Skeletal System

Bones – the organ of the skeletal system

Long Bones

-Longer than they are wide-This bone classification reflects the elongated shape of these bones not the overall size.

Long Bones

Epiphysis – the bone ends

Diaphysis – the shaft that forms the long axis of a long bone

Articular Cartilage – hyaline cartilage that coats the end of bones in synovial joints

Periosteum – a tough, vascular covering of fibrous tissue on the surface of the bone

Long Bones

Processes – sites for attachment of ligaments and tendons

Grooves & openings – passageways for blood vessels and nerves

Depressions – articulate with a process of another bone

Long Bones

Medullary Cavity- The center of the diaphysis - Hollow chamber filled with yellow bone marrow

Endosteum -The thin layer of cells that cover the internal bone structures

Long Bones

Compact Bone-solid, strong, and resistantto bending-makes up wall of diaphysis

Spongy Bone -bone made up of bars and plates separated by irregularspaces, which help reduce weight of bone, provide strength, and decrease compression-make up most of the epiphysis

Compact Bone

Osteocyte – bone cells

Osteon – long, cylindrical shaped structures that runparallel to the long axis of the bone

Osteonic Canals – core of the osteon which contains 2 sm blood vessels that supply nutrients to the bone cells

*The osteocytes are spider shaped cells that occupy the small matrix called the lacunae

Compact Bone

Volkmann’s Canal – (perforating canals) extend longitudinally through bone tissue and connectthe blood and nerve supply to the central canals and marrow cavity.

Intramembranous Bones

-Flat bones that develop from sheet-like masses of connective tissue…..exp (bones in skull)

Osteoblasts – bone forming cell that develops around week 8 of embryonic development

Fontanels. . . Soft spots in the baby's skull where the membrane has not yet been ossified.

Endochondral Bones

-The formation of long bones …..Fig 7.5 p127

epiphyseal disk/plate – between the primary and secondary ossification centers

*This cartilaginous disk thickens as a person grows and new cells divide.

osteoclasts – stimulated to reabsorb bone tissue

Bone Function

1. Support & Protection

2. Body Movement – levers

3. Blood Cell Formation – hematopoiesis: process of blood cell formation

*red marrow – functions in formation of red and white blood cells and blood platelets

*hemoglobin – red oxygen carrying pigment*yellow marrow – functions in fat storage, and is

inactive in blood cell production. It replaces red marrow with age.

Bone Function

4. Storage of Inorganic Salts– excess calcium and phosphorus is stored in intracellular matrix of the bone

Read Osteoporosis in text

Organization Of The Skeleton

I. Axial Skeleton – bony and cartilaginous bones that protect and support the organs of thehead, neck, and trunk.

1. Skull2. Hyoid Bone 3. Vertebral Column4. Thoracic Cage

Figure 6.1 The Axial Skeleton

• Anteriorview of theskeleton,highlightingcomponentsof the axialskeleton.

Organization Of The Skeleton

II. Appendicular Skeleton

1. Pectoral Girdle (scapula and clavicle)2. Upper Limbs (humerus, radius-outside, ulna-inside, carpals, metacarpals, phalanges)3. Pelvic Girdle (coxal bones) 4. Lower Limbs (femur, tibia-inside, fibula-outside, patella, tarsals metatarsals, phalanges)

Skull Consists of 22 bones held together by sutures

Skull

A. Cranium - surrounds and protects the brain, provides sites for muscles attachment (8 bones)

1. Frontal bone 2. Parietal bone (2)3. Occipital bone 4. Temporal bone (2) 5. Sphenoid bone 6. Ethmoid bone

Facial Bones

1. Maxillae 2. Palatine 3. Zygomatic bones 4. Lacrimal bones 5. Nasal bones 6. Vomer 7. Inferior nasal conchae 8. Mandible

Figure 6.2 Cranial and Facial Subdivisions of the Skull

• The skull canbe dividedinto thecranial andthe facialdivisions.

Figure 6.2 Cranial and Facial Subdivisionsof the Skull

Sutures

*Immovable joints*Form boundaries between skull bones

5 Sutures -Coronal (between frontal and parietal bones)

-Sagittal (between parietal bones)

-Lambdoid (between occipital and parietal bones)

-Squamous (between parietal and temporal bones)

-Frontonasal (between frontal and nasal bones)

Figure 6.3a/b The Adult Skull (posterior/superior)

Infantile Skull

Fontanels – fibrous membranes or soft spots that permit movement as skull develops and also helps pass during delivery.

Vertebral Column

-Vertebrae extend from the skull to the pelvis and areseparated by intervertebral disks.

3. Pedicle : 2 short stalks5. Laminae : 2 plates 6. Spinous process : the laminae fuse together4. Transverse process: between the pedicles and

laminae2. Transverse foramen :

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Cervical Vertebrae

•Bony axis of the neck •C1-C7

•The smallest and lightest vertebrae

Cervical Vertebrae

Thoracic Vertebrae

•12 Vertebrae •T1 – T12

•All articulate with ribs

Lumbar Vertebrae

•Large strong bodies to support weight•L1-L5 •Makes up the small of your back •Receives the most stress

Lumbar Vertebrae

Sacrum

•A curved, triangular structure, that shapes the posteriorwall of the pelvis•S1-S5 : fused

Coccyx

•Tailbone, small and triangular•Normally consists of 4 fused bones (sometimes 3 or 5)•Besides giving the pelvic organs little support it is almostuseless

Thoracic Cage -The chest and its bony framework

*Ribs •True ribs (1-7)•False ribs (8-12)•Floating ribs (11-12)

Sternum

1. Manubrium2. Body 3. Xiphoid process

Pectoral Girdle

-Shoulder girdle: consists of the clavicles, and the scapulas

1. Clavicles – collarbones2. Scapulae – shoulder bladea) acromion process – “apex of shoulder”b) coracoid process – “beak-like”c) glenoid cavity – “pit-shaped”

Upper Limbs

-humerous, radius, ulna, carpals, metacarpals, phalanges

Humerous

Radius-outside (lateral bone) of forearm, or thumb side of the forearm-thin at its proximal end and widened at its distal end

Ulna

-inside (medial bone) of forearm, or little finger side of forearm-proximal end is a coronoid process,olecranon process, and trochlear notch - grips the humerus like a pliers

Hand -carpals: (8) wrist -metacarpals: palm-phalanges: fingers

-proximal -middle -distal

Gliding joints

Synovial joints

Skeletal SystemDon’t forget…….

Always wear your…….

HELMET!!!