Chapter 7

The Adult Skeleton

- 206 bones - Axial skeleton 80 bones - Appendicular 126 bones

Dens

- in C2 -is inside the vertebral foramen of the atlas(C1) -forms a pivot for head to move side to side (no )

Vertebral curvature

-Curves increase the strength and maintain balance -curves absorb shock & prevent fracture Cervical--convex---lordosis thoracic--concave--kyphosis Lumbar--convex--lordosis Sacral--concave--kyphosis

Vertebral column

-aka spine/backbone cervical (7) thoracic (12) lumbar (5) fused sacral (5 fused) fused coccyx (3-4)

Ethmoid bone

-anterior to sphenoid and posterior to the nasal bones -major superior supporting structure of nasal cavity BONE FEATURES: -perpendicular plate -cribiform plate -crista galli -superior and middle nasal cavity

moveable bones

-auditory ossicles (help w/ sound) -occipital bone (articulates with the 1st vertebrae (atlas)) -mandible (chew)

Sphenoid Bone

-called "keystone" of cranial bones -provides stability to the skull -looks like a butterfly BONE FEATURES: -sella turcica (houses the pituitary gland) -optic canal -superior orbital fissure -foramen rotundum -foramen ovale -foramen spinosum (ROS foramens)

Paranasal sinuses

-cavities within the frontal, sphenoid, ethmoid bones, and maxilla FUNCTION: -lightens the skulls mass (skull grow in in size during development but doesn't get heavier ) -plays a role in resonance. serves as resonance chamber to intensify & prolong sounds. when sick the chambers fill with mucous and dampen sound -absent at birth -increases in size during eruption of teeth and onset of puberty -lined with mucous membrane that secretes mucous into the lateral wall of the nasal cavity and causes pressure (sinus headache/cold)

intervertebral foramen

-due to the intervertebral disks -Allows passage of spinal nerves and vessels. -in all vertebrae from Cervical to Last Lumbar

intervertebral discs

-fibrocartilage pads that separate and cushion the vertebrae -start at C-2, between C-2 and C-3 -nucleus pulposis inside the annulus converts into fibrocartilage as it dehydrated with age (why you shrink with age)

Nasal septum

-formed superiorly by the perpendicular plate of the ethmoid and inferiorly by the vomer bone CLINICAL CONNECTION: -a deviated nasal septum constricts passageway of nasal cavity (makes it hard to breathe)

Fontanels at birth

-found in developing embryos -consist of cartilage and mesenchyme -aka soft spots -eventually replaced with bone via intramembranous ossification -thin collagenous connective tissue turns into the sutures FUNCTION: -allows skull to change shape when passing through birth canal permits rapid growth of brain during infancy

5 openings associated with the orbit (details of the orbit)

-optic canal -superior orbital fissure -inferior orbital fissure -supraorbital foramen -lacrimal fossa

palatine bones

-paired L-shaped bones that form the: -posterior edge of the hard palate -portions of nasal cavity wall and floor -portions of eye socket

zygomatic bone

-paired bones known as cheekbones FORM: -prominences of cheeks -part of lateral floor and wall of each orbit ARTICULATES WITH: -frontal -maxilla -sphenoid -temporal BONE FEATURE: -temporal process

lacrimal bones

-paired bones that form the anterior portion of the medial wall of the eye socket -smallest bone of the face -contains the lacrimal fossa -w/ the maxilla. houses the lacrimal sac that houses tears

inferior nasal conchae

-paired scroll-like shape -help to swirl and filter air before it passes into lungs -NOT part of the ethmoid bone

vertebrosternal ribs

-ribs 1-7 -true ribs bc... -has its own cartilage -starts at vertebrae and ends at sternum

vertebral ribs

-ribs 11-12 -floating ribs bc... -no sternal attachment -starts at vertebrae and doesn't end anywhere

vertebrochondral ribs

-ribs 8-10 -false ribs bc... -cartilage of 8-10 merges with cartilage of #7. -does not have its own cartilage that reaches the sternum -starts at vertebrae and ends at cartilage

Sacrum and coccyx

-tailbone -5 fused vertebrae HAS: -ala -articular facet -foramen -canal -hiatus -fused spinous process = SACRAL CREST

hyoid bone

-unpaired bone of the axial skeleton -does not articulate with any other bone -suspended by ligaments and muscles that come from the styloid process & attach to the hyoid bone

Vomer bone

-unpaired triangular shaped bone -forms inferior portion of nasal septum articulates : -superiorly with the perpendicular plate of the ethmoid and sphenoid -inferiorly with the maxillae and palatine

Mandible

-unpaired, arch-shaped lower jawbone -largest and strongest facial bone -only movable skull bone BONE FEATURES: -mandibular condyle -mental foramen -mandibular foramen -alveolar part (porous part for teeth)

Vertebrae typically consist of:

-vertebral body -vertebral arch -processes -intervertebral disk

Functions of cranial bones

1) brain protection 2) stabilization -Inner surfaces attach to meninges (membrane that covers the brain) 3) Muscle attachment -outer surfaces -move the head -facial expressions 4) provide protection and support -digestive and respiratory systems (entrances to these) -special senses organs (eyes, nose, mouth, ears) 5) Auditory ossicles -help amplify sound waves -Inner ear (monitor position and movement of head) (balance)

