NEET Locomotion and Movement Previous Year Questions with Solutions

The vertebral column forms the central axis of the human body, extending from the base of the skull and protecting the spinal cord. In an adult human, it consists of 26 serially arranged articulated units called vertebrae separated by intervertebral discs.

• • Cervical vertebrae: 7 (in neck, including Atlas C1 and Axis C2).
• • Thoracic vertebrae: 12 (articulate with ribs).
• • Lumbar vertebrae: 5 (in lower back).
• • Sacrum: 1 (formed by fusion of 5 sacral vertebrae).
• • Coccyx: 1 (tail bone, formed by fusion of 4 coccygeal vertebrae).

In human infants, there are 33 individual bones. However, upon skeletal maturation, the 5 sacral vertebrae fuse into 1 sacrum, and the 4 coccygeal vertebrae fuse into 1 coccyx. Thus, the adult anatomical standard taught in the core curriculum is 26.

• • Adult functional bones = 26.

The total number of vertebrae in a human is 26.

• • Matches Option (3).

Each human lower limb is made of 30 bones arranged in a linear anatomical hierarchy from proximal (hip articulation) to distal (toes): 1. Femur: Longest, heaviest bone (thigh bone). 2. Patella: Cup-shaped sesamoid bone covering the knee ventrally. 3. Tibia and Fibula: Two parallel long bones of the shank (tibia is medial and larger). 4. Tarsals: Ankle bones (7 in number). 5. Metatarsals: Sole bones (5 in number). 6. Phalanges: Toe bones (14 in number, formula 2,3,3,3,3).

• • Femur articulates with acetabulum proximally and tibia/patella distally.

1. Option (1): Femur - tibia - patella - tarsal (Incorrect: places patella distal to tibia). 2. Option (2): Patella - femur - tibia - tarsal (Incorrect: places patella proximal to femur). 3. Option (3): Femur - patella - tibia - tarsal (Correct: strictly proximal to distal order). 4. Option (4): Femur - tarsal - patella - tibia (Incorrect: places tarsals before knee and shin).

• • Option (3) is the only correct sequence.

The correct sequence is Femur-patella-tibia-tarsal.

• • Matches Option (3).

Cells of the human body exhibit three main types of movements: amoeboid, ciliary, and muscular, along with flagellar movement exhibited by specialized cells.

• • NCERT explicitly singles out spermatozoa for flagellar movement.

The sperm tail consists of an axoneme comprising a classical "9+2" microtubule doublet arrangement powered by dynein motor arms. ATP generated by the mitochondrial spiral of the middle piece drives sinusoidal wave propagation along the flagellum, propelling the sperm forward through the female genital tract.

• • Ciliary movement propels the non-motile ovum along the Fallopian tube, not the sperm itself.

Option (1) flagellar movement is the exact mechanism. Option (2) ciliary movement is in oviducts/trachea. Option (3) amoeboid is in phagocytes. Option (4) muscular is in tissues.

• • Matches official NTA final answer key Option A / (1).

A neural signal reaching the neuromuscular junction (the junction between a motor neuron and the sarcolemma of the muscle fibre) releases a neurotransmitter (acetylcholine) which generates an action potential in the sarcolemma.

• • Vesicles in synaptic knobs fuse with presynaptic membrane and release ACh into synaptic cleft.

This spreads through the muscle fibre and causes the release of calcium ions into the sarcoplasm from the sarcoplasmic reticulum, initiating sliding filament contraction.

• • Acetylcholinesterase subsequently degrades ACh to terminate muscle stimulation.

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.

• • Total 26 vertebrae in adult human skeleton (fused from 33 in embryonic stages).

Align the given anatomical regions: (b) Cervical vertebra -> (a) Thoracic vertebra -> (c) Lumbar vertebra -> (d) Sacrum.

• • Cranial means superior/headward; caudal means inferior/tailward.

Examine respiratory and cardiovascular pathology from NCERT:

• • A matches II (A-II).
• • B matches III (B-III).

Examine excretory and musculoskeletal disorders:

• • C matches IV (C-IV).
• • D matches I (D-I).

Assemble the pairs:

• • Matches Option (4) perfectly.

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 (A -> III). 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 (B -> I).

Hinge joint (knee joint) permits movement primarily in one plane helping in walking/locomotion (C -> IV). Ball and socket joint between humerus and pectoral girdle allows rotational, wide-range movement (D -> II).

A-III, B-I, C-IV, D-II corresponds to Option (2).

Joints are classified into three structural categories based on the tissue joining the articulating bones:

NCERT states under Joints: - "Fibrous joints do not allow any movement... shown by the flat skull bones which fuse end-to-end with the help of dense fibrous connective tissues in the form of sutures." - "In cartilaginous joints, the bones involved are joined together with the help of cartilages... between the adjacent vertebrae in the vertebral column." - "Ball and socket joint (between humerus and pectoral girdle), Saddle joint (between carpal and metacarpal of thumb)."

Matching A-II, B-IV, C-I, D-III uniquely corresponds to Option (3).

