CBSE Class 11 Biology Locomotion And Movement Enrichment Worksheet Set A

Locomotion and Movement MCQ Questions with Answers Class 11 Biology 

Question. ATP binding site is located on the
(a) Tropomyosin
(b) Actin
(c) Myosin
(d) Troponin
Answer: C

Question. The dark band present on myofibril is
(a) Isotropic band
(b) Anisotropic band
(c) Hensen’s zone
(d) M-line
Answer: B

Question. Muscle fatigue occurs due to accumulation of
(a) CO₂
(b) Myosin ATPase
(c) Lactic acid
(d) Creatine phosphate
Answer: C

Question. Number of floating ribs are
(a) 2 pairs
(b) 12 pairs
(c) 7 pairs
(d) 3 pairs
Answer: A

Question. The two cells of the body which show pseudopodial movement are
(a) RBC and WBC
(b) WBC and macrophages
(c) Liver cell and WBC
(d) Macrophages and liver cell
Answer: B

Question. Which of the following structures contract and relax rhythmically to produce movement?
(a) Flagella
(b) Cilia
(c) Muscles
(d) Pseudopodia
Answer: C

Question. Amoeba shows movement with help of
(a) Pseudopodia
(b) Flagella
(c) Cilia
(d) Muscle
Answer: A

Question. The muscle is a specialised tissue which is originated from
(a) Endoderm
(b) Mesoderm
(c) Ectoderm
(d) Yolk sac
Answer: B

Question. The specialised cells that make the muscular tissue are
(a) Neuroblast
(b) Osteoblast
(c) Osteocytes
(d) Myocytes
Answer: D

Question. A human body contains how many muscles?
(a) 640
(b) 639
(c) 600
(d) 700
Answer: B

Question. A collagenous connective tissue layer hold the muscle bundles together.
(a) Perimysium
(b) Endomysium
(c) Epimysium
(d) Fascia
Answer: D

Question. Which of the following is not a function of locomotion?
(a) Procurement of food
(b) Finding mate
(c) Peristaltic movements
(d) Searching and building of shelter
Answer: C

Question. The sheath covering the bundle of muscle fibres is
(a) Epimysium
(b) Endomysium
(c) Perimysium
(d) Mesoderm
Answer: C

Question. __________ circulates blood to different parts of the body.
(a) Peristaltic movement of oesophagus
(b) Pumping of heart
(c) Peristaltic movement of intestine
(d) Ciliary movement of oviduct
Answer: B

Question. Tendons connects
(a) Muscle to bone
(b) Bone to vertebral column
(c) Bone to bone
(d) Bone to cartilage
Answer: A

Question. The plasma membrane of the muscle fibre is called
(a) Sarcoplasma
(b) Sarcolemma
(c) Sarcoplasmic Reticulum
(d) Syncytial
Answer: B

Question. M-line passes through the centre of
(a) Z-disc
(b) I-band
(c) HMM
(d) H-zone
Answer: D

Question. The structural and functional unit of myofibril which contracts to cause movement is called
(a) Sarcolemma
(b) Sarcomere
(c) Fascia
(d) Myosin
Answer: B

Question. A bundle of muscle fibre is called
(a) Fascia
(b) Glenoid cavity
(c) Myocyte
(d) Fasciculus
Answer: D

Question. A sarcomere consists of
(a) One A-band and one I-band
(b) Half A-band and two half I-band
(c) Half A-band and one I-band
(d) One A-band and two half I-band
Answer: D

Question. The monomeric protein which polymerises to form myosin is
(a) Actin
(b) Meromyosin
(c) Tropomyosin
(d) Troponin
Answer: B

Question. Select the correct option
(a) HMM = Tail + Short arm
(b) LMM = Tail + Head
(c) HMM = Head + Short arm
(d) LMM = Head
Answer: C

Question. The anaerobic contraction of skeletal muscle causes deposition or accumulation of
(a) Gluconic acid
(b) Lactic acid
(c) Pyruvic acid
(d) Hydrochloric acid
Answer: B

Question. The movements which results in change of place or location constitutes
(a) Locomotion
(b) Protoplasmic streaming
(c) Vital movement
(d) Elasticity
Answer: A

Question. 80% of the lactic acid is converted to _______ in the liver.
(a) Cellulose
(b) Acetyl CoA
(c) Glycogen
(d) Starch
Answer: C

