Subtopics - Locomotion and Movement (NEET)
Seven content blocks: skeleton types and bone classification, axial skeleton (skull, vertebral column, ribs, sternum), endoskeleton overview, appendicular skeleton (girdles and limb bones), joints and disorders, body muscles, and movement types.
1) Skeleton
Introduces the skeleton as the framework of hardened tissues in the vertebrate body. Covers the three types of vertebrate skeletons: epidermal/horny exoskeleton (keratinised derivatives like scales, feathers, hairs, nails, hoofs — all living amphibians lack exoskeleton), dermal/bony skeleton (scales, plates, scutes, fin rays, antlers derived from dermis), and endoskeleton (deeper skeleton from mesenchyme, formed by bones). Also covers the classification of bones: cartilage/replacing bones (from preexisting cartilage — vertebrae, girdles, limb bones), membrane/dermal/investing bones (from connective tissue — ribs, sternum, clavicle, nasal), sesamoid bones (in ligaments/tendons — patella, pisiform), and pneumatic bones (hollow with air spaces — bird bones, frontal, sphenoid, ethmoid, maxilla in humans). Functions of endoskeleton including support, protection, movement, mineral storage, and haematopoiesis.
2) Axial Skeleton (Human)
The most extensive topic covering 80 bones of the axial skeleton. The skull section details the chondrocranium (brain box with cranium proper housing the brain in a cavity averaging 1475 cc in adult males, sense capsules for eye and ear), splanchnocranium (facial skeleton from visceral arches — mandibular, hyoid, branchial arches; skull suspension types: autostylic in frog, craniostylic in mammals), skull of man (8 cranial bones — 1 frontal, 2 parietal, 1 occipital with foramen magnum and 2 occipital condyles making it dicondylic, 2 temporal with ear ossicles, 1 sphenoid butterfly-shaped with sella turcica, 1 ethmoid; 14 facial bones including mandible as largest and only movable skull bone; hyoid as horse-shoe shaped bone not articulated with any other bone), ear ossicles (malleus from articular, incus from quadrate, stapes from hyomandibular). The vertebral column section covers 33 vertebrae (7 cervical, 12 thoracic, 5 lumbar, 5 sacral fused into sacrum, 4 coccygeal fused into coccyx), curvatures (primary: thoracic and sacral anteriorly concave; secondary: cervical and lumbar anteriorly convex; disorders: kyphosis, lordosis, scoliosis), intervertebral discs with nucleus pulposus as vestigial notochord, vertebra types by centrum shape (procoelous, opisthocoelous, heterocoelous, acoelous, amphicoelous), special vertebrae (atlas without centrum, axis with odontoid process/dens, sacrum fusing at 16-18 years completed by 30, coccyx fusing at 20-30 years). The thoracic basket covers 12 pairs of ribs (7 true/vertebrosternal, 3 false/vertebrochondral, 2 floating/vertebral; bicephalous with capitulum and tuberculum) and sternum (manubrium + 5 sternebrae + xiphisternum with xiphoid cartilage; absent in fish and turtle; 17 cm in males).
3) Endoskeleton of Vertebrates
A brief bridging topic that classifies the vertebrate endoskeleton into its two major divisions: axial endoskeleton (skull + vertebral column + sternum + ribs) and appendicular endoskeleton (girdles + limb bones). This division provides the organisational framework for studying human skeletal anatomy and is a frequent one-liner in NEET.
4) Appendicular Skeleton
Covers 126 bones of the appendicular skeleton: pectoral girdle (scapula — large, flat, triangular cartilage bone with acromion process, coracoid process, glenoid cavity for humerus head; clavicle — long, slender membrane bone connecting acromion to presternum), pelvic girdle (innominate/hip bone = fusion of ilium + ischium + pubis; acetabulum for femur head; obturator foramen; pelvis = 2 innominates + sacrum; pubic symphysis as cartilaginous joint), fore limb bones (humerus = longest upper limb bone with greater/lesser tuberosity, deltoid tuberosity, trochlea, olecranon fossa; radius and ulna with olecranon process forming elbow prominence; 8 carpals in 2 rows, 5 metacarpals, 14 phalanges = 27 hand bones), and hind limb bones (femur = longest and strongest body bone with greater/lesser/3rd trochanter, fovea capitis, patellar groove; patella = sesamoid knee cap from tendon ossification; tibia and fibula; 7 tarsals, 5 metatarsals, 14 phalanges = 26 foot bones).
