Examples of digastric muscle in the following topics:
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- The hypoglossal nerve (cranial nerve XII) controls the muscles of the tongue.
- The hypoglossal nerve is the twelfth cranial nerve (XII) and innervates all extrinsic and intrinsic muscles of the tongue, except for the palatoglossus.
- After passing deep to the posterior belly of the digastric muscle it proceeds to the submandibular region to enter the tongue.
- It supplies motor fibers to all of the muscles of the tongue, with the exception of the palatoglossus muscle, which is innervated by the vagus nerve (cranial nerve X) or, according to some classifications, by fibers from the glossopharyngeal nerve (cranial nerve IX) that hitchhike within the vagus.
- Tongue muscle atrophy may also occur.
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- Vertebral muscles are associated with the vertebral column.
- Digastric – The digastric muscle is split into two parts that are connected by a tendon attached to the hyoid bone.
- Splenius
Capitis – A thick rectangular muscle, the most
superior of the neck muscles.
- Longissimus – Located between the iliocostalis and spinalis muscles, this is the
largest of the intermediate layer muscles.
- Several other muscles act
on the head and neck.
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- It is controlled by four muscles of the face.
- Masseter - The most powerful muscle of mastication.
- It covers the other muscles of mastication.
- Produced by the lateral pterygoid, assisted
by the digastric, mylohyoid and geniohyoid muscles found in the neck.
- Highlighted in orange, the temporalis muscle is a broad muscle extending from zygomatic bone.
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- The motor function activates the muscles of the jaw, mouth, and inner ear.
- Motor fibers pass through the trigeminal ganglion on their way to peripheral muscles, but their cell bodies are located in the nucleus of the trigeminal nerve, deep within the pons.
- The motor component of the mandibular division
(V3) of the trigeminal nerve controls the movement of eight muscles, including
the four muscles of mastication: the masseter,
the temporal, and the medial and lateral pterygoids.
- The other four muscles
are the tensor veli palatini, the mylohyoid,
the anterior belly of the digastric, and the tensor tympani.
- With the exception of the
tensor tympani, all of these muscles are involved in biting, chewing and
swallowing, and all have bilateral cortical representation.
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- Parallel muscles are characterized by fascicles that run parallel to one another, and contraction of these muscle groups acts as an extension of the contraction of a single muscle fiber.
- Convergent muscles have a common point of attachment, from which the muscle fascicles extend outward, not necessarily in a specific spatial pattern, allowing the muscle to cover a broad surface.
- In Pennate muscles, the tendon runs through the length of the muscle.
- However, these muscles tend to have relatively more muscle fibers than similarly sized parallel muscles, and thus carry more tension.
- If the central tendon branches within a pennate muscle, the muscle is called multipennate.
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- Sustained, repeated overload of a muscle group leads to hypertrophy and strengthening of those muscles.
- In the short term muscle can become fatigued and sore for reasons like impaired blood flow, ion imbalance within the muscle, nervous
fatigue, loss of desire to continue exercising, and most importantly, the accumulation
of lactic acid in the muscle.
- Muscle hypertrophy, or the increase in muscle mass due to exercise , particularly weight training, is a noticeable long-term effect of exercise.
- Exercise of specific muscles can often result in hypertrophy in the opposite muscles as well, a phenomenon known as cross education.
- With sufficient training the metabolic capacity
of a muscle can change, delaying the onset of muscle fatigue.
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- The function of muscles is movement, but the types of movement elicited differ between skeletal, cardiac, and smooth muscle.
- Skeletal muscle fibers are the longest muscle fibers and have stripes on their surface.
- Cardiac muscle is found in the walls of the heart.
- Although cardiac muscle is involuntary in nature, it is structurally different from smooth muscle.
- Cardiac muscle is striated, similar to skeletal muscle, but beats involuntarily.
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- Skeletal muscles are grouped into fascicles, which are bunches of muscle fibers surrounded by a perimysium.
- Skeletal muscle tissue is composed of numerous
muscle fibers which are separated from adjacent muscles and other tissues by a
layer of dense, elastic connective tissue termed the fascia.
- This fascia can
project beyond the end of the muscle and attach to bones, other muscles, and
other tissues.
- The fascia surrounding a muscle or muscle group does not
contain many blood vessels, but is rich with sensory receptors.
- It extends inwards and becomes the
perimysium, then into the muscle separating
muscle fibers into small bundles termed fascicles.
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- Muscle contractions are defined by changes in the length of the muscle during contraction.
- Isotonic contractions maintain constant tension in the muscle as the muscle changes length.
- Cross-bridge cycling occurs, shortening the sarcomere, muscle fiber, and muscle.
- Cross-bridge cycling occurs even though the sarcomere, muscle fiber, and muscle are lengthening, controlling the extension of the muscle.
- In both instances, cross-bridge cycling is maintaining tension in the muscle; the sarcomere, muscle fibers, and muscle are not changing length.
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- Involuntary muscle contractions are referred to as spasms, and can be due to abnormal activity of the nerve or the muscle.
- In medicine, a spasm is a sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ, or a similarly sudden contraction of an orifice .
- Examples of spasms include muscle contractions due to abnormal nerve stimulation, or abnormal activity of the muscle itself.
- In this case, the hypertonic muscle tone is excessive and the muscles are unable to relax.
- Hypertonic muscle spasms is the state of chronic, excessive muscle tone, or tension in a resting muscle – the amount of contraction that remains when a muscle is not actively working.