Axial Muscles of the Head Neck and Back Study Pack
Kibin's free study pack on Axial Muscles of the Head Neck and Back includes a 7-section study guide, 25 quiz questions, 30 flashcards, and 5 open-ended Explain review questions. Sign up free to track your progress toward mastery, plus upload your own notes and recordings to create personalized study packs organized by course.
Last updated May 28, 2026
Axial Muscles of the Head Neck and Back Study Guide
Master the axial muscles of the head, neck, and back — from the masseter and pterygoids driving mandible movement to the erector spinae and transversospinalis groups stabilizing the vertebral column.
Key Takeaways
- •Axial muscles of the head, neck, and back originate on the axial skeleton and control facial expression, mastication, eye movement, tongue movement, neck positioning, and vertebral column stabilization.
- •Muscles of facial expression are unique because they insert into skin or other muscles rather than bone, allowing them to move the face for communication and emotion.
- •The muscles of mastication — masseter, temporalis, medial pterygoid, and lateral pterygoid — generate the powerful forces needed for chewing by elevating, depressing, and laterally shifting the mandible.
- •Extrinsic eye muscles, six per eye, work in antagonistic pairs to produce all directions of gaze, with the superior and inferior obliques handling rotational movements.
- •The deep back muscles, organized into the erector spinae and transversospinalis groups, run along the length of the vertebral column and maintain posture, enable extension, and produce lateral flexion and rotation of the spine.
- •Muscles are named systematically using descriptors such as location, shape, fiber direction, number of origins, relative size, and action — understanding these conventions helps identify unfamiliar muscles.
- •The sternocleidomastoid and scalene muscles are the primary movers of the neck, with the sternocleidomastoid rotating and flexing the head and the scalenes assisting with both neck flexion and forced inspiration.
Logic Behind Muscle Names
Skeletal muscles are named according to a consistent set of descriptive criteria, so learning the naming conventions transforms unfamiliar muscle names into self-describing labels.
Location-Based Naming
- •Many muscles are named after the bone or region where they sit — the temporalis overlies the temporal bone, the frontalis covers the frontal bone, and the tibialis anterior lies along the front of the tibia.
- •When two muscles share a region, qualifiers such as 'anterior/posterior' or 'superficial/deep' are added to distinguish them.
Shape, Size, and Fiber Direction
- •Shape descriptors include orbicularis (circular), deltoid (triangular), and rhomboid (diamond-shaped).
- •Relative size is encoded in terms like maximus (largest), minimus (smallest), longus (long), and brevis (short).
- •Fiber direction terms — rectus (straight/parallel to midline), oblique (diagonal), and transverse (perpendicular to midline) — indicate how muscle fibers run relative to the body's long axis.
Number of Origins and Action
- •The prefix bi-, tri-, or quadri- before 'ceps' tells you how many heads of origin a muscle has: biceps (two), triceps (three), quadriceps (four).
- •Some muscles are named for their primary action, such as the flexor carpi radialis (flexes the wrist on the radial side) or the levator scapulae (elevates the scapula).
Muscles of Facial Expression
The muscles that produce facial expression are structurally unusual: instead of spanning two bones, they originate on bone or fascia and insert directly into the skin or into adjacent muscles, so their contraction moves the overlying skin rather than a joint.
Muscles Surrounding the Eyes and Forehead
- •The orbicularis oculi is a sphincter muscle encircling each eye; its orbital portion closes the eyelid tightly (as in a forceful blink) and its palpebral portion produces the gentle blink reflex.
- •The frontalis, covering the frontal bone, elevates the eyebrows and wrinkles the forehead horizontally when a person looks surprised.
- •The corrugator supercilii pulls the eyebrows medially and downward, producing the vertical furrows associated with a frowning or concerned expression.
Muscles of the Mouth and Cheeks
- •The orbicularis oris encircles the mouth and purses the lips for whistling, kissing, or articulating certain speech sounds.
- •The zygomaticus major and zygomaticus minor run from the zygomatic bone to the corner of the mouth and pull the lip corners superiorly and laterally to produce a smile.
