Name the 3 regions of the axial skeleton
skull vertebral column thoracic cage
what does the cranial bone consist of?
frontal bone, (2) parietal bone, occipital bone, (2) temporal bones,
sphenoid bone and ethmoid bone
Describe the Frontal bone
anterior portion of the cranium most of anterior
cranial fossa superior walls of orbits contains
air-filled frontal sinus
Describe Parietal Bones and major associate sutures
superior and lateral aspect of cranial vault
4 sutures mark the articulations of parietal bones w/frontal,
occipital, and temporal bones:
Coronal suture- btw parietal bones and frontal bone
sagittal suture- btw right and left parietal bones
lambdoid suture- btw parietal bones and occipital bone
squamous (squamosal) sutures- btw parietal and temporal bones on
each side of skull
Describe Occipital bone
most of skull's posterior wall and posterior cranial fossa
articulates w/1st vertebrae sites of attachment for the
ligamentum nuchae and many neck and back muscles
Temporal Bone
paired inferolateral aspects of skull and parts of
cranial floor 4 major regions- 1. squamous 2. tympanic 3.
mastoid 4. petrous
Sphenoid Bone
complex, bat-shaped bone keystone bone- articulates
w/all other cranial bones 3 pairs of processes- greater
wings, lesser wings, and pterygoid processes
Ethmoid Bone
deepest skull bone superior part of nasal septum, roof
of nasal cavities contributes to medial wall or orbits
(eyes)
Sutural Bones
thin irregularly shaped bones that appear within sutures
What are the Facial Bones
mandible, (2- maxillae) maxillary bones, (2) Zygomatic bones,
(2) nasal bones, (2) lacrimal bones, (2) palatine bones, vomer, and
(2) inferior nasal conchae.
Mandible
lower jaw largest, strongest bone of the face
temporomandibular joint; only freely movable joint in skull
Articulated w/zygomatic bones
Zygomatic Bones
cheekbones inferolateral margins of orbits
articulates w/lower part of the frontal and
orbitals
Maxillary bones
medially fused to form upper jaw and central portion of facial
skeleton keystone bones articulate with all other
facial bones except mandible
Nasal and Lacrimal Bones
nasal bnes- form bridge of nose
Lacrimal bones
In medical walls of orbits lacrimal fossa houses
lacrimal sac
Palatine and Vomer Bones
Palatine Bones
posterior 1/3 of hard plate posterolateral walls
of the nasal cavity small portion of the orbits
Vomer
plow shaped lower part of nasal septum
Inferior Nasal conchae
form part of lateral walls of nasal cavity
Orbits
eyes encase eyes and lacrimal glands sites of
attached for eye muscles formed by part of 7 bones
Paranasal sinuses
mucosa-lines, air filled spaces lighten the skill
enhance resonance of voice
Hyoid Bone
not a bone of the skull
does not articulate directly with another bone
site of attachment for muscles of swallowing and speech
Vertebral Column
transmits weight of trunk to lower limbs surrounds and
protects spinal cord flexible curved structure containing
26 irregular bones
Cervical vertebrae (7)- neck Thoracic (12)
thoracic cage Lumbar (5)- lower back Sacrum- bone
inferior to the lumbar vertebrae Coccyx- terminus of
vertebrae column (4 or 5)
Scoliosis
abnormal lateral curve
Kyphosis
hunchback
Lordosis
swayback
Intervertebral discs are composed of 2 cushionlike pads.
Nucleus pulposus- inner gelatinous nucleus that gives the disc
its elasticity and compressibility Anulus fibrous- outer
collar composed of collagen and fibrocartilage
General structure of the 7 processes per vertebrae
Spinal process- projects posteriorly Transverse
processes (2)- project laterally Superior articular
processes (2)- protrude superiorly inferiorly Inferior
articular processes (2)- protrude inferiorly
Describe Atlas (C1)
no body or spinous process consists of anterior and
posterior arches, and 2 lateral masses superior surfaces of
lateral masses articulate w/the occipital condyles
Describe Axis (C2)
Dens projects superiorly into the anterior arch of the
atlas Dens is a pivot for the rotation of the atlas
Thoracic vertebrae
T1 to T12
all articulate w/ribs at facets and demifacets
long spinous process
location of articular facets allows rotation of this area of
spine
Lumbar Vertebrae
L1 to L5 short, thick pedicles
and laminae flat hatchet-shaped spinous processes
orientation of articular facets locks lumbar vertebrae together
so as to prevent rotation
Sacrum
5 fused vertebrae (S1 to S5)
forms posterior walls of pelvis
Articulates with L5 superiorly, and with
auricular surfaces
Coccyx
tailbone 3-5 fused vertebrae
Articulates superiorly with sacrum
Thoracic Cage
composed of thoracic vertebrae (posteriorlly) sternum
(anteriorlly) ribs and their costal cartilages
(laterally)
What are the functions of the thoracic cage?
