Netter's 3D Interactive Anatomy:Professional Edition Online commitment on the part of Cyber-Anatomy, Inc. or Elsevier, Inc. The manuals for products in the Interact Elsevier series are available in printable pdf as well. You can not forget human anatomy after watching diagrams in netter atlas. This atlas is widely used and better then other human anatomy. Atlas of Human Anatomy by Netter, Frank H. 5th edition. Stoelting's Anesthesia and co-existing. Diseases: Adapted for. South-Asian. Curriculum by Paul.
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4A Calvaria: Superior View. 4B Calvaria: Inferior View. 5 Cranial Base: Inferior View. 6 Bones of Cranial Base: Superior View. 7 Foramina of Cranial Base. In this post, we have shared an overview and download link of Netter's Atlas of Human Anatomy 7th Edition PDF. Read the overview below and. page 1. 1 Topographic Surface Anatomy. STUDY AIMS. At the end of your study, you should be able to: Identify the key landmarks in the midline of the neck and.
Osteoarthritis is the most common form of arthritis and often involves erosion of the articular cartilage of weight-bearing joints, including the cervical spine. As new research and experience broaden our knowledge, changes in practice, treatment and drug therapy may become necessary or appropriate. Thus, it is important to know these structures and their relationships to the cranial base. Fractures or trauma involving any of these foramina may result in clinical signs and symptoms associated with the neurovascular elements passing through the foramina. When the hyoid bone remains fixed, this muscle also helps retract and depress the mandible.
The clarity and detail related to each human anatomical structure are unprecedented and absolutely remarkable. For years, this book has remained the top choice for students and as well as teachers for studying anatomy. Carlos Machado. High-definition and visual region-by-region coverage of challenging and intricate anatomical structures make studying anatomy not only fun but highly productive as well.
This exciting and innovative new feature offers additional support to students who are curious and crave for a more in-depth understanding. With Student Consult, the students are able to access self-assessment exercises, dissection videos, regional MCQs, illustrated axial cross-sections and additional plates from previous editions thus making the overall reader experience more rewarding and enlightening.
Frank H. Netter, born in New York in — was a gifted genius. Later he went to med-school at New York University and qualified as an M. D in the year Cement Cementum Root central canals containing vessels and nerves Apical foramina Comment: Each tooth is composed of an enamel-covered crown, dentine, and pulp.
The pulp fills a central cavity and is continuous with the root canal. Blood vessels, nerves, and lymphatics enter the pulp through an apical foramen. The crown projects above the gum, or gingival surface.
The narrow portion between the crown and root is called the neck. The root is embedded in the alveolar bone of the maxilla or mandible and is covered by cement, which is connected to the alveolar bone by the periodontal ligament. Dental caries tooth decay is caused by oral bacteria that convert food into acids that then form dental plaque a combination of bacteria, food particles, and saliva.
If not removed by brushing, the plaque can mineralize and form tartar. Acid in the dental plaque can erode the tooth enamel and create a cavity. Atlas and Axis 2 1 9 10 4 Atlas C1: Axis C2: Atlas and Axis 1. Anterior tubercle 2. Transverse process 3. Superior articular surface of lateral mass for occipital condyle 4.
Groove for vertebral artery 5. Transverse foramen 6. Anterior arch 7. Spinous process 8. Dens 9. Superior articular facet for atlas Pedicle Comment: The 1st cervical vertebra is the atlas. It is named after the Greek god Atlas, who is often depicted with the world on his shoulders. The atlas has no body or spine but is made of anterior and posterior arches.
The transverse processes contain a foramen that transmits the vertebral vessels. The 2nd cervical vertebra is the axis. Its most characteristic feature is the dens odontoid process.
A blow to the top of the head may fracture the atlas, usually across the anterior and posterior arches. Such a fracture is called a Jefferson fracture. Fractures of the axis often involve the dens or involve a fracture across the neural arch between the superior and inferior articular facets. Posterior atlanto-occipital membrane 2. Capsule of atlanto-occipital joint 3.
