Facial Muscles Anatomy PDF

**FACIAL MUSCLES** **1. What nerve innervates the muscles of facial expression, and through which foramina does it exit the skull?** - **Rationale:** This question assesses the student's knowledge of the facial nerve (CN VII), which innervates all the muscles of facial expression, and it...

**FACIAL MUSCLES** **1. What nerve innervates the muscles of facial expression, and through which foramina does it exit the skull?** - **Rationale:** This question assesses the student's knowledge of the facial nerve (CN VII), which innervates all the muscles of facial expression, and its exit through the stylomastoid foramen. **2. Identify the primary muscles involved in raising the eyebrows and their innervation.** - **Rationale:** The frontalis muscle, part of the occipitofrontalis, raises the eyebrows and is innervated by the facial nerve (CN VII). Understanding specific muscles of facial expression is fundamental for clinical application. **3. Which muscles are responsible for closing the eyelids, and what could be the clinical implication of damage to their innervating nerve?** - **Rationale:** The orbicularis oculi muscle closes the eyelids, and it is innervated by the facial nerve. Damage to this nerve (e.g., in Bell\'s palsy) can lead to incomplete eye closure, resulting in corneal damage. **4. Which muscle is primarily responsible for compressing the cheeks against the teeth, and how is this muscle innervated?** - **Rationale:** The buccinator muscle, responsible for compressing the cheeks (as in blowing or chewing), is also innervated by the facial nerve (CN VII). This helps in identifying muscles that are used in specific movements. **5. Describe the function of the platysma muscle and explain the effects of its paralysis.** - **Rationale:** The platysma is a superficial neck muscle involved in tensing the skin of the neck and facial expression. Paralysis of this muscle (due to facial nerve injury) may result in drooping of the skin of the neck, leading to a characteristic clinical appearance. **6. Which cranial nerve provides sensory innervation to the face, and how does it differ from the motor innervation to facial muscles?** - **Rationale:** The trigeminal nerve (CN V) provides sensory innervation, while the facial nerve (CN VII) is responsible for motor innervation to facial muscles. This distinction is important for understanding conditions like trigeminal neuralgia or Bell's palsy. **7. Explain the role of the zygomaticus major muscle in facial expression and its innervation.** - **Rationale:** The zygomaticus major elevates the corners of the mouth (as in smiling) and is innervated by the zygomatic and buccal branches of the facial nerve. This question helps to reinforce knowledge of specific facial muscle functions. **8. How does the facial nerve divide after leaving the stylomastoid foramen, and what are the implications of injury to these branches?** - **Rationale:** The facial nerve divides into five major branches: temporal, zygomatic, buccal, mandibular, and cervical. Understanding the specific functions of each branch helps in localizing facial nerve injuries. These questions are designed to integrate anatomy knowledge with clinical relevance, highlighting both muscle functions and the consequences of nerve damage. **1. What are the muscles responsible for elevating the eyebrows and forehead wrinkles?** - **Answer:** The frontalis muscle, which is part of the occipitofrontalis muscle, is responsible for elevating the eyebrows and creating horizontal forehead wrinkles. - **Innervation:** Temporal branch of the facial nerve (CN VII). **2. Which muscle closes the eyelids, and what are its clinical implications if paralyzed?** - **Answer:** The orbicularis oculi muscle closes the eyelids. Paralysis of this muscle (e.g., in Bell's palsy) can result in incomplete eye closure, which may lead to corneal drying and ulceration. - **Innervation:** Zygomatic and temporal branches of the facial nerve (CN VII). **3. What muscle is responsible for elevating the upper lip and what is its function in facial expression?** - **Answer:** The levator labii superioris elevates the upper lip, helping to expose the teeth during expressions like smiling or sneering. - **Innervation:** Zygomatic and buccal branches of the facial nerve (CN VII). **4. Name the muscle that raises the corners of the mouth to produce a smile.** - **Answer:** The zygomaticus major muscle elevates the corners of the mouth to create a smile. - **Innervation:** Zygomatic and buccal branches of the facial nerve (CN VII). **5. Which muscle is responsible for compressing the cheeks against the teeth, as in blowing or chewing?** - **Answer:** The buccinator muscle compresses the cheeks against the teeth and aids in chewing and blowing. - **Innervation:** Buccal branch of the facial nerve (CN VII). **6. What muscle is involved in lowering the bottom lip and making a \"pouting\" face?