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Axial Muscles of the Body - Anatomy & Physiology

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  • Muscles of facial expression innervation

    Innervated by the facial nerve (cranial nerve VII), these muscles lie in the face and scalp and often insert into the skin.
  • Epicranius muscle parts and action

    The epicranius has a frontal belly that raises the eyebrows and wrinkles the forehead and an occipital belly at the back of the head.
  • Function of orbicularis oculi

    The orbicularis oculi closes the eyelids during blinking.
  • Zygomaticus major muscle action

    The zygomaticus major produces a smile by extending from the zygomatic region toward the mouth.
  • Buccinator muscle role

    Forms the muscular wall of the cheek and compresses the cheek during chewing.
  • Muscles of mastication innervation

    Innervated by the mandibular division of the trigeminal nerve (cranial nerve V).
  • Prime movers of jaw closure

    The masseter and temporalis muscles are the prime movers of jaw closure.
  • Function of lateral and medial pterygoid muscles

    These deep muscles assist with side-to-side jaw movement.
  • Extrinsic tongue muscles innervation

    Innervated by the hypoglossal nerve (cranial nerve XII), they move the tongue in various directions.
  • Suprahyoid muscles and location

    Located superior to the hyoid bone, includes mylohyoid, stylohyoid, and digastric muscles.
  • Infrahyoid muscles and location

    Located inferior to or associated with the hyoid and laryngeal cartilages, includes sternohyoid, omohyoid, sternothyroid, and thyrohyoid.
  • Pharyngeal constrictors function

    These muscles compress the pharynx and direct food toward the esophagus during swallowing.
  • Sternocleidomastoid muscle action

    Responsible for head flexion and divides the neck into anterior and posterior triangles.
  • Erector spinae muscle group components

    Consists of three longitudinal columns: iliocostalis, longissimus, and spinalis.
  • Diaphragm role in respiration

    The diaphragm is the most important muscle of respiration; its contraction flattens it and increases thoracic cavity volume.
  • External vs internal intercostals function

    External intercostals lift the rib cage during inspiration, internal intercostals assist expiration during heavy breathing.
  • Layers of the abdominal wall muscles

    From superficial to deep: external oblique, internal oblique, transversus abdominis, with rectus abdominis running vertically.
  • Linea alba significance

    A midline fibrous seam formed by interlacing abdominal aponeuroses; insertion site for rectus abdominis.
  • Pelvic diaphragm composition

    Consists of the levator ani (iliococcygeus, puborectalis, pubococcygeus) and coccygeus muscles.
  • Urogenital diaphragm muscles

    Includes the sphincter urethrae (external urethral sphincter) and deep transverse perineus muscles.
  • Superficial perineal muscles

    Includes ischiocavernosus, bulbospongiosus, and superficial transverse perineus muscles.
  • Pectoralis major muscle location

    A large superficial muscle covering the upper anterior thorax.
  • Pectoralis minor muscle location

    A smaller deep muscle exposed when pectoralis major is removed.
  • Serratus anterior muscle identification

    Has saw-toothed slips along the lateral ribs.
  • Distinction between facial expression and mastication muscles

    Facial expression muscles insert into skin and use CN VII; mastication muscles use the mandibular division of CN V.
  • Difference between buccinator and masseter

    Buccinator compresses the cheek; masseter closes the jaw.
  • Omohyoid muscle bellies

    Has superior and inferior bellies separated by an intermediate tendon.
  • Digastric muscle bellies

    Has anterior and posterior bellies connected by an intermediate tendon.