Transverse process of atlas C1 4. Capsule of lateral atlanto-axial joint 5. Ligamenta flava 6. Capsule of atlanto-occipital joint 7. Posterior atlanto-occipital membrane 8. Ligamenta flava 9. Ligamentum nuchae Anterior longitudinal ligament Vertebral artery Comment: The atlanto-occipital joint, on each side, is covered with an articular capsule and posteriorly reinforced by the posterior atlanto-occipital membrane.
The ligamentum nuchae is a strong median fibrous septum. It is an extension of the thickened supraspinous ligaments that arise from the spinous process of C7 and extend to the external occipital protuberance. While there are usually 7 cervical vertebrae, fusion of adjacent vertebrae can occur. Most commonly, this fusion in the cervical region is seen between C1 and C2 the atlas and axis or between C5 and C6.
Capsule of atlanto-occipital joint 2. Capsule of lateral atlanto-axial joint 3. Capsule of zygapophysial joint C 4.
Cruciate ligament Superior longitudinal band; Transverse ligament of atlas; Inferior longitudinal band 5. Alar ligaments 6. Posterior longitudinal ligament 7. Tectorial membrane Comment: The atlanto-occipital joint is a biaxial condyloid synovial joint between the atlas and the occipital condyles. It permits flexion and extension, as when the head is nodded up and down, and some lateral bending. The atlanto-axial joints are uniaxial synovial joints. They consist of plane joints associated with the articular facets and a median pivot joint between the dens of the axis and the anterior arch of the atlas.
The atlanto-axial joint permits the atlas and head to be rotated as a single unit, as when the head is turned from side to side. These joints are reinforced by ligaments, especially the cruciate and alar ligaments. The alar ligaments limit rotation.
Osteoarthritis is the most common form of arthritis and often involves erosion of the articular cartilage of weight-bearing joints, including the cervical spine. Extensive thinning of the intervertebral discs and of the cartilage covering the facet joints can lead to hyperextension of the cervical spine, narrowing of the intervertebral foramen, and the potential for impingement of the spinal nerves exiting the intervertebral foramen.
Epiglottis 2. Hyoid bone 3. Thyrohyoid membrane 4. Arytenoid cartilage 5. Thyroid cartilage lamina 6. Vocal ligament 7. Median cricothyroid ligament 8. Cricoid cartilage 9. Trachea Comment: The cartilages of the larynx include the thyroid cartilage, cricoid cartilage, epiglottis, and the paired arytenoid, corniculate, and cuneiform cartilages. Not shown in the illustration are the cuneiform cartilages. These paired elastic cartilages lie in the ary-epiglottic folds and have no articulations with other cartilages or bones.
The thyrohyoid membrane has an opening through which the internal branch of the superior laryngeal nerve enters the larynx to provide sensory innervation above the vocal folds. Trauma to the cartilages of the larynx may result in fractures. Consequently, the underlying laryngeal mucosa and submucosa may hemorrhage, resulting in significant edema and the potential for airway obstruction. Malleus head 2. Handle of malleus 3. Stapes 4. Base of stapes footplate 5.
Lenticular process of incus 6. Incus Comment: The 3 auditory ossicles reside in the middle ear, or tympanic cavity. They amplify sonic vibrations from the tympanic membrane and transmit them to the inner ear. The 3 ear ossicles are the malleus hammer , incus anvil , and stapes stirrup. The handle of the malleus is fused with the medial aspect of the tympanic membrane; the head articulates with the incus. The incus articulates with the stapes, whose footplate is attached to the oval window.
Two small muscles attach to the auditory ossicles; the tensor tympani muscle attaches to the malleus and the stapedius muscle to the stapes. These very small skeletal muscles dampen large vibrations resulting from excessively loud noises.
Frontal belly of occipitofrontalis muscle Origin: This muscle has no bony origin, and its fibers arise and are continuous with 2 other anterior facial muscles, the procerus and the corrugator supercilii. The fibers are directed upward. They join the galea aponeurotica anterior to the coronal suture.
