ANATOMY

By Dr.Ajish Abraham

Defn -- It is a subject that deals with the study of the structures and their relations within the body of a living organism.

“Ana” – means Apart “Tomy”- means to cut

Standard Anatomical position

Common terms used in Anatomy

Anterior Posterior Medial Lateral Superior/Cranial Inferior/Caudal Proximal/Central Distal/Peripheral

Ipsilateral Contra lateral Unilateral Bilateral Isolateral Prone Supine

Branches Gross Anatomy – Its the study of the macroscopic

details of human body mostly through dissection

Living Anatomy – Study of the structures of live human being using techniques like palpation,auscultation,percussion etc

Microanatomy/Histology – Study of microscopic details of tissues that make the human body

Surface Anatomy – It is a branch which studies the relation between internal structures of human body with its surface.

Clinical Anatomy – It is application of anatomical knowledge to clinical practice.

Heircharcy of Cellular organisation

Cell –Smallest structural and functional unitTissue – Group of similar or dissimilar cells performing common function.

Organ – Group of similar or dissimilar tissues specific function

Organ system –Organ with blood vessels like artery, vein and capillary

Organism –Many organ systems working in harmony under control of brain.

Musculo-Skeletal systems Skeletal System – made of bones

Muscular system- made of muscles

Articular system – made of joints

Bone Def – dense.semirigid,porous ,calcified connective

tissue which make up the skeleton.

Cells of the boneA)Osteoblasts –Immature growth cells.B)Osteoclasts – Remodelling cellsC)Osteocytes – Mature cells with high calcium

phosphorus salt deposition.

Types of Bones 1)Long bone – Central shaft with globular ends

Types of Bones 2) Short bones – Small and thick bones

Types of Bones 3) Flat bones – Two dimensional and plate like

Types of Bones4)Irregular bone – No geometric shape

Types of Bones5) Sesamoid bone – Bones shaped like sesame

developing in tendons or capsule

Skeletal systemSkeletal numbersAxial skeleton -80 Appendicular skeleton-126total bones -206Engage in voluntary movements-177

Axial skeleton – bones along the central axis includes Skull bones 28 (facial 14,auditory 6 ,cranial 8) Neck bone 1 (hyoid) Bones of spine(26 vertebral units) Flat bones of thorax (Ribs 24 ,sternum 1) Total – 80 bones

Skull,Thorax,Vertebral column

Thoracic Cage

Skeletal system Appendicular Skeleton – it includes the bones of the extremities

Upper body - 64 bones Clavicle - 2,Scapula - 2,Humerus -2,Radius -2,Ulna -

2,Carpals-16,Metacarpals-10, Phalanges-28 Lower body – 62 bones Innominates -2,Femur – 2,Tibia-2,Fibula-2, Patella-2,Tarsals-14,Metatarsals-10,Phalanges-28

Total -126 bones

Clavicle

Scapula

Humerus

Radius-Ulna

Carpals,Metacarpals & Phalanges

Innominate

Femur and Patella

Tibia-Fibula

Tarsals,Metatarsals,Phalanges

Musculus” in Latin which means a Mouse. It is a tissue responsible for pulling on the structure to perform work Types A)Skeletal – Voluntary striated.Muscle attached to the bone B)Visceral –Involuntary non striated/smooth.Muscle of organs C)Cardiac – Involuntary branched striated.Muscle of heart

TYPES OF SKELETAL MUSCLE FIBERS

Characteristics TYPE 1-Slow twitch TYPE 2A - Fast Intermediate twitch

TYPE 2B – Fast-Fastest twitch

Diameter Small Moderate LargeFatigue Low Moderate HighForce Generation

Low Moderate High

Mitochondrion High Low AbsentEnergy System Aerobic Anaerobic lactic

acidAnaerobic-Cp-ATP

Classification of skeletal muscle according to muscle fiber arrangementParallel arrangementA)Fusiform musclesB)Longitudinal/Flat musclesC)Quadrate musclesD) Fan shaped

