SKELETAL MUSCLES.S.MOORTHY SEMENCHALAM

M.Sc. Comm Health (Occ Health) UKMB.HSc. Nursing (Aust)

Dip Med Sc. (Moh)

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Learning Objective

At the end of these session students should be able to:• State the 2 classifications of bones• List the functions of bones• Name the types of bones• List the composition of bone• List the types of joints• Described 3 types of muscle tissue• State the characteristics & structure of muscle tissue• State the relations of muscle and movement

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Classification of Bones

Axial Skeleton – forms the long axis of the bodyeg. bones of the skull, vertebral column,

rib cage, hyoid bone

Appendicular Skeleton – relating to an appendage, 126 boneseg. bones of the upper and lower limbs, shoulder girdle, hip girdle

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1. BONE

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Functions:Axial skeleton/bones Involved in protecting and supporting of

the body and organsAppendicular skeleton/bones Help in movement

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Functions of Bones

• Support – forms the framework (central axis of body); gives shape, supports the body

• Protection – provide protective case for brain, spinal cord & organs ( heart & lungs)

• Movement – provide levers for muscle• Mineral storage – reservoir for minerals; e.g.

calcium & phosphorus• Blood cell formation – haematopoiesis occurs

within the marrow cavities of bones• Attachment for muscles & tendons04/12/23 6 7

Number of Bones

There are 206 bones in our whole body• Upper limbs - 64• Lower limbs - 62• Vertebrae - 33 ( C7,T12,L5,S5,CO4 )• Skull - 22• Ribs - 24• Sternum - 1 04/12/23 7 8

Sesamoid bones

Irregular bones

Flat bones

Short bones

Long bones

Types of bones

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i. LONG BONES

• Bones of the extremities• Cylindrically in shape (shaft) with

expanded end• E.g. femur,humerus, tibia, fibula

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ii. SHORT LONG BONES & SHORT BONES

• Describes the bones of the hand & foot• E.g. metatarsal, metacarpal,carpals, tarsals

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iii. FLAT BONES

• Like flat plate; curved or straight• E.g. sternum,

scapula & parietal

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iv. IRREGULAR BONES• Shape cannot be described because it is irregular• E.g. vertebrae, pelvic bone

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v. SESAMOID BONES

• Seed- like bones seen in tendon eg.patella (knee cap)

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GROSS ANATOMY OF BONES

• External features of bones – projections, depression & openings- as sites for muscle, ligament & tendon attachment- as surface joints- conduits for blood vessels & nerves

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Internal features:• Compact bone –

dense outer layer & hard

• Spongy bone less hard (cancellous bone) – honeycomb of trabeculae filled with bone marrow

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Structure of Typical Long Bone• Diaphysis

- tubular shaft; forming the axis of long bones- composed of compact bone + central medullary canal (houses fatty yellow bone marrow)

• Epiphysis- expanded end of long bones- spongy bones inside

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Con`tThin layer of articular

cartilage covers end of epiphysis

Long bone that are still growing has an epiphyseal plate or growth plate

When the bone growth stops, the epiphyseal plate is replaced by bone- epiphyseal line

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Structure of Typical Long Bone: Periosteum

double-layered protective membrane

supplied with nerve fibers, blood, and lymphatic vessels entering the bone via nutrient foramina

Secured to underlying bone by Sharpey’s fibers (collagen)

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AXIAL SKELETONAXIAL SKELETON

1. Skull2. Vertebral column3. Thoracic cage

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1. Skull1. Skull

• Consist of 2 parts1. Cranium – contain the brain2. The face

• Fused/ joined bones – not moveable• Mandible bone – moveable

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Consist of 11 bones1. Frontal bone2. Parietal bone3. Temporal bone4. Occipital bone

5. Sphenoid bone6. Nasal bone7. Lacrimal bone8. Ethmoid bone9. Zygomatic bone10.Maxilla bone11.Mandible bone

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Frontal

Parietal

Temporal

occipital

Mandible

Maxilla

zygomatic

Nasal

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Function of the skullFunction of the skull