Question. Which of the protein is not a part of thin myofilament?
(a) Myosin
(b) Actin
(c) Troponin
(d) Tropomyosin
Answer: A

Question. Which of the following is incorrect about visceral muscles?
(a) Non-striated muscle (Smooth muscle)
(b) Involuntary muscle
(c) Located in inner walls of hollow visceral organs of the body
(d) They are under in voluntary control
Answer: D

Question. The functional unit of the contractile system in the striped muscle is
(a) Z-band
(b) A-band
(c) Myofibril
(d) Sarcomere
Answer: D

Question. Select the correct statement regarding the specific disorder of muscular or skeletal system.
(a) Muscular dystrophy – Age related shortening of muscles
(b) Osteoporosis – Decrease in bone mass and higher chances of fractures with advancing age
(c) Myasthenia gravis – Autoimmune disorder which inhibits sliding of myosin filaments
(d) Gout – Inflammation of joints due to extra deposition of calcium
Answer: B

Question. Which one of the following is not a disorder of bone?
(a) Arthritis
(b) Osteoporosis
(c) Rickets
(d) Atherosclerosis
Answer: D

Question. Select the correct statement:
(a) A-band is made up of thick myosin filament.
(b) H-zone is present in the middle of A-band.
(c) Actin and myosin are polymerized protein with contractility.
(d) All the above
Answer: D

Question. According to the sliding filament theory
(a) Actin (thin filament) moves over myosin (thick filament)
(b) Myosin moves over actin
(c) Both myosin and actin move on each other
(d) None of the above
Answer: A

Question. Which of the following option shows the correctly matched bones (given in column I) with its pair (given in column II)?
   Column-I          Column-II
A. Carpals          I. Bones that form the fingers and toes
B. Tarsals           II. Bones that form wrist
C. Phalanges      III. Bones that form the palms of the hands
D. Metacarpals    IV. Bones that form the ankles
(a) A – II, B – IV, C – I, D – III
(b) A – I, B – II, C – III, D – IV
(c) A – III, B – II, C – IV, D – I
(d) A – IV, B – I, C – III, D – II
Answer: A

Question. Which set clearly identify striated muscles?
(a) Cylindrical, Syncytial and Unbranched
(b) Spindle, Unbranched and Uninucleated
(c) Cylindrical, Striped and Nucleated
(d) Cylindrical, Striped and Branched
Answer: A

Question. Match the following and mark the correct option:
Column  I                  Column II
(A) Fast muscle fibres (i) Myoglobin
(B) Slow muscle fibres (ii) Lactic acid
(C) Actin filament        (iii) Contractile unit
(D) Sarcomere             (iv) I-band
Options:
(a) A – i, B – ii, C – iv, D – iii
(b) A – ii, B – i, C – iii, D – iv
(c) A – ii, B – i, C – iv, D – iii
(d) A – iii, B – ii, C – iv, D – i
Answer: C

Question. Three of the following pairs of the human skeletal parts are correctly matched with their respective inclusive skeletal category and one pair is not matched. Identify the non-matching pair. Pair of skeletal parts Category
(a) Sternum and ribs Axial skeleton
(b) Clavicle and glenoid Pelvic girdle cavity
(c) Humerus and ulna Appendicular skeleton
(d) Malleus and stapes Ear ossicles
Answer: B

Question. Sarcoplasmic reticulum is a storehouse of which ion
(a) Ca²⁺
(b) Na⁺
(c) K⁺
(d) Fe²⁺
Answer: A

Question. There are three blanks in the following statement. Mark the correct option having suitable words for filling the blanks. The thin filaments of myofibril contain ....... ‘A’......actin and two filaments of ....... ‘B’......protein along with ....... ‘C’......protein for masking binding site for myosin.
      ‘A’    ‘B’           ‘C’
(a) 1F troponin tropomyosin
(b) 1F tropomyosin troponin
(c) 2F troponin tropomyosin
(d) 2F tropomyosin troponin
Answer: D

Question. Which one of following options is incorrect?
(a) Hinge joint – Present between humerus and pectoral girdle
(b) Pivot joint – Present between atlas, axis and occipital condyle
(c) Gliding joint – Present between the carpals
(d) Saddle joint – Present between carpal and metacarpal of thumb
Answer: A

Question. Which of the following muscular disorders is inherited?
(a) Botulism
(b) Tetany
(c) Muscular dystrophy
(d) Myasthenia gravis
Answer: C