Pennate arrangementA)UnipennateB)BipennateC)Multipennate

Muscle names according to location

1)Sub-Scapularis Sub - Below Scapularis – Scapula

2)Pectoralis Major Pectoralis – Muscle of chest Major – Big

3)Illiacus – muscle of illum

Muscle names according to shape

Trapezius – Kite shaped Rhomboids – Rhombus shaped

Muscle names according to role

Erector Spinae – Keep spine erect Levator Scapulae – elevates scapula

Functional Classification of muscles

A)Prime movers/Agonist/Primary muscles B)Synergists/Assistors/Secondary muscles C)Stabilizors/Fixators D)Antagonists

Micro Anatomy of skeletal muscle

Sarcomere

Flow chart Sarcomere Sarcomere groups(in series)

Myofibril Myofibril bundles Muscle fiber

Fasculi Muscle fiber bundles

Fasculi bundles Muscle

Sarcoplasmic reticulum is a fibrous fluid network which has calcium ion

Proteins within sarcomere Myosin (thick filament) Actin (thin filament)

Proteins within Actin filament Troponin – which is a calcium binder Tropomyosin –Its bound to troponin to form a

complex

Cross Bridge theory or sliding filament theory of muscle

contraction During muscle contraction Signal from brain reaches muscle via nerves Calcium released from sarcoplasmic reticulum deep into

muscle Calcium binds to troponin Troponin pull tropomyosin to expose binding site on actin Myosin heads attach to binding site and walk past closer to

the end on actin by a series of attachment and detachment using ATP

This looks like Cross Bridging or the filament looks to slide over each other

During muscle relaxation Electric signal to muscle stopped Calcium to troponin bind brakes Tropomyosin returns back to close binding site Bond between actin and myosin heads break Due to elasticity the return back to original shape.

Properties of muscle 1)Excitability/Irritability 2)Contractility 3)Extensibility 4)Elasticity 5)Tonicity

Types of contractions 1)Isotonic A)Concentric B)Eccentric

2)Isometric

3)Isokinetic

Anatomic adaptations in muscles

1)Hypertrophy

2)Hyperplasia

3)Atrophy

4)Dystrophy

Nervous system Central nervous system – It consist of brain and

spinal cord.It is the primary site for receiving sensory stimuli and center from which signals are sent for motor response

Peripheral nervous system – These are the nerves associate with the brain and spinal cord which allow the brain and spinal cord to communicate with rest of the body

Autonomic nervous system – This system consist of the sympathetic and parasympathetic pathways which help the body to regulate the subconcious drives like heart rate ,breathing , muscular tone etc .

Neuro-Muscular control The information received and sent by the nerves are in

the form of electric energy called “Nerve Impulse”. The end where the nerve communicates with the

muscle is called neuromuscular junction.Here the nerve endings release excitatory chemical called Acetylcholine.

A nerve which reaches the muscle divides into branches and goes deeper into muscle.Individual branches control few muscle fibers within its capacity.

The branch of nerve and its associated muscle fibers is called a “Motor Unit”.

Large motor units contain about 1,000 muscle fibers and is used for strength

Small motor units contain less than 50 muscle fibers and are used for accuracy of movement

Medium motor units contain about 100 to 400 muscle fibers and are used for activities that require moderate strength and accuracy.

Properties of motor units All or none principle Selective recruitment Post activation potentiation

Connective tissues 1)Cartilage –These are made of chondrocytes and the spaces in

between filled with collagen and elastin fibers Types A)Hyaline cartilage – Semirigid moderately dense cartilage

having proportionate collagen and elastin.Eg articular cartilage at ends of bones

B)Fibrous cartilage –Semirigid and dense cartilage with more collagen fibers than elastin

Eg joint at the pubis C)Elastic cartilage – Flexible and thin cartilage made of more

elastin than collagen Eg)pinna of ears

Ligaments –Fibrous connective tissue which joints bone to bone

Tendons – Fibrous connective tissue which connects muscle to bone

Fascia – Thin transparent membrane which covers muscle or muscle groups.

Proprioceptors 1)Golgi tendon organs – located at the ends of

tendons which detect and inhibit excess muscular tension

2)Muscle spindle fibers – They lie parallel to muscle fibers and inhibit excessive or rapid stretching of muscles