Post on 23-Feb-2016
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SKELETAL SYSTEMPART 2THE AXIAL SKELETON
Honors Anatomy & Physiology
Essential Question What is the main contribution the
axial skeleton makes to homeostasis?
Divisions of the Skeleton AXIAL
SKELETON Skull
Cranium Face
Hyoid Auditory
Ossicles Vertebral
Column Thorax
APPENDICULAR SKELETON:
Pectoral Girdle Upper Limbs Pelvic Girdle Lower Limbs
Types of Bone bones fall into 1 of 5 main types
based on shape: Long Short Flat Irregular Sesamoid
Long Bones longer than they are wide may be slightly curved (to absorb
stress of weight at more points along the bone i.e. straight bones would fracture more easily)
consist of: shaft & variable #s of ends compact bone in diaphysis and spongy
bone in epiphysis
Long Bones
Short Bones somewhat cube-shaped nearly equal in length as width consist of:
spongy bone except @ surface
Short Bones
Flat Bones Composed of:
2 nearly parallel plates of compact bone enclosing spongy bone inside
Function: give considerable protection place for muscle attachment
Flat Bones
Irregular Bones complex shapes (do not fit in other
categories) vary in amt spongy bone
Sesamoid Bones develop w/in certain tendons where
there is considerable friction, tension, & physical stress
function: protect tendon from excessive wear & tear
vary in # person to person but everyone has 2 patella which develop in quadriceps femoris tendon
Sesamoid Bone
Sutural Bones classified by location (w/in a suture:
a seam between 2 cranial bones) not everyone has them
Bone Surface Markings 2 major types:1. depressions & openings
form joints or allow passage of vessels & nerves
2. processes projections or outgrowths that either
help form joints or serve as attachment points for ligaments & tendons
Bone Surface Markings
Bone Surface Markings-2
Axial skeleton
SKULL
Skull 22 bones in 2 categories:1. Cranium
8 bones that form cranial cavity1. 1 frontal bone2. 2 parietal bones3. 2 temporal bones4. 1 occipital bone5. 1 sphenoid bone6. 1 ethmoid bone
Skull 2. Facial Bones
14 bones that form the face 2 nasal bones
2 maxillae 1 mandible 2 zygomatic 2 lacrimal 2 palantine 2 inferior nasal conchae 1 vomer
Skull: Cavities1. Cranial Cavity2. Nasal Cavity3. Orbits4. Paranasal Sinuses5. Middle & Inner Ear Cavities
Cavities of the Skull
Movable Joints of the Skull1. Mandible2. Auditory Ossicles
Functions of Cranial Bones1. protecting brain2. stabilizing position of brain,
vessels, & nerves through attachments to the meninges
3. outer surfaces provide large areas of attachment for muscles that move parts of the head & some for facial expression
Cranial Bones: Frontal Bone forms:
forehead upper part of eye socket most of anterior part of cranial floor in newborns: rt & lt which fuse
shortly after birth
Frontal Bone
Parietal Bones form greater portion of sides & roof
of cranial cavity
Temporal Bones form inferior, lateral aspects of the
cranium & part of the cranial floor its zygomatic process forms the
lateral half of the zygomatic arch mandibular fossa: where condylar
process of mandible forms TMJ (temporal mandibular joint)
Temporal Bones
Temporal Bones external auditory meatus: ear canal mastoid: posterior & inferior to
external auditory meatus, contains “air cells” (mastoiditis: inflammation in air cells)
Temporal Bone: Petrous Portion
base of skull between sphenoid & occipital bones
houses middle & inner ear Carotid foramen & Jugular foramen
Temporal Bones internal auditory meatus: passage
of Cranial nerves VII (facial n.) and VIII (vestibulocochlear n.)
styloid process: point of attachment for muscles & ligaments of the tongue & neck
Temporal Bone: Internal Surface
Occipital Bone forms back of head & most of base
of skull foramen magnum: large hole spinal
cord passes thru, occipital condyles: articulate with
1st cervical vertebra (atlas)
Occipital Bone
Sphenoid Bone middle base of skull *articulates with all other cranial
bones shape resembles a bat
Sphenoid Bone sella turcica: (Turkish saddle) the
“seat” of the saddle is the hypophyseal fossa: where the pituitary gland sits
optic foramen: between body & lesser wings, cranial nerve II (optic n.) and opthlamic artery pass thru
Sphenoid Bone
Ethmoid Bone “like a sieve” midline of anterior part of cranial
floor, anterior to sphenoid, posterior to nasal bones
cribiforme plate: forms roof of nasal cavity, the holes of the sieve where olfactory nerves pass from roof of nasal cavity to brain
crista galla: triangular process which serves as pt of attachment for meninges of brain
Ethmoid Bone perpendicular plate: forms superior
portion of nasal cavity superior & middle nasal conchae: (or
turbinate) increase vascular & mucous membrane surface area in nasal cavities: aids in sense of smell, warms, filters & moistens air being inhaled. Filters because the turbinates cause air to swirl as a result inhaled particles strike & become trapped in mucus
“Sometimes when you study anatomy, you start seeing others differently.”