5) Joints
Comprehensive classification of joints (arthrology) into three categories by mobility. Synarthrosis/immovable joints: sutures (fibrous, between skull bones), gomphosis (cone in socket — teeth in jaw), syndesmosis (more fibrous — tibia-fibula distally). Amphiarthrosis/slightly movable: cartilaginous joints without synovial cavity (pubic symphysis, between vertebral bodies, manubrium-body of sternum). Diarthrosis/freely movable: synovial joints with articular cartilage (hyaline), synovial membrane secreting synovial fluid (lubricant and nutrition; decreases in old age causing stiffness), comprising ball-and-socket (humerus-glenoid, femur-acetabulum, incus-stapes), hinge (knee, elbow, lower jaw, malleus-incus, phalanges), pivot (atlas-axis = atlanto-axial), gliding (tarsals, zygapophysis, radius-ulna), saddle (thumb metacarpal-carpals), condyloid/ellipsoidal (radius-carpals at wrist). Disorders section: sprain (stretched/torn ligaments/tendons with poor regeneration), arthritis (joint inflammation), osteoarthritis (synovial fluid stops, cartilage erosion, bony spurs, ankylosis), rheumatoid arthritis (autoimmune, synovial membrane inflammation, starts 20-40 years, women more), gout (inherited purine disorder, uric acid/sodium urate crystals in joints, affects great toe), osteoporosis (reduced bone mass, crush fracture of vertebrae, femoral neck fracture), dislocation, slipped disc, fracture types (green-stick in children, comminuted, compound, evulsive), bursitis, osteomyelitis.
6) Body Muscles
Covers muscle classification by action and key muscles of the human body. Antagonistic muscles work in opposing pairs: flexor (bends joint) vs extensor (straightens), pronator (palm down/backward) vs supinator (palm up/forward), abductor (away from midline = elevation) vs adductor (toward midline = depression), protractor (pulls forward) vs retractor (pulls backward). Synergists act together; prime movers are most powerful. Inversion = soles face each other; eversion = soles face laterally. Important muscles: sartorius femoris (longest), gluteus maximus (largest, buttock), stapedial (smallest), gastrocnemius (calf). Rigor mortis: body stiffening after death due to non-separation of actin-myosin from ATP unavailability. Cori cycle: muscle lactic acid passes to liver where 80% is converted to glucose/glycogen (returned to muscles) and 20% is oxidised.
7) Movement and Locomotion
Distinguishes movement (body part displacement) from locomotion (whole organism displacement from place to place). Covers muscular locomotion types: cursorial (running — horse, flightless birds), saltatorials (hopping — frog, rabbit), natatorial (swimming — fish, whale), volant (flying — insects, birds). Also covers non-muscular movement: ciliary (cilia in trachea for dust, vasa efferentia for sperms, oviducts for eggs, flame cells in flatworms), flagellar (choanocytes in sponges, gastrodermis in Hydra, sperm), pseudopodial (leucocytes, macrophages), and cyclosis (cytoplasmic streaming in most cells). Morphogenetic movement in early embryo where cells stream to form tissues/organs. Kinesiology defined as the study of movement.
Locomotion and Movement Download Notes & Weightage Plan
For each topic in the Locomotion and Movement chapter below, you get (2) the exact resources to download and how to use them, and (3) a simple importance & time plan so NEET students know what to do first and what to revise last.
Introduction to skeleton types, bone classification, and endoskeleton functions — a short foundational section.
1) Download Packs For This Topic (And How To Use Them)
Don't download everything and forget it. Use these like a small "attack kit": read → highlight → test → revise the same sheet again.
2) Importance, Weightage & Time Allocation (Practical)
Use this to avoid over-studying. This topic is usually low effort, quick return if your recall is clean.
