Structure and Function Skeletal System Structure and Function

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

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

Periosteum Dense, fibrous membrane covering bone; specialized connective tissue covering all bones of the body Contains blood vessels Essential for bone cell survival and bone formation

Connective Tissue Ligaments- fibrous band of tissues that connects bone to bone Tendon- fibrous cords by which muscle is attached to bone Cartilage- specialized fibrous tissue that acts as a shock absorption for joints and is the cushion between bones

Classification of Bones According to Shape **Bones are classified according to shape Long Bones Short Bones Flat Bones Irregular Bones Sesamoid Bones There are 206 separate bones in the adult skeleton

Long Bones Extremities Femur, tibia, fibula, humerus, ulna, radius, clavicle, metacarpals, metatarsals Levers Epiphysis: at the end of long bones; 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

Short Bones Cube-shaped Allows flexible movement Carpals, tarsals, phalanges

Flat Bones Flat Plates Protect Vital Organs Provide Broad Surface Area for Attachment of Muscles Cranial Bones, Facial Bones, Scapula, Sternum, Ribs

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

Sesamoid Bones Extra Bones Found in Certain Tendons i.e. Patella

Bone Markings Process: bony prominence or projection (acromion) Condyle: (Occipital Condyle) a rounded knuckle-like prominence usually at a point of articulation Epicondyle: small projection (Medial epicondyle) Head: rounded articulating process at the end of a bone (head of humerus) Spine: a sharp, slender projection (Spinous process) Tubercle: a small rounded process (rib tubercle) Tuberosity: a large rounded process (ulnar tuberocity)

Bony Markings Trochanter: a large process for muscle attachment (on femur) Fossa: a depression or a hollow (supra spinous fossa) Foramen: a hole (obturator foramen) Crest: a sharp ridge (iliac crest) Line: a less prominent ridge of a bone than a crest Meatus: a tube-like passage (urinary meatus) Sinus/antrum: a cavity within a bone (frontal sinus)

Depression: a hollow-region or opening Fissure: narrow, slit-like opening Sulcus: a groove Facet: a small area on a bone

Skull (22 Bones) Ear (12 Bones) & Hyoid Vertebral Column (26 Bones) Axial Skeleton Skull (22 Bones) Ear (12 Bones) & Hyoid Vertebral Column (26 Bones)

Skull - Cranium Houses and protects the brain Frontal: 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 Zygomatic- cheek bones

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

Skull Bones- Superior View

Sutures of Skull Coronal Suture: between the frontal and parietal bones Sagittal Suture: between right and left parietal bones Lambdoidal Suture: between the parietal and occipital bones Squamous Suture: between temporal and parietal bones

Veterbral Column

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)

Vertebral Sections Cervical - 7 bones Thoracic – 12 bones Lumbar – 5 bones Sacral – 5 fused bones Coccyx (tailbone): 3– 4 fused bones Kyphosis- hunchback appearance of thoracic region Scoliosis- lateral curvature of spine Lordosis- curvature of the lumbar spine inward Cervical - 7 Smallest, oblong bodies, wide transverse processes Atlas: 1st cervical vertebra; supports head by articulating condyles of occipital bone; allows forward and backward motion Axis: 2nd cervical vertebra; small body with projection called the odontoid process that acts as the axis for rotation of the skull 3rd, 4th, 5th, & 6th Vertebrae: forked to cradle strong ligaments of head 7th Vertebra: prominent spinous process called the vertebra prominens that can be felt at the base of the neck Thoracic - 12 Progressively increase in size from neck down Long spinous processes pointed downward 6 articular facets for rib attachment Lumbar - 5 Largest and strongest Short projections for muscle attachments Sacral – 5 Fused Triangular Forms dorsal part of pelvis Joins ilium bone at the iliosacral joint Coccyx – 3 to 4 Fused Articulates with the tip of the sacrum Slightly movable to assist in childbirth

Costal Cartilage Hyaline cartilage Connect ribs to sternum in 1 – 7 and to anterior ribs in 8 - 10

Ribs 12 pairs Attached posteriorly with vertebrae and anteriorly with costal cartilage True ribs: 1st seven pairs of ribs False ribs: 8 – 10 Floating ribs: 11 and 12

Appendicular Skeleton – 126 Bones Contains more bones than the axial skeleton

Shoulder Girdle Clavicles (2): collar bones; most common broken bone in children Scapulas (2): shoulder blades “shoulder bone”

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

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

Lower Extremities Femur: thigh bone (longest and heaviest bone) Patella: kneecap (largest sesamoid bone in body) Tibia: shin bone (medial larger bone of lower leg) Fibula: smaller, lateral bone of lower leg Tarsals (7): ankle bones; talus and calcaneus Metatarsals (5): foot bones Phalanges (14): toe bones; great toe = halux

The Framework