Introduction to musculoskeletal system

dr. Irwan

Content:Vignette ►Bone

Learning objectives ►Functions of bones ► Bone structure ►Bone Development ►Types of bones ►

Muscle ►

A 45-year-old man with:– Experience sciatica– Continuous pain at thigh– Numbness in the toe. Dermatome– Symptom are experienced only on left side of the

body– Characteristic posture

Using your knowledge of anatomy, make the diagnosis.

Vignette

After studying this section you should be able to:• list five types of bones and give an example of each• outline the general structure of a long bone• describe the structure of compact and cancellous bone

tissue• describe the development of bone• state the functions of bones.

Learning objectives

• Support - framework that supports body and cradles its soft organs

• Protection - for delicate organs, heart, lungs, brain

• Movement - bones act as levers for muscles

• Mineral storage - calcium & phosphate

• Blood cell formation - hematopoiesis

Function of the Skeletal System

• There are 206 bones in the adult human body. • The largest bones in the adult human body is

the femur.• There are about 300 bones in a newborn baby

but they grow together to make 206 when an adult.

Facts

• One function of spongy bone is to produce red blood cells.

• The smooth, flexible layer of tissue covering the ends of bones is called cartilage.

• The hard, strong layer of bone is called compact bone.

• Minerals make bones strong.• The human skeleton has 206 bones of various

sizes and shapes.

The Facts About Bones.

• Bone enclosed in periosteum, which is continuouswith tendons and ligamentsblood vessels in periosteum Fig. 1

• Epiphysis- endsspongy bone contains red marrowcompact bone, articular cartilage

• Diaphysis- middlecompact bonemedullary cavity- contains yellow marrow (fat)lined with endosteum (squamous epithelium)

Bone Structure

• Compact boneosteocytes within lacunaearranged in concentric circles called lamellae

 • This surround a central canal; complex is called

Haversian system Fig. 2 • Canaliculi connect osteocytes to central canal and

to each other

• skeleton is mostly cartilaginous Fig. 3• Cartilage cells and then osteoblasts start to

deposit minerals• Cartilaginous disk (epiphyseal disk) remains

in epiphysis• Cells eventually stop dividing

Prenatal development

• Initial skeleton of cartilage in infants Fig. 3• Replaced with bone by osteoblasts• More than 300 bones at birth – fuse to 206• Always growing and breaking down

– Osteoblasts – form new bone cells– Osteoclasts – break bone cells down– Osteocytes – mature bone cells

Bone Development

• Adults continually break down and build up bone

• Osteoclasts remove damaged cells and release calcium into blood

• Osteoblasts remove calcium from blood and build new matrix. They become trapped→ osteoclasts

• Red marrow – produces blood cells and clotting factors– Found in humerus, femur, sternum, ribs, vertebrae,

pelvis– Produces RBC 2 million per second

• Yellow marrow – stores fat– Found in many bones

Bone Marrow

Broken Bones• Fracture is a break of the bone Fig. 4• Simple or Complex fracture• Regrowth of bone:

o Spongy bone forms in first few dayso Blood vessels regrow and spongy bone hardens o Full healing takes 1-2 months

Fracture repair Fig. 4• Hematoma- blood clot in space between edges of

break• Fibrocartilage callus - begins tissue repair• Bony callus - osteoblasts produce trabeculae

(structural support) of spongy bone and replace fibrocartilage

• Remodeling - osteoblasts build new compact bone, osteoclasts build new medullary cavity

• Long Bones - metacarples, metatarsals, phelangies, humerus, ulna, radius, tibia, fibula

• Short Bones - carpals, tarsals• Flat Bones - rib, scapula, skull, sternum• Irregular Bones - vertebrae, some facial

bones• Sesamoid – patella Fig. 5

Types of bones

Axial skeleton (Fig. 6)• Forms the long axis

of the body• 80 bones in three

major regions– skull– vertebral column– bony thorax

RibsSternum

Appendicular Bones of upper & lower extremities and girdles126 bones in three major regions•Girdles

Shoulder girdle Pelvic girdle

•upper extremity•lower extremity

both bone and cartilage tend to deteriorate• cartilage: chondrocytes die, cartilage becomes

calcified• osteoporosis; bone is broken down faster than

it can be built• bones get weak and brittle; tend to fracture

easily

Aging and bones

• Skin makes vitamin D which enhances calcium absorption

• Skeleton stores calcium for muscle contraction, nervous stimulation, blood clot formation

• Red marrow - site of blood cell formation• Calcium levels regulated by

o parathyroid hormone and calcitonino kidneys (can help provide vitamin D)o digestive system (can release calcium into

blood

Skeleton and other systems

• Growth hormone regulates skeletal growth stimulates cell division in epiphyseal disks in long bones

• Growth stops when epiphyseal disks are converted to bone

• When excess growth hormone is produced in childhood → gigantism

• In adulthood → acromegaly. Bones can’t grow but soft tissue can Fig. 21

• There are three types of muscle tissue– Skeletal muscle– Cardiac muscle– Smooth muscle

• These muscle tissues differ in the structure of their cells, their body location, their function, and the means by which they are activated to contract

Overview of Muscle Tissue

Muscle Tissue

Muscle Tissue

• Patellar tendon reflex (knee jerk): L2, 3, and 4 (extension of the knee joint on tapping the patellar tendon)

• Achilles tendon reflex (ankle jerk): S1 and S2 (plantar flexion of the ankle joint on tapping the Achilles tendon)

Segmental Innervation of Muscle

Segmental Innervation of Muscle

Created by:dr. Irwan

Bagian AnatomiFK Unsri

Palembang

Fig. 1 Bone structure

Fig. 2 Haversian system

Fig. 3 Bone development

Fig. 4 Remodeling

Fig. 5 Bone Classification

Fig. 6 Axial skeleton

Fig. 7 Skull

Fig. 8 Cranial base

Fig. 9 Skull posterior view

Fig. 10 Suture

Fig. 11 Suture & fontanelle

Fig. 12 Orbita

Fig. 13 Nasal cavity

Fig. 14 Sinuses

Fig. 15 Fontanelle

Fig. 16 Vertebra & curvature

Fig. 17 Deviasi vertebra

Fig. 18 Curvature development

Fig. 19 HNP

Fig. 20 Thoracic cage

Fig. 21 Acromegaly & gigantisme