Embryology Quiz 1 PDF

**[Embryology Quiz 1]** **Branchial arches:** a\. all share a common blood supply. **b. each have their own nerve supply.** c\. have derivatives for all 6 arches. d\. are made up of ectoderm, mesoderm and endoderm.\ \ Each **branchial arch** has its own **distinct nerve supply**, which is typic...

**[Embryology Quiz 1]** **Branchial arches:** a\. all share a common blood supply. **b. each have their own nerve supply.** c\. have derivatives for all 6 arches. d\. are made up of ectoderm, mesoderm and endoderm.\ \ Each **branchial arch** has its own **distinct nerve supply**, which is typically from a **cranial nerve**. For example: - **Branchial Arch I** is innervated by the **trigeminal nerve (cranial nerve V)**. - **Branchial Arch II** is innervated by the **facial nerve (cranial nerve VII)**. - **Branchial Arch III** is innervated by the **glossopharyngeal nerve (cranial nerve IX)**. - **Branchial Arch IV** is innervated by the **vagus nerve (cranial nerve X)**. - **Branchial Arch VI** is also innervated by the **vagus nerve (cranial nerve X)**. **Derivatives of the ectoderm include:** **a. skin** b\. skeleton- mesoderm c\. muscles- mesoderm **d. enamel** - **a. skin:\ The ectoderm gives rise to the epidermis of the skin, as well as other structures like hair and nails. This is one of the major derivatives of the ectoderm.** - **d. enamel:\ The ectoderm is responsible for the development of enamel, the hard outer layer of the teeth. This is because enamel forms from ameloblasts, which originate from the ectoderm.** **During embryology the blastocyst:** **Question 3Select one:** a\. is a fluid filled ball of cells that forms after fertilisation of the zygote. **b. is a fluid filled ball of cells that forms after formation of the morula.** c\. is a solid ball of cells that forms from cleavage of the zygote. d\. is a solid ball of cells that forms from cleavage of the morula. **The blastocyst is a stage in embryonic development that forms after the morula. Here\'s a breakdown of the process:** - **After fertilization, the zygote undergoes cleavage, which results in a solid ball of cells called the morula.** - **As the morula continues to divide, it forms a hollow structure with a fluid-filled cavity called the blastocyst cavity. This marks the blastocyst stage.** **At the blastocyst stage, the embryo consists of two main components:** 1. **Inner cell mass: which will develop into the embryo.** 2. **Trophoblast: which will form the placenta.** **Neural crest cells give rise to:** Question 4Select one: a\. neuroectoderm and nerves in the head. b\. somites and blood vessels in the head. **c. ectomesenchyme and connective tissue in the head.** d\. the neural tube and spinal cord of the body. **Neural crest cells** are a group of cells that emerge from the **neuroectoderm** during early development. These cells migrate to various parts of the body and differentiate into a wide variety of structures, particularly in the **head and neck**. **Neural crest cells** give rise to: - **Ectomesenchyme**: A type of mesenchyme that contributes to the formation of **bone, cartilage**, and **connective tissue** in the head. - **Connective tissue**: Neural crest cells help form the **craniofacial structures**, including the bones, muscles, and soft tissues of the face and skull. **Select the correct answer regarding the development of the tongue:** Question 5Select one: **a. The tongue is innervated by the glossopharyngeal nerve and the trigeminal nerve.** b\. The tongue develops before the stomodeum. c\. The tongue develops from bulges in the 1st branchial arch. d\. The tongue develops after the palate. The **development of the tongue** is a complex process that involves contributions from several branchial arches and is innervated by different cranial nerves. Here\'s a breakdown of the correct answer: - **c. The tongue develops from bulges in the 1st branchial arch**:\ The tongue primarily develops from the **1st branchial arch** (pharyngeal arch), specifically from structures known as the **medial and lateral lingual swellings**. These swellings form most of the tongue, and the posterior part of the tongue is derived from the **2nd, 3rd, and 4th branchial arches**. **This branchial arch does NOT give rise to any structures:** **Question 6Select one:** a\. I. b\. II. c\. III. d\. IV. **e. V.** f\. VI. g\. none of the above. - **Branchial Arch V** is considered **non-functional** in humans, meaning it does **not** give rise to any significant structures in the head or neck. While it may have some transient elements during development, it does not contribute to any permanent anatomical structures. **Breakdown of the other branches:** - **a. Arch I:\ This arch gives rise to important structures, including the maxilla, mandible, muscles of mastication, and the trigeminal nerve (CN V).** - **b. Arch II:\ This arch contributes to the formation of the hyoid bone, muscles of facial expression, and is innervated by the facial nerve (CN VII).** - **c. Arch III:\ This arch contributes to the hyoid bone and the stylopharyngeus muscle. It is innervated by the glossopharyngeal nerve (CN IX).** - **d. Arch IV:\ This arch contributes to the laryngeal cartilages and the cricothyroid muscle, innervated by the vagus nerve (CN X).** - **f. Arch VI:\ This arch forms the laryngeal cartilages and the intrinsic muscles of the larynx, also innervated by the vagus nerve (CN X).