General Introduction - Muscles Study of muscles – Myology / Sarcology Conductivity & contractility are the two main characteristics of muscle. Voluntary or skeletal muscles Involuntary or smooth muscles Cardiac muscles Muscles Voluntary or skeletal muscles Transverse lines are found at regular interval. Hence these muscles are also called as striped or striated muscle Muscle fibre is covered by a layer of connective tissue which is called Endomysium, Many muscle fibers are combined to form fasciculi, covered by Perimysium Many fasciculi combined to form a muscle, is also covered by a layer of connective tissue which is called as Epimysium Muscle fibres attached to a tough cord of connective tissue called Tendon & Tendon is further attached with a bone. LOCOMOTION AND MOVEMENT:
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General Introduction- Muscles
Study of muscles – Myology / Sarcology
Conductivity & contractility are the two main characteristics of muscle.
Voluntary or
skeletal muscles
Involuntary or
smooth musclesCardiac
muscles
Muscles
Voluntary or skeletal muscles
Transverse lines are found at regular interval. Hence these muscles are also called as striped
or striated muscle
Muscle fibre is covered by a layer of connective tissue which is called Endomysium, Many
muscle fibers are combined to form fasciculi, covered by Perimysium
Many fasciculi combined to form a muscle, is also covered by a layer of connective tissue
which is called as Epimysium
Muscle fibres attached to a tough cord of connective tissue called Tendon & Tendon is
further attached with a bone.
LOCOMOTION AND MOVEMENT:
Structure of muscle fibre
Fine structure of muscle fibre:
Outer membrane of muscle fibre is sarcolemma enclosed a
multinucleated sarcoplasm
Myofibril are arranged in parallel row & form the dark & light
line made up of actin & myosin protein.
Actin filaments are thin while myosin filaments are thick
Light band made up of only actin filament, these band are
monorefractive in polarised light so it is called Isotropic
band (I band).
Actin filaments are connected with Z–line protein (Actinin)
which is called as Z line (Zweichenschiebe) or (Double's
membrane) or (Krause's membrane).
Dark line is made up of actin & myosin, is double monorefractive in polarised light
due to overlapping so it is called Anisotropic band.
Terminal end of actin filament are embedded among the myosin filament so peripheral part of a
band is darker as compared to the middle part of A band called as H-Zone or Hensen zone
Diagrammatic representation of
(a) anatomy of a muscle fibre
showing a sarcomere
(b) a sarcomere
Chemical Composition of Skeletal Muscles
A dark line is also found in the central part of H-zone which is called as M line.
The distance between two Z–lines is Sarcomere.
Sarcomere = 1A band + two half I band.
1 Myosin filament is surrounded by 6 Actin filaments & 1 Actin filament is surrounded by 3
At the point of fusion of above bones is a cavity called acetabulum to which thigh bone
articulate.
Two halves of the pelvis girdle meet ventrally to form the pubic symphysis containing
fibrous cartilage.
Sternum
Sternum divided into Manubrium, body and xiphoid process.
Manubriums lateral border joints with first rib pair.
In its clavicular notch, clavicle bone articulates.
Body (Middle part) forms joint with lower part of 2nd C.C. & 3rd to 6th C.C. & upper
half of 7th CC
Lower part Xiphoid process, Smallest part, lower half of 7th C.C. articulates.
THE RIBS
12 pairs of ribs connected dorsally to the
vertebral column and ventrally to sternum.
Rib has two articular surfaces hence called
as bicephalic.
First 7 ribs are True Ribs, Vertebrosternal ribs
Remaining 5 are False Ribs, 8th, 9th & 10th
ribs are Joined to the next higher cartilage,
called Vertebrochondral ribs, 11th & 12th ribs
are free & are called floating ribs (Vertebral
ribs).
Costal cartilages are unossified anterior parts
of ribs are made of hyaline cartilage
C.C. of first seven ribs are directly attached
to sternum. 8th, 9th & 10th C.C. articulate
with one another. The cartilage of 11th & 12th ribs are small.
THE VERTEBRAL COLUMN
Made of 33 vertebrae or 26 bones
Formula = C7T12L5S 5 C(4), ∴ 24
movable or true vertebrae and (5) +
(4) = 9 fused or false vertebrae
(immovable) Sacrum & coccyx.
Vertebral column has 4 curvatures
which are known as cervical,
thoracic, lumber and pelvic
curvature.
Cervical vertebrae
All cervical vertebrae have Foramina transversal is which aligned to form vertebrarterial
canal through which artery passes.
Spinous process of cervical vertebrae is bified (Except C7)
The number of cervical vertebrae are seven
Atlas (𝐂𝟏)
Centrum and Pre and postzygapophysis
processes are absent
The foramen divided into two parts by a
ligament. In upper part, spinal cord is
present. In lower part, Odontoid fossa is
present in which odontoid process of axis
is fitted to make medial Atlanta-axial joint
(Pivot Joint).
Articular facets are present. In upper pair
of articular facets condyles of skull are
fitted to make Atlanto-occipital joint, in
lower pair of articular faceles condyles of
axis are fitted to make lateral Atlanto-
axial joint.