1. Cranial bones protect the brain2. Bone eye sockets protect the eye3. Temporal bone protects the ear4. Gives resonance of voice due to the air filled

cavities called sinuses5. Keeps the air passage open to facilitate

breathing04/12/23 27 32

2. Vertebral Column2. Vertebral Column• Consist of 24 movable bones• Sacrum & coccyx• Separated by intervertebral discs (cartilage)

i. 7 cervicalii. 12 thoraciciii. 5 lumbariv. 5 sacrum v. 4 coccyx

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1. Protects the spinal cord. 2. Houses 31 pairs of spinal nerves going

through the foramina3. Vertebrae articulate with the ribs, forming

joints which move during respiration.

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Functions of vertebral column

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3. Thoracic cage3. Thoracic cage

• Formed by 12 thoracic vertebrae• 12 pairs of ribs• 1 sternum/ breast bone• The ribs are attached to the sternum by costal

cartilage• Two pairs of ribs (rib 11 & 12) –called as floating ribs-

no anterior attachment

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1) Protects heart, lungs, major blood vessels 2) Forms joints between the upper limbs and the

axial skeleton.3) Manubrium (upper part of sternum),

articulates with the clavicle bones4) Gives attachment to the respiratory muscles

to enables respiration

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Functions of thoracic cageFunctions of thoracic cage

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The Sternum (breast bone )

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APPENDICULAR SKELETONAPPENDICULAR SKELETON

1. Shoulder girdle and the upper limb/extremity2. Pelvis girdle and the lower limb/extremity3. Arches of the foot

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LigamentsLigaments

• A band of fibrous tissue that connects bones or cartilages

• Function: support and strengthen joints

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2. JOINTS

Joints = Articulations

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Articulation – site where two or more bones meet

Two Fundamental Functions of Joints:Allow the skeleton to have mobilityHold the skeleton together

Classification of Joints: Structural

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Fibrous Cartilaginous

Synovial

Classification of Joints: Functional

Fibrous joints – immovableCartilaginous joints – slightly movableSynovial joints – freely movable

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Structural - Fibrous Joints

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-The bones are joined by fibrous tissues

- No joint cavity

- Most are immovable (synarthroses)

Example of fibrous joint

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Example of fibrous joint

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Example of fibrous joint

Structural – Cartilaginous Joints

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- Articulating bones are joined by cartilage- No joint cavity

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Example of cartilaginous joint

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Example of cartilaginous joint

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Example of cartilaginous joint

Structural – Synovial Joints

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Articulating bones are separated by a joint cavity containing fluid

All are freely movable diarthroses

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Example of synovial joint

Synovial Joints: General Structures

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Synovial Joints: Friction-Reducing Structures

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Synovial Joints: Range of Motion

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Nonaxial – slipping movements onlyUniaxial – movement in one planeBiaxial – movement in two planesMultiaxial – movement around all planes

Three General Types of Movements:

Gliding (slipping)AngularRotation

Gliding (slipping) movements

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One flat bone surface glides or slips over another bone

Angular movements

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Involve change of angle between bones

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Flexion - bending movement that decreases the angle of the joint

Example of angular movement

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Example of angular movement

Extension-straightening movement that increases the angle of the joint

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Dorsiflexion & Plantar flexion- Up and down movement of the foot

Example of angular movement

• Abduction — movement of a limb away from the midline or median plane

• Adduction — movement of a limb toward the midline or median plane

• Circumduction — movement of a limb describing a cone in space

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Example of angular movement

Rotation movements

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Turning of a bone around its own axis

Example:

Hip and shoulder joints

Special Movements

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Supination and Pronation – movements of radius around the ulna –

Special Movements

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Protraction and Retraction

Inversion and Eversion

Special Movements

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Elevation and Depression

Opposition

Types of Synovial Joints-Diarthrotic

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Six Major Categories:

Plane Condyloid

Hinge Saddle

Pivot Ball-and-Socket

Types of Synovial Joints - Hinge

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Motion is along a single plane (only permits flexion and extension)