Elevates the eyebrows and wrinkles the forehead, as when a person looks surprised. Terminal branches of the facial nerve; temporal branch. The epicranius muscle consists largely of the frontal and occipital bellies and an intervening galea aponeurotica aponeurosis. As a muscle of facial expression, this cutaneous muscle lies within the layers of the superficial fascia.
These muscles vary from person to person, and they often blend together. All of the muscles of facial expression are derived embryologically from the 2nd pharyngeal branchial arch and are innervated by the terminal branches of the facial nerve CN VII. Occipital belly of occipitofrontalis muscle Origin: Arises from the lateral two-thirds of the superior nuchal line of the occipital bone and the mastoid process of the temporal bone. Inserts into the epicranial aponeurosis. The occipital and frontal bellies of the epicranial muscle act together to draw back the scalp.
This action raises the eyebrows and wrinkles the forehead. The extensive aponeurosis called the galea aponeurotica connects the frontal belly and occipital belly of the epicranial muscle. Orbicularis oculi muscle Origin: Arises from the nasal portion of the frontal bone, the frontal process of the maxilla, the lacrimal bone, and the medial palpebral ligament.
Attaches to the skin of the eyelids, surrounds the bony orbit, and inserts into the superior and inferior tarsi medial to the lacrimal puncta. This muscle is a sphincter that closes the eyelids. Its palpebral portion closes the lids gently, as in blinking. The orbital portion closes the eyelids more forcibly. Terminal branches of the facial nerve; primarily the zygomatic branch.
The orbicularis oculi has 3 parts: Orbicularis oris muscle Origin: Fibers arise near the median plane of the maxilla above and from the mandible below. Fibers insert into the skin of the lips and into the mucous membrane beneath the lip. This muscle acts primarily to close the lips. Its deep and oblique fibers pull the lips toward the teeth and alveolar arches. When all of its fibers act together, they can protrude the lips. Terminal branches of the facial nerve; primarily the mandibular branch.
A major portion of this muscle is derived from the buccinator and blends with other facial muscles around the oral cavity. This muscle is especially important in speech because it alters the shape of the mouth. Buccinator muscle Origin: Arises from the mandible, pterygomandibular raphe, and alveolar processes of the maxilla and mandible.
Attaches to the angle of the mouth. Contraction of this muscle presses the cheek against the molar teeth and aids in chewing. This muscle also can expel air from the mouth, as when a musician plays a woodwind or brass instrument.
Terminal branches of the facial nerve; buccal branch. By pressing the cheek against the teeth, the buccinator holds food between the molars. When the muscle contracts too forcefully during chewing, the teeth bite the cheek. The buccinator is a muscle of facial expression. Fibers of this muscle blend with other muscles around the mouth.
Platysma muscle Origin: Arises from the superficial fascia covering the superior portions of the pectoralis major and deltoid muscles. Ascends over the clavicle and is directed medially to insert into the mandible below the oblique line.
Other portions of the muscle insert into the skin and subcutaneous tissue of the lower portion of the face.
Draws the lower lip and corner of the mouth inferolaterally and partially opens the mouth, as during an expression of surprise. When all the fibers act together, the skin over the clavicle and lower neck is wrinkled and drawn upward toward the mandible.
Terminal branches of the facial nerve; cervical branch. Auricularis superior muscle 7. Zygomaticus minor and 2. Auricularis anterior muscle major muscles 3. Epicranial aponeurosis 8. Mentalis muscle 4. Corrugator supercilii 9. Depressor labii inferioris muscle Frontalis and muscle Orbicularis oculi, partially Depressor anguli oris cut away muscle 5.
Procerus muscle Risorius muscle 6. Nasalis muscle Transverse part; Alar part Comment: This lateral view shows additional muscles of facial expression. The muscles around the eyes, ears, nose, and mouth blend with muscles of the lips, chin, and cheek. All are innervated by terminal branches of the facial nerve.