Question. Select the correct statement with respect to disorders of muscles in humans.
(a) Failure of neuromuscular transmission in myasthenia gravis can prevent normal swallowing.
(b) Accumulation of urea and creatine in the joints causes their inflammation.
(c) An overdose of vitamin D causes osteoporosis.
(d) Rapid contractions of skeletal muscles cause muscle dystrophy.
Answer: A

Question. Red muscle fibres are rich in
(a) golgi bodies
(b) mitochondria
(c) lysosomes
(d) ribosomes
Answer: B

Question. Which of the following statement is incorrect ?
(a) All movements lead to locomotion.
(b) Ciliary movement help in passage of ova through female reproductive tract.
(c) Microfilaments are involved in amoeboid movement.
(d) In Paramecium, the cilia help in movement of food through cytopharynx and in locomotion as well.
Answer: A

Question. Which of the following is a simple form of movement?
(a) Streaming of protoplasm in amoeba
(b) Ciliary movement in paramecium
(c) Flagellar movement in Euglena
(d) All of these
Answer: A

Question. Muscle is derived from
(a) Mesoderm
(b) Ectoderm
(c) Endoderm
(d) All of these
Answer: A

Question. Calcium is important in skeletal muscle contraction because it
(a) binds to troponin to remove the masking of active sites on actin for myosin
(b) activates the myosin ATPase by binding to it
(c) detaches the myosin head from the actin filament
(d) prevents the formation of bonds between the myosin cross bridges and the actin filament.
Answer: A

Question. All or None law is associated with
(a) skeletal
(b) muscle fibre
(b) neuron
(c) cardiac muscle fibres
(d) all of the above
Answer: D

Question. Smooth muscles help in
(a) Transportation of food through the digestive tract
(b) Transfer of gametes through genital tract
(c) Micturition by urinary bladder
(d) All the above
Answer: D

Question. Match the followings and mark the correct option:
     Column I                  Column II
(A) Sternum                  (i) Synovial fluid
(B) Glenoid Cavity          (ii) Vertebrae
(C) Freely movable joint (iii) Pectoral girdle
(D) Cartilaginous joint    (iv) Flat bones
Options:
(a) A – ii, B – i, C – iii, D – iv
(b) A – iv, B – iii, C – i, D – ii
(c) A – ii, B – i, C – iv, D – iii
(d) A – iv, B – i, C – ii, D – iii
Answer: B

Question. Which muscle protein acts as ATPase?
(a) Actin
(b) Troponin
(c) Myosin
(d) Tropomyosin
Answer: C

Question. A cup shaped cavity for articulation of femur head is
(a) acetabulum
(b) glenoid cavity
(c) sigmoid notch
(d) obturator foramen
Answer: A

Question. The type of muscle present in our
(a) heart is involuntary and unstriated smooth muscle
(b) intestine is striated and involuntary
(c) thigh is striated and voluntary
(d) upper arm is smooth muscle and fusiform in shape.
Answer: C

Question. Which of the following statement is correct?
(a) All striated muscles are voluntary.
(b) Visceral muscles are faintly striated.
(c) Cardiac muscles are not striated.
(d) All non-striated muscles are involuntary
Answer: D

Question. Match column I (types of synovial joints) with column II (bones involved) and choose the correct option.
            Column I              Column II
(Type of synovial joint)   (Bone involved)
A. Ball and Socket joint   I. Carpal and metacarpal of thumb
B. Hinge joint                   II. Humerus and pectoral girdle
C. Pivot joint                    III. Knee
D. Saddle joint                 IV. Atlas and axis
(a) A – I; B – II; C – III; D – IV
(b) A – II; B – III; C – IV; D – I
(c) A – III; B – I; C – IV; D – II
(d) A – IV; B – III; C – II; D – I
Answer: B

Question. Which of the following is incorrect about skeletal muscles?
(a) Striped appearance under microscope hence called striated muscle.
(b) They are voluntary muscles.
(c) Primarily involved in locomotory actions and changes the body postures.
(d) They are Involuntary muscles.
Answer: D

Question. Name the ion responsible for unmasking of active sites for myosin for cross-bridge activity during muscle contraction.
(a) Calcium
(b) Magnesium
(c) Sodium
(d) Potassium
Answer: A

Question. Which of the following vertebrae are fused?
(a) Cervical
(b) Sacral
(c) Lumber
(d) Thoracic
Answer: B