** **The branchial arches innervated by the glossopharyngeal nerve (cranial nerve IX) are:** **Question 7Select one:** a\. IV. b\. V. c\. VI. d\. none of the above. e\. I. **f. III.** g\. II. **Explanation:** The **glossopharyngeal nerve (Cranial Nerve IX)** innervates structures that develop from **Branchial Arch III**. This includes the **stylopharyngeus muscle** and contributes to the **posterior 1/3** of the tongue (both sensory and taste sensation). **The derivatives of these branchial arches are innervated by the trigeminal nerve (cranial nerve V):** **Question 8Select one:** a\. III. b\. none of the above. c\. II. d\. VI. **e. I.** f\. IV. g\. V. **Branchial Arch I** is primarily innervated by the **trigeminal nerve (cranial nerve V)**. This arch gives rise to important structures such as: - The **maxilla** and **mandible** (bones of the face). - The **muscles of mastication** (e.g., masseter, temporalis). - The **anterior belly of the digastric muscle**. - The **tensor veli palatini** and **tensor tympani** muscles. The **trigeminal nerve** provides sensory innervation to the skin of the face and motor innervation to the muscles of mastication. **a. III.**:\ Branchial Arch III is innervated by the **glossopharyngeal nerve (Cranial Nerve IX)**, not the trigeminal nerve. **b. none of the above**:\ This is incorrect because Branchial Arch I is indeed innervated by the trigeminal nerve. **c. II.**:\ Branchial Arch II is innervated by the **facial nerve (Cranial Nerve VII)**. **d. VI.**:\ Branchial Arch VI is innervated by the **vagus nerve (Cranial Nerve X)**. **f. IV.**:\ Branchial Arch IV is also innervated by the **vagus nerve (Cranial Nerve X)**. **g. V.**:\ Branchial Arch V does not give rise to any structures and does not have an associated nerve. **The development of the face begins in:** **Question 9Select one:** a\. week 2. b\. week 3. **c. week 4.** d\. week 5. The development of the **face** begins during **week 4** of embryonic development. Around this time, the first branchial arch (pharyngeal arch) starts to form the basic structures that will develop into the face, including the **maxilla, mandible**, and other facial elements. This is a critical period where the initial formation of the **pharyngeal arches** and facial prominences occurs. By the end of **week 4**, the **stomodeum** (the primitive oral cavity) is established, and the facial prominences are beginning to come together to form the initial shape of the face. - **a. week 2**:\ The second week is focused on **implantation** and early **bilaminar disc** development, not the formation of facial structures. - **b. week 3**:\ By week 3, the **primitive streak** and **gastrulation** occur, and early organ development begins, but facial structures start to take shape in week 4. - **d. week 5**:\ By week 5, the basic structures of the face are starting to form, but facial development is already well underway by this point, starting in week 4. **The development of the secondary palate:** **Question 10Select one:** a\. forms from an extension of the primary palate. b\. enables fusion with the nasal septum and upper lip. c\. takes place in week 4 of embryogenesis. **d. creates the barrier between the oral and nasal cavities.** **The secondary palate is responsible for forming the barrier between the oral and nasal cavities. It begins developing during week 6 to 7 of embryogenesis and plays a crucial role in the separation of the nasal and oral cavities. The secondary palate is formed from the palatal shelves of the maxillary prominences, which fuse in the midline to form the hard and soft palate.** **a. forms from an extension of the primary palate:\ This is incorrect. The primary palate forms from the intermaxillary segment and gives rise to the premaxilla (including the upper lip and the anterior part of the hard palate), while the secondary palate forms later and is not an extension of the primary palate.** **b. enables fusion with the nasal septum and upper lip:\ This is incorrect. The secondary palate primarily fuses with the nasal septum, but it does not directly fuse with the upper lip. The upper lip forms from the fusion of the maxillary and medial nasal processes in the early weeks (around weeks 4-7).** **c. takes place in week 4 of embryogenesis:\ This is incorrect. The secondary palate begins forming around week 6 of embryonic development, not in week 4.** **The face begins to form from which processes:** **Question 11Select one:** a\. nasal placodes. b\. maxillary. c\. mandibular. **d. frontonasal.** The face begins to form from the **frontonasal process** during early embryonic development. The frontonasal process is a prominent structure in the developing embryo that contributes to the formation of the **forehead, nose**, and **nasal septum**. It is crucial for the development of the upper part of the face. As development progresses, the **maxillary** and **mandibular** processes (from the first branchial arch) contribute to the **formation of the cheeks, upper jaw, and lower jaw**. - **a. nasal placodes**:\ The **nasal placodes** give rise to the **olfactory epithelium** and the **nasal cavities**, but they are not the primary structures from which the face forms. - **b. maxillary**:\ The **maxillary processes** are involved in forming the **upper jaw, cheeks**, and part of the **upper lip**, but they are not the first structures to form the face. - **c. mandibular**:\ The **mandibular processes** give rise to the **lower jaw** and **lower lip**, but they do not form the entire face. **The muscular derivatives of these branchial arches are the muscles of facial expression:** **Question 12Select one:** a\. V. b\. I. c\. none of the above. d\. III. e\. IV. f\. VI. **g. II.