Transcript The+Axial+Skeleton

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Forms the longitudinal axis of the body
Divided into three parts
◦ Skull- protects the brain
◦ Vertebral column – protects the spinal column
◦ Bony thorax-protects thoracic cavity (heart & lungs)
Figure 5.6a
Figure 5.6b
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Two sets of bones
◦ Cranium
◦ Facial bones
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Bones are joined by sutures- interlocking
joints; immovable joints that connec bones of
skull
Only the mandible is attached by a freely
movable joint
Suture
Bones they connect
Sagittal
2 parietal bones
Coronal
Parietals meet frontal bone
Squamous
Temporal meets parietal
Lamboid
Occipital meets parietal
1.
2.
3.
4.
5.
6.
7.
8.
Frontal
Sphenoid
Ethmoid
Right Parietal
Left Parietal
Right Temporal
Left Temporal
Occipital
1.
2.
3.
4.
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6.
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8.
Maxillae
Palantine
Zygomatic
Lacrimal
Nasal
Vomer
Inferior Nasal Conchae
Mandible
Bone forming anterior cranium
Bone pair united by sagittal suture
Site of external auditory meatus
Has greater and lesser wings
Superior and inferior nasal conchae are part of
this bone
Its “holey plate allows olfactory fibers to pass
Allows tear ducts to pass
Boney skeleton of the nose
Cheek bone
Forms most of hard palate
Upper jaw
Figure 5.7
•Has greater and lesser wings
•Contains a “saddle” that houses
the pituitary gland
**forms a plateau across
the width of the skull
Figure 5.8
Forms most of hard palate
Posterior roof of mouth
Inferior part of nasal septum
Site of jugular foramen and carotid canal
•Its oval-shaped protrusions articulate with the atlas
•Spinal cord passes through opening
Figure 5.9
Sagittal suture
Contains a paranasal sinus
Contains a paranasal
sinus
Squamous sutrue
Contains a
paranasal sinus
(Greater wing)
•Contain alveoli bearing teeth
•Facial bone that contains a sinus
Inferior part of nasal septum
•Forms the chin
•Contain alveoli bearing teeth
Figure 5.11
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Hollow portions of bones surrounding the
nasal cavity
Functions of paranasal sinuses
1. Lighten the skull
2. Give resonance and amplification to voice
Figure 5.10a
Figure 5.10b
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Seven skull bones form the orbit: frontal,
sphenoid, ethmoid, lacrimal, maxilla,
palatine, and zygomatic
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The middle ear contains three tiny bones known as the ossicles: malleus,
incus, and stapes. The ossicles were given their Latin names for their
distinctive shapes; they are also referred to as the hammer, anvil, and
stirrup, respectively. The ossicles directly couple sound energy from the ear
drum to the oval window of the cochlea. While the stapes is present in all
tetrapods, the malleus and incus evolved from lower and upper jaw bones
present in reptiles.
*not
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really a skull bone
The only bone that does not articulate with
another bone
Serves as a moveable base for the tongue
Aids in swallowing and speech
Figure 5.12
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The fetal skull is large compared to the
infant’s total body length
◦ Fetal skull is 1/4th total body length
◦ Adult skull is only 1/8th total body length
Adolescence
Epiphyseal plates become
ossified and long bone
growth ends
Figure 5.13a
Growth (ossification) center:
conical projection on some
cranial bones
Face is smaller in proportion to cranium
Figure 5.13b
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Fontanels—fibrous membranes connecting
the cranial bones
◦ Allows skull to be compressed during birth and
allows for brain growth during late fetal life
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At birth, the skull bones are incomplete
Bones are joined by fibrous membranes
called fontanels
Fontanels are completely replaced with bone
within two years after birth
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Fetus
◦ Long bones are formed of hyaline
cartilage
◦ Flat bones begin as fibrous
membranes
◦ Flat and long bone models are
converted to bone
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Birth
◦ Fontanels remain until around
age 2
Ossification Centers in a 12-week-old Fetus
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Size of cranium in relationship to body
◦ 2 years old—skull is larger in proportion to the
body compared to that of an adult
◦ 8 or 9 years old—skull is near adult size and
proportion
◦ Between ages 6 and 11, the face grows out from the
skull
Between ages 6 and
11, the face grows out
from the skull
Figure 5.33a
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Each vertebrae is given a name according to
its location
◦ There are 24 single vertebral bones separated by
intervertebral discs - made up of fibrocartilage
 Seven cervical vertebrae are in the neck
 Twelve thoracic vertebrae are in the chest region
 Five lumbar vertebrae are associated with the lower
back
 Herniated disc= a slipped disc; protruding cartilage
from vertebra. Causes pain and numbness
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Nine vertebrae fuse to form two composite
bones
◦ Sacrum- five components; fused
◦ Coccyx- tail bone
Figure 5.14
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The spine has a normal curvature
◦ Primary curvatures are the spinal curvatures of the
thoracic and sacral regions…like a c
 Present from birth
◦ Secondary curvatures are the spinal curvatures of
the cervical and lumbar regions…like an s
 Develop after birth
Figure 5.15
Figure 5.16
Figure 5.17
Atlas lacks a body
Pivots with C2
Axis articulates
with the occipital
condyles
Figure 5.18a
Forked spinous process
Figure 5.18b
Bear facets for articulation with ribs;
form part of the bony thoracic cage
Figure 5.18c
Vertebrae with blocklike body and
short stout spinous process
Figure 5.18d
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Sacrum
◦ Formed by the fusion of five vertebrae
◦ Forms a joint with the hip bone
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Coccyx
◦ Formed from the fusion of three to five vertebrae
◦ “Tailbone,” or remnant of a tail that other
vertebrates have
Figure 5.19
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Forms a cage to protect major organs-cone
shaped
Consists of three parts
◦ Sternum
◦ Ribs
 True ribs (pairs 1–7)
 False ribs (pairs 8–12)
 Floating ribs (pairs 11–12)
◦ Thoracic vertebrae
Figure 5.20a
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Lordosis is a condition that causes the spine to curve towards the
body at an exaggerated rate. This curvature makes the individual
appear to have a swayback.
Signs of lordosis include a prominent protrusion of the buttocks. An
inflexible spine in the affected area signals a severe case of lordosis.
Individuals with lordosis and a flexible spine may require no
treatment beyond physical therapy. Treatment for lordosis with an
inflexible spine includes using a brace and possible surgery.