosal suture meets the lambdoidal suture and the parietal bone and greater wing of the sphenoid
Sphenoid Fontanels:
Location between the inferior parietal bone and the wing of the sphenoid bone Right and Left Area of the pterion intersection in adults
Mastoid Fontanels:
Location between the occipital and parietal bones Right and Left Area of the Asterion interaction in adults
Posterior Fontanel:
Location between the occipital bone and right and left parietal bones Area of the Lambda intersection in adults
Anterior Fontanel:
Location where the frontal and parietal bones come together Area of the Lambda intersection in adults
What are intersections of the skull?
Location where two sutures meet
Middle Cranium Floor:
Neurovascular structures
Frontal Tuberosity
Pair of elevated frontal bones on either side of the MSP
Where are the cerebellum, PONS, and medulla oblongata located?
Posterior Cranial Fossa
External Occipital Protuberance (inion)
Protuberance of the posterioinferior (lower rear) of the occipital bone
How many Fontanels are there?
Six (6): -Anterior Fontanel -Posterior Fontanel -Right Sphenoid Fontanel -Left Sphenoid Fontanel -Right Mastoid Fontanel -Left Mastoid Fontanel
How many intersections are there in total?
Six (6): -Bregma -Lambda -Right Pterion -Left Pterion -Right Asterion -left Asterion
What are Fontanels?
Soft spots ***when we are born our cranial bones are not completely grown together ***Sutures form as the fontanels grown together as we age
What are sutures?
They are located where the different bones of the cranium unite. Fibrous joint classification
T or F: The back of the head is wider than the front of the head?
True
Parietal Tubercle (eminence):
bulge near the center of each parietal bone ***distance between the parietal eminence is widest portion of cranium
The horizontal portion of the frontal bone...
forms the orbital plates, roof of nasal cavity, and greater part of the anterior fossa.
Frontal Bone
forms the roof of the orbits and part of the roof of the nasal cavity
Nasion
frontal nasal suture where the frontal bone meets the nasal bones
The vertical portion of the frontal bone is called the...
frontal squama forms the forehead and anterior part of the vault
Supraorbital Notch (foramen)
nerves and blood vessels pass through here
Right & Left Occipital Condyle
paired prominences of the occipital bone; oval or bean shaped structures forming lateral aspects of the foramen magnum
Supraorbital Margin (SOM)
superior aspect of the orbital
Foramen Magnum
the hole in the base of the skull through which the spinal cord passes