Analyzing skeletal muscle ultrastructure according to NCERT: - Statement B: The sarcoplasmic reticulum ($SR$) is a specialized endoplasmic reticulum network whose terminal cisternae sequester and release $Ca^{2+}$ upon depolarization. (Statement B is TRUE) - Statement C: Myofibrils exhibit alternating isotropic (I) bands and anisotropic (A) bands arising from the parallel interdigitating arrangement of thin actin and thick myosin myofilaments. (Statement C is TRUE)

Analyzing the anatomical errors planted in A and D: - Statement A: Each muscle consists of muscle bundles called fascicles. The collagenous connective tissue layer holding these fascicles together is called fascia. Statement A mistakenly calls the connective tissue layer "fascicle". - Statement D: The functional contractile unit of a myofibril is the sarcomere, defined as the portion between two successive Z-lines, NOT the M-line (the M-line is simply a thin fibrous membrane holding thick filaments in the middle of the A-band).

Statements B and C are correct, while A and D are false. Option (3) is the required answer.

Myasthenia gravis is a classic autoimmune disease of the peripheral nervous and muscular systems: - Autoantibodies (IgG) target and destroy nicotinic acetylcholine receptors (nAChRs) situated on the sarcolemma of the post-synaptic neuromuscular junction (NMJ). - When acetylcholine is released from motor neurons, fewer receptors are available to generate end-plate potentials. - Over time, repetitive muscular contraction fails, precipitating severe fatigue, flaccid weakness, and eventual paralysis of skeletal muscles (frequently initiating with ptosis of eyelids and diplopia).

- Arthritis: Inflammation of one or more joints, causing pain and stiffness. - Muscular dystrophy: Progressive degeneration of skeletal muscle caused by an X-linked recessive genetic defect (dystrophin gene mutation), NOT an autoimmune disorder. - Gout: Inflammation of joints caused by accumulation and crystallization of uric acid salts.

Muscle contraction occurs via the sliding of thin (actin) filaments over thick (myosin) filaments without any change in the physical length of the individual filaments themselves: - (d) ATP Hydrolysis: The globular myosin head acts as an ATPase enzyme, hydrolyzing ATP into $\text{ADP} + \text{P}_i$. This energizes the head into a cocked high-energy state that binds the exposed active sites on actin to form a cross-bridge. - Power Stroke & Z-Line Movement: Release of $\text{ADP}$ and $\text{P}_i$ triggers the power stroke, tilting the myosin head and pulling the attached actin filaments inward toward the centre of the sarcomere ($M$-line). Consequently, the Z-lines attached to actins are pulled inwards ((e) is True). - (c) I-Band Shortening: The isotropic (I) bands (composed of actin filaments only) narrow and reduce in width ((c) is True). - (a) Disappearance of H-Zone: The central H-zone (the region of thick myosin not overlapped by thin actin at rest) progressively narrows and disappears as opposing actin filaments overlap ((a) is True). - (b) Constancy of A-Band: The anisotropic (A) band corresponds to the entire physical length of the myosin filament. Because myosin filaments do not lengthen or expand, the A-band retains its constant length and NEVER widens ((b) is FALSE).

$$\begin{array}{l|l} \textbf{Sarcomere Metric} & \textbf{Status During Contraction} \\ \hline \text{Sarcomere Length (Z to Z)} & \text{Shortens} \\ \text{I-Band (Actin only)} & \text{Reduces in width (Shortens)} \\ \text{H-Zone (Myosin only)} & \text{Narrows and Disappears} \\ \mathbf{A\text{-Band (Total Myosin)}} & \mathbf{Retains\,Length\,(Constant,\,DOES\,NOT\,WIDEN)} \\ \end{array}$$ Therefore, the events that occur are (a), (c), (d), and (e) only.

- (a) Scapula: A large, thin, triangular flat bone situated in the dorsal part of the thorax between the second and seventh ribs. It features a spine terminating in the acromion process. - (b) Cranium: Cranial bones are firmly knit together end-to-end by dense fibrous connective tissue in the form of sutures to form the brain box; these are classic fibrous joints that permit zero movement (synarthroses). - (c) Sternum: A dagger-shaped flat bone positioned along the ventral midline of the thorax, providing anterior anchorage for true ribs. - (d) Vertebral column: Adjacent vertebrae are articulated by intervertebral fibrocartilaginous discs, which constitute cartilaginous joints (amphiarthroses) permitting limited flexibility and shock absorption.

Matching sequence is: (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i). This corresponds perfectly to Option (4).

The last 2 pairs of ribs (11th and 12th) are not connected ventrally to the sternum and are therefore called floating ribs. Thus, (a) matches (iv).

The dorsal, flat, triangular body of the scapula has a slightly elevated ridge called the spine which projects as a flat, expanded process called the acromion. The clavicle articulates with this acromion process. Thus, (b) matches (iii).

Scapula is a large triangular flat bone situated in the dorsal part of the thorax between the second and the seventh ribs. Thus, (c) matches (i).

Below the acromion is a shallow depression called the glenoid cavity which articulates with the head of the humerus to form the shoulder joint. Thus, (d) matches (ii).