2. Human skeleton
Tissue : it is defined as a group of cells that possess a similar structure and perform a
specific function.
The word tissue originates from French, which means “to weave.”
3. The vertebrate skeleton is composed either of cartilage or bone.
Both tissues provide an internal supporting framework of the body.
Human adults have bony skeleton, but cartilage is also present in some regions
4. Cartilage
Cartilage is a type of connective tissue consisting of cells called chondrocytes and a
tough flexible matrix made of type II collagen.
Unlike other connective tissues, cartilage does not contain blood vessels and the
chondrocytes are supplied by diffusion. Because of this, it heals very slowly.
Key Point
Function of chondrocytes: involved in nutrient diffusion and matrix
repair.
Chondrocytes are the only specialized cell type found in the
cartilage tissue.
5. Collagen is protein molecules made up of amino
acids.
It provides structural support to the extracellular
space of connective tissues.
Due to its rigidity and resistance to stretching, it is
the perfect matrix for tendons (tissue that connects
muscle to bone), bones, and ligaments (bone to
bone).
Collagen
6. The human skeleton is made up of cartilages and fibrous membranes, most of these early
supports are soon replaced by bones.
A few cartilages that remain in adults are found mainly in regions where flexible skeletal
support is needed.
Key Point
Fibrous membranes are thin tissue layers that cover some organs and body
cavities of the human body.
Made up of tough protein fibers called collagen.
7. Three types of cartilage in human body
1. Hyaline cartilage
2. Elastic cartilage
3. Fibrocartilage
8. Hyaline cartilage is slippery and smooth which helps your bones move smoothly past
each other in your joints. It’s flexible but strong enough to help your joints hold their
shape.
Hyaline cartilage locations in your body include:
At the ends of bones that form joints.
Between your ribs.
In your nasal passages.
9. Fibrocartilage is tough cartilage made of thick fibers. It’s the strongest and least flexible
of the three types. It’s tough enough to hold parts of your body in place.
Fibrocartilage locations in your body include:
The meniscus in your knee.
In disks between the vertebrae in your spine.
11. Elastic cartilage : is most flexible cartilage. It supports parts of your body that need to
bend and move to function.
Elastic cartilage locations in your body include:
Your external ears.
In your voice box.
12. Bone
Provides rigid framework.
Support and protect delicate internal organs.
Act as a storage place for some minerals.
Make up less than 20% of the body mass.
14. Composition of Bone
Rigid form of connective tissue.
Bone is living hard and strong structure.
It consist of hard ground substance or matrix and cells.
In the adult human, the matrix consist of about;
65% inorganic matter (calcium, phosphate and carbonate).
35% organic substances (protein, type I collagen) and cells are
embedded in the matrix.
17. Bone is surrounded by membrane or periosteum.
The prefix per- means around. The root word -
oste means bone and the suffix -um means
tissue.
18. Blood vessels in the periosteum connect back to your circulatory system to supply fresh,
oxygen-rich blood to your bones.
Nerves in the periosteum give your bones and the area around them feeling.
19. Below the periosteum is a layer of bone forming
cells (osteoblast).
It secrets bone substance (proteins), which helps in
increasing the thickness or diameter of bone and
repairing a break or other damage to the bone.
Osteoblasts : are the cells that form new bones and grow and heal existing bones.
20. Bone contains numerous round canals, the
Haversian Canals.
Haversian canals are microscopic tubes or
tunnels in bone that house nerve fibers and a
capillaries. This allows bone to get oxygen
and nutrition
21. Haversian Lamellae. It's the extracellular matrix around the cells that gives compact bone
its hardness and rigidity.
Each canal is surrounded by
concentrically arranged boney plates
called Haversian lamellae that consist of
calcified matrix in which collagen fibers
are embedded.
22. The fluid filled spaces present between the lamellae are called lacunae (radiate
canaliculi).
In which the bone cells called osteocytes are present that communicate with each
other by a network of fine canals called canaliculi.
Canaliculi helps the bone cells to receive food and oxygen and also to eliminate waste
materials.
