Download the skull - Mayfield City Schools

THE SKULL
SIMPLY, AMAZING!
• Most complex bony structure
• 22 bones in all
• Mostly flat bones, but not all!
Functions of Cranial Bones
• Enclose and protect the fragile brain and
furnish attachment sites for head and neck
muscles
Functions of Facial Bones
• 1. form framework of face
• 2. contain cavities for special sense
organs
• 3. openings for food/air passage
• 4. secure the teeth
• 5. anchor the facial muscles of expression
• ALL BONES OF THE SKULL ARE
FIRMLY LOCKED IN PLACE BY JOINTS
CALLED SUTURES
• Four major sutures
THE CRANIUM (8)
1 frontal bone
2 parietal bones
2 temporal bones
1 occipital bone
1 sphenoid bone
1 ethmoid bone
THE FRONTAL BONE
Parietal Bones: Form most of the superior and
lateral aspects of the skull
Figure 7.3a
Parietal Bones and Major Associated Sutures
• Four sutures mark the articulations of the
parietal bones
– Coronal suture – articulation between
parietal bones and frontal bone anteriorly
– Sagittal suture – where right and left parietal
bones meet superiorly
– Lambdoid suture – where parietal bones
meet the occipital bone posteriorly
– Squamosal or squamous suture – where
parietal and temporal bones meet
Occipital Bone and Its Major
Markings
• Forms most of
skull’s posterior
wall and base
• Major markings
include the
posterior cranial
fossa, foramen
magnum, occipital
condyles, and the
hypoglossal canal
Figure 7.2b
Temporal Bones
• Form the inferolateral aspects of the skull
and parts of the cranial floor
• Divided into four major regions –
squamous, tympanic, mastoid, and
petrous
• Major markings include the zygomatic,
styloid, and mastoid processes, and the
mandibular and middle cranial fossae
Temporal Bones
• Major openings include the stylomastoid
and jugular foramina, the external and
internal auditory meatuses, and the carotid
canal
Temporal Bones
Figure 7.5
Sphenoid Bone
• Spans the width of the middle cranial
fossa. Has a butterfly like shape.
• Articulates with all other cranial bones.
• Markings and regions to know:
• Sphenoid sinuses
• Hypophyseal fossa: a snug enclosure for
the pituitary gland.
• Greater and Lesser Wings
• Optic Canals: (opening for optic nerves)
• Superior Orbital fissures: long slit
between greater and lesser wings, allows
cranial nerves to control eye movement.
• Pterygoid processes: anchors muscles
used in chewing
• Foramen rotundum and Foramen ovale
Ethmoid Bone
• Lies between the sphenoid and nasal
bones of the face. Most deeply situated.
• Markings/Regions
• Cribriform plates: help form roof of nasal
cavities and cranial fossa.
• Olfactory foramina: allow olfactory nerves
to pass from nasal cavities to the brain.
• Crista galli
• Ethmoid sinuses
Maxillary Bones
• Medially fused bones that make up the
upper jaw and the central portion of the
facial skeleton
• Facial keystone bones that articulate with
all other facial bones except the mandible
• Their major markings include palatine,
frontal, and zygomatic processes, the
alveolar margins, inferior orbital fissure,
and the maxillary sinuses
Maxillary Bone
Figure 7.8b
Zygomatic bones
• Paired bones aka Cheek bones
• Form prominences of the cheeks and
parts of the inferolateral margins of orbits.
• Articulates with temporal, frontal, and
maxillary bones.
Nasal Bones
• Form bridge of nose
• Articulates with frontal, maxillary, and
ethmoid bones.
Lacrimal Bones
• Located in the medial wall of the orbits.
• Articulates with the frontal, ethmoid, and
maxillary bones.
Palatine Bones
• Complete the posterior part of the hard
palate.
• Forms part of the posterolateral walls of
the nasal cavity.
• Small part of the orbits.
The Vomer
• Forms part of the nasal septum dividing
the nasal cavity in left and right halves.
The Inferior Nasal Conchae
• Thin curved bones in the nasal cavity.
• Forms the lateral wall of the nasal cavity.
Application Question
• Mr. and Mrs. Walkabots have recently
given birth to a beautiful baby girl, Zeplin.
After a few months of great joy they notice
that their daughter vomits often, sleeps a
lot, is irritable all the time and cannot look
them in the eye. Zeplin does not meet
developmental milestones over the next
six months. HELP!