Chapter 7AXIAL SKELETON

Skeletal SystemGROSS ANATOMY

OBJECTIVES• Distinguish between the axial and appendicular

skeletons and name the bones of each.• Explain the types of vertebra, the curvature of

the vertebra, and number them.• Explain the types of ribs and number them.• Explain the differences between the male and

female skeleton’s pelvic cavity.• Are their any additional variations in other

locations in the body?

WAY COOL WEBSITE • Body Online

• http://www.innerbody.com/image/skelfov.html

Anatomical Terms used for Bone Featurespage 1

• Terms– Body: main part– Head: enlarged end– Neck: constriction

between head and body– Margin or border: edge– Angle: bend– Ramus: branch off body– Condyle: smooth

rounded articular surface– Facet: small flattened

articular surface

• Projections– Process: prominent

projection– Tubercle: small

rounded bump– Tuberosity: knob– Trochanter:

tuberosities on proximal femur

– Epicondyle: near or above condyle

Anatomical Terms used for Bone Featurespage 2

• Ridges– Line or linea: low

ridge– Crest or crista:

prominent ridge– Spine: very high ridge

• Openings– Foramen: hole– Canal or meatus:

tunnel– Fissure: cleft– Sinus or labyrinth:

cavity

• Depressions– Fossa: general term

for a depression– Notch: depression in

bone margin– Fovea: little pit– Groove or sulcus:

deeper, narrow depression

General Information• There are 206 bones of the human

body.• The bones of the skeleton are divided

up into – AXIAL BONES– APPENDICULAR BONES

AXIAL SKELETONgeneral bones

• Skull• Auditory ossicles• Hyoid Bone• Vertebral Column• Rib Cage (thoracic cage)

80 bones

APPENDICULAR SKELETONgeneral bones

• Contains: – Pectoral Girdle– Upper Limb– Pelvic Girdle– Lower Limb

• Function: – Protects the Brain,

Spinal Cord & Vital Organs located in the Thorax

126 Total Bones

AXIAL SKELETONSKULL

Skull (aka: Cranium)• Neurocranium (Braincase)• Viscerocranium (Face)

Neurocranium• Parietal• Temporal• Frontal• Sphenoid• Occipital• Ethmoid

Parietal Bone

Lamboid Suture

Coronal Suture

Squamous Suture

Temporal Bone

Temporal Bone Landmarks

Mastoid Process

Styloid Process

Zygomatic Process

External Acoustic Meatus(ear canal)

Carotid Canal (Carotid Foramen)

Temporal Bone Landmarks

Temporal Bone Landmarks

9) Internal Acoustic Meatus

Frontal Bone & Landmarks

Supraorbital Margin

Sphenoid Bone & Landmarks

Resembles a bat or butterfly

Sella Turcica (houses pituitary)

Occipital Bone & Landmarks

Opening where brain & spinal cord connect

Foreman Magnum

Occipital Condyle

(articulation {meeting of

two bones} between the skull & 1st Vertebra)

Ethmoid Bone

Ethmoid Bone Landmarks

Inferior Nasal Concha

Middle Nasal Concha

Olfactory Foramina – holes in the Cribriform Plate

Fontanals

Closes during the

1st year

Closes at end of 2nd

year

VISEROCRANIUM

Viscerocranium (face)Bones of the Face

• Maxilla• Zygomatic – “cheekbone”• Palatine• Lacrimal• Nasal• Inferior Nasal Concha• Mandible• Vomer

Mandibular Condyle

Mandible Landmarks

Maxilla LandmarksPalatine Process

Incisive Foramen

Lacrimal Bone

Inferior Nasal Concha

Vomer

Hyoid BoneUnlike other bones, the hyoid does NOT

articulate with other bones.

Its name is derived from the Greek word hyoeides meaning

"shaped like the letter upsilon" (υ).

