Chapter 8-The Skeletal System
8-1
Ch. 8 Study Guide
1. Critically read Chapter 8 pp. 242-267 before
section 8.4 (The pectoral girdle and upper limb)
2. Comprehend Terminology (those in bold in the
textbook) within the reading scope above
3. Study-- Figure questions, Think About It
questions, and Before You Go On (section-ending)
questions (within the reading scope above)
4. Do end-of-chapter questions—s
– Testing Your Recall— 1-6, 11-16
– True or False– #1 and #7
– Testing Your Comprehension--#1 and #3
8-2
I. Overview of the skeleton
8-3
§ Regions of the skeleton
1. axial skeleton = central axis
•
•
•
•
•
Skull-- Cranial bones + Facial bones
Auditory ossicles—
Hyoid bone-Vertebral column –
Thracic cage—ribs + sternum
2. appendicular skeleton
– upper limb + lower limb
– pectoral girdle? + pelvic girdle ?
Fig. 8.1
8-4
8-5
§ Number of bones
1. 206 in typical adult skeleton
2. start at 270 at birth, decreases with
fusion; Ex.—Os coxae, fused from the
ilium, ischium, and pubis
• 206--varies with development of
sesamoid bones-- that form within
tendons in response to stress; Ex.
Patella, knuckles
• Extra bones in some people– wormian
(sutural) bones
Fig. 8.6
8-6
8-7
II. Skull– A. Sutures and
major skull cavities
8-8
1.
2.
Name the
4th major
suture?
3.
8-9
§ The Skull
• 22 bones joined together by S________
• The skull (8 cranial bones) contains
several cavities (Fig. 8.7)
• Facial bones support teeth and form
nasal cavity and orbit
– 14 bones with no direct contact with brain
or meninges
– attachment of facial and jaw muscles
8-10
Major Skull Cavities
 Paranasal

sinuses (next)



 Middle- and
inner-ear cavities
8-11
Fig. 8.8--Paranasal sinuses
Functions of these sinuses—
1. Lighten the __________
2. Resonance to the voice
8-12
II. Skull– B. Eight cranial
bones
8-13
§ The Cranium (brain case)-A. 8 cranial bones– what are they? (Fig.
8.4)
B. Consists of 2 major parts– the calvaria
(skullcap) and the base
– Calvaria—forms the roof and walls
– Cranial base—(floor); (a separate
slide)
8-14
Calvaria--
3
2
1
Figure 8.4b
4
5
6
8-15
§ Cranial base and fossa, Fig. 8.9
A?
B?
• 3 basins that comprise the cranial floor or base
– anterior c. fossa holds the ___________ of the brain
– middle c. fossa holds the temporal lobes of the brain
– posterior c. fossa contains the _____________
• Swelling of the brain may force tissue through foramen
magnum (what passes here? Fig. x) resulting in death8-16
8-17
1. Frontal Bone
A. forms forehead
B. part of the roof of the
cranium
C. to __suture posteriorly
D. Markings on the right?
E. forms which fossa?
Anterior c. fossa
F. Forms roof of the
orbit.
G. Contains glabella,
frontal sinus (next
slide)
Which
sinus?
8-18
Supraorbital notch
8-19
2. Parietal Bones
A
B
Q
C
D
• Cranial roof and part
of its lateral walls
• Bordered by 4 sutures
(A-D); what are they?
• Parietal foramen (Q)
• Temporal lines of
Temporal lines
temporalis muscle
8-20
(Fig. 10.9)
8-21
3. Temporal Bones- 4 parts
• Lateral wall and part of
floor of cranial cavity
A
C
A. squamous part
• zygomatic process
• mandibular fossa
B. tympanic part
• external auditory
meatus
• styloid process (Fig. )
C. mastoid part
• mastoid process
• mastoid notch
– digastric muscle8-22
8-23
D. Petrous Part of Temporal Bones
• Part of cranial floor
– separates middle from
posterior cranial fossa
• Houses middle and inner
ear cavities
– internal auditory
meatus
= opening for CN VIII
(vestibulocochlear
nerve)
8-24
A
B= ? process
Openings in
Temporal Bone
• Carotid canal
– passage for internal
carotid artery
supplying the brain
• Jugular foramen
– between temporal
and occipital bones
– passageway for
internal jugular vein
Inferior view of base
of the skull
8-25
4. Occipital Bone
A. Foramen magnum
admits the spinal cord
B. Skull rests on atlas at
occipital condyle
C. Basilar part-D. Condylar canal– vein
passage
E. External occipital
protuberance– medial bump
F. Nuchal (back of the neck)
lines mark neck muscles
attachments
G. Hypoglossal canal (next
slide)
C
B A
8-26
Hypoglossal canal-transmits hypoglossal
nerve (CN XII)
8-27
Superior view
5. Sphenoid Bone--A
1. Lesser wing-2. Greater wing-3. Optic foramen-guarded by anterior
clinoid processes
4. Body (the sphenoid)– sella turcica contains
hypophyseal fossa
– houses pituitary gland
Superior view
8-28
Sphenoid bone-- B
Several foramina in greater wing:
1. foramen rotundum & ovale for
two branches of trigeminal nerve (V.)