23. The harversian canal together with
its surrounding lamellae, lacunae
and canaliculi constitute the
Haversian system.
24. Bone Marrow
Bone contain soft tissue called bone marrow.
Red bone marrow : Found in spongy
bone, the ends of the long bones, ribs,
vertebrae, the sternum and the pelvis.
Produce RBC’s
Platelets.
WBC’s
Yellow bone marrow : fills the shafts of
long bones.
It contains mostly of fat cells and serves
as an energy reserve.
25. Bone cells
There are three types of cells in human bones. These cells are responsible for bone growth and
mineral homeostasis;
Osteogenic
Osteoblasts
Osteocytes
Osteoclasts
26. Osteogenic cells are the only bone cells that divide.
Osteogenic cells differentiate and develop into
osteoblasts which, in turn, are responsible for forming
new bones.
27. Osteoblasts synthesize and secrete a collagen matrix
and calcium salts.
A mononucleate cell from which bone develops.
28. Osteocyte: A mature bone cell involved with the
maintenance of bone.
34. 1. Maxilla: This bone forms the upper jaw and supports
the teeth in the upper arch.
35. 2. Mandible : This bone forms the lower jaw and is the only movable bone in the skull.
The mandible is the largest and strongest bone in the face.
50. The xiphoid process is a small, triangular
part of the sternum.
Its main function is to act as an area for
muscular attachment.
The jugular notch provides an attachment
site for the interclavicle ligament.
52. 1. Pectoral girdle
Clavicles (Collar Bones): Pair of curved
bones.
One end articulates with the sternum.
The other end articulates with the scapula.
Scapula (Shoulder Blades): Pair of flat,
triangular bones.
53. 2. Upper Limb (Forelimb)
Humerus: Long bone with a spherical head.
Head fits into the glenoid cavity (a shallow
depression) of the scapula.
Radius: Long bone on the thumb side of the
forearm. Outer bone of the forearm.
Ulna: Long bone on the inner side of the
forearm. Slightly bigger than the radius.
54. Carpals: 2 rows of 8 short bones forming the
wrist. Upper row articulates with the radius to
form the wrist joint.
Metacarpals: Five bones forming the palm of
the hand.
Phalanges: Bones of the fingers. 3 phalanges in
each finger, except the thumb which has 2.
55. 3. Pelvic Girdle
Composed of three bones:
Ileum
Ischium
Pubis
These 3 bones form the coxal (hip bone).
The two halves of the pelvic girdle are joined at the pubic symphysis.
Acetabulum: A cavity present where the head of the femur fits to form the hip joint.
56. 4. Lower Limb (Hind Limb) :
Femur (Thighbone): Long bone with a head that
fits into the acetabulum.
Patella (Kneecap): A small bone embedded in the
tendon running over the knee joint.
Tibia (Shin Bone): The large and strong bone in the
leg.
Fibula (Outer Bone): A thin bone parallel to the
tibia, joined just below the knee and above the
ankle.
57. Tarsals : Seven tightly attached bones forming the
ankle.
Metatarsals : Five bones that form the sole of the
foot, articulating with the tarsals and phalanges.
Phalanges : Small bones making up the toes. Each
toe has three phalanges, except the big toe, which
has two.
58. Joints or Articulations
The sites where two or more bones meet are called joints or articulations.
Functions:
Provide mobility to the skeleton.
Hold the skeletal parts together.
59. Structural Classification of Joints
Based on:
The material binding the bones together.
The presence or absence of a joint cavity.
60. Structure: A thin layer of fibrous connective tissue holds the bones firmly in position. No
joint cavity is present.
Movement: Generally immovable.
Functions: Provide strength and support for the body.
1. Fibrous Joints
Examples:
Between the bones of the skull.
Between sacrum and iliac of pelvic girdles.
Between the bones of the pelvic girdle.
61. 3. Cartilaginous Joints
Structure: Connected entirely by fibrocartilage or hyaline cartilage.
No joint cavity is present.
