Skeletal System

Axial SkeletonChapter 7

Divisions of the Skeletal System• The adult human skeleton consists of 206 named

bones.• Infants have more bones because not all bones have

fused.• Axial skeleton – 80 bones– Longitudinal axis (center of the body)– Bones arranged along the axis: skull bones, auditory

ossicles, hyoid bone, ribs, breastbone, and backbone• Appendicular skeleton – 126 bones– Upper and lower limbs (extremities), girdles (connect limbs

to axial skeleton)

Axial Skeleton• Skull– Cranium 8– Face 14

• Hyoid 1• Auditory Ossicles 6• Vertebral Column 26• Thorax– Sternum 1– Ribs 24

• Total 80

Appendicular Skeleton• Pectoral (Shoulder) girdles– Clavicle 2– Scapula 2

• Upper limbs (extremities)– Humerus 2– Ulna 2– Radius 2– Carpals 16– Metacarpals 10– Phalanges 28

Appendicular Skeleton• Pelvic (hip) girdle– Hip, pelvic, or coxal bones 2

• Lower limbs (extremities)– Femur 2– Fibula 2– Tibia 2– Patella 2– Tarsals 14– Metatarsals 10– Phalanges 28

• Total 126

Types of Bones

• Long Bones• Short Bones• Flat Bones• Irregular Bones• Sesamoid Bones• Sutural

Types of Bones Based on Shape

Bone Surface Markings

• Depressions and Openings– Sites allowing the passage of soft tissue (nerves,

blood vessels, ligaments, tendons) or formation of joints.

• Processes– Projections or outgrowths on bone that form

joints or attachment points for connective tissue, such as ligaments and tendons).

Depressions and Openings

• Fissure – narrow slit• Foramen – opening (hole)• Fossa – shallow depression (trench)• Sulcus – furrow (groove)• Meatus – tubelike opening (passageway)

Processes

• Processes that form joints– Condyle – Large, round protuberance at the end

of a bone (knuckle)– Facet – smooth, flat articular surface– Head – rounded articular projection supported on

the neck of a bone

Processes

• Processes that form attachment points– Crest – prominent ridge or elongated projection– Epicondyle – projection above a condyle– Line – long narrow ridge or border– Spinous process – sharp, slender projection– Trochanter – very large projection– Tubercle – small, rounded projection– Tuberosity – large, rounded projection

Mastoiditis

• Inflammation of the mastoid air cells subsequent to a middle ear infection.

• The infection may spread to the brain.

Cleft Palate and Cleft Lip

• Failure of the palatine processes of the maxillary bone to unite during embryogenesis.

• Cleft lip is a split in the upper lip.• Speech and swallowing may be affected.• Children with this may be prone to many

middle ear infections.

Temporomandibular Joint Syndrome

• TMJ• Dull pain around the ear• Tenderness of the jaw• A clicking or popping noise when opening or closing

the mouth• Limited or abnormal opening of the mouth• Headache• Tooth sensitivity

TMJ Treatment• Applying moist heat or ice• Chiropractic• Eating a soft diet• Pain relievers• Muscle retraining• Adjusting or reshaping the teeth• Orthodontic treatment• Surgery

Principle Foramina of the Skull

• Carotid • Hypoglossal • Infraorbital • Jugular • Lacerum • Magnum • Mandibular

Principle Foramina of the Skull• Mastoid• Mental• Olfactory• Optic• Ovale• Rotundum• Stylomastoid• Supraorbital

Fontanels

• Membrane-filles spaces between the cranial bones

• “soft spots”• Allow the skull to change shape as it passes

through the birth canal

Fontanels• Anterior fontanel– Between the parietal bones and the frontal bone

• Posterior fontanel– Between the parietal bones and the occipital bone

• Anterolateral fontanels– Between the frontal, parietal, temporal, and sphenoid

bones• Posterolateral fontanels– Between the parietal, occipital, and temporal bones

Medical Terminology

• Kyphosis – exaggeration of the thoracic curve• Lordosis – an exaggeration of the lumbar curve or

cervical curve• Lumbar spine stenosis – narrowing of the spinal

canal• Scoliosis – lateral bending of the vertebral column