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The Skeletal System Notes H Skeletal System.htm.

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1 The Skeletal System Notes H Skeletal System.htm

2 Terminology 1Condyle – Rounded prominence
2Facet – Smooth articular surface 3Fissure – Narrow opening 4Foramen – Opening or hole through bone 5Fossa – Depression or groove






8 6Process – Any bone projection 7Spine – A narrow or pointed projection
8Trochanter – A large, blunt process Notes H Skeletal Features.htm




12 9).Tubercle – A small, rounded process
10).Tuberosity – A rounded, elevated area of a bone that is usually roughened



15 Types of bones 4 types of bones.
Long bones - longer than they are wide. Short bones - equal in length and width. Flat bones - thin and flat. Irregular bones do not fit into any of these categories.

16 http://upload. wikimedia. org/wikipedia/commons/9/94/Illu_long_bone




20 Bone Structure The shaft of the long bone is called the diaphysis.
The extreme ends of the bones are known as the epiphyses. The diaphysis is between the two epiphyses.


22 Epiphysis of one bone meets the epiphysis of another bone is called a joint.
Cartilage in joint known as the articular cartilage.


24 Bone - covered by a layer of connective tissue (periosteum).
Provides nourishment attaches ligaments and tendons.


26 Two types of bone tissue in the diaphysis.
Compact bone is tightly packed and forms the walls of the diaphysis. Spongy bone is less compact and is found in the diaphysis.

27 http://training. seer. cancer

28 Within the spongy bone is red marrow.
Within the diaphysis is a chamber called the medullary cavity. This cavity has yellow marrow which is used for energy storage.


30 Leukemia Red marrow - makes red blood cells (hematopoiesis), white blood cells, and platelets. When white blood cells can’t fight off infection, leukemia develops. Treatment for leukemia - injecting new bone marrow into the patient.


32 *Bone cells There are three types of bone cells.
1Osteoblasts - come from embryonic cells and found on surface of bone tissue. They lay bone down around themselves - become surrounded by bone matrix. Then they are called 2osteocytes.

33 http://academic. kellogg

34 3Osteoclasts are found in the bone tissue and are involved with secretion of a substance that breaks down the bones. Osteoclasts help to break down the bone so that osteoblasts can lay new bone. This is how a bone grows.



37 Under the microscope Osteocytes are found in spaces called lacunae, which are found between lamellae. These lamellae are layered in circles around canals known as Haversian canals.



40 Bone Growth 2 forms of development.
1Intramembranous bones - cells develop between sheetlike layers of connective tissue. 2Endochondral bones - masses of cartilage are later replaced by bone tissue.

41 Intramembraneous bones - bones of the skull.
Connective tissue appears where the bones will eventually be. Some of that connective tissue differentiates into the osteoblasts, which lay down bone.


43 In endochondral bone (most other bones) - masses of cartilage have same basic shape as future bones.
The cartilage cells die - osteoblasts replace them. Happens in two stages - primary and secondary ossification centers.

44 When bone nears end of early development, a narrow band of cartilage remains between epiphyses and the diaphysis (epiphyseal plate) These are growth plates - located at each end of the bone. Determines how long your bones will be.

45 http://www. nlm. nih. gov/medlineplus/ency/images/ency/fullsize/18022


47 Growth plate injuries can happen.
This is when the growth plate area is broken. In severe cases (only in children), it can stunt growth of the bone. When these growth plates close, you are done growing.


49 Osteoblasts and osteoclasts - lay down bone and breaking down bone.
Once the epiphyseal plate is gone - done growing. The osteoblasts and osteoclasts are important in broken bones.


51 Broken bones Complete fractures - bone is completely broken.
Greenstick fracture - fracture is not completely through. Comminuted fracture - bone is shattered.


53 Organization of Skeletal System
Skeleton is divided into two parts. 1Axial skeleton - bones that are located medially. 2Appendicular skeleton - bones that are responsible for appendages.

54 http://ae. medseek. com/bguide/reftext/images/Axial_AppendicularSkel

55 Axial skeleton - skull, the hyoid bone, vertebral column, and thoracic cage.
Appendicular skeleton - the pectoral girdle, upper limbs, pelvic girdle, and lower limbs.

56 http://nsca. hkeducationcenter

57 Axial Skeleton * ASkull - Consists of 22 bones that are joined by sutures. Sutures are rigid, narrow joints. The “soft spot” in infants is an area where the sutures have not fully closed yet.


59 Sinuses - chambers in the skull that are lined with mucous membranes.
Drain fluids, reduce the weight of the skull, and resonate sound from the voice. Sinuses can become infected (sinus infection).

60 http://www. nlm. nih. gov/medlineplus/ency/images/ency/fullsize/1108

61 Bones of the skull The cranium encloses and protects the brain. It is made of 8 bones. 1Frontal bone – large bone that forms the anterior part of the skull above the eyes. Contains the eye sockets (orbits).