Movement: Allow slight movement; bones can glide over each other to a limited extent.
Examples:
Between vertebrae.
Between wrist and ankle bones
62. 4. Synovial Joints
Structure: Articulating bones are separated by a fluid-containing joint cavity (synovial
cavity).
Reinforced and strengthened by ligaments.
Movement:
Freely movable.
63. Hinge Joints:
Structure: A cylindrical projection of one bone
fits into a trough-shaped surface on another.
Movement: permit (allow) movement in one
plane (flexion-bending movement and
extension-straighten only).
Examples: Elbow, knee joint.
Types of Synovial Joints
64. Ball-and-Socket Joints:
Structure: The spherical or hemispherical head of one bone articulates with the
cuplike socket of another.
Movement: The most freely moving synovial joints.
Examples: Shoulder, hip joints.
65. Disorder of Skeleton
Although the human skeleton is hard and strong, deformities can occur.
These deformities may result in reduced movement or complete immobility.
Deformities of the skeleton can be caused by :
Genetic factors
Hormonal imbalances
Nutrient deficiencies
66. Disc Slip
A term often used to describe the condition where a
disc may split or rupture, allowing the inner gel
portion to escape into surrounding tissue, causing
pain and pressure on the spinal cord or nerves.
Intervertebral Discs: Protective shock-absorbing
pads located between the bones of the spine
(vertebrae).
67. Herniated Disc: The correct term for a
condition where the inner gel portion of the
disc (nucleus pulposus) protrudes through the
outer ring (annulus fibrosus).
Commonly Affected Area: The lower
back, though herniation can occur in any
disc, including those in the neck.
68. Causes:
Aging, leading to degeneration and loss of elasticity of discs and supporting
structures.
Injury from improper lifting, especially with twisting or turning.
Excessive strain forces associated with physical activities.
69. Disc Structure:
Nucleus Pulposus: Inner semifluid that gives the disc its elasticity and
compressibility.
Annulus Fibrosus: Strong outer ring of fibrocartilage that holds vertebrae together
and maintains disc structure.
Function: Discs act as shock absorbers for the spine.
Trauma: Severe or sudden trauma to the spine can result in herniation, leading to
pain or nerve damage.
Misconception: The term "slipped disc" is misleading, as the entire disc does not slide
out of position; rather, the inner gel protrudes through a rupture in the outer ring.
70. Spondylosis
Spondylosis (Spinal Osteoarthritis): A
degenerative disorder leading to the loss of
normal spinal structure and function.
Primary Cause: Aging.
Affected Regions: Can impact the cervical
(neck), thoracic (mid-back), or lumbar
(lower back) regions of the spine.
Individual Variation: The location and rate
of degeneration vary from person to person.
71. Sciatica
Symptoms: Pain, weakness, numbness or tingling in the leg.
Cause: Injury to or pressure on the sciatic nerve, which starts in the lower spine and runs
down the back of each leg.
Common Causes:
Slipped disc
Piriformis syndrome (pain disorder involving a narrow muscle in the buttocks)
Pelvic injury or fracture
Tumors
73. Arthritis
Inflammation of joints characterized by symptoms such as:
Pain after walking, which may later occur even at rest.
Creaking sounds in the joint.
Difficulty getting up from a chair.
Pain when walking up and down stairs.
Causes:
Broken bone
Infection in the area
Autoimmune disease
General wear and tear on joints
74. Types of Arthritis
Osteoarthritis: A progressive disease where articular cartilages gradually soften and
disintegrate, commonly affecting the knee, hip, and intervertebral joints.
Rheumatoid Arthritis: An autoimmune disorder where the synovial membrane
becomes inflamed due to a faulty immune system.
Gouty Arthritis: Caused by a metabolic disorder, leading to an abnormal amount of
uric acid in the blood, with sodium urate crystals deposited in joints, commonly
affecting the big toe.
76. Bone Fractures
The medical term for a broken
bone.
Occurs when the physical force
exerted on the bone is stronger
than the bone itself.
Bones break when they cannot
withstand the force or trauma
applied to them.
