The semispinalis capitis is innervated by the descending branches of the greater occipital nerve (C2) and spinal nerve C3, while the semispinalis cervicis and multifidus cervicis are innervated by the medial branches of posterior rami of spinal nerves. These muscles receive their blood supply via branches of the vertebral, deep cervical and occipital arteries. The longus colli, also called the longus cervicis, is a long muscle that spans the entire length of the cervical spine and the upper vertebrae of the thoracic spine. It is divided into three parts: Unipennate, in which the fascicles insert into only one side of the tendon, as in the extensor digitorum longus muscle of the leg;

Muscular dystrophy is a group of muscle diseases that weaken the musculoskeletal system and hamper locomotion. Muscular dystrophies are characterized by progressive skeletal muscle weakness, defects in muscle proteins, and the death of muscle fibres (muscle cells) and tissue. Ellis, Harold; Susan Standring; Gray, Henry David (2005). Gray's anatomy: the anatomical basis of clinical practice. St. Louis, Mo: Elsevier Churchill Livingstone. pp. 538–539. ISBN 0-443-07168-3. The twitching phenomenon that happens in the early stage of sleep is called a hypnagogic massive jerk, or simply a hypnic jerk. It has also been referred to as a sleep start. There has been little research on this topic, but there have been some theories put forth. Moore, K. L., Dalley, A. F., & Agur, A. M. R. (2014). Clinically Oriented Anatomy (7th ed.). Philadelphia, PA: Lippincott Williams & Wilkins. The digastric muscle is a small muscle situated below the mandible, that extends from the mastoid process of temporal bone to the chin. The muscle is composed of a posterior and an anterior belly, connected by an intermediate tendon, which represents their common insertion point.At first, try painkillers like paracetamol to ease the pain and ibuprofen gel, mousse or spray to bring down swelling.

The posterior scalene is the smallest and most posterior of the scalene muscles that arises from the posterior tubercles of transverse processes of cervical vertebrae C4-C6. It then extends posterolaterally and inserts into the external surface of the second rib. Obliquus capitis superior, that arises from the transverse process of atlas and inserts on the occipital bone, between the superior and inferior nuchal lines. A large group of muscles in the cervical area, responsible for the movement of the head in all directions Muscle atrophy resulting from disease rather than disuse is generally one of two types, that resulting from damage to the nerves that supply the muscles, and disease of the muscle itself. Structure of a sarcomere: Colorado Community College System, https://pressbooks.ccconline.o..., CC4)growth in the girth of muscle fibers is thought to take place through ‘splitting’ of existing myofibrils as a result of stress placed on sarcomeres during physical activity, thereby increasing the mass of the muscle as whole. When the vertebral column is fixed, the muscle produces elevation of the 1st rib, which combined with the action of the external intercostals expands the antero-posterior diameter of the thoracic cage. This action is important during forced respiration. All of the infrahyoid muscles are innervated by the ansa cervicalis from the cervical plexus ( C1- C3) [4] [5] except the thyrohyoid muscle, which is innervated by fibers only from the first cervical spinal nerve travelling with the hypoglossal nerve. [1] Function [ edit ] The intermediate part arises from the anterior surface of bodies of vertebrae C5-T3 and inserts into the anterior surface of bodies of vertebrae C2-C4.

Merea, Valeria Silva; Pitman, Michael J. (1 January 2019), Chhetri, Dinesh K.; Dewan, Karuna (eds.), "Chapter 5 - Anatomy and Physiology of the Upper Esophageal Sphincter", Dysphagia Evaluation and Management in Otolaryngology, Elsevier, pp.29–34, doi: 10.1016/b978-0-323-56930-9.00005-x, ISBN 978-0-323-56930-9, S2CID 80855923 The trapezius muscle is innervated by the accessory nerve (CN XI). Its blood supply stems from branches of the occipital, superficial cervical, transverse cervical and dorsal scapular arteries. The muscle is innervated by the anterior rami of the spinal nerves C2-C6. Its blood supply stems from branches of the vertebral, inferior thyroid and ascending pharyngeal arteries. Cesmebasi, Alper (1 January 2015), Tubbs, R. Shane; Rizk, Elias; Shoja, Mohammadali M.; Loukas, Marios (eds.), "Chapter 31 - Anatomy of the Cervical Plexus and Its Branches", Nerves and Nerve Injuries, San Diego: Academic Press, pp.441–449, doi: 10.1016/b978-0-12-410390-0.00032-9, ISBN 978-0-12-410390-0The nerve supply to the omohyoid is provided by the ansa cervicalis. Its blood supply stems from the superior thyroid branch of the external carotid artery, and inferior thyroid branch of the thyrocervical trunk. All four of the suboccipital muscles are innervated by the suboccipital nerve (C1), and vascularized by the vertebral artery and the deep descending branches of the occipital artery.

Rectus capitis posterior minor, that arises from the posterior tubercle of atlas and inserts into the medial part of the inferior nuchal line. The term infrahyoid refers to the region below the hyoid bone, while the term strap muscles refers to the long and flat muscle shapes which resembles a strap. The stylopharyngeus muscle is considered by many to be one of the strap muscles, [ citation needed] but is not an infrahyoid muscle. The posterior belly arises from the medial surface of mastoid notch, a deep groove found on the mastoid process of temporal bone.Myosin is visible as the A band of the sarcomere. Actin filaments are anchored to a structure known as the Z disc (or Z line) located at either end of the sarcomere; they are present across the entire length of the I band (region of actin filaments only, no myosin) and a portion of the A band (region where actin and myosin filaments overlap). The A band is especially important when considering the dynamics of muscle contraction, as it is the location where filament movement occurs. Actin filaments do not extend completely into the A bands, leaving a central region, known as the H zone, which appears slightly lighter than the rest of the A band due to the fact that it does not contain both myofilaments. The center of the H zone has a vertical line, known as the M line, which connects myosin filaments to each other. Kayalioglu, Gulgun (1 January 2009), Watson, Charles; Paxinos, George; Kayalioglu, Gulgun (eds.), "Chapter 4 - The Spinal Nerves", The Spinal Cord, San Diego: Academic Press, pp.37–56, doi: 10.1016/b978-0-12-374247-6.50008-0, ISBN 978-0-12-374247-6 At its most basic level, muscle tissue is classified as either striated or non-striated/smooth based on the presence or absence of ‘striations’ (i.e. stripes/furrows) seen at a microscopic level; these are formed due to a particular arrangement of actin and myosin filaments within the myocyte (discussed below). The sternocleidomastoid muscle is innervated by the accessory nerve (CN XI) and anterior rami of spinal nerves C2 and C3. Vascular supply to this muscle is derived from branches of the occipital, posterior auricular, superior thyroid and suprascapular artery. When the body drifts off into sleep, it undergoes physiological changes related to body temperature, breathing rate and muscular tone. Hypnic jerks may be the result of muscle changes. Another theory suggests that the transition from the waking to the sleeping state signals the body to relax. But the brain may interpret the relaxation as a sign of falling and then signal the arms and legs to wake up. Electroencephalogram studies have shown sleep starts affect almost 10 percent of the population regularly, 80 percent occasionally, and another 10 percent rarely.