Bones that form the orbit

3 cranial bones -frontal bone -sphenoid bone -ethmoid bone 4 facial bones -palatine bone -zygomatic bone -maxilla -lacrimal bone

sutures

Areas where the cranial bones have joined together -immovable joints coronal sagittal lambdoid squamous

Head of ribs

Articulates with: -superior and inferior costal facets of the thoracic vertebrae HAS: superior and inferior facets

appendicular skeleton

Bones of the limbs and limb girdles that are attached to the axial skeleton appendicular = think of appendages

typical cervical vertebrae

C3-C7 -smallest bodies(when compared) -largest vertebral foramen (when compared) -all have superior articular facet -inferior articular facet -transverse foramen in transverse process -bifid spinous process -intervertebral foramen

Typical vertebrae

Contain: -spinous process -vertebral foramen (where spinal column passes through) -vertebral body/centrum -transverse process -facet of superior articular process

The skull

Cranial bones and facial bones

Lumbar vertebrae

DOES NOT HAVE: -transverse foramen (cervical) -costal facets (thoracic) HAS: -superior and inferior articular process and facets -spinous process -intervertebral foramen -largest body/centrum -smallest vertebral foramen

Frontal bone

FORM: -forehead -eye socket (superior part) -forms much of the anterior part of the cranial floor

parietal bones

FORM: form much of the sides and roof of the cranial cavity BONE FEATURES: external surfaces are convex

Temporal Bones

FORM: the inferior lateral part of the cranial floor plus the lateral wall near the ear BONE FEATURES: -zygomatic process -mandibular fossa -mastoid process -carotid canal -styloid process -external and internal acoustic meatus

Occipital Bone

FORMS: -forms much of the posterior wall and posterior floor of the cranial cavity BONE FEATURES: -foramen magnum -occipital condyles -hypoglossal canal (underneath the occipital condyles) -jugular foramen

Sternum

Manubrium (articulates with clavicle) Body (articulates with the cartilage that articulates with the ribs Xiphoid process (bottom)

Thoracic vertebrae

ONLY ONE THAT HAS: -costal facets HAS: superior and inferior costal facets -superior and inferior articular facets -spinous process -vertebral foramen/ intervertebral foramen (spinal nerves pass through)

Bones of the skull

Small cavities paranasal sinuses middle and inner ear (temporal bone)

unique features of the skull

Sutures, Paranasal sinuses, Fontanels

Cervical Vertebrae surface features

Vertebral foramina Transverse foramen Bifid Atlas C1 Axis C2

scoliosis

abnormal lateral curvature of the spine

Rib tubercle

articulates with the transverse costal facets of the thoracic vertebrae

Cervical cuvature

baby starts to hold head up

hyperlordosis

exaggerated anterior lumbar curvature (---->)

Hyperkyphosis

extreme curve of thoracic region thoracic region curves too much posteriorly (<----)

Atlas C1

first cervical vertebrae -largest vertebral foramen -NO spinous process -NO vertebral body HAS: superior articular facet -articulates with the occipital condyle (nodding head/moving up and down) transverse foramen -blood vessels to brain

cranial bones

frontal (flat) Occipital (flat) sphenoid bone (irregular) ethmoid bone (pneumatized) parietal (flat) temporal (irregular)

Coronal suture of the skull

frontal and parietal

Structure of ribs

head (capitulum) neck tubercle shaft

Cavities

house the brain smaller cavities: -nasal and orbits

unpaired bones

mandible vomer ethmoid bone sphenoid bone occipital bone frontal bone

lambdoid suture of the skull

occipital and parietal

Maxillae bone

paired bone that unites to form the upper jawbone -articulates with every bone of the face except the mandible FORMS: -lateral walls and floor of the nasal cavity -floor of orbits -most of hard palate BONE FEATURES: -infraorbital foramen -alveolar part (porous part where teeth are inserted

nasal bones

paired bones that form the bridge of the nose -provide attachment for facial expression muscles -small, flattened, rectangular shape

paired bones

parietal inferior nasal conchae maxilla zygomatic palantine temporal nasal bone lacrimal

squamous suture of the skull

parietal and temporal

crista galli

part of ethmoid bone that extends superiorly into the cranium

thoracic cage

ribs sternum

sagittal suture of the skull

right and left parietal

Clinical connection of vertebral curvature

scoliosis hyperkyphosis hyperlordosis spina bifida herniated disk

Axis C2

second cervical vertebrae HAS: -Dens -inferior articular process and facet -spinous process -superior articular facet -transverse foramen (in the transverse process)

Thorax

skeletal part of the thorax is the thoracic cage

Axial skeleton

skull, vertebral column, and sternum skull to sacrum

Facial bones

vomer inferior nasal conchae maxilla mandible zygomatic bone palatine bone nasal bone lacrimal bone

lumbar curvature

when baby sits up/walks