** - **Answer:** The depressor labii inferioris pulls the lower lip downward, aiding in the expression of sadness or pouting. - **Innervation:** Mandibular branch of the facial nerve (CN VII). **7. What is the function of the orbicularis oris muscle, and what might occur if it is paralyzed?** - **Answer:** The orbicularis oris muscle encircles the mouth and is responsible for closing the lips and protruding them (as in kissing). Paralysis may lead to drooling or difficulty with speech and eating. - **Innervation:** Buccal and mandibular branches of the facial nerve (CN VII). **8. Which muscle helps wrinkle the skin of the chin and protrude the lower lip?** - **Answer:** The mentalis muscle wrinkles the skin of the chin and protrudes the lower lip, as seen in a \"pouting\" expression. - **Innervation:** Mandibular branch of the facial nerve (CN VII). **9. Name the muscle responsible for tensing the skin of the neck and explain its clinical importance.** - **Answer:** The platysma muscle tenses the skin of the neck and assists in depressing the mandible. Paralysis of the platysma can cause the skin of the neck to sag. - **Innervation:** Cervical branch of the facial nerve (CN VII). **10. Which muscles pull the corners of the mouth downward, contributing to a frowning expression?** - **Answer:** The depressor anguli oris muscle pulls the corners of the mouth downward, producing a frowning expression. - **Innervation:** Mandibular and buccal branches of the facial nerve (CN VII). **11. What is the function of the nasalis muscle, and what is its role in facial expressions?** - **Answer:** The nasalis muscle consists of two parts: the transverse part compresses the nasal cartilages, and the alar part dilates the nostrils, assisting in facial expressions related to breathing or intense emotions like anger. - **Innervation:** Buccal branch of the facial nerve (CN VII). **12. Which muscle draws the corners of the mouth laterally, helping create a grimacing expression?** - **Answer:** The risorius muscle draws the corners of the mouth laterally, contributing to expressions such as grimacing. - **Innervation:** Buccal branch of the facial nerve (CN VII). **13. Which muscle elevates the upper lip and contributes to deepening the nasolabial fold?** - **Answer:** The levator anguli oris muscle elevates the corners of the mouth and deepens the nasolabial fold, often seen in expressions of joy or contempt. - **Innervation:** Buccal branch of the facial nerve (CN VII). **14. Which muscle aids in pulling the ears backward and why is it mostly vestigial in humans?** - **Answer:** The auricularis muscles (anterior, superior, and posterior) pull the ears in different directions. These muscles are vestigial in most humans, with limited movement compared to animals that actively move their ears. - **Innervation:** Temporal branch of the facial nerve (CN VII). **15. What are the clinical implications of injury to the facial nerve (CN VII) regarding facial muscles?** - **Answer:** Injury to the facial nerve results in paralysis of the muscles of facial expression on the affected side, leading to asymmetry in facial movements (e.g., drooping of the mouth or inability to close the eye) and conditions like Bell\'s palsy. **NECK MUSCLES** **1. What is the origin, insertion, function, and innervation of the sternocleidomastoid muscle?** - **Origin:** - Sternal head: Anterior surface of the manubrium. - Clavicular head: Medial third of the clavicle. - **Insertion:** Mastoid process of the temporal bone and the superior nuchal line of the occipital bone. - **Function:** - Unilateral contraction: Rotates the head to the opposite side and tilts it to the same side. - Bilateral contraction: Flexes the neck and extends the head at the atlanto-occipital joint. - **Innervation:** Spinal accessory nerve (CN XI) and branches of C2 and C3 (for proprioception). **2. What are the origins, insertions, and functions of the scalene muscles (anterior, middle, and posterior), and how are they innervated?** - **Anterior Scalene:** - **Origin:** Transverse processes of C3-C6. - **Insertion:** First rib. - **Function:** Elevates the first rib during forced inspiration and laterally flexes the neck. - **Innervation:** Ventral rami of C4-C6. - **Middle Scalene:** - **Origin:** Transverse processes of C2-C7. - **Insertion:** First rib, posterior to the anterior scalene insertion. - **Function:** Elevates the first rib during forced inspiration and assists in lateral flexion of the neck. - **Innervation:** Ventral rami of cervical nerves (C3-C8). - **Posterior Scalene:** - **Origin:** Transverse processes of C4-C6. - **Insertion:** Second rib. - **Function:** Elevates the second rib and laterally flexes the neck. - **Innervation:** Ventral rami of C6-C8. **3. What are the origin, insertion, function, and innervation of the platysma muscle?** - **Origin:** Fascia of the upper thorax and lower neck (over the pectoralis major and deltoid muscles). - **Insertion:** Lower border of the mandible and skin of the lower face. - **Function:** Tenses the skin of the neck and depresses the mandible, contributing to facial expressions of fear or sadness. - **Innervation:** Cervical branch of the facial nerve (CN VII). **4. Describe the origin, insertion, function, and innervation of the trapezius muscle, focusing on its role in neck movement.