by dr mb samarawickrama (mbbs ms) 31 th batch july 2008 muscles and tendons
TRANSCRIPT
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