25_Axial Muscles.pptx

Axial Muscles Chapter 10, Human Anatomy (LibreTexts) "Muscular System" by Termininja is licensed under CC BY-SA 3.0 Facial Expression Muscles - Naming • Classified by shape: • Orbicularis: circular muscle • Classified by action: • Corrugator: makes ridges and grooves • Levator: elevates (pulls u...

Axial Muscles Chapter 10, Human Anatomy (LibreTexts) "Muscular System" by Termininja is licensed under CC BY-SA 3.0 Facial Expression Muscles - Naming • Classified by shape: • Orbicularis: circular muscle • Classified by action: • Corrugator: makes ridges and grooves • Levator: elevates (pulls up) • Depressor: depresses (pulls down) • Classified by region: • • • • • • • • Supercilii: eyebrows Palpebrae: eyelids Oculi: eyes Oris: mouth Labii: lips Superioris: superior Inferioris: inferior Anguli: corner Facial Expression Muscles - I • Actions: move skin of the face , that covers the eyes, nose and mouth. • Occipitofrontalis is divided into frontalis and occipitalis joined together by epicranial aponeurosis (flat tendon). It wrinkles the skin of the forehead, elevates eyebrows, draws scalp anteriorly. • Corrugator supercilii is deep to occipitofrontalis near the eyebrows region. It draws eyebrows together and creates vertical wrinkles above nose. • Orbicularis oculi is a circular muscle around the eyes that closes the eye (i.e. when you wink, blink, squint). • Levator palpebrae superioris is the muscle that raises superior eyelid to open the eyes. Facial Expression Muscles - II • Nasalis is the lateral muscle of the nose. It elevates corners of nostrils (“flares the nostrils”). • Levator labii superioris extends from under eye to upper lip. It pulls upper lip up in snarl or sneer. • Levator anguli oris is a deep muscle attached to corner of mouth and zygomatic bone. It pulls corner of mouth superiorly and laterally in a smile. • Zygomaticus minor (superior) and zygomaticus major (inferior) pull corner of mouth superiorly and laterally to show a big smile with teeth. Facial Expression Muscles - III • Orbicularis oris is a circular muscle around the mouth that puckers lips (the kissing muscle). • Buccinator is a deep muscle on the cheeks that compresses cheek against teeth as in whistling. • Depressor anguli oris is attached to corner of the mouth and mandible. It pulls corners of mouth down in a frown. • Depressor labii inferioris is attached to lower lip and mandible. It pulls lower lip down. • Mentalis is attached to lower lip and mandible. It protrudes lower lip in a pout. Facial Expression Muscles (Image) Levator labii superioris Nasalis Levator anguli oris Levator palpebrae superioris Zygomaticus minor Zygomaticus major Depressor anguli oris Depressor labii inferioris Mentalis "Front and Side Views of the Muscles of Facial Expressions" by Openstax is licensed under CC BY 4.0 Other Facial Expression Muscles - I (Not shown in PowerPoint picture) • Procerus is the vertical muscle across bridge of nose. It wrinkles the nose. • Risorius pulls corner of mouth laterally to smile without teeth. Extrinsic Eye Muscles • Actions: move the eyes. • Six extraocular muscles innervated by the abducens nerve (CN VI), trochlear nerve (CN IV) and oculomotor nerve (CN III): 1. 2. 3. 4. 5. Superior rectus elevates the eye to look upwards. Medial rectus adducts the eye to look towards nose. Inferior rectus depresses the eye to look downwards. Lateral rectus abducts the eye to look towards sides. Superior oblique abducts, depresses, and internally rotates (intorsion) the eye to look towards sides or downwards. 