** **The muscles of facial expression are derived from Branchial Arch II (also known as the hyoid arch). These muscles are innervated by the facial nerve (Cranial Nerve VII) and include:** - **Frontalis (raises the eyebrows)** - **Orbicularis oculi (closes the eyelids)** - **Orbicularis oris (closes the mouth)** - **Buccinator (compresses the cheeks)** - **Zygomaticus (smiling muscles)** **Branchial Arch II plays a significant role in forming the facial muscles that allow for facial expression.** **a. V.**:\ **Branchial Arch V** does not give rise to any structures in humans and is therefore not involved in the development of muscles. **b. I.**:\ **Branchial Arch I** forms the **muscles of mastication** (such as the **masseter** and **temporalis**) and is innervated by the **trigeminal nerve (Cranial Nerve V)**, not the muscles of facial expression. **c. none of the above**:\ This is incorrect because **Branchial Arch II** is the correct answer. **d. III.**:\ **Branchial Arch III** gives rise to the **stylopharyngeus muscle** and is innervated by the **glossopharyngeal nerve (Cranial Nerve IX)**, not the muscles of facial expression. **e. IV.**:\ **Branchial Arch IV** forms muscles involved in **swallowing** (such as the **cricothyroid**), innervated by the **vagus nerve (Cranial Nerve X)**. **f. VI.**:\ **Branchial Arch VI** forms muscles related to the **larynx** (such as the **intrinsic muscles of the larynx**) and is also innervated by the **vagus nerve**. **The philtrum forms:** **Question 13Select one:** **a. from fusion of the maxillary and medial nasal processes.** b\. at the midline of the face. c\. from fusion of the mandibular and maxillary processes. d\. the lateral of the upper lip. The **philtrum** (the vertical groove in the middle of the upper lip) forms from the **fusion of the maxillary processes** and the **medial nasal processes**. This fusion occurs during the early stages of facial development and is a crucial part of the formation of the **upper lip** and **nose**. **b. at the midline of the face**:\ While the philtrum is located at the midline of the upper lip, this answer doesn\'t explain the developmental processes involved in its formation. **c. from fusion of the mandibular and maxillary processes**:\ The **mandibular processes** and **maxillary processes** do fuse, but this fusion results in the formation of the **lower lip** and **cheeks**, not the philtrum. **d. the lateral of the upper lip**:\ The **lateral portions** of the upper lip are formed by the **maxillary processes**, not by the philtrum itself. The philtrum is a **medial structure**. **The three layers of the embryonic trilaminar disc are:** **Question 14Select one:** **a. ectoderm, mesoderm and endoderm.** b\. ectoderm, ectomesenchyme and endoderm. c\. ectoderm, neuroectoderm and endoderm. d\. ectoderm, mesenchyme and endoderm. During **gastrulation**, which occurs around **week 3** of embryonic development, the **trilaminar disc** forms three primary germ layers: 1. **Ectoderm** -- This layer gives rise to structures such as the **nervous system**, **skin**, and **sensory organs**. 2. **Mesoderm** -- This layer forms the **muscles**, **bones**, **circulatory system**, and **connective tissues**. 3. **Endoderm** -- This layer forms the **lining of the digestive tract**, **respiratory tract**, and **glands** like the liver and pancreas. **\ c. ectoderm, neuroectoderm and endoderm**:\ **Neuroectoderm** refers to a region of the ectoderm that specifically develops into the **nervous system** (neural tube), but it is not a separate layer in the trilaminar disc.\ \ **d. ectoderm, mesenchyme and endoderm**:\ **Mesenchyme** is a type of tissue that originates from mesoderm but is not one of the primary germ layers in the trilaminar disc. **Which branchial arches give rise to the mandible:** **Question 15Select one:** **a. I.** b\. II. c\. III. d\. IV. e\. V. f\. VI. g\. none of the above. The **mandible** develops primarily from **Branchial Arch I** (also known as the **mandibular arch**). During embryonic development, the **mesodermal tissue** from this arch forms the **bones** of the lower jaw, including the **mandible**. The **first arch** also gives rise to the **muscles of mastication** and is innervated by the **trigeminal nerve (cranial nerve V)**. **b. II.**:\ **Branchial Arch II** contributes to the formation of structures such as the **hyoid bone**, but not the mandible. **c. III.**:\ **Branchial Arch III** contributes to the **greater horn** of the **hyoid bone** and muscles of the **pharynx**, not the mandible. **d. IV.**:\ **Branchial Arch IV** contributes to structures in the **larynx** and **pharynx**, not the mandible. **e. V.**:\ **Branchial Arch V** does not form any structures in humans. **f. VI.**:\ **Branchial Arch VI** forms muscles related to the **larynx**, but not the mandible. **g. none of the above**:\ This is incorrect because **Branchial Arch I** is responsible for the development of the mandible. **Which branchial arches give rise to the palatine tonsils:** **Question 16Select one:** a\. I. b\. II. c\. III. d\. IV. e\. V. f\. VI. **g. none of the above.**