CHAPTER 7
“The Axial Skeleton”
Review your A&P revealed discs
Course objectives:
Define and identify the bones of the axial
skeleton
Axial Skelton
– 80 total bones
– consists of the bones that form the long axis
of the body including the:
• Skull (total 28 with ear bones)
• Vertebral column [(total 26) C7;T12; L5; S1; Co1]
• Bony thorax [ribs and sternum (total 25)]
• Hyoid bone (1)
• Bones of the axial skeleton
Axial Skelton
Skull Bones
Review A&P revealed discs animation of skull
– the skull has two major divisions:
Cranium and Facial bones
Cranium – the 8 bones that enclose the brain.
-1 occipital, 1 frontal, 2 parietal, 2 temporal,
1 sphenoid and 1 ethmoid.
•
These typical flat bones of the cranium are
connected by a special kind of joint called a
suture (Synarthroses).
Cranial bones
Cranial Bones Midsaggital section
Cranial Bones Midsaggital section
Cranium
•
Made up of 2 major divisions:
1. Calvarium (skull cap)
2. Base
•
Base contains three large depressions (fossa):
–
–
–
Anterior cranial fossa where the frontal lobes sit
Middle cranial fossa where the temporal lobes sit
Posterior cranial fossa where the cerebellum sits
Cranial Bones
Cranial Bones
Sutures/Sutural Bones
• Sutures (synarthroses) are immovable
fibrous joints.
-all bones in the skull, except for the jaw, are
united by sutures. The major sutures are:
-Coronal
-Sagittal
-Squamous
-Lamboid
Sutural bones- small bones that occur within
the sutures, especially the lamboid suture.
They are not present in all people.
Sutures/Sutural Bones
Facial bones
•
•
There are 14 bones that can be thought of as
creating the face.
As part of this function they provide:
- protection for many sense organs,
-anchors for many muscles
-the openings for air and food to pass.
Facial Bones
2-maxillae; 2-palatine; 2-nasal; 2- zygomatic;
2-lacrimal; 2-inf nasal conchae; 1- vomer; and
1-mandible
Sphenoid bone
Looks like a Bat in flight. Greater and lesser
wings; optic foramen; sella turcica, superior
orbital fissure. Dorsal view.
Sphenoid bone
Dorsal view
Anterior view
Ethmoid bone
• Anterior to
sphenoid bone
forms anterior
base of skull
and nasal cavity.
• Cribriform plate.
• Crista gali
• Perpendicular
plate
Ethmoid bone
Ethmoid bone
Foramen/ Orbits
• Foramen: Special openings in bones where
nerves, blood vessels enter into the bone
cavity.
- Ex.: Foramen magnum, Supraorbital
Infraorbital, Mental, Jugular, Olfactory,
Mandibular
• Orbits: Cone shaped bony cavities that hold the
eyes, fat, occular muscles and tear glands.
Bones of the eye orbit
Meatus/ Sinuses
• Meatus: a canal or opening into bone
- Ex.: external auditory, internal acoustic
• Sinus: cavities within bones filled with air.
-Ex.: frontal, ethmoid, sphenoid and
maxillary sinuses
Cranial sinuses
Cranial fossa
Fossa are depressions or cavities in the skull.
The Fetal Skull
• Sutures are called fontanels in fetus.
• Fontanels
-Frontal (anterior)
-Occipital (posterior)
-Sphenoidal (anterior lateral)
-Mastoid (posterior lateral)
The Fetal Skull
The Fetal Skull