- Scoring Focus: Direct recall: which bones are sesamoid, which are pneumatic, which organism lacks exoskeleton (amphibians). 1-2 questions possible.
- High-risk Area: Confusing cartilage bones with membrane bones — students often place ribs and clavicle under cartilage bones. Remember: ribs and clavicle are membrane/dermal bones despite seeming like deep bones.
- Best Practice Style: Single read with a comparison table. Revise from table only. Low time investment, guaranteed 1-mark pickup.
Heaviest topic: skull (cranial + facial bones, ear ossicles), vertebral column (33 vertebrae, curvatures, vertebra types), ribs and sternum.
1) Download Packs For This Topic (And How To Use Them)
Don't download everything and forget it. Use these like a small "attack kit": read → highlight → test → revise the same sheet again.
2) Importance, Weightage & Time Allocation (Practical)
Use this to avoid over-studying. This topic is usually low effort, quick return if your recall is clean.
- Scoring Focus: The densest section for NEET: cranial bone count, mandible as only movable skull bone, ear ossicle derivation, vertebra count formula 7-12-5-5-4, atlas lacking centrum, curvature disorders, rib types.
- High-risk Area: Three major traps: (1) Total skull bones = 22 (not 29 — students forget bones are paired), (2) Ear ossicle derivation (malleus from articular vs incus from quadrate), (3) Mixing primary and secondary curvatures.
- Best Practice Style: Diagram-based study with labeled figures. Flash cards for bone facts. This topic demands 2-3 revision passes minimum.
Appendicular Skeleton and Joints
Covering girdles (pectoral and pelvic), limb bones (fore and hind), and all joint types with skeletal disorders.
1) Download Packs For This Topic (And How To Use Them)
Don't download everything and forget it. Use these like a small "attack kit": read → highlight → test → revise the same sheet again.
2) Importance, Weightage & Time Allocation (Practical)
Use this to avoid over-studying. This topic is usually low effort, quick return if your recall is clean.
- Scoring Focus: Glenoid vs acetabulum location, femur as longest bone, patella as sesamoid, joint type-example matching, gout = uric acid, osteoporosis = bone mass decrease.
- High-risk Area: Confusing glenoid cavity (pectoral girdle, for humerus) with acetabulum (pelvic girdle, for femur). Mixing hinge and pivot joint examples. Gout cause = uric acid, NOT calcium (which is osteoporosis).
- Best Practice Style: Flowchart for limb bones. Table for joint types with movement directions and examples. Disease comparison chart.
Body Muscles, Movement and Locomotion
Muscle classification by action, important muscles with superlatives, movement vs locomotion, and non-muscular movement types.
1) Download Packs For This Topic (And How To Use Them)
Don't download everything and forget it. Use these like a small "attack kit": read → highlight → test → revise the same sheet again.
2) Importance, Weightage & Time Allocation (Practical)
Use this to avoid over-studying. This topic is usually low effort, quick return if your recall is clean.
- Scoring Focus: Muscle superlatives (longest = sartorius, largest = gluteus maximus, smallest = stapedial), rigor mortis mechanism, Cori cycle 80-20 ratio, locomotion type examples.
- High-risk Area: Confusing abductor (away from midline) with adductor (toward midline). Mixing up smallest muscle (stapedial) with shortest muscle. Forgetting that rigor mortis is due to ATP depletion, not lactic acid.
- Best Practice Style: Quick-reference card with muscle pairs, superlatives, and locomotion types. 30-minute review session is sufficient.
Locomotion and Movement Chapter NEET Traps & Common Mistakes (Topic-Wise)
Each subtopic below is of the Locomotion and Movement chapter and shows what NEET students usually do wrong in NEET examination, a short example of the mistake, and how NEET frames the question to trick you with close options are given below.
Mistake Snapshot (What Students Do Wrong)
- Confusing rib counts in each category: True ribs are 7 pairs (1-7) attached DIRECTLY to sternum via hyaline cartilage. False ribs are 3 pairs (8-10) attached INDIRECTLY via 7th rib cartilage. Floating ribs are 2 pairs (11-12) completely FREE anteriorly. Students often say 10 false ribs or include floating ribs in the false rib count.
