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Biology 231
Human Anatomy and Physiology
Chapter 7 Lecture Outline
Divisions of the Skeletal System (total 206 bones)
Axial Skeleton (80 bones) – bones arranged around body’s longitudinal axis
Skull – cranium and facial bones
Spine (vertebral column)
Thoracic cage – breastbone and ribs
Hyoid and Auditory ossicles
Appendicular Skeleton (126 bones) – upper and lower limbs and bony girdles
(pelvis, shoulder blades, collar bone) that connect them with axial skeleton
Types of Bones – based on general shape
Long bones – greater length than width; mainly compact bone with spongy bone
in ends; levers for body motion
(thigh, leg, arm, forearm, hands and feet, fingers and toes)
Short bones – nearly equal length and width; spongy bone except at surface
(wrists and ankles)
Flat bones – 2 thin layers of compact bone enclosing spongy bone; enclose
structures providing protection and provide large surface area for
muscle attachment (cranium, breastbone and ribs, shoulder blades)
Irregular bones – don’t fit other categories; complex shapes and variable
composition (vertebrae, some facial bones)
Sesamoid bones (shaped like sesame seed) – develop in tendons where they
provide strength to areas of unusual mechanical stress; variable in
individuals (kneecaps are largest)
(Sutural bones – small bones which may occur within sutures between cranial
bones in some individuals)
Bone Surface Markings – develop in response to mechanical forces on bone surfaces
depressions and openings – result from compressive force; allow passage of soft
tissues, form joints
fissure – crack
foramen – hole
meatus – tunnel
fossa – pocket or cup
sulcus – groove
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processes – prominences on bones; result from tension (pulling)forces;
attachment points for tendons and ligaments, form joints
joints – condyle
facet
head
sites of attachment
line
crest
spinous process
tubercle
tuberosity
trochanter
epicondyle
Vertebral Column (spine) – 26 vertebrae in adult; strong, flexible rod that can flex and
extend in 2 planes and rotate around axis; encloses and protects spinal cord;
attachment site for head, ribs, pelvic girdle and back muscles
Divisions:
Cervical vertebrae (7) – neck
Thoracic vertebrae (12) – chest
Lumbar vertebrae (5) – lower back
Sacrum (5 fused vertebrae) – attachment site for pelvic girdle
Coccyx (4 fused vertebrae) – tailbone
Spinal curvature – primary curve seen in fetus
4 normal curves in adult:
thoracic curve – primary curve
sacral curve – primary curve
cervical curve – secondary to lifting head
lumbar curve – secondary to standing upright
abnormal curves:
kyphosis (humpback)
lordosis (swayback)
scoliosis – lateral curvature
Parts of Typical Vertebra
vertebral body – anterior portion; thick disc that bears weight; have
intervertebral discs between
vertebral arch – extends posteriorly from body and surrounds spinal cord
pedicles – form anterior margin of arch
laminae – form posterior margin of arch
vertebral foramen – contains spinal cord, connective tissue, and
blood vessels
vertebral canal – formed by all vertebral foramina
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intervertebral foramina – openings in vertebral canal between
2 adjoining vertebrae; allows passage of spinal nerves
processes – 7 total
transverse processes (2) – lateral; muscle attachment sites
spinous process (1) – posterior; muscle attachment site
superior and inferior articular processes (2 of each) – sites of
vertebral articulation; joint surfaces called facets
Intervertebral Discs (C2-sacrum) – cartilaginous discs between bodies of
vertebrae which absorb shock and can compress to allow flexion of
the vertebral column
annulus fibrosus – outer fibrocartilage ring
nucleus pulposus – inner soft, pulpy connective tissue
herniated (slipped) disc – annulus fibrosus ruptures and nucleus pulposus
herniates, compressing spinal nerve or cord; laminectomy relieves
pressure
Cervical vertebrae (C1-C7)
Atlas (C1) – supports head; ring of bone with large vertebral foramen;
articulates with occipital condyles of skull = nodding head
Axis (C2) – dens (odontoid process) makes pivot joint with atlas =
shaking head no; first intervertebral disc between C2-C3
C3-C7 – small body, large vertebral foramen, superior and inferior
articular facets; transverse foramina for vertebral nerves and
vessels; spinous processes often bifid (split in 2);
C7 (vertebra prominens) – large spinous process
Thoracic vertebrae (T1-T12) – large body with facets for articulation with rib
heads; long, flat spinous processes directed inferiorly; transverse
processes with facets for articulation with rib
superior and inferior articular facets
Lumbar vertebrae (L1-L5) – largest, thickest body; thick, rectangular spinous
processes; articular facets directed medially and laterally
Sacrum (S1-S5) – fuse by age 30
base – wide superior end; articulates with L5
apex – narrow inferior end; articulates with coccyx
transverse lines – fused bodies
median sacral crest – fused spinous processes
sacral canal – fused vertebral foramina
sacral foramina – nerves and vessels pass through
auricular surface – articulates with pelvis (sacroiliac joint)
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Coccyx (Co1-Co4) – fuse by age 30