77. Common Types of Fractures
Simple Fracture
(Closed Fracture): The
skin remains intact, and
the bone does not
penetrate the skin.
Compound Fracture
(Open Fracture): The
bone ends penetrate the
skin, forming an open
wound.
Complicated Fracture:
A fracture that also
damages adjacent
organs.
78. Bone Repair
Bone is a living tissue that undergoes repair following fracture.
The repair process of a simple fracture takes place in four major steps:
Formation of Hematoma
Formation of a Fibrocartilaginous Callus
Formation of a Bony Callus
Bone Remodeling
79. Repair of Bone fractures
A fracture is treated by reduction which follows realignment (the action of changing
or restoring) of the broken bone ends.
There are two types of reduction:
Closed Reduction
Open Reduction
80. Closed Reduction
In closed reduction the bone ends are coaxed
(to do something gently) back to their normal
position by physician’s hand.
81. Open Reduction
In open reduction surgery is performed and the
bone ends are secured together with pins or
wires.
After broken bone is reduced, it is immobilized
by a cast (or by traction) to allow the healing
process to begin.
Healing time is 8-12 weeks, but it is much
longer for large weight bearing bones and for
bones of elderly people (because of their poorer
blood circulation).
82. Hematoma or Clot Formation
When a bone breaks, blood vessels in the bone and
surrounding tissues are torn, leading to hemorrhage.
A hematoma, or mass of clotted blood, forms at the
fracture site.
Bone cells deprived of nutrition die, and the tissue at the
site becomes swollen, painful, and inflamed.
83. Fibrocartilaginous Callus Formation
Within a few days, capillaries grow into the hematoma.
Phagocytic cells invade the area and begin cleaning up the debris.
A fracture ruptures the periosteum, stimulating the production
and release of osteoblasts.
Osteoblasts, along with cartilage-forming cells, secrete a porous
mass of bone and cartilage called a callus (or cartilaginous
callus).
The callus replaces the original blood clot and holds the ends of
the bones together.
This process takes 3-4 weeks.
84. Bony Callus Formation or Callus Ossification
Within a week, the soft callus is gradually converted
into a hard bony callus of spongy bone.
Bony callus formation continues until a firm union is
formed, typically around two months later.
Osteoclasts break down the cartilage, while osteoblasts
replace it with bone.
85. Bone Remodelling
Compact bone forms across the fracture line to
connect both sides.
Initially, more bone is produced at the healing site than
needed to replace the damaged tissue.
Osteoclasts gradually remove the excess bone.
The final structure resembles the original bone,
adapting to the same mechanical stressors as before.
86. Torsion (twisting) or sudden impact to the
side of a joint can be devastating.
Joint Injuries
87. A dislocated joint is a joint that slips out of
place. It occurs when the ends of the bones
are force away from their normal positions.
Results in improper joint function.
Severe dislocation can tear muscles,
ligaments, and tendons supporting the joint.
Joint Dislocation
88. Symptoms:
Swelling,
intense pain,
immobility of the affected joint.
Causes:
Blow, fall,
trauma, disease, or defective ligament.
rheumatoid arthritis can also cause dislocation.
Treatment:
Reduction by a medical professional.
surgery may be needed to repair or tighten ligaments.
89. Sprain
Injury to a ligament, often occurring in the
ankle, knee, or wrist.
Caused by ligaments being stretched too far
from their normal position.
Ligaments:
Function to hold the skeleton together and
maintain normal alignment.
Prevent abnormal movements but can be
stretched when excessive force is applied,
such as during a fall.
90. Treatment:
Resting the sprain.
Icing and physical therapy.
Immobilizing the sprain with dressings, bandages, or ace-wraps for support.
91. Muscles
Origin:
Muscle is a specialized tissue of mesodermal origin (Mesoderm is the
middle developmental layer between the ectoderm and endoderm,
which gives rise to the skeleton, muscle, heart and bones.)
Body Mass:
Makes up nearly half of the human body mass.
Functional Characteristic:
Ability to transform chemical energy (ATP) into mechanical energy.