As muscles of facial expression, these cutaneous muscles lie within the layers of the superficial fascia. They vary from person to person, and they often blend together. All of the muscles of facial expression are derived embryologically from the 2nd pharyngeal branchial arch and are innervated by the facial nerve CN VII. Ipsilateral facial muscle paralysis results in an asymmetric facial appearance, with an inability to wrinkle the skin of the forehead, close the eyelids, smile, frown, purse the lips as in kissing , and tighten the skin of the neck.
Levator palpebrae superioris muscle Origin: Arises from the lesser wing of the sphenoidal bone, anterior and superior to the optic canal. Attaches to the skin and tarsal plate of the upper eyelid. Raises the upper eyelid. At the distal end of this muscle, near its attachment to the tarsal plate, is a small amount of smooth muscle called the superior tarsal muscle.
The fibers of the superior tarsal muscle are supplied by postganglionic sympathetic fibers of the autonomic nervous system. Because of the dual nature of this muscle it is skeletal and has a small smooth muscle component , drooping of the upper eyelid can result from a nerve lesion affecting the oculomotor nerve or the sympathetic fibers. This drooping is called ptosis. Ptosis can result from nerve damage at 2 different sites. Damage to the oculomotor nerve CN III can result in paralysis of the levator palpebrae superioris muscle and significant ptosis.
Damage anywhere along the sympathetic pathway from the upper thoracic sympathetic outflow to the head, the cervical sympathetic trunk, or the superior cervical ganglion and beyond can result in denervation of the small tarsal muscle smooth muscle that is found at the free distal margin of the levator palpebrae superioris muscle.
This will result in a mild ptosis: Superior rectus muscle 4. Superior oblique muscle 2.
Medial rectus muscle 5. Lateral rectus muscle 3. Inferior rectus muscle 6. Inferior oblique muscle Origin: The inferior oblique arises from the floor of the orbit. The 4 rectus muscles insert into the sclera, just posterior to the cornea. The superior oblique muscle passes forward, and its tendon passes through a fibrous ring trochlea and inserts into the sclera deep to the superior rectus muscle. The inferior oblique inserts into the sclera deep to the lateral rectus muscle. In clinical testing, when the eye is abducted, the superior rectus elevates the globe and the inferior rectus depresses it.
When the eye is adducted, the superior oblique depresses the globe and the inferior oblique elevates it. The medial rectus is a pure adductor, whereas the lateral rectus is a pure abductor. The anatomic actions differ from the actions tested for clinical evaluation of the muscles. Third nerve palsy will result in ptosis, a dilated pupil, and an inability to adduct the eye at rest, the affected eye will be directed down and out. Temporalis muscle Origin: Floor of the temporal fossa and the deep surface of the temporal fascia.
Attaches to the tip and medial surface of the coronoid process and anterior border of the ramus of the mandible. This muscle elevates the mandible and closes the jaws. Its posterior fibers retract the mandible retrusion. Mandibular division of the trigeminal nerve. The temporalis is 1 of the 4 muscles of mastication. It is a broad, radiating muscle whose contractions can be seen during chewing. The muscles of mastication are derived embryologically from the 1st pharyngeal branchial arch and are innervated by the mandibular division of the trigeminal nerve CN V3.
Tension headache can be muscular in origin. Tensing the temporalis muscle, for example clenching the teeth , can lead to this type of headache.
Masseter muscle Origin: Arises from the inferior border and medial surface of the zygomatic arch. Attaches to the lateral surface of the mandible and lateral surface of the coronoid process. Closes the jaws by elevating the mandible. The masseter muscle is 1 of the 4 muscles of mastication. Some of its fibers also may protrude the mandible, and its deep fibers retract the mandible. The hearty spore of Clostridium tetani is commonly found in soil, dust, and feces and can enter the body through wounds, blisters, burns, skin ulcers, insect bites, and surgical procedures.
If the individual is infected and unvaccinated, the toxin from the bacteria can destroy the inhibitory neurons of the brainstem and spinal cord and cause nuchal rigidity, trismus lockjaw, a spasm of the masseter muscle , dysphagia, laryngospasm, and acute muscle spasms that can lead to death.