** - **Origin:** - External occipital protuberance. - Ligamentum nuchae. - Spinous processes of C7-T12. - **Insertion:** - Lateral third of the clavicle. - Acromion and spine of the scapula. - **Function:** - Upper fibers: Elevate and upwardly rotate the scapula, extend the neck. - Middle fibers: Retract the scapula. - Lower fibers: Depress the scapula. - **Innervation:** Spinal accessory nerve (CN XI) and C3-C4 ventral rami (for sensory and proprioception). **5. What is the origin, insertion, function, and innervation of the digastric muscle?** - **Origin:** - Anterior belly: Digastric fossa of the mandible. - Posterior belly: Mastoid notch of the temporal bone. - **Insertion:** Hyoid bone via a fibrous loop. - **Function:** Depresses the mandible (opening the mouth) and elevates the hyoid bone during swallowing. - **Innervation:** - Anterior belly: Mylohyoid nerve (a branch of the inferior alveolar nerve from CN V3). - Posterior belly: Facial nerve (CN VII). **6. What are the origins, insertions, functions, and innervations of the infrahyoid muscles?** - **Sternohyoid:** - **Origin:** Manubrium of the sternum and the medial end of the clavicle. - **Insertion:** Body of the hyoid bone. - **Function:** Depresses the hyoid bone after swallowing. - **Innervation:** Ansa cervicalis (C1-C3) - **Sternothyroid:** - **Origin:** Posterior surface of the manubrium. - **Insertion:** Oblique line of the thyroid cartilage. - **Function:** Depresses the thyroid cartilage (larynx). - **Innervation:** Ansa cervicalis (C1-C3). - **Thyrohyoid:** - **Origin:** Oblique line of the thyroid cartilage. - **Insertion:** Lower border of the hyoid bone. - **Function:** Depresses the hyoid bone or elevates the thyroid cartilage. - **Innervation:** C1 via the hypoglossal nerve (CN XII). - **Omohyoid:** - **Origin:** - Inferior belly: Superior border of the scapula. - Superior belly: Intermediate tendon (attached to the clavicle). - **Insertion:** Body of the hyoid bone. - **Function:** Depresses and stabilizes the hyoid bone. - **Innervation:** Ansa cervicalis (C1-C3). **7. What is the origin, insertion, function, and innervation of the mylohyoid muscle?** - **Origin:** Mylohyoid line of the mandible. - **Insertion:** Body of the hyoid bone and the midline raphe. - **Function:** Elevates the floor of the mouth and the hyoid bone during swallowing and speaking. - **Innervation:** Mylohyoid nerve, a branch of the inferior alveolar nerve (from CN V3). **8. Describe the origin, insertion, function, and innervation of the levator scapulae muscle.** - **Origin:** Transverse processes of C1-C4 vertebrae. - **Insertion:** Superior part of the medial border of the scapula. - **Function:** Elevates the scapula and tilts the glenoid cavity inferiorly by rotating the scapula downward. Also assists in lateral flexion of the neck. - **Innervation:** Dorsal scapular nerve (C5) and cervical nerves (C3-C4). **9. What is the origin, insertion, function, and innervation of the longus colli muscle?** - **Origin:** - Inferior oblique part: Anterior surfaces of T1-T3 vertebrae. - Superior oblique part: Transverse processes of C3-C5. - **Insertion:** - Inferior oblique part: Transverse processes of C5-C6. - Superior oblique part: Anterior arch of the atlas (C1). - **Function:** Flexes the neck anteriorly and laterally; aids in rotation of the neck. - **Innervation:** Ventral rami of C2-C6. **10. What are the origins, insertions, functions, and innervations of the splenius capitis and splenius cervicis muscles?** - **Splenius Capitis:** - **Origin:** Nuchal ligament and spinous processes of C7-T3. - **Insertion:** Mastoid process of the temporal bone and lateral third of the superior nuchal line. - **Function:** Extends, rotates, and laterally flexes the head. - **Innervation:** Dorsal rami of cervical spinal nerves. - **Splenius Cervicis:** - **Origin:** Spinous processes of T3-T6. - **Insertion:** Transverse processes of C1-C3. - **Function:** Extends, rotates, and laterally flexes the neck. - **Innervation:** Dorsal rami of cervical spinal nerves. **THORACIC WALL MUSCLE** **1. What is the origin, insertion, function, and innervation of the external intercostal muscles?** - **Origin:** Inferior border of the rib above. - **Insertion:** Superior border of the rib below. - **Function:** Elevates the ribs during inspiration, increasing the anteroposterior and lateral dimensions of the thoracic cavity. - **Innervation:** Intercostal nerves (T1-T11). **2. Describe the origin, insertion, function, and innervation of the internal intercostal muscles.** - **Origin:** Inferior border of the rib above. - **Insertion:** Superior border of the rib below. - **Function:** - Interosseous part: Depresses the ribs during forced expiration. - Interchondral part: Elevates the ribs during inspiration. - **Innervation:** Intercostal nerves (T1-T11). **3. What is the origin, insertion, function, and innervation of the innermost intercostal muscles?