6. Inferior oblique abducts, elevates, and externally rotates (extorsion) the eye to look towards sides or upwards. Extrinsic Eye Muscles (Image) "Extraocular Muscles" by OpenStax is licensed under CC BY 3.0 Muscles of Mastication • Actions: elevate, depress, protract and retract mandible for chewing (mastication). • Masseter is attached to zygomatic bone and mandible. It elevates and protracts the mandible for chewing. • Temporalis extends from parietal and frontal bones to coronoid process of mandible. It elevates and retracts mandible. Muscles of Mastication (Image) "Muscle that Move the Lower Jaw" by Openstax is licensed under CC BY 4.0 Muscles that Move the Neck - I • Actions: elevation and depression of hyoid bone. • Suprahyoid muscles elevate hyoid bone during swallowing or speaking: • • • • Geniohyoid muscle Digastric muscles Mylohyoid Stylohyoid muscle • Infrahyoid muscles depress hyoid bone during swallowing or speaking: • • • • Thyrohyoid Omohyoid Sternohyoid Sternothyroid Anterior Muscles that Move the Neck (Image) "Muscles of the Anterior Neck" by Openstax is licensed under CC BY 4.0 Muscles that Move the Neck - II • Actions: flexion, extension and rotation of head and neck. • Platysma is an anterior neck muscle. It tenses skin of neck and pulls lower lip down. • Sternocleidomastoid is attached to sternum, clavicle and mastoid process of temporal bone. Bilateral contraction flexes the neck. Unilateral contraction rotates head to opposite side and laterally flexes the neck (i.e. right sternocleidomastoid muscle turns head to the left and laterally flexes head to the right). • Scalene muscles are attached to transverse processes of cervical vertebrae and ribs 1 and 2. Synergists to sternocleidomastoid for flexion of the neck. Also elevate ribs 1 and 2 during inhalation. • Trapezius is synergist to sternocleidomastoid and scalene muscles. Posterior Muscles that Move the Neck (Image) "Posterior and Side Views of the Neck" by Openstax is licensed under CC BY 4.0 Muscles that Move the Vertebral Column • Actions: flex and extend vertebral column • Erector spinae muscles maintain posture: • Iliocostalis muscles • Longissimus muscles • Spinalis muscles • Transversospinalis muscles connect and stabilize vertebrae, extend and rotate vertebral column: • • • • • Semispinalis capitis Semispinalis cervicis Semispinalis thoracis Multifidus Rotatores thoracis • Quadratus lumborum is attached to lumbar vertebrae. Bilateral contraction extends vertebral columns, while unilateral contraction flexes vertebral column laterally. Muscles that Move the Vertebral Column (Image) "Muscles of the Neck and Back" by Openstax is licensed under CC BY 4.0 Quadratus Lumborum (Image) "Muscles of the Abdomen" by Openstax is licensed under CC BY 4.0 Muscles that Move the Thoracic Cage • Actions: respiration (inhalation or exhalation). During inhalation, muscles contract to elevate the ribs and increase volume of lungs. During exhalation, muscles contract to depress the ribs and decrease volume of lungs, forcing air out. • Diaphragm is sheet of muscle that separates thoracic cavity from abdominal cavity. It contracts during inhalation. • External intercostals are in between ribs and superficial to internal intercostals. They elevate ribs during inhalation. • Internal intercostals are in between ribs and deep to external intercostals. They depress ribs during exhalation. • Serratus posterior superior attaches to ribs 2-5 and elevate them during inhalation. • Serratus posterior inferior attaches to ribs 8-12 and depresses them during exhalation. • Transversus thoracis extends across inner surface of ribs 2-6 and depresses them during exhalation. Diaphragm (Image) "The Diaphragm" by Openstax is licensed under CC BY 4.0 Intercostals (Image) "The Thorax" by Openstax is licensed under CC BY 4.0 Serratus Posterior Superior and Inferior "Serratus posterior superior muscle back2" by Anatomography is licensed under CC BY-SA 2.0 "Serratus posterior inferior muscle back3" by Anatomography is licensed under CC BY-SA 2.0 Muscles that Move the Abdomen • Actions: stabilize, flex and rotate vertebral column; unilateral contraction flexes vertebral column laterally. • Rectus abdominis enclosed in rectus sheath which is made by aponeuroses of other abdominal muscles. Medial border is called linea alba. Four segments created by three tendinous intersections. • External obliques are most superficial of abdominal muscles. Fibers run from superior lateral to inferior medial (\). • Internal obliques are deep to external obliques. Fibers run from inferior lateral to superior medial (/). • Transversus abdominis is deep to internal obliques. Fibers are horizontal (-). Muscles that Move the Abdomen (Image) "Muscles of the Abdomen" by Openstax is licensed under CC BY 4.0