92. Functions:
Movement: Provide movement of body parts or the whole body.
Posture: Hold body parts in postural (the position of the body in space) positions.
Fluid Movement: helps in the movement of body fluids.
Heat Production: Generate heat through muscle contractions.
Study: The study of muscles is called myology.
93. Types of Muscles
There are three Types of Muscles
1. Skeletal Muscles
2. Cardiac Muscles
3. Smooth Muscles
94. 1. Smooth Muscle
Distribution: Widely distributed throughout the body with varied
functions.
Cell Shape: Spindle-shaped cells.
Nucleus: Single nucleus located centrally in each cell.
Myofilament (protein filaments) Organization:
Myofilaments are not organized into sarcomeres.
Lack of striated appearance due to this.
Intermediate Filaments: Contain non-contractile intermediate
filaments (cytoskeletal structural component).
95. Function: Involuntary control.
Locations: Found in the walls of hollow visceral (smooth) organs such as:
Stomach
Urinary bladder
Respiratory passages
Blood vessels
96. 2. Cardiac Muscle
Location:
Found only in the heart.
Constitutes the bulk (mass) of the heart walls.
Cell Shape:
Branch extensively.
Characteristic branching pattern
Nucleus:
Each cell usually contains one nucleus located near the center
97. Striations:
Striated like skeletal muscle.
Intercellular Connections:
Adjacent cells join to form branching fibers.
Specialized cell-to-cell attachments called intercalated discs.
Intercalated discs have gap junctions that allow action potentials to pass
from cell to cell.
98. Function:
Involuntary control.
Rhythmic contraction pumps blood throughout the body.
Contraction rate can be adjusted by neural controls for brief periods.
Control:
Usually contracts at a steady rate.
Neural controls can increase the rate temporarily.
99. 3. Skeletal Muscle
Attachment:
Attached to and cover the bony skeleton.
Responsible for movements of body parts
and whole body movements
(locomotion).
Cell Characteristics:
Skeletal muscle fibers are multinucleated.
Longest muscle cells.
Exhibit obvious stripes called striations.
100. Control :
Under voluntary control.
Contraction :
Can contract rapidly.
Tends to fatigue easily and requires rest after short periods of activity.
Capable of exerting tremendous power.
Adaptability :
Remarkably adaptable in force exertion.
Example: Hand muscles can exert forces ranging from a fraction of an ounce
to several pounds.
Primary Functions:
Involved in locomotion, Responsible for changes in body posture.
102. Structure of Skeletal Muscles
Skeletal muscles are attached to the skeleton.
Externally, muscle is covered in a connective
tissue wrapping called epimysium.
Each muscle is divided into bundles of muscle
cells called fascicles. The fascicle is
surrounded by perimysium.
Each muscle fiber within the fascicle is
covered by a layer of connective tissue called
endomysium.
103. The main function of epimysium is the protection of muscles from friction against other
muscles and bones.
The endomysium’ separates single
muscle fibres from one another. It
allows their autonomous gliding
during muscle contraction.
The perimysium contributes to
provide a path for nerves and blood
vessels.
The muscle fascicle is made up of groups of muscle fibers bundled together which allow
the fascicle to produce more force during contraction.
104. Each fiber consists of a semi fluid matrix, the sarcoplasm containing many nuclei and
large number of mitochondria.
Sarcolemma is the name of the cell
membrane that encloses each muscle
cell.
The sarcolemma of muscle fiber cell
penetrates deep into the cell to form
hollow elongated tube called
transverse tubule T-tubule.
T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into
the center of muscles cells.
105. The sarcoplasm contains the
sarcoplasmic reticulum.
It contains usually large amount of
stored glycogen and unique oxygen
bonding protein myoglobin, a red
pigment that stores oxygen.
106. When viewed in high magnification: Each muscle fibre
is seen to contain a large number of myofibrils 1-2 mm in
diameter that run in parallel fashion and extend entire
length of the cell.
The myofibrils consist of smaller contractile
units called sarcomere (actin+myosin).