- Forgetting the attachment mechanism: True ribs attach via hyaline cartilage directly to sternum. False ribs connect to the costal cartilage of the 7th rib, NOT directly to sternum. Floating ribs do not reach the sternum at all. NEET tests the mechanism, not just the count.
Q: 'How many pairs of true ribs are present in humans?' Correct: 7. Trap: choosing 10 (which includes false ribs) or 12 (total ribs).
How NEET Frames The Trap
NEET often lists options like 7, 10, 12, 24 to test whether students know exactly which ribs belong to which category.
Q. Which of the following ribs are attached directly to the sternum by hyaline cartilage?
A. First 7 pairs (true ribs) B. First 10 pairs (true + false ribs) C. All 12 pairs D. Last 2 pairs (floating ribs)
Trick: Option A is correct. Only the first 7 pairs (true/vertebrosternal ribs) attach directly to the sternum via hyaline cartilage. Option B is the most common trap because students include false ribs (8-10) which attach indirectly through the 7th rib's cartilage, not directly to the sternum.
Mistake Snapshot (What Students Do Wrong)
- Swapping derivation of malleus and incus: Malleus (hammer) is derived from the ARTICULAR bone. Incus (anvil) is derived from the QUADRATE bone. Students frequently reverse these two. Stapes (stirrup) is derived from hyomandibular — this one is usually remembered correctly.
- Confusing which bone forms the suspensorium: In autostylic skulls (frog), the suspensorium is formed by quadrate. In craniostylic skulls (all mammals), it is formed by squamosal. Students mix up which suspension type applies to which animal group.
Q: 'Incus of mammals is homologous to which bone?' Correct: Quadrate. Trap: choosing articular (which gives malleus).
How NEET Frames The Trap
NEET places articular, quadrate, hyomandibular, and dentary as options. The malleus-articular and incus-quadrate pairing is the single most confused fact in this chapter.
Q. The incus (anvil) of the mammalian middle ear is derived from which ancestral bone?
A. Articular B. Quadrate C. Hyomandibular D. Dentary
Trick: Option B is correct. Incus is derived from the quadrate bone. Option A (articular) is the trap because students confuse it with malleus, which is derived from the articular bone. Stapes comes from hyomandibular (option C). Dentary (option D) forms the mammalian mandible.
Mistake Snapshot (What Students Do Wrong)
- Swapping which girdle has which cavity: Glenoid cavity is in the PECTORAL girdle (scapula) and receives the head of the HUMERUS. Acetabulum is in the PELVIC girdle (innominate) and receives the head of the FEMUR. Students frequently reverse these associations.
- Confusing the bones forming each cavity: Glenoid cavity is formed by the scapula alone. Acetabulum is formed by the junction of ilium, ischium, and pubis (three bones contribute). Students often say acetabulum is formed by scapula or glenoid by multiple bones.
Q: 'Acetabulum is part of which girdle?' Correct: Pelvic girdle. Trap: choosing pectoral girdle (which has glenoid cavity).
How NEET Frames The Trap
Both cavities are cup-shaped and both receive the head of a long bone, making them easy to confuse. NEET exploits this similarity.
Q. The head of the femur articulates with which structure of the pelvic girdle?
A. Glenoid cavity B. Acetabulum C. Obturator foramen D. Pubic symphysis
Trick: Option B is correct. The acetabulum is the cup-shaped depression in the innominate bone of the pelvic girdle where the femur head fits. Option A (glenoid cavity) is the trap because it is the equivalent socket in the pectoral girdle for the humerus — students swap these two sockets frequently.
Mistake Snapshot (What Students Do Wrong)
- Confusing the causative agents: Gout = deposition of URIC ACID (sodium urate) crystals in joints (inherited purine metabolism disorder). Osteoporosis = excessive CALCIUM and PHOSPHORUS resorption from bone (reduced bone mass). Osteoarthritis = cessation of SYNOVIAL FLUID production and cartilage erosion. Students frequently attribute calcium deposition to gout or uric acid to osteoporosis.