Question. A sarcomere is best described as a
(a) movable structural unit within a myofibril bounded by H zones.
(b) fixed structural unit within a myofibril bounded by Z lines.
(c) fixed structural unit within a myofibril bounded by A bands.
(d) movable structural unit within a myofibril bounded by Z lines.
Answer: D

Question. Lack of relaxation between successive stimuli in sustained muscle contraction is known as
(a) tetanus
(b) tonus
(c) spasm
(d) fatigue.
Answer: A

Question. Cardiac muscle is characterized by
(a) Striated appearance
(b) Involuntary control
(c) Branching pattern
(d) All of these
Answer: D

Question. The H-zone in the skeletal muscle fibre is due to
(a) the central gap between actin filaments extending through myosin filaments in the A-band
(b) extension of myosin filaments in the central portion of the A-band
(c) the absence of myofibrils in the central portion of A-band
(d) the central gap between myosin filaments in the A-band.
Answer: A

Question. Match the following columns and select the correct option.
Column-I Column-II
(A) Floating ribs (i) Located between second and seventh ribs
(B) Acromion (ii) Head of the humerus
(C) Scapula (iii) Clavicle
(D) Glenoid cavity (iv) Do not connect with the sternum
(A) (B) (C) (D)
(a) (ii) (iv) (i) (iii)
(b) (i) (iii) (ii) (iv)
(c) (iii) (ii) (iv) (i)
(d) (iv) (iii) (i) (ii)
Answer: D

Question. Select the correct option.
(a) There are seven pairs of vertebrosternal, three pairs of vertebrochondral and two pairs of vertebral ribs.
(b) 8th, 9th and 10th pairs of ribs articulate directly with the sternum.
(c) 11th and 12th pairs of ribs are connected to the sternum with the help of hyaline cartilage.
(d) Each rib is a flat thin bone and all the ribs are connected dorsally to the thoracic vertebrae and ventrally to the sternum.
Answer: A

Question. Which of the following is not a function of the skeletal system?
(a) Production of body heat
(b) Locomotion
(c) Production of erythrocytes
(d) Storage of minerals
Answer: A

Question. What is not true about human skull?
(a) It is dicondylic.
(b) It includes 6 ear ossicles.
(c) It includes 14 facial bones.
(d) Hyoid is not included in skull bones.
Answer: D

Question. Which of the following joints would allow no movements?
(a) Synovial joint
(b) Ball and socket joint
(c) Fibrous joint
(d) Cartilaginous joint
Answer: C

Question. Muscle fibre is a
(a) Anatomical unit of muscle
(b) Physiological unit of muscle
(c) Biochemical unit of muscle
(d) None of these
Answer: A

Question. During muscle contraction in humans, the
(a) sarcomere does not shorten
(b) A band remains same
(c) A, H and I bands shorten
(d) actin filaments shorten.
Answer: B

Question. Stimulation of a muscle fibre by a motor neuron occurs at
(a) the neuro-muscular junction
(b) the transverse tubules
(c) the myofibril
(d) the sacroplasmic reticulum
Answer: A

1. Movement → Significant features of living beings.

2. Streaming of protoplasm → In Amoeba (a simple form of movement)

3. Movement of cilia, flagella and tentacles → in many organisms.

4. Human beings → can move limbs, jaws, eyelids, tongue, etc.

5. Movements that result in a change of place or location. → Such voluntary movements are called LOCOMOTION.
• Walking, running, climbing, flying, swimming

6. ALL LOCOMOTIONS ARE MOVEMENTS BUT ALL MOVEMENTS ARE NOT LOCOMOTIONS.

7. METHODS OF LOCOMOTION → vary with animal’s habitats and the demand of the situation.

8. LOCOMOTION → Generally for search of food, shelter, mate, suitable breeding grounds, favourable climatic conditions or to escape from enemies/predators.

9. Cells of the human body exhibit three main types of movements, namely,
AMOEBOID, CILIARY AND MUSCULAR.

10. Immune cells macrophages and leucocytes in blood → exhibit amoeboid movement. → It is effected by pseudopodia formed by the streaming of protoplasm → Cytoskeletal elements like microfilaments are also involved in amoeboid movement.

11. Ciliary movement occurs in most of our internal tubular organs which are lined by CILIATED EPITHELIUM.
• The coordinated movements of cilia in the trachea help us in removing dust particles and some of the foreign substances inhaled along with the atmospheric air.
• Passage of ova through the female reproductive tract is also facilitated by the ciliary movement.