In each sarcomere a series of dark and light
band are evident along the length of each
myofibril.
107. Each dark band is called A band,
because it is anisotropic ( direction-
dependent), i.e. it can polarize visible
light.
It gives the cell as a whole its striped
appearance.
Each A band has a lighter stripe in its
mid section called H – zone (H stands for
“hele” mean bright).
108. The H-zone is bisected by dark line called M - line. The I bands have mid line called Z -
line (Z for zwishen means between).
A sarcomere is the region of a
myofibril between two
successive Z - lines and is the
smallest contractile unit of
muscle fibre.
111. Infrastructure of Myofilament
The myofibrils contain myofilaments. Myofilament is made up of thick and thin
filaments.
The central thick filaments
extend the entire length of the
A-band.
The thin filaments extend
across the I-band and partly
into A band.
112. Thick Myofilament
The thick filament which is about 16 nm in diameter is composed of myosin.
Each myosin molecule has a tail terminating in two globular heads.
Myosin tail consists of two long polypeptide chains coiled together.
The heads are sometimes called cross bridges because they link the thick and the thin
myofilaments together during contraction
113. Thin Myofilament
Thin filaments are 7 - 8 nm thick and are composed chiefly of actin molecule.
The actin molecules are arranged in two chain which twist around each other like a
twisted double strand of pearls.
Twisting around the actin chains are two strands of another protein, tropomyosine.
114. The other major protein in thin filament is troponin.
It is actually three polypeptide complex, one binds to actin, another binds to tropomyosin
while third binds calcium ions.
Each myosin filament is surrounded by six actin filaments on each end.
115. Muscle Contraction-Sliding Filament Model
The sliding filament hypothesis, proposed by H.E. Huxley and A. F. Huxley, states that
muscle contraction occurs as thick and thin filaments slide past each other without
changing length.
The sliding filament theory of contraction states that during contraction, thin
myofilaments slide past thick ones, causing greater overlap.
116. In a relaxed muscle fiber, thick and thin myofilaments overlap only at the ends of the A
band.
When stimulated by the nervous system, myosin heads attach to binding sites on actin in
thin myofilaments, and sliding begins.
These links, called cross bridges, form and break repeatedly during contraction, generating
tension and moving thin myofilaments toward the center of the sarcomere.
Sarcomeres throughout the muscle cell contract simultaneously, leading to muscle cell
shortening.
During contraction, I bands shorten, the distance between Z discs decreases, the H zone
disappears, and A bands move closer together without changing length.
118. Muscle Contraction Process
Muscle contraction is initiated by a nerve
impulse at the neuromuscular junction.
The impulse travels through the sarcolemma
to the T tubules and then to the sarcoplasmic
reticulum (SR). Calcium gates in the SR
open, releasing calcium into the cytosol.
Calcium binds to troponin, causing a shift in
tropomyosin to expose myosin binding sites
on actin.
119. Myosin heads attach to actin,
hydrolyze ATP, and power the
heads forward, breaking cross
bridges and repeating the cycle.
As long as calcium and ATP are
available, myosin heads continue
to slide along actin filaments,
contracting the sarcomere and
muscle.
120. Control of Muscle Contraction
Contractility is essential for movement, except growth and cytoplasmic streaming.
Muscle fiber contraction is an all-or-none phenomenon; fibers contract to a set length
regardless of the stimulus intensity.
Fine control of muscular activity is achieved through motor units, where a motor neuron
branches to stimulate multiple muscle fibers.
The strength of muscle contraction depends on the number of motor units activated by
motor neurons.
More active motor units result in stronger overall muscle contraction.
121. Antagonistic Arrangement of Skeletal Muscles
•Bones are connected to each other through ligaments.
•When a muscle contracts, one end remains stationary (origin) while the other end is drawn
towards it (insertion).
•The origin is the point of attachment that stays stationary, while the insertion is the point that
moves.
•The belly is the thick part of the muscle between the origin and insertion that contracts.