SINUSES• Frontal• Maxillary• Ethmoidal• Sphenoidal

Maxillary Sinus

Sphenoidal Sinus

Terms• Wormian Bones

– also known as extra sutural bones[1] are extra bone pieces that occur within a suture in the cranium. These are irregular isolated bones which appear in addition to the usual centers of ossification of the cranium and, although unusual, are not rare.

Terms• Foramen – hole• Condyle – smooth, rounded articular

surface• Articular – of or relating to joints• Process – prominent projection• Fossa – general term for a depression• Canal/Meatus – tunnel

THORACIC (rib) CAGE

Functions of the Vertebral Column• Supports weight• Protects the spinal cord• Allows spinal nerves to exit the spinal

cord• Provides site for muscle attachment• Permits movement of head & trunk

Vertebral Columngeneral information• Consists of 26 bones called “vertebrae”• Vertebrae can be divided into 5 regions:

– (C) Cervical vertebrae (7)– (T) Thoracic vertebrae (12)– (L) Lumbar vertebrae (5)– Sacral bone (1)– Coccygeal bone (1)

*hint to remember the numbers think of mealtimes (7, 12, and 5)

Developing embryo have about 33-34 vertebrae that fuse: 5 sacral fuse to form 1 bone

Counting Vertebrae• The vertebrae are designated by a letter

(C, T or L) with a number after the number.

• The number indicates the number of the vertebrae from superior to inferior within each region.

Curvature of the Vertebral Column• There are 4 major curvatures which

help accommodate our upright posture by aligning our body weight with our pelvis and lower limbs.– 2 curvatures appear during embryonic

development

Appear during embyronic

development

First Cervical Vertebrae• The first cervical (neck)

vertebra is called the atlas. It supports the head. – The atlas bone is

named for the Greek god Atlas who was condemned to support the earth and its heavens on his shoulders.

Second Cervical Vertebrae • The second cervical vertebra

is called the axis. It is so-named because the uppermost cervical vertebra (called the atlas) rotates about the odontoid process of the second cervical vertebra.

• The joint between the axis and atlas is a pivot type of joint. It allows the head turn.

• The Latin word "axis" means axle or pole.

• The axis bone serves as the axle about which the atlas (and the head) turn.

Dens (aka: Odontoid Process)

Transverse Foramen

Transverse Foramen – indicated by the BLUE ARROWS

Anatomy of Vertebrae• Body – weight

bearing portion• Arch – projects

posteriorly from the body

• Various Processes

SACRAL VERTEBRAE• Highly

modified• 5 vertebrae

are fused into a single bone called the SACRUM

POSTERIOR VIEW

SACRAL VERTEBRAE ANTERIOR VIEW

COCCYX”tailbone”

• Most inferior portion of the vertebral column and usually consists of 3-5 semi-fused vertebrae that form a triangle

• Easily broken

RIB CAGE (thoracic cage)

Functions of the RIB CAGE• Protects vital organs within the thorax• Forms a semi-rigid chamber that can

increase and decrease in volume during respiration

• Consists of:– 3 thoracic vertebrae– The ribs– Associated costal(rib) cartilages– Sternum

Ribs• There are 12 pairs of ribs

– True Ribs (vertebrosternal ribs)• Superior 7 Ribs• Articulate with the thoracic vertebrae and attach directly

to their costal cartilages to the sternum– False

• Inferior 5 pairs• Articulate with the thoracic vertebrae but DO NOT

ATTACH directly to the sternum.• Consist of 2 groups

– Vertebrochondral Ribs (8th, 9th, 10th ribs)» Joined by common cartilage to the 7th rib

– Floating Ribs (vertebral ribs) (11th & 12th ribs)» Do NOT attach to sternum

Each rib has two extremities, a posterior or vertebral, and an anterior or sternal, and an intervening portion—the

body or shaft.

STERNUM“breastbone”

• Sword Shaped• 3 Parts

– Manubrium– Body– Xiphoid Process

– Superior Margin of the manubrium has a JUGULAR NOTCH or suprasternal notch