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The Cranium. Made up of 22 bones Except for the mandible, all of the bones are held together by sutures Rigid articulations permitting very little movement.

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Presentation on theme: "The Cranium. Made up of 22 bones Except for the mandible, all of the bones are held together by sutures Rigid articulations permitting very little movement."— Presentation transcript:

1 The Cranium

2 Made up of 22 bones Except for the mandible, all of the bones are held together by sutures Rigid articulations permitting very little movement

3 Coronoid process – mandible ADD THIS

4 The neurocranium includes 8 bones 1 frontal2 parietals 1 occipital2 temporals 1 sphenoid1 ethmoid The hyoid bone (supports the tongue) does not articulate with any other bones

5 Mental Foramen

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7 Sinus Cavities Several of the bones have developed air spaces that are lined with mucous membranes It is this mucous membrane that becomes infected in sever cases of sinusitis It is also irritation of the mucous membrane that results in excessive fluid production that can fill the air spaces and give you a stuffy nose feeling.

8 Since these sinuses are embedded in bone, they cannot be seen easily on regular skull preparations and usually require sawing into the bone to see them. Some believe that the function of the sinuses are: 1) makes the skull lighter to carry around 2) serve as resonating chambers during speech

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10 Formed by intramembranous and endochondral ossification Intramembranous (dermal) ossification The skull roof Sides and roof of the neurocranium Endochondral ossification Temporal bones Occipital Sphenoid Ethmoid

11 The cranium changes rapidly during fetal development The 1 st trimester is crucial for development of skull defects At birth, the skull is made up of 44 separate bony elements

12 The skull normally protects the brain from damage The skull is one of the least deformable substances found in nature Head injuries can raise intracranial pressure Subdural hematoma - Concussions No space for the brain to expand Brain damage or death

13 Male skulls tend to be more robust Female skulls are lighter and smaller The male body is larger than the female body, so proportionally the male skull is about the same size as the female skull Males – more prominent supraorbital ridges, more prominent temporal lines, squarer orbits, squarer chins and thicker mandibles

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15 The Cranium Review (Teeth & Ears)

16 Mental Foramen

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18 Human teeth show a morphology mainly differentiated by: 1. The SHAPE of their upper surface = crown 2. The NUMBER of tooth roots 3. The PURPOSE of each tooth type Cutting Shredding Grinding

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20 Incisors Cutting teeth 8 incisors Very front of the mouth Rather flat surfaces A straight sharp horizontal edge for cutting and biting 1 long conical root

21 Canines 4 canines Very strong, pointed corner teeth Used for tearing and shredding Larger and stronger than the incisors Upper canines are sometimes called “eyeteeth” 1 single root

22 Premolars 8 premolars Used for chewing food Placed lateral to & behind the canine teeth Flat upper surface 1-2 roots Crown has 2 cusps

23 Molars 12 molars Back of the mouth Large and flat upper surface 2-4 roots Largest of the permanent teeth Used for final chewing and grinding before swallowing 3 rd molars = Wisdom teeth

24 3 smallest bones in the body Ossicles mean “tiny bones” Contained within the middle ear space Serve to transmit sounds from the air In order from the eardrum to the inner ear (superficial to deep) 1. Malleus 2. Incus 3. Stapes

25 Malleus – Hammer Articulates with the incus and is attached to the eardrum (or tympanic membrane) Incus – Anvil Connected to the other ear bones Stapes – Stirrup Articulates with the incus

26 Malleus – aka Hammer Incus – aka Anvil

27 Stapes – aka Stirrup

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31 Major Functions Cervical (7) – Support the weight of the head and trunk Thoracic (12) – Protect spinal cord Lumbar (5) – Allow spinal nerves to exit spinal cord Sacral – Site for muscle attachment

32 Abnormalities Scoliosis Lateral curvature of spine (usually in children )

33 Abnormalities Lordosis Exaggerated anterior curve of lumbar spine Barrel chest

34 Abnormalities Kyphosis Exaggerated posterior curve of thoracic spine Humpback

35 Each bone consists of: A body An arch Several processes

36 Body Weight bearing portion Vertebral arch Surround vertebral foramen Formed from joining laminae and pedicales Vertebral foramen All form the vertebral canal = spinal cord

37 BODY ARCH Foramen

38 Transverse Process Extends laterally from each side of the arch between the pedicle and lamina 2 Laminae Extend from transverse processes to spinous process

39 Transverse Process 2 Laminae

40 Articular Processes Where vertebrae articulates with each other Spinous Process Extends dorsally from 2 laminae

41 Articular Processes Spinous Process

42 Intervertebral discs Dense fibrous connective tissue Drying along with the weakening of ligaments of the vertebral column Predisposes older people to herniated discs “Slipped discs”

43 Cervical st – Atlas “Yes” motion No body 2 nd – Axis “No” motion

44 Cervical Small bodies Each transverse process has transverse foramen Whiplash – hyperextension of the cervical vertebrae

45 Thoracic - 12 Long, thin spinous processes Articulates with the ribs

46 Lumbar - 5 Large, thick bodies Heavy rectangular transverse and spinous processes Sturdiest of the vertebrae

47 Sacrum Alae – wings Articulates with the hip bones 5 fused vertebrae

48 Coccyx Tailbone Usually 4 fused vertebrae Very reduced bodies No foramina or processes

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50 The Rib Cage Bony and cartilaginous structure Supports the pectoral girdle Provides attachments for the muscles of the neck, thorax, upper abdomen and back Consists of 24 ribs The sternum 12 thoracic vertebrae

51 The rib parts: Head – end of the rib closest to the vertebral column Neck - is the flattened portion which extends laterally Tubercle - articulates with the transverse process Angle – bending portion

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54 Manubrium The broad, upper part of the sternum Articulates with the clavicles and first 2 ribs Body The lengthier and narrow part of the sternum Below the manubrium

55 Xiphoid Process Small cartilaginous process of the lower sternum Ossified in adults Costal Cartilage Bars of hyaline cartilage Push ribs forward Contribute to the elasticity of the rib cage

56 Vertebrosternal or “True Ribs” Upper 7 ribs Attached to the sternum (costal cartilage) Allow movement (breathing) False ribs 5 sets of ribs below true ribs Has no direct attachment to the sternum

57 Vertebrocostal ribs Those ribs connected to the lower thoracic vertebrae with costal cartilage Ribs 7 or 8 down to rib 10 Each rib is attached to the costal cartilage of the rib located superiorly to it (above it) AKA “False ribs” because their costal cartilage does not attach directly to the sternum

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