Medial pterygoid muscle Origin: This muscle arises from 2 slips. Its deep head arises from the medial surface of the lateral pterygoid plate and pyramidal process of the palatine bone. Its superficial head arises from the tuberosity of the maxilla. The muscle fibers blend to attach to the medial surface of the ramus of the mandible, inferior to the mandibular foramen.
Helps close the jaws by elevating the mandible. With the lateral pterygoids, the 2 medial pterygoids protrude the mandible. When 1 medial and 1 lateral pterygoid on the same side of the head act together, the mandible is protruded forward and to the opposite side. Alternating these movements moves the jaws from side to side in a grinding motion. The medial pterygoid is 1 of the 4 muscles of mastication. It acts with the temporalis and masseter muscles to close the jaws.
The medial pterygoid and masseter muscles are important in biting, but all 3 muscles are necessary for biting and chewing with the molars. Sometimes individuals clench their teeth and grind their molars while in deep sleep. This grinding action of the pterygoid muscles can erode the teeth, and people suffering from this malady should seek the attention of their health care specialist.
Lateral pterygoid muscle Origin: This short, thick muscle has 2 heads. The superior head arises from the infratemporal surface and infratemporal crest of the greater wing of the sphenoidal bone.
The inferior head arises from the lateral surface of the lateral pterygoid plate. Its fibers converge to insert on the neck of the mandible, articular disc, and capsule of the temporomandibular joint. Opens the mouth by drawing the condyle of the mandible and articular disc of the temporomandibular joint forward. With the medial pterygoid of the same side, the lateral pterygoid protrudes the mandible. The jaw is rotated to the opposite side, producing a grinding movement.
The other 3 muscles of mastication help close the jaws, whereas the lateral pterygoid opens the jaws.
At the beginning of this action, it is assisted by the mylohyoid, digastric, and geniohyoid muscles. Mylohyoid muscle Origin: Arises from the mylohyoid line of the mandible.
Attaches to a median fibrous raphe and the body of the hyoid bone. Elevates the hyoid bone and raises the floor of the mouth during swallowing, pushing the tongue upward as in swallowing or protrusion of the tongue. By the mylohyoid nerve, a branch of the mandibular division of the trigeminal. The mylohyoids also can help depress the mandible or open the mouth. They are active in mastication, swallowing, sucking, and blowing. The mylohyoid and geniohyoid muscles form the floor of the mouth.
Soft tissue injury in this area or fractures of the anterior mandible can cause significant bleeding in this area. These muscles are also important in multiple actions associated with the mouth. Geniohyoid muscle Origin: Inferior mental spine of mandible. Attaches to the body of the hyoid bone.
Slightly elevates and draws the hyoid bone forward, shortening the floor of the mouth. When the hyoid bone remains fixed, this muscle also helps retract and depress the mandible. Genioglossus muscle Origin: Arises from the superior part of the mental spine of the mandible. Dorsum of the tongue and body of the hyoid bone.
Its central fibers depress the tongue. Its posterior fibers protrude the tongue, as in sticking the tongue out of the mouth. The genioglossus is 1 of the 3 extrinsic muscles of the tongue.
This occurs because of the strong force of pull by the posterior fibers of the contralateral genioglossus, which is unopposed by the paralyzed ipsilateral fibers. This causes the tongue to protrude and then deviate beyond the midline to the unopposed side side of the nerve lesion.
Hyoglossus muscle Origin: Arises from the body and greater horn of the hyoid bone. Attaches to the lateral and dorsal surface of the tongue. Depresses, or pulls, the tongue into the floor of the mouth. Also retracts the tongue. The lingual artery, a branch of the external carotid artery in the neck, is the major blood supply to this area and can be located as it passes deep to the hypoglossus muscle.
