Chapter 6: Skeletal System

Axial Division

The bones of the skull, thorax, and vertebral column.

Axial Skeletons consist of ..

206 Bones!!

• Skull (cranial and facial bones)

• Thoracic cage

• Vertebral column

Skull is composed of…

• cranial,

• facial bones

• associated bones

What is the Cranium compose of what bones?

• Occipital

• Parietal 2

• Frontal

• Temporal 2

• Sphenoid

• Ethmoid

Cranial Bones encloses…

• The cranial cavity-Fluid filled chamber that supports the brain.

• Cranium provides an extensive area for muscle attachment

• Movement of eyes, jaw and head.

What does the Cranium provide?

Extensive area for muscle attachment and movement of eyes, jaw and head.

What are Sutures?

Dense fibrous connective tissue joints between flat bones of the skull.

• Fission of bone

What are the 5 Sutures in the skull?

• Lambdoid - occipital and parietal bones

• Sagittal - between parietal bones

• Coronal - Frontal to parietal bones

• Squamous - Boundary between parietal and temporal

• Frontonasal - Boundary between the nasal bone and the frontal bone

What does the lambdoid connect?

Occipital and parietal bones

What does the sagittal suture connect?

Between parietal bones

What does the Coronal suture connect?

Frontal to parietal bones

What does the Squamous suture connect?

Boundary between parietal and temporal

Where is the Frontonasal Suture located?

Boundary between the nasal bone and the frontal bone.

What is the calvaria/Cranial vault? What 3 bones does it consist of?

Cranial space that encases and protects the brain together with the base of the skull

• Occipital

• Parietal

• Frontal

Occipital bone (1) - part of Posterior, lateral and inferior surface of the cranium

• Hypoglossal Canal

• Foramen magnum

• Occipital condyle

• Occipital bone

• Superior nuchal line

• External occipital protuberance

• Inferior nuchal line External occipital crest

What are the 3 markings of the inferior view of the occipital bone? location?

• Hypoglossal Canal

• Foramen magnum

• Occipital condyle

What are the 2 lines and 2 protuberances of the superior view of the occipital bone? location?

• Superior nuchal line

• External occipital protuberance

• Inferior nuchal line

• External occipital crest

Parietal Bones overview. - form the major part of the calveria

What do the lines indicate?

Attachment of the temporalis muscles (closes mouth)

Where are the 2 lines, 2 borders, and markings of the parietal bone?

• Border of sagittal suture

• Parietal eminence

• Superior temporal line

• Inferior temporal line

• Border of squamous suture

Where are the Anterior surface, lateral surface, and frontal part the frontal bone? (7)

Anterior view

• Squamous Part

• Frontal (metopic) suture

• Superior temporal line

• Supercillary Arch

• Supra-orbital margin

• Supra-orbital notch

• Supra-orbital formen

What is the Anterior surface, Lateral surface, frontal part of the Frontal bone

• Anterior surface: the squamous part.

• Lateral surface: anterior continuous of the superior temporalis lines.

• Frontal part: supraorbital margins

What is the Inferior view (orbital part) of the Frontal bone compose of?

What does the orbital surface of the Frontal bone form?

• Frontal air cells

• Lacrimal fossa - form lacrimal gland

• Orbital part (orbital surface) - forms the roof of each orbit

Inferior surface - forms opening for blood vessels

Frontal Bone internal surface (posterior view) What are the 5 components? Location?

What is the purpose of the Frontal Bone?

Conforms the shape of the anterior potion of the brain

• Margin of coronal suture

• Squamous part

• Frontal crest

• Orbital part

• Notch for ethmoid

What does the frontal crest function?

Attachment of membranes that protect the brain

Temporal Articulate with? (5)

• Zygomatic

• Parietal

• Occipital

• Sphenoid

• Mandible

The inferior of the parietal bone function? (5)

• Form an attachment area to muscles for jaw and head movement.

• Form the articulation with the mandible

• Form part of the lateral and inferior walls of the cranium

• Form the zygomatic arches of the cheek

• Protect organs of the internal ear

What are the three parts of the Temporal bones?

• Squamous

• Tympanic

• Petrous - dominates medial surface of the temporal bone

What are the 7 components of the petrous part of the temporal bones?

• Mastoid process

• Mandibular fossa

• Styloid process

• Stylomastoid

• Carotid Canal

• External acoustic meatus

• Internal acoustic meatus

What are the Mastoid process and mandibular fossa location? What are their functions?