Facial Bones shape of face changes dramatically
during 1st 2 yrs of life: brain & cranial bones expand 1st set of teeth erupt paranasal sinuses enlarge growth of face stops ~16 years old
Facial Bones 14 facial bones:1. 2 nasal bones2. 2 maxillae3. 2 zygomatic bones4. 1 mandible5. 2 lacrimal bones6. 2 palatine bones 7. 2 inferior nasal conchae8. 1 vomer
Nasal Bones form part of the bridge of the nose
(rest is cartilage)
Maxillae = upper jaws *articulate with every bone in face
except the mandible form part of floor of orbits, parts of
nasal cavity, & most of the hard palate (bony roof of mouth)
each one has large maxillary sinus alveolar process is small arch that
contains the alveolar sockets for upper set of teeth
Cleft Palate & Cleft Lip 10-12 wks gestation the palatine
processes of maxillae typically join not doing so cleft palate +/- cleft
lip speech & swallowing can be affected many ear infections reparative surgery recommended 1st
few wks of life / surgery needs to be completed by 12 – 18 mos b/4 speech: speech therapy & orthodontic care frequently necessary
Zygomatic Bones “cheekbones”:
the temporal process of the zygomatic bone articulates with the zygomatic process of the temporal bone
also part of floor of orbit
Lacrimal Bones thin, about the size of pinky
fingernail (smallest bones of face part of medial wall of each orbit each contain lacrimal fossa that
houses lacrimal sac: gathers tears nasal cavity
Inferior Nasal Conchae inferior to the middle nasal conchae
of the ethmoid bone forming part of lateral wall of nasal cavity
same function as superior & middle conchae: swirling inhaled air to deposit particulates but not involved in sense of smell
Vomer Δ shaped bone on the floor of nasal
cavity forming inferior portion of nasal septum
Mandible largest & strongest facial bone
(lower jaw) alveolar processes hold lower teeth
sockets mental foramen: dentist numb
mental nerve
Sutures an immovable joint in an adult
found only between skull bones & holds most skull bones together
name generally reflects bones they unite
Sutures
Hyoid Bone “U-shaped “ *does not articulate with any other
bone in skeleton suspended by ligaments from
styloid process of temporal bone in anterior neck between mandible
& larynx function: supports tongue *frequently fractured during
strangulation
Hyoid Bone
Vertebral Column aka spine, backbone 2/5 of person’s height 26 in adult (starts as 33, some fuse
to form sacrum & coccyx) 7 cervical 12 thoracic 5 lumbar 1 sacrum 1 coccyx
Vertebral Column Fetus has
anteriorly concave curve
3 mos old when holds head cervical curve develops
lumbar curve develops as infant sits up, stands, walks
Intervertebral Discs between bodies of consecutive
vertebra under compression they flatten &
broaden harden, less elastic w/aging & narrow
loss of height annulus fibrosus: outer fibrous ring nucleus pulposus: inner soft, highly
elastic
Intervertebral Discs
Parts of a Vertebra Body
thicker, anterior portion, weight bearing portion
Vertebral Foramina contains spinal cord, adipose, areolar CT,
blood vessels Spinous Process
1 of 7 processes, posterior, palpable on back of body
Transverse Processes: on each side, extending laterally
Vertebrae: 1st & 2nd Cervical Atlas
ring-shaped articulates with
condyles of occipital bone
allows you to nod head “yes”
Axis 2nd cervical v. allows you to
shake head “no”
Typical Cervical Vertebrae
C-3 to C7 smaller than
other v. except coccyx but vertebral foramen largest
all cervical v. have extra foramen: 2 transverse foramen for vertebral a., v., & n.
Typical Thoracic Vertebrae T-1 to T-12 larger &
stronger than cervical v.
distinguishing feature: articulate with ribs (facets on transverse processes of T-1 to T-10
Typical Lumbar Vertebrae
L-1 to L-5 largest &
strongest of the vertebrae
processes are short & thick
Sacrum triangular bone
formed by union of S-1 to S-5
fusion begins ~16, complete by age 30
female: shorter, wider, more curved S-2 to S-3
Coccyx small triangle formed by
fusion of 4 coccygeal v. (Co-1 to Co-4), start between 20 & 30
females points inferiorly; males it points anteriorly
Thorax refers to entire chest skeletal part of thorax is thoracic
cage Sternum Ribs
Sternum aka “breastbone” flat bone in center of anterior
thorax 3 bones that fuse by age 25
Sternum1. Manubrium superior portion suprasternal notch clavicular notches articulates with
costal cartilage of 1st & 2nd rib
sternal angle: where it articulates with body
Sternum2. Body middle &
largest portion articulates with
costal cartilage of 2nd thru 10 ribs
Sternum 3. Xiphoid
Process cartilagenous in
infancy not completely
ossified until ~age 40
avoid it during CPR
Ribs: 12 Pair
increase in length 1st thru 7th then decrease in length to 12th
1st thru 7th ribs (true ribs) have direct anterior attachment to sternum by strip of hyaline cartilage which contribute to elasticity of thoracic cage
8th thru 10th ribs attach to each other & then to cartilages of 7th rib
11th & 12th ribs: floating ribs
Ribs all 12 attach posteriorly to
vertebrae Parts of a Rib1. Head2. Neck3. Tubercle 4. Body 5. Costal Angle
Abnormal Curvatures of Spine Scoliosis lateral bending usually in
thoracic region
Abnormal Curvature of Spine
Kyphosis exaggeration of
the thoracic curve
seen in TB of spine, congenital malformation, elderly
Kyphoscoliosis
THAT’S ALL FOLKS