Axial skeleton Flashcards
Skull
Bones of the head
How many bones make up the calvarium.
- 8 bones.
==1 Frontal bone , 2 Parietal bones, 2
Temporal bones, 1 Occipital bone, 1 sphenoid bone, 1
ethmoid bone
How many bones make up the facial skeleton.
- 14 bones
- 2 zygomatic bones
- 2 maxillae
- 2 nasal bones
- 2 lacrimal bones
- 1 vomer
- 2 palatine bones
- 2 inferior nasal conchae
- 1 mandible
Divisions of the skull
- Calvarium
- Facial skeleton.
Bregma
The junction of coronal suture and sagittal suture
Coronal suture.
Joins the frontal bone with the right and left
parietal bones,
Sutures of the skull
- Coronal suture
- Sagittal suture
- Lambdoid suture
- Squamous suture
Lambdoid suture
posteriorly joins the right and left parietal
bones with the occipital bone
Sagittal suture.
joins the two parietal bones
The base
Orbital opening onto the face.
Squamous suture
cranial suture that connects the temporal and parietal bones of the skull.
Lambda
the junction of sagittal suture and
lambdoid suture is lambda
Parts of the orbit
- Base
- Apex
- Floor
- Lateral and medial walls
bones that form the roof of the orbit
- Lesser wing of sphenoid bone
- Frontal bone
Bones that form the medial wall of the orbit.
- Process of maxilla
- Lacrimal one
- Orbital plate of ethmoid and sphenoid
Bones that form the lateral wall of the orbit.
Greater wing of sphenoid bone.
In lateral view of the skull the following are noted.
- Anteriorly, the frontal bone articulates at its posterior
border with the parietal bone at the coronal suture. - Parietal bone articulates with occipital bone posteriorly
at lambdoid suture and inferiorly with the temporal
bone. - The squamous portion of the temporal bone forms side
of the vault of the skull. - Posterior to zygomatic process is the external auditory
meatus. - Mastoid part of the temporal bone projects downwards
forming mastoid process. - Inferior to frontal bone anteriorly there are zygomatic
bone, maxilla and mandible.
Three divisions of the base of the skull.
- Anterior part
- Medial part
- Posterior part
Anterior part
- found at a lower level than the rest of
the base. - Extends from the front teeth to the posterior margin of
the hard palate. - It is formed by the hard palate and the alveolar process
of the maxillae
Middle/medial part
Starts from the posterior margin of the hard palate to the anterior margin of the foramen magnum.
* The vomer – is in the midline anteriorly
* Basal part of the sphenoid bone – a wider bar of bone
extending backwards to the anterior margin of the foramen
magnum
* Pterygoid process of sphenoid bone – found posteriorly to the
alveolar process and protrudes downwards from greater wing
of sphenoid.
* Infratemporal fossa – is found lateral to the pterygoid process.
* Squamous part of the temporal bone, forms the rest of the infratemporal roof.
Posterior part
Lies behind the anterior margin of the
foramen magnum.
structures found; Foramen magnum, occipital condyles, hypoglossal canal,
stylomastoid foramen, mastoid process, external occipital crest.
The divisions of the interior base of the skull.
- The anterior cranial fossa
- The middle cranial fossa.
- The posterior cranial fossa
Bones that make up the anterior cranial fossa.
- Formed almost entirely by the frontal bone.
- Lesser wings of the sphenoid form the posterior edges.
- Cribriform plate forms a small part in the midline.
The anterior cranial fossa.
– It lies at a higher level than the middle cranial fossa.
– In the midline of the anterior cranial fossa is a sharp raised projection
of the bone called crista galli of the ethmoid bone.
The middle cranial fossa.
- Has a central raised portion formed by
the body of the sphenoid extending from the optic groove
anteriorly to the dorsum sallae posteriorly. - Behind the optic groove there is a hollow called sella turcica
which contains the pituitary gland. - And the posterior wall of the sella turcica is formed by the
dorsum sellae.
The posterior cranial fossa.
– In the floor midline is the foramen magnum which narrows
on either side by the occipital condyles.
– Posteriorly there is a bulge which corresponds with the
external protuberance on the outside skull
nasal cavity
irregularly-shaped cavity lying
above the floor of the mouth and below the anterior
cranial fossa
What structure divides the nasal cavity,
nasal septum
Bones that make up the nasal septum.
- Vomer bone
- Perpendicular plate of the ethmoid bone.
Divisions of the nasal cavity.
- Roof, floor, lateral and
medial walls
Roof of nasal cavity.
- Central portion formed by cribriform plate of ethmoid.
- Anterior part formed by nasal bones.
- Posterior formed by body of sphenoid.
The floor of the nasal cavity.
- formed by the upper surface of the hard palate which
separates the nasal cavity from the mouth.
The medial wall of the nasal cavity.
- Formed by the bony septum
Lateral wall of the nasal cavity.
- Is irregular due to the presence of the 3 nasal conchae.