12. Movement of our limbs, jaws, tongue, etc, require muscular movement. The CONTRACTILE PROPERTY OF MUSCLES are effectively used for locomotion and other movements by human beings and majority of multicellular organisms.

13. Locomotion requires a perfect coordinated activity of muscular, skeletal and neural systems.

14. MUSCLE
• a specialised animal tissue
• mesodermal origin.
• About 40-50 per cent of the body weight of a human adult
• Have special properties : excitability, contractility, extensibility and elasticity.
• Based on their location, three types of muscles are identified :
• (i) Skeletal
• (ii) Visceral and
• (iii) Cardiac.

• Skeletal muscles
• closely associated with the skeletal components of the body.
• a striped appearance → called STRIATED MUSCLES.
• activities are under the voluntary control of the nervous system,  → VOLUNTARY MUSCLES
• Primarily involved in locomotory actions and changes of body postures.

• Visceral muscles
• Located in the inner walls of hollow visceral organs of the body like the alimentary canal, reproductive tract, etc.
• Not have any striation & are smooth in appearance. → also called
SMOOTH MUSCLES (NONSTRIATED MUSCLE).
• Their activities are not under the voluntary control of the nervous system and are therefore known as INVOLUNTARY MUSCLES.
• They assist, for example, in the transportation of food through the digestive tract and gametes through the genital tract.

• Cardiac muscles
• muscles of heart.
• Many cardiac muscle cells assemble in a branching pattern to form a cardiac muscle.
• cardiac muscles are striated.
• They are involuntary

15. SKELETAL MUSCLE IN DETAIL
• Each organised skeletal muscle in our body is made of a number of muscle bundles or fascicles held together by a common collagenous connective tissue layer called FASCIA.
• Each muscle bundle contains a number of muscle fibres
• Each muscle fibre is lined by the plasma membrane called SARCOLEMMA enclosing the SARCOPLASM.
• Muscle fibre is a syncitium as the sarcoplasm contains many nuclei.
• The endoplasmic reticulum, i.e., sarcoplasmic reticulum of the muscle fibres is the store house of calcium ions.
• A characteristic feature of the muscle fibre is the presence of a large number of parallelly arranged filaments in the sarcoplasm called myofilaments or myofibrils.
• Each myofibril has alternate dark and light bands on it.
• Striated appearance is due to the distribution pattern of two important proteins – ACTIN AND MYOSIN.
• The light bands contain actin and is called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin.
• Both the proteins are arranged as rod-like structures, parallel to each other and also to the longitudinal axis of the myofibrils.
• Actin filaments are thinner as compared to the myosin filaments, hence are commonly called thin and thick filaments respectively. 
• In the centre of each ‘I’ band is an elastic fibre called ‘Z’ line which bisects it.
• The thin filaments are firmly attached to the ‘Z’ line.
• The thick filaments in the ‘A’ band are also held together in the middle of this band by a thin fibrous membrane called ‘M’ line.
• The ‘A’ and ‘I’ bands are arranged alternately throughout the length of the myofibrils.
• The portion of the myofibril between two successive ‘Z’ lines is considered as the functional unit of contraction and is called a sarcomere.
• In a resting state, the edges of thin filaments on either side of the thick filaments partially overlap the free ends of the thick filaments leaving the central part of the thick filaments.
• This central part of thick filament, not overlapped by thin filaments is called the ‘H’ zone.

16. STRUCTURE OF CONTRACTILE PROTEINS
• Each actin (thin) filament is made of two ‘F’ (filamentous) actins helically wound to each other.
• Each ‘F’ actin is a polymer of monomeric ‘G’ (Globular) actins.
• Two filaments of another protein, tropomyosin also run close to the ‘F’ actins throughout its length.
• A complex protein Troponin is distributed at regular intervals on the tropomyosin.
• In the resting state a subunit of troponin masks the active binding sites for myosin on the actin filaments
• Each myosin (thick) filament is also a polymerised protein.
• Many monomeric proteins called Meromyosins constitute one thick filament.
• Each meromyosin has two important parts, a globular head with a short arm and a tail, the former being called the heavy meromyosin (HMM) and the latter, the light meromyosin (LMM).
• The HMM component, i.e.; the head and short arm projects outwards at regular distance and angle from each other from the surface of a polymerised myosin filament and is known as cross arm.
• The globular head is an active ATPase enzyme and has binding sites for ATP and active sites for actin.