- •The buccinator is the deep cheek muscle that compresses the cheek against the teeth, keeping food between the molars during chewing and allowing forceful expulsion of air (as when a musician plays a brass instrument).
- •The depressor anguli oris and depressor labii inferioris pull the mouth corners and lower lip downward respectively, producing expressions of sadness or displeasure.
- •The mentalis, on the chin, wrinkles the chin skin and protrudes the lower lip.
Scalp and Neck Muscles of Expression
- •The epicranius (occipitofrontalis) consists of the frontalis anteriorly and the occipitalis posteriorly, connected by the galea aponeurotica; together they move the scalp forward and backward.
- •The platysma is a broad, thin sheet in the superficial neck; it depresses the mandible, tenses the neck skin, and contributes to expressions of fear or extreme effort.
Muscles of Mastication and the Tongue
Chewing requires precisely controlled forces to close and grind food between the teeth; four muscles of mastication attach to the mandible and produce these movements, while the tongue is controlled by both intrinsic and extrinsic muscle groups.
Four Muscles of Mastication
- •The masseter is the most powerful jaw-closing muscle; it originates on the zygomatic arch and inserts on the mandibular ramus, elevating the mandible to bite.
- •The temporalis fans out across the temporal fossa and inserts on the coronoid process of the mandible; it elevates and retracts the mandible.
- •The medial pterygoid originates on the pterygoid plates of the sphenoid bone and assists the masseter in elevating the mandible; it also contributes to lateral (side-to-side) grinding movements.
- •The lateral pterygoid is the only muscle of mastication that depresses (opens) the mandible; bilateral contraction protracts the jaw, while unilateral contraction shifts the jaw to the opposite side for grinding.
Extrinsic Muscles of the Tongue
- •The genioglossus, originating on the mandible's inner surface, is the primary tongue protruder and also depresses the tongue's center to form a trough.
- •The hyoglossus depresses and retracts the tongue, while the styloglossus retracts it and curls its sides upward.
- •The palatoglossus elevates the posterior tongue and helps initiate swallowing by narrowing the oropharynx.
Suprahyoid and Infrahyoid Muscles
- •Suprahyoid muscles (digastric, mylohyoid, geniohyoid, stylohyoid) elevate the hyoid bone and floor of the mouth during swallowing and depress the mandible when the hyoid is fixed.
- •Infrahyoid muscles (sternohyoid, sternothyroid, thyrohyoid, omohyoid) depress the hyoid and larynx after swallowing, returning them to resting position.
Extrinsic Muscles of the Eye
Six extrinsic (extraocular) muscles attach to the outer surface of each eyeball and produce the full range of gaze directions; they are organized into two groups based on the geometric plane of their pull.
Four Recti Muscles
- •The superior rectus, inferior rectus, medial rectus, and lateral rectus originate from the common tendinous ring (annular ring) at the apex of the orbit.
- •The medial and lateral recti produce purely horizontal gaze: the medial rectus adducts (moves the eye nasally) and the lateral rectus abducts (moves it temporally).
- •The superior rectus primarily elevates the eye but also adducts and produces medial (intorsion) rotation due to the angle at which it pulls.
- •The inferior rectus primarily depresses the eye and also adducts and laterally rotates (extorts) the eyeball.
Two Oblique Muscles
- •The superior oblique originates at the back of the orbit, threads through the trochlea (a fibrocartilage pulley at the superomedial orbital rim), and inserts on the posterior-superior eyeball; it intorts, depresses, and abducts the eye.
- •The inferior oblique originates on the floor of the orbit near the nasal side and inserts on the posterior-inferior eyeball; it extorts, elevates, and abducts the eye — the opposite of the superior oblique.
- •The oblique muscles are especially important for holding stable gaze during head tilts, counteracting rotational displacement of the eye.
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About this Study Pack
Created by Kibin to help students review key concepts, prepare for exams, and study more effectively. This Study Pack was checked for accuracy and curriculum alignment using authoritative educational sources. See sources below.
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What makes the muscles of facial expression structurally unique compared to most other skeletal muscles?
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Muscle Naming Conventions
Explain how skeletal muscles are named in your own words. What kinds of descriptors are used, and how can knowing these conventions help you figure out what an unfamiliar muscle does?
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