1 Skeletal System Structure and Function

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3 Functions Support: body structure and shapeProtection: vital organs surrounded Movement/Anchorage of Muscles Mineral Storage: calcium & phosphorus Blood Formation

4 Bone Composition Collagen: chief organic constituent (protein)Inorganic Calcium Salts: Vitamin D essential for absorption

5 Cells Osteoblasts: bone building, bone repairing cells in the periosteum Osteocytes: osteoblast embedded within the bone matrix Osteoclasts: cells that cause absorption of bone

6 Periosteum Dense, fibrous membrane covering boneContains blood vessels Essential for bone cell survival and bone formation

7 Types of Bones Based on Composition: Compact BoneVery Dense, Stress Bearing Haversian Systems Lamellae: concentric cylinder shaped calcified structure Lacunae: small lakes containing tissue fluid Osteocytes: facilitate exchange of calcium between blood and bone Canaliculi: canals connecting the lacunae together and to the haversian canal which carries nutrients/wastes

8 Cancellous Bone Light, SpongyLow Stress Areas Where Weight of Bone Would Be a Problem Found at Ends of Long Bones, Ribs, Sternum, Hips, Vertebrae, Cranium No Haversian Systems Web-Like Arrangement

9 Classification of Bones According to ShapeLong Bones Short Bones Flat Bones Irregular Bones Sesamoid Bones

10 Long Bones ExtremitiesFemur, tibia, fibula, humerus, ulna, radius, clavicle Levers Epiphysis: at the ends; covered with hyaline cartilage for articulating bones; cancellous bone Diaphysis: shaft, covered with periosteum for bone growth, repair, nutrition; medullary canal with yellow and red marrow; endosteum lining; compact bone

11 Short Bones Cube-shaped Allows flexible movementCancellous bone covered by compact bone Carpals, tarsals, metacarpals, metatarsals, phalanges

12 Flat Bones Flat Plates Protect Vital OrgansProvide Broad Surface Area for Attachment of Muscles Cranial Bones, Facial Bones, Scapula, Sternum

13 Irregular Bones Peculiarly Shaped to Provide Support and Protection with Flexibility Vertebrae, Ribs, Ear, Hip, Hyoid

14 Sesamoid Bones Extra Bones Found in Certain Tendons (i.e., patella)

15 Bone Formation Initially collagen fibers secreted by fibroblastsCartilage deposited between the fibers Skeleton fully formed by 2nd month of fetal development (all cartilage) Ossification begins after 8th week of fetal development Childhood and adolescence: ossification exceeds bone loss Early adulthood through middle age: ossification equals bone loss After age 35: bone loss exceeds ossification

16 Skull Bone Formation Begins as fibrous membraneOssification center in the middle of the membrane Ossification begins in the middle and radiates out Ossification not complete at birth Fontanels (soft spots): molding of head during birth and allow for brain growth

17 Formation of Other BonesBegin as hyaline cartilage Short bones: one ossification center in middle and proceeds to periphery Long bones: three ossification centers (at each end and in the middle); ossification from each end toward the center and from the center towards each end

18 Bone Growth Grow in length at the epiphyseal lineGrow in width by addition of bone to the surface Controlled by anterior pituitary (GH)

19 Bone Markings - PurposeJoin one bone to another Provide a surface for attachment of muscles Create an opening for passage of blood vessels and nerves Use as landmarks

20 Bone Markings Process: bony prominence or projectionCondyle: a rounded knuckle-like prominence usually at a point of articulation Epicondyle: small projection Head: rounded articulating process at the end of a bone Spine: a sharp, slender projection Tubercle: a small rounded process Tuberosity: a large rounded process

21 Bone Markings Trochanter: a large process for muscle attachmentFossa: a depression or a hollow Foramen: a hole Crest: a sharp ridge Line: a less prominent ridge of a bone than a crest Meatus: a tube-like passage Sinus/antrum: a cavity within a bone

22 Bone Markings Depression: a hollow-region or openingFissure: narrow, slit-like opening Sulcus: a groove Facet: a small area on a bone

23 Bone Marrow - Yellow Medullary Cavity of Long Bones Fat Storage

24 Bone Marrow - Red Hematopoietic Tissue In cancellous bone in childrenIn adults: cancellous bone of vertebrae, hips, sternum, ribs, cranial bones, proximal ends of femur and humerus Forms RBCs, platelets, some WBCs and destroys old RBCs and some foreign materials

25 Axial Skeleton Skull (22 Bones) Ear (12 Bones) & HyoidVertebral Column (26 Bones)

26 Skull - Cranium Houses and protects the brainFrontal: forms forehead and orbits of eyes Ethmoid: forms roof of nasal cavity Parietal: right & left; form sides and roof of skull Temporal: right & left; forms temple, cheek, ear openings

