CHAPTER 7“The Axial Skeleton”

Review your A&P revealed discsCourse 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 BonesReview 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