the axial skeleton
DESCRIPTION
The Axial Skeleton. 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). The Axial Skeleton. Figure 5.6a. The Axial Skeleton. Figure 5.6b. - PowerPoint PPT PresentationTRANSCRIPT
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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)
The Axial Skeleton
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The Axial Skeleton
Figure 5.6a
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The Axial Skeleton
Figure 5.6b
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Two sets of bones◦ Cranium◦ Facial bones
Bones are joined by sutures- interlocking joints; immovable joints that connec bones of skull
Only the mandible is attached by a freely movable joint
The Skull
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Suture Bones they connect
Sagittal 2 parietal bones
Coronal Parietals meet frontal bone
Squamous Temporal meets parietal
Lamboid Occipital meets parietal
Major Sutures of the skull
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1. Frontal2. Sphenoid3. Ethmoid4. Right Parietal5. Left Parietal6. Right Temporal7. Left Temporal8. Occipital
Bones of the Cranium
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Facial Bones1. Maxillae2. Palantine3. Zygomatic4. Lacrimal5. Nasal6. Vomer7. Inferior Nasal Conchae8. Mandible
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Human Skull, Lateral View
Figure 5.7
Bone forming anterior cranium
Has greater and lesser wings
Superior and inferior nasal conchae are part of this boneIts “holey plate allows olfactory fibers to pass
Allows tear ducts to pass
Cheek bone
Forms most of hard palateUpper jaw
Boney skeleton of the nose
Site of external auditory meatus
Bone pair united by sagittal suture
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Human Skull, Superior View
Figure 5.8
**forms a plateau across the width of the skull
•Has greater and lesser wings•Contains a “saddle” that houses the pituitary gland
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Human Skull, Inferior View
Figure 5.9
Site of jugular foramen and carotid canal
•Its oval-shaped protrusions articulate with the atlas•Spinal cord passes through opening
Posterior roof of mouth
Inferior part of nasal septum
Forms most of hard palate
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Human Skull, Anterior View
Figure 5.11
•Contain alveoli bearing teeth•Facial bone that contains a sinus
•Forms the chin•Contain alveoli bearing teeth
Contains a paranasal sinus
Contains a paranasal sinus
Contains a paranasal sinus
Inferior part of nasal septum
Sagittal suture
(Greater wing)Squamous sutrue
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Hollow portions of bones surrounding the nasal cavity
Functions of paranasal sinuses1. Lighten the skull2. Give resonance and amplification to voice
Paranasal Sinuses
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Paranasal Sinuses
Figure 5.10a
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Paranasal Sinuses
Figure 5.10b
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The only bone that does not articulate with another bone
Serves as a moveable base for the tongue Aids in swallowing and speech
The Hyoid Bone*not really a skull bone
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The Hyoid Bone
Figure 5.12
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The Fetal Skull aka BIG HEAD 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
Fontanels—fibrous membranes connecting the cranial bones◦ Allows skull to be compressed during birth and
allows for brain growth during late fetal life◦ Convert to bone within 24 months after birth
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The Fetal Skull
Figure 5.13a
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The Fetal Skull
Figure 5.13b
Face is smaller in proportion to cranium
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The Vertebral Column 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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The Vertebral Column Nine vertebrae fuse to form two composite
bones◦ Sacrum- five components; fused◦ Coccyx- tail bone
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The Vertebral Column
Figure 5.14
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The Vertebral Column The spine has a normal curvature
◦ Primary curvatures are the spinal curvatures of the thoracic and sacral regions Present from birth
◦ Secondary curvatures are the spinal curvatures of the cervical and lumbar regions Develop after birth
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The Vertebral Column C shaped spine
Figure 5.15
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The Vertebral Column
Figure 5.16
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A Typical Vertebrae, Superior View
Figure 5.17
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Regional Characteristics of Vertebrae
Figure 5.18a
Atlas lacks a bodyPivots with C2
Axis articulates with the occipital condyles
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Regional Characteristics of Vertebrae
Figure 5.18b
Forked spinous process
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Regional Characteristics of Vertebrae
Figure 5.18c
Bear facets for articulation with ribs; form part of the bony thoracic cage
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Regional Characteristics of Vertebrae
Figure 5.18d
Vertebrae with blocklike body and short stout spinous process
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Sacrum and Coccyx Sacrum
◦ Formed by the fusion of five vertebrae◦ Forms a joint with the hip bone
Coccyx◦ Formed from the fusion of three to five vertebrae◦ “Tailbone,” or remnant of a tail that other
vertebrates have
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Sacrum and Coccyx
Figure 5.19
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The Bony Thorax 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
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The Bony Thorax
Figure 5.20a
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Kyphosis
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Scoliosis
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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.
Lordosis