27 Skull - Cranium Occipital: back of skull; inferior portion has foramen magnum (opening for spinal cord) and 2 condyles to articulate with atlas Sphenoid: fills space between orbital plates; depression called sella turcica holds the pituitary gland; bat shaped

28 Cranial Sutures Unite the bones of the craniumAs the child grow, irregular bands of connective tissue ossifies and turns into hard bone Abnormalities: microcephalus (premature fusion), hydrocephalus (delayed fusion  increases intracranial pressure)

29 Cranial Sutures Coronal Suture: between the frontal and parietal bonesSagittal Suture: between right and left parietal bones Lambdoidal Suture: between the parietal and occipital bones Squamous Suture: between temporal and parietal bones

30 Fontanels Fusion of the cranial bones is not complete at birthSpace between the bones remains Anterior (Bregmatic): “soft spot”, closes at 18 months Posterior (Occipital): triangular, closes at 2 – 3 months Anteriolateral (Sphenoidal): at 2 temples, closes at 2 – 3 months Posterolateral (Mastoidal): 2 behind ears, closes at 1 year

31 Facial Bones Guard and support eyes, ears, nose, mouthNasal bones (2): form bridge of nose Vomer: forms central nasal septum Maxillary (2): upper jaw bone; fusion before birth; forms roof of mouth, walls of nose, floor of orbitals Mandible: lower jaw bone; largest bone of face

32 Facial Bones Zygoma (2): cheek bonesLacrimal (2): small bones form medial wall of each eye socket Palatine (2): forms back roof of mouth and floor of nose Inferior turbinate (2): forms curved ledge inside side wall of nose

33 Ear Bones Malleus (2): the hammer Incus (2): the anvilStapes (2): the stirrup

34 Hyoid Bone U-shaped bone In neck At base of tongueOnly bone in body that does NOT articulate with another bone

35 Cranial Sinuses Cavities within the craniumResonance chambers for voice Decrease weight of skull Lined with mucous membrane Frontal sinuses (2): above eyebrows, open into nasal cavity Ethmoid sinuses (2): between the eyes Spenoidal sinus (1): posterior to ethmoidal sinus, opens into nasopharynx Maxillary sinus (2): on either side of the nose, opens into the lateral wall of the nasal cavity

36 Vertebral Column - FunctionsSupports trunk and neck Protects spinal cord Multiple joint spaces allow for bending and twisting

37 Curves Allow for resilience and spring for walkingThoracic: present at birth Sacral: bow back Cervical: begins at 3 months when infant first begins to lift head Lumbar: begins when child first walks

38 Vertebrae 26 Separated by intervertebral disk to cushion joints for movement Body: thick, disk-shaped anterior portion Arch: encloses space for spinal cord; 3 processes for muscle attachment (spinous process – dorsally directed, 2 transverse processes) Articular processes: provide for articulation with other vertebrae (2 superior and 2 inferior) Pedicles (2): originate from body of vertebrae notched to allow spinal cord nerves to pass Lamina: posterior wall of vertebrae, weakest point

39 Vertebral Sections Cervical - 7 bones Thoracic – 12 bonesLumbar – 5 bones Sacral – 5 fused bones Coccyx – 3 – 4 fused bones

40 Thorax 25 bones and cartilage Sternum, costal cartilage, ribsWalls covered by skin and muscles Floor formed by the diaphragm

41 Functions Protect and support heart and lungsSupports bones of pectoral girdle Plays leading role in respiration Ribs and sternum aid in RBC formation

42 Sternum Breast bone Sword and handle shapedManubrium: handle, notched for 1st 7 costal cartilages, articulates with acromium end of clavicle and 1st rib Body: blade, notched for 1st 7 costal cartilages Xiphoid process: tip, attachment site for diaphragm

43 Costal Cartilage Hyaline cartilageConnect ribs to sternum in 1 – 7 and to anterior ribs in

44 Ribs 12 pairs Attached posteriorly with vertebrae and anteriorly with costal cartilage True ribs: 1st seven pairs of ribs False ribs: 8 – 12 (11 and 12 are floating)

45 Appendicular Skeleton – 126 BonesShoulder Girdle Clavicles (2): collar bones Scapulas (2): shoulder blades

46 Upper Extremities Humerus: upper arm Radius: thumb side of forearmUlna: little finger side of forearm Carpals (8): wrist bones Metacarpals (5): hand bones Phalanges (14): finger bones

47 Pelvic Girdle Os Coxae (2): contains the acetabulum (hip socket)3 components: ilium, ischium, pubis Also, contains the saccrum

48 Lower Extremities Femur: thigh bone Patella: kneecap Tibia: shin boneFibula: lateral bone of lower leg Tarsals (7): ankle bones; talus and calcaneus Metatarsals (5): foot bones Phalanges (14): toe bones; great toe = halux

49 Articulations Synarthrotic: immovableAmophiarthrotic: limited movement i.e.pubic symphysis, vertebral joints, sacroiliac joint Diarthrotic: freely movable

50 The Framework