Bleeding that results from soft tissue damage in this region causes swelling as the blood accumulates in the floor of the mouth. Styloglossus muscle Origin: Arises from the styloid process and stylohyoid ligament. Attaches to the lateral side of the tongue. Some fibers interdigitate with fibers of the hyoglossus muscle. Retracts the tongue and draws it up during swallowing. The styloglossus is 1 of the 3 extrinsic muscles of the tongue.
All are innervated by the hypoglossal nerve. Three muscles arise from the styloid process: Each is innervated by a different cranial nerve. The styloglossus is important in swallowing because it pushes the bolus of chewed food up against the hard palate and backward into the oropharynx.
Levator veli palatini muscle Origin: Arises from the cartilage of the auditory tube and the petrous portion of the temporal bone. Attaches to the palatine aponeurosis of the soft palate. Elevates the soft palate during swallowing and yawning.
Vagus nerve CN X. After the soft palate has been tensed by the tensor veli muscle which hooks around the pterygoid hamulus , the levator elevates the palate. Note the arrangement of these muscles in the figure posterior view.
If there is damage to the vagus nerve on one side, the soft palate will deviate contralaterally, that is, to the normally functioning side and away from the abnormally functioning side.
Tensor veli palatini muscle Origin: Arises from the scaphoid fossa of the medial pterygoid plate, spine of the sphenoidal bone, and cartilage of the auditory tube. Tenses the soft palate and, by contracting, opens the auditory tube during swallowing and yawning to equalize pressure in the middle ear. This muscle tenses the fibers of the soft palate so that the levator veli palatini muscle can act on them. The tensor not only tenses the soft palate during elevation by the levator veli palatini but also opens the auditory pharyngotympanic, eustachian tube during swallowing and yawning.
This helps equalize the pressure in the middle ear and explains why chewing gum, swallowing, or yawning can relieve the pressure and pain in the middle ear when landing in an airplane. Uvular muscle 2. Palatopharyngeus muscle 3. Palatoglossus muscle 4. Superior pharyngeal constrictor muscle 5. Pterygomandibular raphe 6. Buccinator muscle Comment: Interdigitating fibers of the levator veli palatini muscle make up most of the soft palate, along with the little uvular muscle.
The palatoglossal and palatopharyngeal arches contain small slips of muscle with the same names as the arches beneath their mucosal surfaces.
These thin muscle slips are innervated by the vagus nerve. The palatine tonsil is nestled in the palatine fossa, between these 2 folds. The buccinator muscle lies deep to the oral mucosa of the cheek and helps keep food between the molars.
Numerous minor salivary glands populate the mucosa lining the hard palate. If the parasympathetic fibers of the facial nerve are damaged they travel in the lingual nerve of CN V3 , 2 of the 3 major salivary glands will be denervated the submandibular and sublingual glands , as will the numerous minor salivary glands, also supplied by facial parasympathetic nerves.
Consequently, the oral mucosa will appear drier than normal. Superior pharyngeal constrictor muscle Origin: This broad muscle arises from the pterygoid hamulus, pterygomandibular raphe, posterior portion of the mylohyoid line of the mandible, and side of the tongue.
The muscles from each side meet and attach to the median raphe of the pharynx and pharyngeal tubercle of the occipital bone. Constricts the wall of the upper pharynx during swallowing. Pharyngeal plexus of the vagus nerve CN X. The 3 pharyngeal constrictors help move food down the pharynx and into the esophagus. To accomplish this, these muscles contract serially from superior to inferior to move a bolus of food from the oropharynx and laryngopharynx into the proximal esophagus.
The superior constrictor lies largely behind the mandible. While the motor innervation of the pharyngeal constrictors is via the vagus nerve CN X , the sensory innervation of all but the most superior part of the pharynx the constrictor muscles and the mucosa lining the interior of the pharynx is via the glossopharyngeal nerve CN IX.
Together, the fibers of CN IX and X form the pharyngeal plexus and function in concert with one another during swallowing.
Middle pharyngeal constrictor muscle Origin: Arises from the stylohyoid ligament and the greater and lesser horns of the hyoid bone. The muscles from both sides wrap around and meet to attach to the median raphe of the pharynx. Constricts the wall of the pharynx during swallowing. The middle pharyngeal constrictor lies largely behind the hyoid bone.
