PMCY 4050 Exam 1 - Skeletal Anatomy

Function of Bones

Support and permit movement, protection, marrow functions for formation of blood cells (hematopoiesis), storage of fat (yellow marrow) and minerals (calcium, phosphorus)

Compact Bone

Denser, covers most bones, better storage of minerals

Spongy Bone

Open network of trabeculae, lace-like appearance, trabeculae contain marrow

Osteoblasts

Bone builders; synthesize collagen and proteoglycans, function is to form new bone

Osteocytes

Osteoblasts that are entrapped in the mineralized bone matrix, maintain minerals and organic elements in matrix by coordinating with osteoblasts and osteocytes (construction men)

Osteoclasts

Bone breakers; resorb bone during growth and repair

Bone Formation

Infants’ skeleton is primarily made of cartilage, Cartilage replaced with bone, Growth occurs at epiphyseal plates, New cartilage forms, Older cartilage broken down and becomes ossified, bone remodeling

Bone Remodeling

Increased bone size = muscle hypertrophy
Decreased bone size = muscle atrophy

Long Bone Anatomy

Articular cartilage at ends - epiphyses (compact bone surrounding spongy bone) - diaphysis (compact bone)

Central canal (Haversian system)

Center of osteon, conduit for blood vessels

Volkman's canal

Perpendicular to central canal, conduit for blood vessels and nerves

Lacunae

contain osteocytes, arranged concentrically

lamellae

lacunae present, circle the central canal

canaliculi

transport nutrients to bone cells, radiate from central canal to lacunae

Periosteum (long bone)

Outer covering of shaft connected by Sharpey's fibers

Medullary cavity (long bone)

Contains yellow marrow (adults), red marrow (infants) for formation of blood cells

Synovial Joints

Most movable and most complex joints
-articular capsule
-synovial membrane
-synovial cavity
-synovial fluid
-articular cartilage

Synarthrosis

immovable

Amphiarthrosis

slightly movable

Diarthrosis

freely movable

Joint capsule

Connective tissue covering ends of bones, supplied with nerves, vasculature and lymphatic vessels

Synovial membrane

Smooth inner lining of joint capsule, supplied with blood and lymphatic vessels, rapid repair and regeneration

Synovial cavity

Enclosed fluid filled space between bones, allows bones to move against each other

Synovial fluid

Suprefiltrated plasma from blood vessels in synovial membrane, loss of fluid = rapid deterioration of articular cartilage

Chondrocytes

Cells that compose cartilage, along with a matrix of collagen, proteins, and water.

Axial Skeleton

Maintains upright posture and transfers weight to lower extremities (skull, hyoid, vertebrae, ribs, and sternum)

Skull

Composed of the cranium: frontal, parietal, temporal
Facial bones: maxillary, palatine, nasal, vomer, inferior nasal conchae, zygomatics, lacrimal, mandible
Associated auditory ossicles and hyoid.

Articular cartilage

- Hyaline cartilage covering the end of each

bone

– Functions to reduce friction and to distribute

weight-bearing forces

– Composed of chondrocytes and a matrix of

collagen, proteins and water

– No blood vessels, lymph vessels or nerves

– Regenerates slowly

Sinuses

Hollow areas in the skull named based on the bone; provide resonance and amplify sounds when speaking.

Fetal Skull

Contains fontanelles (soft fibrous membranes that convert to bone at approximately 24 months); the fetal skull is large compared to body length.

Vertebral Column

C1 - Atlas
C2 - Axis
C1 - C7 = Cervical
T1 - T12 = Thoracic
L1 - L5 = Lumbar
Sacral + Coccyx
Vertebrae separated by fibrocartilage discs that absorb shock (degenerated disc disease)

Pelvic Girdle

Ilium, ischium, and pubic bone; protects the bladder/large intestine/reproductive organs, carry the weight of the upper body
Females are lighter/thinner vs male

Aging and Musculoskeletal Function

Characterized by loss of bone tissue, increased rigidity and fragility of cartilage, decreased range of motion, age-related loss in muscle mass (sarcopenia), and decreased lean body mass.

Osteoporosis

Can be generalized/regional, density or mass of bone is reduced, remaining bone normal but insufficient to maintain structural integrity and mechanical support (spongy and compact bone is lost but spongy more easily)

Postmenopausal Osteoporosis

Middle-aged and older women bc decreased estrogens - sensitizes osteoclasts to parathyroid hormone actions and initiates bone resorption.a

Causes of Osteoporosis

Includes shrinkage or alterations in osteoblasts and osteoclasts, reduction in physical activity, insufficient intake or malabsorption of dietary minerals, hormonal imbalances

Pathophysiology of Osteoporosis

Bone remodeling cycle is disrupted --> imbalance between the rate of resorption and the rate of new bone formation.

Clinical Manifestations of Osteoporosis

Symptoms include pain and bone deformity, fractures being common and potential for hunchback and diminished height

Appendicular Skeleton

Shoulder girdle, arm, hand, pelvic girdle, leg, foot