** - **Origin:** Inferior border of the rib above. - **Insertion:** Superior border of the rib below. - **Function:** Acts similarly to the internal intercostals, assisting in forced expiration by depressing the ribs. - **Innervation:** Intercostal nerves (T1-T11). **4. What are the origin, insertion, function, and innervation of the transversus thoracis muscle?** - **Origin:** Posterior surface of the lower sternum and xiphoid process. - **Insertion:** Internal surface of costal cartilages of ribs 2-6. - **Function:** Weakly depresses the ribs and helps compress the thoracic cavity during forced expiration. - **Innervation:** Intercostal nerves (T2-T6). **5. Describe the origin, insertion, function, and innervation of the subcostal muscles.** - **Origin:** Internal surface of the lower ribs near their angles. - **Insertion:** Superior borders of ribs two to three levels below the origin. - **Function:** Depresses the ribs, assisting in expiration. - **Innervation:** Intercostal nerves (T1-T11). **6. What is the origin, insertion, function, and innervation of the diaphragm?** - **Origin:** - Sternal part: Xiphoid process. - Costal part: Internal surfaces of the lower six ribs and costal cartilages. - Lumbar part: L1-L3 vertebrae via crura and the arcuate ligaments. - **Insertion:** Central tendon of the diaphragm. - **Function:** Primary muscle of inspiration; it contracts to increase the volume of the thoracic cavity and decrease intra-thoracic pressure, allowing air to flow into the lungs. - **Innervation:** Phrenic nerve (C3-C5). **7. What is the origin, insertion, function, and innervation of the levatores costarum muscles?** - **Origin:** Transverse processes of C7-T11. - **Insertion:** The rib below (or two ribs below for longus) near the tubercle. - **Function:** Elevates the ribs, aiding in inspiration. - **Innervation:** Dorsal rami of C8-T11 spinal nerves. **8. Describe the origin, insertion, function, and innervation of the serratus posterior superior muscle.** - **Origin:** Nuchal ligament and spinous processes of C7-T3. - **Insertion:** Superior borders of ribs 2-5. - **Function:** Elevates ribs 2-5, assisting in inspiration. - **Innervation:** Intercostal nerves (T2-T5). **9. What is the origin, insertion, function, and innervation of the serratus posterior inferior muscle?** - **Origin:** Spinous processes of T11-L2. - **Insertion:** Inferior borders of ribs 9-12. - **Function:** Depresses ribs 9-12, aiding in forced expiration. - **Innervation:** Intercostal nerves (T9-T12). **10. What is the origin, insertion, function, and innervation of the pectoralis major muscle, specifically its role in thoracic wall movements?** - **Origin:** - Clavicular head: Medial half of the clavicle. - Sternocostal head: Sternum, upper six costal cartilages, and aponeurosis of the external oblique muscle. - **Insertion:** Lateral lip of the intertubercular groove of the humerus. - **Function:** Assists in forced inspiration by elevating the ribs when the arms are fixed; primarily involved in adduction, flexion, and medial rotation of the humerus. - **Innervation:** Lateral and medial pectoral nerves (C5-T1). **11. Describe the origin, insertion, function, and innervation of the pectoralis minor muscle in relation to the thoracic wall.** - **Origin:** Anterior surfaces of ribs 3-5 near their costal cartilages. - **Insertion:** Coracoid process of the scapula. - **Function:** Stabilizes the scapula and assists in forced inspiration by elevating the ribs when the scapula is fixed. - **Innervation:** Medial pectoral nerve (C8-T1). **12. What is the origin, insertion, function, and innervation of the serratus anterior muscle?** - **Origin:** External surfaces of ribs 1-8 or 9. - **Insertion:** Anterior surface of the medial border of the scapula. - **Function:** Elevates the ribs during forced inspiration and protracts the scapula; prevents winging of the scapula. - **Innervation:** Long thoracic nerve (C5-C7). **13. What is the origin, insertion, function, and innervation of the subclavius muscle?** - **Origin:** First rib and its costal cartilage. - **Insertion:** Inferior surface of the middle third of the clavicle. - **Function:** Depresses the clavicle and helps stabilize the sternoclavicular joint; may help elevate the first rib during respiration. - **Innervation:** Nerve to subclavius (C5-C6). **14. Describe the function of the intercostal nerves and their involvement with thoracic wall muscles.** - **Answer:** The intercostal nerves (T1-T11) innervate the intercostal muscles (external, internal, and innermost), transversus thoracis, subcostal muscles, and the serratus posterior muscles. These nerves provide both motor innervation to these muscles and sensory innervation to the skin of the thoracic wall and the pleura. The intercostal nerves play a crucial role in coordinating movements of the thoracic wall during respiration.