- Mixing up which joint is affected first: Gout generally affects the GREAT TOE first. Rheumatoid arthritis starts in SMALL JOINTS of the hand. Osteoarthritis is most common in weight-bearing joints. Students swap these initial presentations.
Q: 'Gout is caused by deposition of ___' Correct: Sodium urate/uric acid crystals. Trap: choosing calcium (which relates to osteoporosis).
How NEET Frames The Trap
NEET places calcium, uric acid, cholesterol, and urea as options. Since osteoporosis involves calcium loss, students associate joints + mineral = calcium and pick the wrong answer.
Q. Gout is characterised by deposition of crystals of which substance in the synovial joints?
A. Calcium phosphate B. Calcium carbonate C. Sodium urate (uric acid) D. Cholesterol
Trick: Option C is correct. Gout is an inherited disorder of purine metabolism where excess uric acid forms sodium urate crystals in synovial joints, especially the great toe. Options A and B are traps because students associate joint disorders with calcium (which relates to osteoporosis, not gout).
Mistake Snapshot (What Students Do Wrong)
- Confusing which vertebra lacks a centrum: ATLAS (C1) lacks a centrum and a neural spine. The centrum of the atlas becomes the ODONTOID PROCESS (dens) of the AXIS (C2). Students often say axis lacks the centrum, or forget that the odontoid process is actually the modified atlas centrum.
- Mixing up which allows rotation vs nodding: Atlanto-AXIAL joint (atlas + axis) = PIVOT joint = allows ROTARY movement of head (shaking head 'No'). Atlanto-OCCIPITAL joint (atlas + occipital) = allows NODDING movement (saying 'Yes'). Students frequently reverse which joint allows which movement.
Q: 'Odontoid process is found in ___' Correct: Axis vertebra (C2). Trap: choosing atlas or any other vertebra.
How NEET Frames The Trap
NEET tests the odontoid process location directly. The confusion arises because odontoid process IS the modified centrum of ATLAS but is found ON the AXIS. Students who remember 'atlas centrum' pick atlas as the answer.
Q. The odontoid process (dens) is a characteristic feature of which vertebra?
A. Atlas (C1) B. Axis (C2) C. 7th cervical (C7) D. 1st thoracic (T1)
Trick: Option B is correct. The odontoid process is found on the axis (C2) vertebra, and it is actually the modified centrum of the atlas that has fused to the axis. Option A is the most common trap because students remember 'centrum of atlas' and pick atlas.
Mistake Snapshot (What Students Do Wrong)
- Attributing rigor mortis to lactic acid accumulation: Rigor mortis is caused by NON-AVAILABILITY OF ATP, which prevents separation of actin and myosin cross-bridges after death. It is NOT caused by lactic acid buildup. Students confuse muscle fatigue (lactic acid) with rigor mortis (ATP depletion). While lactic acid accumulates post-mortem, it does not cause the stiffening.
- Confusing with muscle fatigue: Muscle fatigue in living organisms is caused by lactic acid accumulation (temporary, reversible). Rigor mortis after death is caused by permanent ATP depletion (irreversible stiffening). These are fundamentally different mechanisms.
Q: 'Rigor mortis is caused by ___' Correct: Non-availability of ATP preventing actin-myosin separation. Trap: choosing lactic acid accumulation.
How NEET Frames The Trap
NEET places ATP depletion, lactic acid, calcium excess, and nerve impulse cessation as options. Since both ATP and lactic acid are associated with muscle metabolism, students often pick lactic acid.
Q. The stiffening of the body after death (rigor mortis) occurs because:
A. Lactic acid accumulates in muscles B. Actin and myosin filaments cannot detach due to absence of ATP C. Calcium ions are released from the sarcoplasmic reticulum D. Nerve impulses to muscles cease permanently
Trick: Option B is correct. After death, ATP production stops completely. Without ATP, the myosin heads cannot detach from actin filaments, locking muscles in a contracted state. Option A is the most common trap because lactic acid is associated with muscle fatigue during life, and students conflate fatigue with rigor mortis.