coccygeal cornua – dorsal processes attached to sacrum by ligaments;
apex points inferiorly in females, anteriorly in males
Thoracic Cage – encloses and protects organs of thoracic and upper abdominal cavities;
supports shoulder girdle and upper limbs; includes bodies of thoracic vertebrae,
sternum, ribs and costal cartilages
Sternum (breastbone) – anterior midline
3 parts:
manubrium – superior part; articulates with collar bones and costal
cartilages of ribs 1 and 2
body – largest, middle part; articulates directly or indirectly with costal
cartilages of ribs 2-10
xiphoid process – inferior part; hyaline cartilage that doesn’t fully ossify
until about age 40; no ribs attached; attachment site for abdominal
muscles
CPR done improperly can fracture xiphoid and puncture organs
Ribs (12 pairs) – articulate with corresponding thoracic vertebrae
true ribs (1-7) – attach directly to sternum via costal cartilages
false ribs - don’t attach directly to sternum
8-10 attach to other costal cartilages
11 and 12 (floating ribs) no anterior attachment
Parts of Typical Rib:
head – posterior end; facets articulate with vertebral body
tubercle – articulates with transverse process
body – long, curved portion; has groove for nerve & vessels
intercostal spaces – spaces between ribs
SKULL – consists of 22 bones; forms several cavities; outer surfaces are attachment site
for muscles
cranium (braincase) – protects brain; inner surface is attachment site for
membranes (meninges)
facial bones – create cavities containing special sense organs (nasal cavity, eye
sockets, mouth); assist in intake of foods
CRANIUM – 8 bones; joined at sutures
Frontal bone – forehead, roof of orbits, anterior cranial floor
frontal squama
supraorbital foramen
frontal sinuses
Parietal bones (2) – sides and roof of cranium
sagittal suture
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Temporal bones (2) – lateral cranium and cranial floor
squamous portion
zygomatic process – part of zygomatic arch,
mandibular fossa of temporomandibular (TMJ) joint
external auditory meatus (ear canal)
mastoid portion - mastoiditis (inflammation of mastoid air cells)
mastoid process
styloid process
petrous portion – middle and inner ear
internal auditory meatus
Occipital bone – posterior cranium and cranial floor
foramen magnum – spinal cord passes through to brainstem
occipital condyles
external occipital protruberance – ligamentum nuchae
Sphenoid bone – central cranial floor; articulates with all cranial bones
sphenoid sinuses
sella turcica – hypophyseal fossa (pituitary)
greater wings – foramen ovale, foramen rotundum
lesser wings – optic foramen
Ethmoid bone – cranial floor and nasal cavity
lateral masses – ethmoid sinuses, superior and middle
superior and middle nasal conchae (turbinates) – circulate air
perpendicular plate – nasal septum
cribriform plate – olfactory foramina
crista galli
FACIAL BONES – 14 bones; grow until about age 16
Nasal bones (2) – bridge of nose
Maxillae (2) – upper jaw
maxillary sinus
alveolar margin(process) – alveoli(sockets) for teeth
palatine process – hard palate (cleft palate)
Zygomatic bones (2) – cheekbones, part of orbit
temporal process – part of zygomatic arch
Lacrimal bones (2) – medial orbits
lacrimal fossa – lacrimal sac (collects tears from eye)
Palatine bones (2) – posterioir hard palate
Inferior nasal conchae (2) – turbinates
Vomer – floor of nasal cavity, part of nasal septum
Mandible – lower jaw, only movable skull bone (auditory ossicles
excluded)
body – alveolar margin(process)
ramus (2) – angle
mandibular foramen and canal
coronoid process
mandibular condyle – TMJ joint
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Hyoid Bone – no bony articulation; suspended from styloid processes by ligaments and
muscles; U-shaped; site of attachment for muscles of tongue, pharynx, and neck;
supports tongue
body – anterior part
greater and lesser horns – project posteriorly
Auditory Ossicles – tiny bones of middle ear (3 in each); located in petrous portion of
temporal bone; to be discussed with special senses
SPECIAL FEATURES OF SKULL
Sutures – immovable joints between skull bones
coronal suture – between frontal and parietal bones
sagittal suture – between 2 parietal bones
lamboidal suture – between occipital and parietal bones
squamous sutures – between parietal and temporal bones
Fontanels – in infant; fibrous connective tissue membranes between cranial bones
not yet fully ossified; provide flexibility of skull
anterior fontanel – largest; between frontal and parietal bones; closes
18-24 months after birth
posterior fontanel
anterolateral fontanels
posterolateral fontanels
Paranasal sinuses – cavities in cranial and facial bones lined with mucous
membranes continuous with nasal cavity
(frontal, sphenoid, ethmoid, maxillary bones)
produce mucus; act as resonating chambers
sinusitis – inflammation of sinus membranes
Nasal septum – midsagittal division of nasal cavity
composed of vomer and ethmoid bones and septal cartilage
deviated septum – deflected laterally
Orbits – eye sockets
7 bones:
cranial – frontal, sphenoid, ethmoid
facial – palatine, zygomatic, lacrimal, maxillae
5 openings:
optic foramen, superior and inferior orbital fissures, supraorbital
foramen, lacrimal fossa
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