By Dr MB Samarawickrama (MBBS MS) 31 th Batch July 2008 Muscles and Tendons.
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Transcript of By Dr MB Samarawickrama (MBBS MS) 31 th Batch July 2008 Muscles and Tendons.
By
Dr MB Samarawickrama(MBBS MS)
31th Batch July 2008
Muscles and Tendons
Muscles
Three types
• Skeletal Muscles
• Cardiac Muscles
• Smooth Muscles
MusclesNeed to know
• Histology
• Gross Anatomy
• Physiology
Muscles
Skeletal Muscles
• Formed by number of muscle fibers
• Non branching
Muscles-Histology
• Skeletal muscles
• Consist of unbranched fibres
• Banded by striations
• Small nuclei, placed peripherally on the surface of the fibres
Microscopic structure
• Fiber’s size varies within a single muscle
• Hypertrophy of muscle results increase in size of the fiber
• The number remains the same
• These fibres are bound together by a loose areola tissue
• This envelope is known as epimysium
Muscles-Histology
ENDOMYCIUM,
PERIMYCIUM
EPIMYCIUM
Cardiac muscle
• Also striated
• Fibres are branched
• Large nuclei placed centrally
Smooth muscle• Long spindle shaped cells
• Nucleus lies centrally
• Parallel cells joined to form muscle fibres
• The fibres arrange Circularly, longitudinally or whorls & spirals with no demonstrable layers
The form of muscles
Fibres in a muscle arrange in two ways
• Parallel to the line of pull– increase range
of mobility
The form of muscles
• Oblique to the line of pull – range of mobility
is less– Force of pull is
maximum
The form of musclesE.g.
muscles with Parallel fibers
• Sartorius
• Rectus abdominis
• Infrahyoid muscles
• Anterior & posterior fibres of the deltoid
Muscles with Parallel
Fusiform
The form of muscles
The muscles with oblique fibres
• One of 4 patterns– Unipinate muscles– Bipennate Muscles– Multipinate Muscles-two types
The form of muscles
Unipinate muscle
• The tendon forms along one margin of the muscle
• All the fibres slope into one side of the tendon
• e.g. Flexor Policis Longus
The form of musclesBipennate Muscles• The tendon forms centrally
• muscle fibres slope into the two sides of the central tendon.– Like a feather
• e.g. Rectus Fumoris
The form of muscles
The form of muscles
Multipinate Muscles
• Two varieties
• Series of bipinnate masses lying side by side
• e.g.• Central part of the deltoid• Subscapularies
The form of muscles
Multipennate Muscles • cylindrical muscle within
which a central tendon forms
• Into the central tendon muscle fibres converge from all sides
• e.g. Tibialis anterior
Surface appearance of muscles
• Some more fleshy
• Some largely apponeurotic
• Some have a mixture of two
Surface appearance of muscles
• That reflect the function of the muscle
• If the muscle bears lot of pressure from adjacent structures – it is covered by an apponeurosis
• Where there is no pressure it is usually flesh
Origin and insertion of muscle
• No reality in these terms
• Origin – fixed end
• Insertion – moving end
Origin and insertion of muscle
• But vary depending on the circumstances
• Use the word attachment instead
Bone markings
• Fleshy origins leaves no marks on bones
• The area is flatten or depressed on the bone
•e.g. Pec. Major on the clavicle
Bone markings
• Insertion of a pure tendon almost always leave a smooth mark on the bone
• e.g. Ligamentum patelle attachment
Bone markings
• Rough marks are made where there is admixture of flesh & tendon
• or where there is a lenthy insertion of aponeurosis
• e.g. Linear aspera femur
Bone markingsFlat muscles arise from-flat bone• Muscle origin does not extend to the edge of the flat
bone• It origin from an edge of a curved line
• Between the origin and the edge of the bone is a bare area
• This area is occupied by a bursa
• Which may or may not be communicated with the adjacent joint
• e.g. subscapularis
Actions of muscles
• The action of muscles or muscle groups are often oversimplified
• Terms denoting action, in particular, emphasize only one of a number of habitual actions
• A given muscle may play different roles in different movements
Actions of muscles
• these roles may change if the movements are assisted or opposed by gravity
• Single muscle rarely contract alone
• The action is influence by its companions in contraction
Actions of muscles
• When a muscle crosses two joints
• It mainly act on distal joint to move it
• On proximal joint it act to steady the joint– e.g. Biceps long tendon– Triceps
Actions of muscles
• In such cases
• Position of the proximal joint changes the length of the muscles
• Thus affect the movement of the distal joint
Actions of muscles
• e.g. Action of long flexor tendons of the IPJ is affected by the position of the wrist
• Position of the knee affect the action of the Gastrocnemius on the ankle joint
Actions of musclesSynergic actions• Muscles acting as a prime movers on a certain
joint have a different action when a more distal segment of the limb is in motion.
• Then they act synergistically to stabilized the joint during the movement of the distal joint.
• e.g. short muscles of the shoulder estabilized the shoulder when – wrist fingers & elbow in movement
Actions of muscles
• Muscles act synergistically in another way
• This is to cancel out unwanted secondary effect.
• e.g. Tricep contract when the forearm is supinated while the elbow is flexed.
Actions of muscles
• This prevent the flexion of the elbow by the contraction of the biceps
• This will not oppose the supination action.