2. foramen spinosum for a
meningeal artery
8-29
Sphenoid Bone-- C
• Body of sphenoid (also see next slide)
• Medial and lateral pterygoid plates
• Medial and lateral pterygoid processes
(narrower extensions)—attachment for the
jaw muscles
8-30
Sphenoid Bone-- D
• Sphenoid
sinus–
• within the
body of the
sphenoid
bone
8-31
6. Ethmoid bone—A (location)
8-32
Ethmoid Bone-- B
Location-• Between the nasal and
sphenoid bones
• Between the orbital
cavities (medial wall)
• Lateral walls and roof of
nasal cavity
8-33
Ethmoid Bone– C; three parts:
1. Superior surface
(Cribriform plate):
• Crista galli (a triangular
process from midline of the
cribriform plate)
• Cribriform foramina–
holes; olfactory bulbs rest in
these depressions
Anterior view • See the olfactory nerve in
the next slide
8-34
Fig. 14.28—
olfactory nerve
8-35
Ethmoid Bone-- D
2.Perpendicular plate:
• forms superior part of nasal
septum; dividing the nasal
cavity into 2 halves
3
3. Labyrinth: includes
2
• Ethmoidal (air) cells form
ethmoid sinuses
• Nasal concha (turbinates)
on lateral wall (superior and
middle ones, respectively)
• Fig. 8.13
8-36
Ethmoid Bone-- E
• Superior and middle
concha
• Perpendicular plate of
nasal septum
8-37
II. Skull– C. 14 facial bones
8-38
§ Facial bones (14 all together)
Unpaired:
Palatine bones
(next slide)
8-39
8-40
1. Maxillae– keystone bones of
the facial skeleton
A. Forms upper jaw
– alveolar processes are bony
points between teeth
– alveolar sockets hold teeth
B. Forms inferomedial wall of orbit
– infraorbital foramen
C. Palatine processes form
anterior 2/3’s
of hard palate
– incisive foramen (behind incisors)
– cleft palate (if _____ fail to join)
8-41
2. Palatine Bones
A. L-shaped bone
B. Posterior 1/3 of the
hard palate
C. Part of lateral nasal
wall
D. Small part of the
orbital floor
8-42
3. Zygomatic Bones (inverted
T shape)
A. Forms angles of the
cheekbones and
part of lateral orbital
wall
B. Zygomatic arch is
formed by temporal
process of
zygomatic bone and
zygomatic process
of temporal bone
C. Zygomaticofacial
foramen —nerve
passages
8-43
4. Lacrimal Bones
A. Form part of
medial wall of
each orbit
B. Lacrimal fossa
houses lacrimal
sac in life
– tears collect in
lacrimal sac and
drain into nasal
cavity
8-44
5. Nasal Bones
A. Form the bridge
of nose
B. Attach to the
cartilages (lower
portion) of nose
(next slide)
C. Often fractured
by blow to the
nose
8-45
8-46
6. Inferior Nasal Conchae
A. Two separate
bones to from
largest conchae in
nasal cavity
B. Not part of ethmoid
(the superior and
middle conchae or
turbinates)
C. Together there are 3
conchae in the nasal
cavity
8-47
7. Vomer (unpaired)
A. Forms inferior half
of the nasal
septum, the
deviding wall of
the nasal cavity
B. Supports cartilage
of nasal septum
8-48
8. Mandible (unpaired)
A. Only movable bone of the skull
– jaw joint between mandibular fossa (?)
and mandibular condyles
B. Holds the lower teeth
C. Attachment of muscles of chewing
– temporalis muscle to coronoid process
– masseter muscle onto angle of mandible
D. Mandibular foramen
E. Mental foramen
(blood vessels
& nerves of the chin)
8-49
8-50
II. Skull– D. Bones
associated with the skull;
E. the fetal skull
7-51
§ Bones Associated With Skull
A. Auditory ossicles
– malleus, incus, and
stapes (Fig. x2)
B. Hyoid bone
– suspended from
styloid process of
skull by muscle and
ligament
– greater and lesser
cornua
8-52
Internal anatomy of the ear
§ Anterior, posterior, sphenoid,
A
and mastoid fontanels
B
C
D
• Spaces between unfused
bones called fontanels (4)
– filled with fibrous membrane
– allow shifting of bones during
birth and growth of brain
• 2 frontal bones fuse by age
six (called metopic/frontal
suture)
• Skull reaches adult size by 8
or 9
8-55