• Mastoid process - Attachment site for muscles that rotate the head

• Mandibular fossa - Depression → Mendible

Where are the styloid process and stylomastoid foramen located? What are their functions?

• Styloid process - Ligament that support the hyoid (muscles: tongue, pharynx, and larynx)

• Stylomastoid foramen _ facial nerve

What are the location of the External acoustic meatus and Carotid canal of the petrous part of the temporal bone? What are the functions of each?

• Carotid canal - Carotid artery (supplies blood to the brain)

• External acoustic meatus - Passageway that ends at the eardrum (tympanic membrane)

What is the location of the internal acoustic meatus, petrous part of the temporal bone? What is the function?

• Internal acoustic meatus - carries blood vessels and nerves - internal ear

The Sphenoid unites all the … and … bones? and also articulates with them.

Cranial and Facial bones

What is the sphenoid composed of? Superior view (9)?

Superior view:

• Optic canal

• Greater wing

• Sella turcica

• Hypophysial fossa

• Body of sphenoid

• Lesser wing

• Foramen rotundum

• Foramen ovale

• Foramen spinosum

What is the sphenoid composed of? Posterior view (5)?

• Greater wing

• Lesser wing

• Body of sphenoid

• Superior orbital fissure

• Pterygoid process

The Sphenoid is composed of what process? Function? (temporal bone)

Pterygoid processes - attachment site for muscles that move lower jaw and soft palate.

What is the Foramina and Sella turcica of the sphenoid of the temporal bone? functions

• Foramina: Blood vessels and cranial nerves to orbits, face and jaw.

• Sella turcica encloses Hypophysial fossa. Pituitary gland

What are the Three parts of the Ethmoid? (temporal bone)

• Cribriform plate

• Ethmoidal labyrinth

• Perpendicular plate (olfactory receptors)

Where is the Cribriform plate, Ethmoidal labyrinth, Perpendicular plate located? what are their functions?

Extra - Where is the:

• Crista galli

• Superior nasal concha

• Middle nasal concha

• Cribriform plate: Foramina →olfactory nerves Separated by Crista Galli.

• Ethmoidal labyrinth: Superior and middle nasal conchae.

• Perpendicular plate: Thin plate of bone that form part of the nasal septum

Cranial Fossae is composed of three sections. What are they?

• Anterior cranial fossa

• Middle Cranial fossa

• Posterior Cranial fossa

Location of the Anterior cranial fossa? What bones do they compose of? (3) What organs do they contain?

Bones:

• Frontal bone

• Ethmoid

• Lesser wing of the sphenoid

Contains:

• Frontal lobes of the cerebral hemispheres

Location of the Middle cranial fossa? What bones do they compose of? (3) What organs do they contain?

Extends of the posterior nasal apertures to the petrous part of the temporal bones

• Sphenoid

• Temporal

• Parietal bones

Contains:

• Temporal lobe, diencephalon, brain stem

Location of the Posterior cranial fossa? What bones do they compose of? (3) What organs do they contain?

Extends from the petrous parts of the temporal bones to the posterior skull surface

• Occipital

• Part of Temporal

• Part of Parietal

Contains

• Occipital lobes

• Cerebellum

• Brain stem (pon and medulla)

Skull of Infants, Children and Adults

At birth areas of …. connect that cranial bone

The fibrous regions are called?

Connective tissue

Fontanelles

Before age 5, there is … of the cranium

Significant growth

After age 5, growth… and the cranial sutures…

growth stops and cranial sutures develop

Fontanelles allow?

Cranial expansion, and distortion at birth

What are the 4 Fontanelles in children?

• Anterior Fontanelle

• Posterior Fontanelle

• Sphenoidal Fontanelles

• Mastoids Fontanelles

Locations the anterior fontanelle and posterior fontanelle? What are their junctions?

• Anterior Fontanelle Junction: Frontal/coronal/sagittal sutures

• Posterior Fontanelle Junction: Lambdoid/sagittal sutures

Locations the Sphenoidal fontanelle and Mastoid fontanelle? What are their junctions?

• Sphenoidal Fontanelles Junction: Squamous/coronal sutures

• Mastoid Fontanelles Junction: Lambdoid/squamous sutures

Where are the Coronal, frontal, sagittal, lambdoid sutures of the skull of infants?

Where are the Coronal, squamous, lambdoid sutures of the skull of infants?