17. MECHANISM OF MUSCLE CONTRACTION
• Best explained by the sliding filament theory
• contraction of a muscle fibre takes place by the sliding of the thin filaments over the thick filaments.
• Muscle contraction is initiated by a signal sent by the central nervous system (CNS) via a motor neuron.
• A motor neuron along with the muscle fibres connected to it constitute a motor unit.
• The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction or motor-end plate. A neural signal reaching this junction releases a neurotransmitter (Acetyl choline) which generates an action potential in the sarcolemma.
• This spreads through the muscle fibre and causes the release of calcium ions into the sarcoplasm.
• Increase in Ca++ level leads to the binding of calcium with a subunit of troponin on actin filaments and thereby remove the masking of active sites for myosin.
• Utilising the energy from ATP hydrolysis, the myosin head now binds to the exposed active sites on actin to form a cross bridge
• This pulls the attached actin filaments towards the centre of ‘A’ band.
• The ‘Z’ line attached to these actins are also pulled inwards thereby causing a shortening of the sarcomere, i.e., contraction. It is clear from the above steps, that during shortening of the muscle, i.e., contraction, the ‘I’ bands get reduced, whereas the ‘A’ bands retain the length.
• The myosin, releasing the ADP and P1 goes back to its relaxed state.
• A new ATP binds and the cross-bridge is broken
• The ATP is again hydrolysed by the myosin head and the cycle of cross bridge formation and breakage is repeated causing further sliding.
• The process continues till the Ca++ ions are pumped back to the sarcoplasmic cisternae resulting in the masking of actin filaments.
• This causes the return of ‘Z’ lines back to their original position, i.e., relaxation.
• The reaction time of the fibres can vary in different muscles.
• Repeated activation of the muscles can lead to the accumulation of lactic acid due to anaerobic breakdown of glycogen in them, causing fatigue.
• Muscle contains a red coloured oxygen storing pigment called myoglobin.
• Myoglobin content is high in some of the muscles which gives a reddish appearance. Such muscles are called the Red fibres. These muscles also contain plenty of mitochondria which can utilise the large amount of oxygen stored in them for ATP production. These muscles, therefore, can also be called aerobic muscles.
• On the other hand, some of the muscles possess very less quantity of myoglobin and therefore, appear pale or whitish. These are the White fibres.
Number of mitochondria are also few in them, but the amount of sarcoplasmic reticulum is high. They depend on anaerobic process for energy.