62 Frontal bone

63 Located above each orbit is the supraorbital foramen which is a hole through which blood vessels and nerves travel. The frontal bone also has the frontal sinuses.

64 Supraorbital foramen

65 2The parietal bones (2) Two parietal bones - one left and one right. Form the lateral part of the cranium. Meet at the top (the sagittal suture); meet the frontal bone at the coronal suture.

66 Parietal bones



69 3Occipital bone - forms the posterior wall of the cranium.
Meets the parietal bones at the lambdoidal suture. Foramen magnum - large opening that allows spinal cord to pass between the cranium and the spinal cavity.

70 Occipital Bone

71 4Temporal bones (2) - on either side of the cranium (think temples!!)
External auditory meatus located here and is the opening to the inner ear. Zygomatic arch (your cheekbone) joins the temporal bone to the zygomatic bone.

72 Temporal Bone

73 Zygomatic Arch

74 The mastoid process is located posterior and is the location of the attachment of neck muscles.
The styloid process is the location of the attachment of the muscles of the tongue.

75 Mastoid process

76 Styloid process


78 External auditory meatus

79 5Sphenoid bone- wedged between other bones in the skull.
Home of the optic foramen, where the optic nerve passes to go to the brain. Pituitary gland is housed in the sella turcica in the sphenoid bone. Sphenoidal sinuses here.

80 Sphenoid Bone

81 Sella Turcica (means “Turkish saddle”)

82 Optic foramen

83 6Ethmoid bone - anterior to the sphenoid.
Mostly internal and forms part of nasal cavity. Ethmoid forms into the superior and middle nasal conchae (into the nostrils) Ethmoidal sinuses here.


85 Nasal conchae

86 * BFacial bones - 13 immovable bones in the face and a movable lower jaw. Support the face and provide attachments for the muscles that control facial expressions.

87 1Maxillary bones - two bones located on side of the face that form the upper jaw.
Maxillary sinuses (the largest ones) are located here. The roof of the mouth (including both palates) are formed by these bones.


89 2Palatine bones - 2 L-shaped bones that are located posterior to the maxillary bones.
Form the posterior roof of the mouth.


91 3Zygomatic bones – 2 bones that are found on the side of the face and form the cheekbones.
Forms the zygomatic arch with the temporal bones.

92 Zygomatic bones

93 4Nasal bone - the two bones meet at the midline to form the bridge of the nose.
The rest of the nose is formed from cartilage.

94 Nasal Bones

95 5Lacrimal bones – 2 bones that are posterior and lateral to the nasal bones.
Lacrimal means tears, so they are located in approximately the same area as your tear ducts.

96 Lacrimal Bone

97 6Vomer (1) - Located along the midline of the nasal cavity.
The nasal septum divides the cavity into the left and right sides. A deviated septum is when the cavity is not divided into equal halves.

98 Vomer

99 7Inferior nasal conchae (2) - Found below the superior and middle conchae of the ethmoid bone.

100 Inferior nasal conchae

101 8Mandible - lower jaw bone that articulates with the temporal bones.
The only movable bone of the skull.


103 The hyoid bone This bone does not articulate with any other bone in the entire body. It supports the tongue and provides attachment for some of the muscles of the tongue.


105 CVertebral column - support for the trunk of the body.
It runs from the skull to the pelvis. The bones that make up this column are known as vertebrae and are separated from each other by intervertebral discs.


107 A herniated disk happens when the disk breaks and puts pressure on the spinal nerve.

108 The 33 vertebrae are divided into regions.
Cervical vertebrae (7) are in the neck. Thoracic vertebrae (12) in the thorax.

109 Lumbar vertebrae (5) in the lower trunk
Sacral vertebrae (5) are fused (sacrum) The coccygeal (3-5) are fused (coccyx). Each region has a curve associated with it.


111 A vertebrae made up mostly of the body.
Middle - vertebral foramen that the spinal cord passes through. Spiny part of the vertebrae called the spinous process. Connected to the body by pedicle. Transverse process are lateral projections.

112 http://www. hunterian. gla. ac

113 The cervical vertebrae have two unique members.
The atlas is the first vertebrae and it articulates with the skull. The second vertebrae is the axis and allows the nodding of the head by articulating with the atlas.

114 http://www. spineuniverse. com/displaygraphic. php/127/atlasaxis3-BB

115 The thoracic vertebrae are larger than the cervical vertebrae.
The lumbar vertebrae are thicker than the thoracic. The sacrum is triangular as a result of the fusion. The coccyx is your tailbone.



118 DThoracic cage - formed from the sternum and ribs.
Sternum is the breastbone and located in the middle of the chest. It is made of three parts; the superior manubrium, the body, and the inferior xiphoid process.