Atlas and Axis
Atlas (𝑪𝟐)
Centrum present, Neural spine well
developed and bifid. Prezygapophysis
processes are absent but post
zygapophysis processes are present.
Other Vertebrae
Thoracic Vertebrae
They are identifying by the presence of costal demifacetes.
On their transvers processes articulates ribs
Lumbar vertebrae are the largest sized
vertebrae because they have to support the
weight of upper body
SACRUM formed by fusion of five sacral
vertebrae, it is large Hat and triangular bone
Coccyx formed by fusion of 4 coccygeal
vertebrae.
SKULL
Skull consist of 29 bones
Cranium – 8
Face – 14
Ear Ossicles – 3 + 3 = 6
Hyoid – 1
All skull bones (except mandible & ear ossicles) are immovable
Cranium (Brain box) encloses the brain, has large opening called foramen magnum
Cranium:
Cranium Bones – [8]
All these bones of skull are joined together by suture,
E.g. (1) Coronal suture: Between the frontal and parietal bone
(2) Lambdoid suture: Between parietal and - occipital
Frontal bone [1] forms the forehead and
roofs of eye sockets
Parietals bones [2] form the roof of
cranium and maximum part of side of
cranium.
Occipital bone [1] has magnum is present,
on each side of this foramen one condyle is
present called as occipital condyle which fit
in particular faceted of atlas vertebrae. So
the human skull is dicondylic.
Temporal bones [2] form the lower parts of each sides of cranium.
In the house of this bone internal and middle ear are present - Malleus, incus,
stapes.
Sphenoid bone [1] forms middle and anterior part of base of cranium.
It articulates with frontal bone occipital bone and temporal.
In this bone Sella turcica is present in which pituitary gland is situated.
Ethmoid bone [1] in front of sphenoid and behind nasal bones.
Sensory capsule
1. Malleus (Modification of articular bone)
2. Incus (Modification of Quadrate bone)
3. Stapes modification of Hyomandibular bone
Facial - Bones
Nasal bones [2] forms dorsal surface of nasal chambers.
Inferior turbinal’s [2] situated on lateral surface of more. There projections are called
turbinels which projected into nasal cavity
Vomer [1] present is posterior part of nasal chambers.
Lachrymal [2] located in the lateral sides of nasal bones, also form a part of the wall
of eye sockets.
Zygomaticus or malar bones also called as cheek bones. Forms the prominences of
our cheeks.
Palatines [2]: 'L' shaped bones that form the (posterior) part of our hard palate
Maxillary [2]: Large, upper jaw bones that form the major part of our face and upper
jaw comprise anterior part of our hard palate.
Mandible [1] is only movable bone of skull. In the posterior part of this bone condyle is
present which fit in the cavity of temporal bone
Lower jaw is attached with cranium this suspension is called craniostylic.
Hyoid bone [1] (Tongue bone) between lower jaw and larynx, it is not articulated to any bone of axial skeleton.
JOINTS - 1
Fibrous joints (Immovable) or Synarthrosis
Synovial joints or Diarthrosis
Cartilaginous joints (Slightly movable) or Amphiarthrosis
Sutures - Immovable: e.g. Skull
Syndesmosis: Bones are connected by interosseous ligament e.g. inferior tibio fibular joints
Gomphosis – e.g. tooth in its socket
Primary or synchondrosis, after certain age the cartilage is replaced by bone. e.g. joint between Epiphysis & Shaft
Secondary or Symphysis fibro cartilage or hyaline cartilage is present between two bones at joint. e.g. Symphysis pubis, intervertebral disc, between rib and sternum.
Plain synovial or gliding joint: Permit slight gliding movement e.g., joint between zygapophysis, between carpals, between tarsals processes of vertebrae
Hinge Joint: Movements are permitted in one plane around transverse axis e.g. elbow joint, ankle joint, interphalangeal joint, knee joint
Pivot Joint: movement are permitted in one plane around vertical axis. e.g. radioulnar joint, median Atlanta axial joint.
JOINTS - 2
Condylar joint: Movement are permitted in both transverse & vertical axes. E.g. Jaw joint,
Knee joint, Atlanto-Occipital joint.
Ellipsoid joint: Movement are permitted in both axis. e.g. Wrist joint,
Metacarpophalangeal joint.
Saddle Joint are improperly developed ball & socket joints e.g. first carpometacarpal joint.
Ball & socket joint: Movements are around infinite axis. e.g. Shoulder & Hip joint.
Disorders of Bones:
Arthritis
Caused by the inflammation of the joints.
The rheumatoid arthritis: It is diagnosed by the presence of rheumatoid factor (a type of immunoglobulin IgM).
Primary symptom inflammation of synovial membrane
If it is left untreated, membrane then starts secreting abnormal granules, called pannus,
which after accumulating on the surface of the cartilage, cause its erosion. As a result, the
fibrous tissues are attached with the bones and become ossified, making the joints immovable.
Osteoarthritis characterized by the degeneration of the articular cartilage, afflicted joints are of spine, knees and hands.
Gouty arthritis or gout caused either due to excessive formation of uric acid, gets deposited in joints as monosodium salt.
Osteoporosis characterized by decreased bone mass increased changes of tractures. Decreased level of estrogen is a common cause.