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Answer all the questions
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Here are the answers to all 20 MCQs from the MBBS First Year Anatomy Paper I (Set D):
MBBS First Year Professional Exam - Human Anatomy Paper I (Set D)
| Q# | Question | Answer | Explanation |
|---|---|---|---|
| 1 | Which joint is classified as a condyloid synovial joint? | (C) Radiocarpal joint | The wrist (radiocarpal) joint is the classic condyloid (ellipsoid) joint - two axes of movement, no rotation. The shoulder is ball-and-socket; hip is ball-and-socket; superior radioulnar is pivot. |
| 2 | A sesamoid bone develops: | (A) Within a tendon | Sesamoid bones (e.g., patella) develop within the substance of tendons, where they reduce friction and change the angle of pull. |
| 3 | The cubital fossa contains all EXCEPT: | (C) Ulnar nerve | The cubital fossa contains: biceps tendon, brachial artery, and median nerve (mnemonic: "Really Need Beer" - Radial nerve also present laterally). The ulnar nerve passes posterior to the medial epicondyle, NOT through the cubital fossa. |
| 4 | Muscle responsible for initiating the first 15° of arm abduction: | (B) Supraspinatus | Supraspinatus initiates the first 15° (some texts say 0-15°) of abduction. After that, the deltoid takes over. |
| 5 | The ulnar nerve passes posterior to the: | (B) Medial epicondyle of humerus | The ulnar nerve passes through the groove on the posterior aspect of the medial epicondyle (cubital tunnel). This is why hitting the "funny bone" causes ulnar nerve symptoms. |
| 6 | Which muscle inserts into the base of the second metacarpal? | (B) Flexor carpi radialis | Flexor carpi radialis inserts primarily into the base of the 2nd metacarpal (and sometimes 3rd). Extensor carpi radialis longus also inserts here, but among the options FCR is correct. |
| 7 | Principal blood supply to the head of humerus in adults: | (B) Anterior circumflex humeral artery | The anterolateral branch of the anterior circumflex humeral artery (arcuate artery) is the dominant supply to the humeral head in adults. (Note: some recent studies suggest posterior circumflex is more dominant, but classically anterior circumflex is the standard answer.) |
| 8 | Injury to the long thoracic nerve results in: | (C) Winging of scapula | The long thoracic nerve (C5, C6, C7) innervates serratus anterior. Damage causes the medial border of scapula to protrude - classic "winged scapula." |
| 9 | The notochord is derived from: | (C) Mesoderm | The notochord is derived from the axial mesoderm (intraembryonic mesoderm). It induces the overlying ectoderm to form the neural plate. |
| 10 | Implantation of blastocyst normally occurs during the: | (B) Second week | Implantation begins around day 6-7 and is completed by day 10-12, which falls within the 2nd week of development. |
| 11 | Matrix of hyaline cartilage is rich in: | (B) Type II collagen | Hyaline (and fibrocartilage) cartilage matrix is rich in Type II collagen. Type I is in bone/tendons; elastic cartilage has elastic fibers. |
| 12 | Cell primarily responsible for antibody production: | (B) Plasma cell | Plasma cells (differentiated B lymphocytes) are the primary antibody-secreting cells. Mast cells release histamine; macrophages are phagocytes; fibroblasts make connective tissue. |
| 13 | The only movable bone of the skull: | (B) Mandible | The mandible is the only bone of the skull with a synovial joint (TMJ) allowing movement. The hyoid is a bone of the neck, not strictly the skull. |
| 14 | The stylomastoid foramen transmits the: | (B) Facial nerve | The facial nerve (CN VII) exits the skull through the stylomastoid foramen, after traversing the facial canal. |
| 15 | The submandibular gland is mainly supplied by the: | (B) Lingual artery | The submandibular (submaxillary) gland is primarily supplied by the lingual artery (a branch of the external carotid). The facial artery also contributes but the lingual is the main supply. |
| 16 | The thalamus is a part of the: | (B) Diencephalon | The thalamus, hypothalamus, epithalamus, and subthalamus are all parts of the diencephalon. |
| 17 | Which ventricle is located between the cerebellum and the pons? | (D) Fourth ventricle | The fourth ventricle lies between the pons/medulla anteriorly and the cerebellum posteriorly. |
| 18 | The posterior pituitary (neurohypophysis) is composed mainly of: | (C) Pituicytes and unmyelinated nerve fibers | The neurohypophysis contains pituicytes (specialized glial cells) and unmyelinated axons of hypothalamic neurons that store/release ADH and oxytocin. Chromophils/chromophobes are in the anterior pituitary (adenohypophysis). |
| 19 | Nissl bodies are absent in the: | (C) Axon | Nissl bodies (rough endoplasmic reticulum) are present in the cell body (perikaryon) and dendrites but are absent in the axon and axon hillock. |
| 20 | The pituitary gland develops from: | (B) Oral ectoderm and neuroectoderm | The anterior pituitary (adenohypophysis) develops from Rathke's pouch (oral ectoderm/stomodeum); the posterior pituitary (neurohypophysis) develops from a downgrowth of the neuroectoderm (floor of diencephalon). Together: oral ectoderm + neuroectoderm. |
Quick Summary of Correct Answers:
C, A, C, B, B, B, B, C, C, B, B, B, B, B, B, B, D, C, C, B
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