protects vital organs of thoracic cavity supports
shoulder girdle and upper limbs provides attachment sites
for many muscles, including intercostal muscles used during
breathing
Sternum
aka breastbone
articulates with costal cartilages
Name the 3 fused bones and their articulations
Manubrium- articulates w/clavicle and ribs 1 & 2
Body- articulates w/costal cartilages of ribs 2 through 7
Xiphoid process- site of muscle attachment. Not ossified until
~age 40
Ribs and their attachments
12 pairs
all attach posteriorly to thoracic vertebrae
pairs 1-7- true (vertebrosternal) ribs
1-7 attach directly to the sternum by individual costal
cartilages
pairs 8-10 also called vertebrochondral ribs.
attach indirectly to sternum by joining costal cartilage of
rib above
Pairs 11-12 are also called vertebral (floating) ribs
no attachment to sternum
Appendicular skeleton
bones of the limbs and their girdles
pectoral girdle attaches the upper limb to the body
trunk pelvic girdle secures the lower limbs
Pectoral girdle
aka shoulder girdle
inferior to clavicle and posterior to scapulae
attach the upper limbs to the axial skeleton provide
attachment sites for muscles that move the upper limbs
Clavicle
aka collarbone
flattened acromial (lateral) end articulates w/scapula
cone-shaped sternal (medial) end articulates w/sternum
acts as braces to hold the scapulae and arms out laterally
Scapula (shoulder blades)
situated on the dorsal surface of rib cage, btw 2 and 7
flat and triangular, with 3 borders and 3 angles 7
large fossae posteriorly it is not articulated w/the rib
cage but with muscle (this allows the arm to move up and down)
Arm
aka Humerus
longest bond of upper limb
articulates superiorly w/glenoid cavity of
scapula
articulates inferiorly w/radius and ulna
Ulna
medial bone in forearm. forms the major portion o the
elbow with the humerus proximally articulates w/humerus,
distally w/carpal
Radius
lateral bone in forearm head articulates w/capitulum
of humerus and w/radial notch of ulna interosseous membrane
connects the radius and ulna along their entire length
Pelvic (Hip) girdle
2 hip bones (each called coxal bone or os coxae)
attach the lower limbs to the axial skeleton w/stronger
ligaments transmit weight of upper body to lower limbs
support pelvic organs
Each hip bone consists of 3 fused bones
ilium (superior) ischium (posteroinferior)
pubis (anterior, form pubic symphysis)
together with the sacrum and the coccyx, these bones form the bony pelvis
Female pelvis
adapted to childbearing (fibrocartilage)
true pelvis (inferior to pelvi brim) defines birth canal
cavity of the true pelvis is broad, shallow and has greater capacity (wider)
Male pelvis
tilted less forward
adapted for support for heavier build and stronger muscles
cavity of true pelvis (narrow but deep)
What are the 3 segments of the lower limb?
Thigh: femur
Leg- tibia and fibula
Foot- 2 tarsals in the ankle, 5 metatarsals an 14 phalanges
Femur
largest and strongest bone in the body
articulates proximally with the acetabulum of hip and distally
with the tibia and patella
Tibia
medial leg bone
receives the weight of the body from the femur and transmits it to
the foot
Fibula
not weight bearing; no articulation with femur
site of muscle attachment
connected to tibia by interosseous membrane
articulates with tibia via proximal and distal tibiofibular joints
Calcaneous
heal of the foot bone
3 arches of the foot
lateral longitudinal medial longitudinal
transverse
Fontanelles
at birth, skull bones are connected to this.
unossified remnants of fibrous membranes between fetal skull bones
anterior, posterior, mastoid and sphenoid