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: Calvarium (skull cap) 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