Assessment of Muscle Action• Common sense
• Feeling of contraction
• Pullin tendons in dead
• Nerve stimulation of motor nerve
• Electromyography
• Comparative anatomy
Action of Paradox
• Multiplicity of common movements are aided by gravity
• In such movements opposing muscles contract to keep the limb against the force of gravity
Action of Paradox
• e.g. When the arm adduct from abducted position
• Deltoid muscle contract which is a muscle of abduction
• This is known as action of paradox
Blood supply
• Muscles have a rich blood supply
• Arteries and veins pierce the surface in company with the motor nerve
• From muscle belly artery supply the tendon
• Lymphatics run back with arteries
• Large blood vessels enter the perimysium
• Branches of perimysial blod vesels ramify
• pass inbetween and surrounds the muscle fibers
Nerve supply of muscles
• Flat muscles of the body wall are pierced by cutaneous nerve
• They do not supply the muscles
Nerve supply of muscles
In limbs• If a nerve pierces a muscle that nerve supplies
the muscle
• The motor branch leaves proximal to the muscle
• In limbs nerves passes between muscle planes
• This planes distinct morphological masses that have fused together
Nerve supply of muscles
In limbs
• All the muscles are not supplied by plexus
• Flexor muscles are supplied by anterior divisions
• Extensor muscles are supplied by posterior divisions
Nerve supply of muscles
• Sensory supply
• In a nerve supply to a muscle contain 40% of sensory nerve fiber
Nerve supply of muscles
• Certain cranial nerves are purely motor (iii, iv, vi, vii, xii) supply ocular & facial muscles.
• Spinal accessory nerve also contain no sensory fibres
• Sensory supply to those muscles are derived from other adjacent nerves– e.g. trigemial V
Physiology of muscle
• All skeletal muscle in the body except heart is supplied by somatic nerves– Voluntary muscles
• Heart & all smooth muscles are supplied by autonomic nerves– Involuntary muscles
Physiology of muscle
• Smooth muscles can elongate to greater extend e.g. bladder
• Skeletal muscle cannot elongate 1/3 of their resting length
Naming of Muscles• The names given to individual muscles are
usually descriptive, based on
• their shape, size, number of heads or bellies
• Position, depth, attachments, or actions
Naming of Muscles
The terms used according to the Shape• Deltoid (= triangular)• Quadratus (= square)• Rhomboid (= diamond-shape)• Teres (= round)• Gracilis (= slender)• Rectus (= straight)• Lumbrical (= worm-like)
Naming of Muscles
The terms used according to the Size
• Major (large)
• Minor (small)
• Longus (= long)
• Brevis (=short)
• Latissimus (= broadest)
• Longissimus (= longest)
Naming of Muscles
The terms use according to the Number of heads or bellies
• Biceps (= 2 heads)
• Triceps (= 3 heads)
• Quadriceps (= 4 heads)
• Digastric (= 2 bellies)
Triceps Digastric
Naming of Muscles
The terms used according to the Position• Interosseus (= between bones)• Supraspinatus (= above spine of scapula)• Infraspinatus (= below spine of scapula)• Dorsi (= of the back)• Abdominis (= of the abdomen)• Pectoralis (= of the chest)• Brachii (= of the arm)• Femoris (= of the thigh)• Oris (= of the mouth)• Anterior , posterior,
Naming of Muscles
The terms used according to the Depth• Superficialis (= superficial)
• Profundus (=deep)
• Externus (or external)
• Internus (or internal)
Naming of Muscles
The terms used according to the Attachment
• sternocleidomastoid (from sternum and clavicle to mastoid process)
• coracobrachialis (from the coracoid process to the arm)
Naming of Muscles
The terms used according to the Action• Extensor , flexor
• Abductor , adductor
• Levator (= lifter), depressor
• Supinator , pronator
• Constrictor , dilator
Naming of Muscles
These terms are often used in combination:
E.G flexor digitorum longus (= long flexor of the digits)
latissimus dorsi (= broadest muscle of the back).
Pathology • Hypertrophy
• Atrophy
• Paralysis
• Ischaemia
• Necrosis
Tendons• Tendons are tissues that connect muscles to
bone, allowing the force of the muscles to move the joints.
• Tendons consist of longitudinally arranged collagen fibres
• Shape cylindrical or flat
• The aponeurosis of the abdominal wall muscles are wide sheats of tendons
Tendons
• Blood supply is by two main sources
• Descending vessels from the muscles
• Periosteal vessels from the bone of insertion
Tendons• In long tendons an additional supply present
• From neighboring artery
• If you tear (rupture) or cut (sever) the tendon anywhere along its route unable to move the distal part
• Tendons are stretched tightly as they connect the muscle to the bone. If the tendon tears, the end must be sewn back together again (a surgical repair)
Tendons
• Synovial sheaths
• Enclose tendons where the range of movement is considerable
• e.g. the tendon in the fingers
• this is to reduce the friction
Tendons
Tendons• Sheeth has two layers
– Parietal– Visceral
• Parietal layer firmly attach to the surrounding structures
• Visceral layer firmly fixed to the tendon
Tendons
• In between
• Thin layer of fluid lubricate the two layers & facilitate movements
• The visceral & parietal layers fused each other on one side
Tendons
• They do not enclose tendon cylindrically
• Tendon looks pushed into double layers of enclosed sheath
• Blood vessels can enter the tendon between this space
Tendons