Resembles action of a hinge

Examples: elbow joint knee joint

Ball & socket

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Example :SHOULDER JOINTHIP JOINT

Condyloid

• Oval shaped condyle

• Angular motion but not rotation

Example : Occipital condyles with atlas; metacarpals & metatarsals with

palanges

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Saddle• Articulating surfaces of both bones (concave &

convex regions)• Permits wide range of movement Example: Carpometacarpal joint of thump is

the only saddle joint in the body 04/12/23 69

Pivot

• Rounded or conical surface of one bone fits into a ring of bone or tendon

• For rotation

Example: Joint between the atlas and axis; proximal radioulnar joint04/12/23 70

Gliding/Plane

• Flat or lightly curved surfaces • Moving against each other• Sliding or twisting without circular movement Example: Between carpals (wrist) & tarsals ( ankle)

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3. MUSCLE

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MUSCLE TISSUE• Study of muscles is called Myology• Muscles form 40-45% of total body

weight• Motion - essential body function that

results from the contraction and relaxation of muscles

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Cont..

• Posture maintaining both during rest and at activity• Heat generated by skeletal muscle contraction

produce 80% of all the body heat• Beating of heart is specific function of cardiac muscle• Smooth muscle throughout body help in movement

of secretions, waste products, etc.

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TYPE OF MUSCLE TISSUE

• 3 Types of muscle in the body - skeletal muscle - cardiac muscle - smooth muscle

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Types- skeletal muscle• 40 % of body weight• It is voluntary as it can be made to contract and

relax at conscious level• Also called as striated muscle• Eg: diaphragm is structurally voluntary but it

works automatically with breathing• Upper part of esophagus is voluntary but is not

under conscious control

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Skeletal muscle tissueOver 600 muscle in bodySkeletal muscle tissue has three

components (epimysium, perimysium, endomysium)

- Connective tissue component- Nerve and blood supply- Muscle tissue proper04/12/23 77

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Blood supply• Skeletal muscle fibers are well supplied by

nerve and vessels which help in contraction, supply energy and transfer of waste products

• Generally an artery and two veins accompany the nerve that penetrate skeletal muscle

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Skeletal muscle and movementSkeletal muscle and movement• It produces movement by exerting force

on tendons which in turn pulls on bones or other structures like skin

• They cross at least one joint and are attached to articulating bone that form joint.

• Abundant blood & nerve supply04/12/23 81

Group actions

- Skeletal muscle act in groups- They are arrange in opposing pairs in joints

like flexor and extensors- Muscle that produce desired movement is

called prime movers / agonist- Muscle moving opposite are relaxing are

antagonist

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• MOST SKELETAL MUSCLES WORK IN PAIRS.

• When one muscle or set of muscles CONTRACTS, the other RELAXES.

• The Muscles of the upper arm are a good The Muscles of the upper arm are a good example of this dual action: example of this dual action: ANTAGONISTIC MUSCLESANTAGONISTIC MUSCLES.  . 

FLEXORFLEXOR, A MUSCLE THAT BENDS A , A MUSCLE THAT BENDS A JOINT.  JOINT. 

EXTENSOREXTENSOR, A MUSCLE THAT , A MUSCLE THAT STRAIGHTENS A JOINT.STRAIGHTENS A JOINT.

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A.A. When the BICEPS CONTRACTS, it When the BICEPS CONTRACTS, it FLEXES FLEXES the elbow jointthe elbow joint

B. When the TRICEPS CONTRACTS, it B. When the TRICEPS CONTRACTS, it EXTENDSEXTENDS the elbow joint the elbow joint

C. A controlled movement requires C. A controlled movement requires contraction by both muscles.contraction by both muscles.

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SMOOTH MUSCLESMOOTH MUSCLE• Smooth muscle cell are small• Not striated• Contract more slowly• Is under involuntary control. And they to

function as a unit and contract at the same time. e.g intestine

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CARDIAC MUSCLECARDIAC MUSCLE

• Share some characteristic with both smooth and skeletal muscle

• Is under involuntary control and are influenced by hormon

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Thank you Questions please

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