18. SKELETAL SYSTEM
• Skeletal system consists of a framework of bones and a few cartilages.
• This system has a significant role in movement shown by the body.
• Bone and cartilage are specialised connective tissues.
• The former has a very hard matrix due to calcium salts in it and the latter has slightly pliable matrix due to chondroitin salts.
• In human beings, this system is made up of 206 bones and a few cartilages.
• It is grouped into two principal divisions – the axial and the appendicular skeleton.
• Axial skeleton comprises 80 bones distributed along the main axis of the body.
• The skull, vertebral column, sternum and ribs constitute axial skeleton.
• The skull is composed of two sets of bones – cranial and facial, that totals to 22 bones.
• Cranial bones are 8 in number.
• They form the hard protective outer covering, cranium for the brain.
• The facial region is made up of 14 skeletal elements which form the front part of the skull.
• A single U-shaped bone called hyoid is present at the base of the buccal cavity and it is also included in the skull.
• Each middle ear contains three tiny bones – Malleus, Incus and Stapes, collectively called Ear Ossicles.
• The skull region articulates with the superior region of the vertebral column with the help of TWO OCCIPITAL CONDYLES (DICONDYLIC SKULL).
• Our vertebral column is formed by 26 serially arranged units called vertebrae and is dorsally placed.
• It extends from the base of the skull and constitutes the main framework of the trunk.
• Each vertebra has a central hollow portion (neural canal) through which the spinal cord passes.
• First vertebra is the atlas and it articulates with the occipital condyles.
• The vertebral column is differentiated into cervical (7), thoracic (12), lumbar (5), sacral (1-fused) and coccygeal (1-fused) regions starting from the skull.
• The number of cervical vertebrae are seven in almost all mammals including human beings.
• The vertebral column protects the spinal cord, supports the head and serves as the point of attachment for the ribs and musculature of the back.
• Sternum is a flat bone on the ventral midline of thorax.
• There are 12 pairs of ribs.
• Each rib is a thin flat bone connected dorsally to the vertebral column and ventrally to the sternum.
• It has two articulation surfaces on its dorsal end and is hence called bicephalic.
• First seven pairs of ribs are called true ribs.
• Dorsally, they are attached to the thoracic vertebrae and ventrally connected to the sternum with the help of hyaline cartilage.
• The 8th, 9th and 10th pairs of ribs do not articulate directly with the sternum but join the seventh rib with the help of hyaline cartilage. These are called vertebrochondral (false) ribs.
• Last 2 pairs (11th and 12th) of ribs are not connected ventrally and are therefore, called floating ribs.
• Thoracic vertebrae, ribs and sternum together form the rib cage.
• The bones of the limbs along with their girdles constitute the appendicular skeleton.
• Each limb is made of 30 bones.
• The bones of the hand (fore limb) are humerus, radius and ulna, carpals (wrist bones – 8 in number), metacarpals (palm bones – 5 in number) and phalanges (digits – 14 in number).
• Femur (thigh bone – the longest bone), tibia and fibula, tarsals (ankle bones – 7 in number), metatarsals (5 in number) and phalanges (digits – 14 in number) are the bones of the legs (hind limb)
• A cup shaped bone called patella cover the knee ventrally (knee cap).
• Pectoral and Pelvic girdle bones help in the articulation of the upper and the lower limbs respectively with the axial skeleton.
• Each girdle is formed of two halves. Each half of pectoral girdle consists of a clavicle and a scapula
• Scapula is a large triangular flat bone situated in the dorsal part of the thorax between the second and the seventh ribs.
• The dorsal, flat, triangular body of scapula has a slightly elevated ridge called the spine which projects as a flat, expanded process called the acromion.
• The clavicle articulates with this. Below the acromion is a depression called the glenoid cavity which articulates with the head of the humerus to form the shoulder joint.
• Each clavicle is a long slender bone with two curvatures. This bone is commonly called the collar bone. Pelvic girdle consists of two coxal bones
• Each coxal bone is formed by the fusion of three bones – ilium, ischium and pubis.
• At the point of fusion of the above bones is a cavity called acetabulum to which the thigh bone articulates.
• The two halves of the pelvic girdle meet ventrally to form the pubic symphysis containing fibrous cartilage.

19. JOINTS
• Joints are essential for all types of movements involving the bony parts
• Joints are points of contact between bones, or between bones and cartilages.
• Force generated by the muscles is used to carry out movement through joints, where the joint acts as a fulcrum.
• The movability at these joints vary depending on different factors.
• Joints have been classified into three major structural forms, namely, fibrous, cartilaginous and synovial.
• FIBROUS JOINTS DO NOT ALLOW ANY MOVEMENT. This type of joint is shown by the flat skull bones which fuse end-to-end with the help of dense fibrous connective tissues in the form of sutures, to form the cranium.
• IN CARTILAGINOUS JOINTS, THE BONES INVOLVED ARE JOINED
TOGETHER WITH THE HELP OF CARTILAGES. The joint between the adjacent vertebrae in the vertebral column is of this pattern and it permits limited movements.
• SYNOVIAL JOINTS ARE CHARACTERISED BY THE PRESENCE OF A FLUID
FILLED SYNOVIAL CAVITY BETWEEN THE ARTICULATING SURFACES OF
THE TWO BONES. Such an arragement allows considerable movement.
These joints help in locomotion and many other movements.
• Ball and socket joint (between humerus and pectoral girdle), hinge joint (knee joint), pivot joint (between atlas and axis), gliding joint (between the carpals) and saddle joint (between carpal and metacarpal of thumb) are some examples.

20. DISORDERS OF MUSCULAR AND SKELETAL SYSTEM

• MYASTHENIA GRAVIS:
• Auto immune disorder
• affecting neuromuscular junction
• leading to fatigue, weakening and paralysis of skeletal muscle.

• MUSCULAR DYSTROPHY:
• Progressive degeneration of skeletal muscle
• mostly due to genetic disorder.

• TETANY:
• Rapid spasms (wild contractions) in muscle
• due to low Ca++ in body fluid.

• ARTHRITIS:
• Inflammation of joints.

• OSTEOPOROSIS:
• Age-related disorder
• characterised by decreased bone mass
• increased chances of fractures.
• Decreased levels of estrogen is a common cause.

• GOUT:
• Inflammation of joints
• due to accumulation of uric acid crystals.