122. During muscle contraction, the insertion point moves towards the origin, causing one bone
to move on the other at the joints.
Flexor muscles bend the bone at the joint when they contract.
Extensor muscles straighten the bone at the joint when they contract.
Muscles work in pairs for bone movement in two directions; when flexors contract,
extensors relax, and vice versa.
This arrangement of muscles is known as the antagonistic arrangement.
123. Muscle Attachment:
Bones are connected by ligaments.
Muscles attach to bones at two points: origin (stationary end) and insertion
(moving end).
Muscle Function:
When a muscle contracts, the origin remains stationary while the insertion
moves toward it.
The thick part of the muscle between origin and insertion is called the belly.
124. Antagonistic Arrangement:
Muscles work in pairs to move bones in two directions.
When flexors contract, extensors relax, and vice versa.
Types of Muscle Action:
Flexor Muscle: Contracts to bend the bone at a
joint.
Extensor Muscle: Contracts to straighten the
bone at a joint.
125. Movement in knee joint
The knee joint is located between the femur and tibia.
It is a complex hinge joint that allows limited rolling, gliding, flexion, and extension.
Flexion is performed by the flexor muscles, mainly the hamstring muscles located at the
back of the thigh.
The biceps femoris, a major hamstring muscle, has two origins: one from the pelvic
girdle and one from the femur.
Its tendon attaches to the upper part of the tibia and fibula.
126. The knee joint is the biggest joint in your
body. It connects your thigh bone (femur) to
your shin bone (tibia). It helps you stand,
move and keep your balance.
127. Extension is performed by the extensor muscles, primarily the quadriceps femoris
located at the front of the thigh.
These muscles originate at the ilium and femur and come together in a tendon
surrounding the patella (kneecap).
They insert at the tibia and are essential for standing, walking, and most leg movements.
128. Muscle Problem
A muscle problem refers to any disorder or issue affecting the function, structure, or
health of muscles.
These problems can result from various causes, including injury, disease, or overuse.
129. Cramps
Sudden, involuntary contractions or spasms
in one or more muscles.
They often occur after exercise or during the
night, lasting from a few seconds to several
minutes.
130. Causes:
Nerve Malfunction: Abnormal nerve activity can trigger cramps.
Muscle Strain or Overuse: Excessive use or strain on a muscle can lead to cramps.
Dehydration: Inadequate fluid levels can contribute to cramping.
Mineral Deficiency: Lack of essential minerals in the diet or depletion of minerals in the
body, such as potassium, calcium, or magnesium.
Insufficient Blood Flow: Reduced blood flow to the muscles can cause cramping.
131. Muscle fatigue
A condition where a muscle’s ability to
generate maximum contraction decreases,
even though it may still receive stimuli.
132. Causes:
Decline in ATP: The availability of ATP (adenosine triphosphate) decreases during
contraction.
A complete lack of ATP leads to contractures (permanent tightening), where muscles
remain in a state of continuous contraction because cross bridges cannot detach.
Lactic Acid Accumulation: Excessive buildup of lactic acid in muscles lowers pH and
alters contractile proteins, causing muscle ache and fatigue.
Ionic Imbalances: Disruptions in ion concentrations within the muscle cells contribute
to fatigue.
133. Tetany
Definition: A symptom characterized by muscle cramps, spasms due to uncontrollable
muscle contractions.
Affected Muscles: Can occur in any muscle of the body, including those in the face,
fingers, or calves.
Symptoms: Muscle cramping associated with tetany can be long-lasting and painful.
Common Cause: Very low levels of calcium in the body.
134. Tetanus
Definition: An infection of the nervous system caused by the bacteria Clostridium tetani.
Source: Spores of C. tetani are found in soil worldwide and can remain infectious for over
40 years.
Infection Pathway: Begins when spores enter the body through an injury or wound.
Mechanism: The spores release bacteria that produce a toxin called tetanospasmin, which
blocks nerve signals from the spinal cord to the muscles.
Symptoms: Causes severe muscle spasms, which can be powerful enough to tear muscles
or cause spinal fractures.