119 http://academic. kellogg

120 Ribs (12 pairs) attaches to individual thoracic vertebra sternum (by costal cartilage)
First seven pairs of ribs are true ribs - attached at both points. Five pairs are false ribs have very little connection. Last two - floating ribs (no cartilage)


122 Appendicular Skeleton
AThe Pectoral Girdle - shoulder girdle is made up of two clavicles (collarbones) and two scapulae (shoulder blades) Scapulae have two processes (the coracoid process and the acromion process) allows for attachment of muscles.

123 http://www. pinkmonkey


125 * BThe upper limb - humerus extends from scapula to elbow.
The head of the humerus fits into the glenoid cavity of the scapula. The two tubercles (the greater and lesser) provide attachments for muscles.


127 Lower end of the humerous - two condyles that articulate with radius and ulna.
Two fossas (the coronoid on the anterior side and the olecranon on the posterior side) allow for elbow movements.


129 Radius - bone located on thumb side of forearm; extends from elbow to wrist.
Head of radius articulates with humerus and a notch of the ulna. Radial tuberosity allows for muscle attachment and styloid process allows for wrist ligament attachment.

130 Radius

131 Ulna is longer than radius and overlaps the end of the humerus.
Proximal end - the ulna has a trochlear notch that articulates with the humerus. Two processes on either end of the notch; the olecranon process and the coronoid process.


133 Distal end of ulna is the head that articulates with the radius.
Ulna also has a styloid process that allows for attachment of the wrist ligaments.

134 Hand is composed of wrist, palm, and five fingers.
Wrist is made up of eight carpal bones. The eight bones of the wrist are the lunate, hamate, triquetrum, pisiform, scaphoid, capitate, trapezoid, and trapezium.

135 http://images. encarta. msn

136 Palm consists of five metacarpal bones.
Finger bones are known as the phalanges. Each finger has proximal, middle, and distal phalanx (the thumb does not have the middle)


138 CPelvic girdle - 2 coxal bones that articulate with each other anteriorly and the sacrum posteriorly. Sacrum, coccyx, and pelvic girdle together form pelvis. Pelvis supports trunk of the body, provides attachments for lower limbs, and protects organs located in that area.


140 * Coxal bone has three parts.
Ilium is part of the bone that you think of as the hip. Flares outward and forms the bony prominence of the hip. Top of this is called the iliac crest. Ilium joins the sacrum at the sacroiliac joint and has anterior superior iliac spine which provides attachments for muscles.


142 Ischium forms the lowest portion of the coxal bone.
Ischial tuberosity points posteriorly and downward and provides attachment for muscles and ligaments. Where the ilium meets the ischium is a projection called the ischial spine.


144 Pubis is anterior part of the coxal bone.
2 pubic bones join at midline, forming a joint called the symphysis pubis. Angle of these bones below the symphysis pubis is called pubic arch. Obturator foramen is found in pelvic girdle and is the largest in the body.


146 DLower limbs form thigh, leg, and foot.
Femur is longest bone in the body and extends from hip to the knee. Head of the femur fits in the acetabulum of the coxal bone. On head is fovea capitis which allows attachment of a ligament.


148 Below the head – 2 processes; the greater trochanter and the lesser trochanter.
Distal end of femur - 2 condyles (lateral and medial) that articulate with tibia of the leg. Patella (kneecap) articulates with femur at distal end.


150 Tibia – shinbone; larger of two lower leg bones (located medially).
Proximal end has medial and lateral condyles that articulate with the condyles of the femur. Below condyles is tibial tuberosity. Distal end - medial malleolus.

151 http://www. allaboutarthritis

152 Fibula - smaller lower leg bone.
Has a head at the proximal end and a lateral malleolus at the distal end. The lateral malleolus is responsible for the bump you feel on the side of your ankle.


154 Foot - 7 tarsal bones (calcaneous, talus, navicular, cuboid, lateral cuneiform, intermediate cuneiform, and the medial cuneiform) Talus moves freely where it meets the fibula and tibia. Calcaneous - largest (heel bone)

155 Talus Calcaneus

156 Tarsal bones articulate with metatarsals.
5 metatarsals articulate with phalanges (the toes). 3 phalanges for each toe; the proximal, middle, and distal phalange. Big toe does not have a middle one.



159 Diseases 1Achondroplasia – form of dwarfism.
Due to cartilage converting to bone during development. Normal-size trunk and head; short extremities.

160 Note the shortened femurs
Note the shortened femurs

161 2Osteoporosis – occurs when the rate of bone formation and bone resorption changes.
Results in fragile bones that break easily.


163 3Rheumatoid Arthritis – cartilage and dense connective tissue breakdown easily.
The joint eventually fuses with the bone. Autoimmune disease – person’s immune system attacks itself.


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