The fibers of the superior and middle pharyngeal constrictors often blend together, but the demarcation point can be seen where the stylopharyngeus muscle intervenes. Inferior pharyngeal constrictor muscle Origin: Arises from the oblique line of the thyroid cartilage and side of the cricoid cartilage. The 2 inferior pharyngeal constrictor muscles wrap posteriorly to meet and attach to the median raphe of the pharynx. Constricts the wall of the lower pharynx during swallowing. The inferior pharyngeal constrictor lies largely behind the thyroid and cricoid cartilages.
Its lower end is referred to as the cricopharyngeal muscle, which is continuous with the esophageal muscle fibers. Where the inferior constrictor attaches to the cricoid cartilage represents the narrowest portion of the pharynx.
Injury to the pharyngeal fibers from CN X can result in difficulty swallowing dysphagia. Stylopharyngeus muscle Origin: Arises from the styloid process of the temporal bone. Attaches to the posterior and superior margins of the thyroid cartilage. Elevates the pharynx and larynx during swallowing and speaking. Glossopharyngeal nerve CN IX. This muscle passes between the superior and middle pharyngeal constrictors.
The stylopharyngeus is 1 of 3 muscles arising from the styloid process of the temporal bone the others are the styloglossus and stylohyoid. Each muscle is innervated by a different cranial nerve and arises from a different embryonic branchial arch. The stylopharyngeus arises embryologically from the 3rd pharyngeal branchial arch and is the only muscle innervated by the glossopharyngeal nerve.
A lesion to the motor fibers of CN IX that innervate the stylopharyngeus muscle can cause pain when the patient initiates swallowing.
Sternocleidomastoid muscle Origin inferior attachment: This muscle has 2 heads of origin. The sternal head arises from the anterior surface of the manubrium of the sternum. The clavicular head arises from the superior surface of the medial third of the clavicle. Insertion superior attachment: Attaches to the lateral surface of the mastoid process of the temporal bone and the lateral half of the superior nuchal line.
Tilts the head to 1 side, flexes the neck, and rotates the neck so the face points superiorly to the opposite side. When the muscles of both sides act together, they flex the neck. When the head is fixed, the 2 muscles acting together can help elevate the thorax during forced inspiration. The sternocleidomastoid SCM is 1 of 2 muscles innervated by the spinal accessory nerve. Although the accessory nerve is classified as a cranial nerve, it does not possess any fibers originating from the brainstem.
The SCM is innervated by the accessory nerve CN XI , and this nerve is susceptible to injury where it crosses the posterior cervical triangle between the SCM muscle and the trapezius muscle.
CN XI innervates both of these muscles. Torticollis is a contraction of the cervical muscles that presents as a twisting of the neck such that the head is tilted toward the lesioned side ipsilateral and the face away from the lesioned side contralateral. Commonly, the SCM is affected unilaterally by this congenital fibrous tissue tumor. Sternohyoid muscle Origin: Manubrium of the sternum and medial portion of the clavicle. Body of the hyoid bone. Depresses the hyoid bone after swallowing.
C1, C2, and C3 from the ansa cervicalis. The sternohyoid is part of the group of infrahyoid muscles. Swelling within this confined space can be painful and potentially damaging to adjacent structures.
Sternothyroid muscle Origin: Arises from the posterior surface of the manubrium of the sternum. Attaches to the oblique line of the thyroid cartilage. Depresses the larynx after the larynx has been elevated for swallowing. C2 and C3 from the ansa cervicalis. The sternothyroid is part of the group of infrahyoid muscles. Omohyoid muscle Origin: This muscle consists of an inferior and a superior belly.
The inferior belly arises from the superior border of the scapula, near the suprascapular notch. The muscle is attached by a fibrous expansion to the clavicle and forms the superior belly, which inserts into the inferior border of the hyoid bone. Depresses the hyoid bone after the bone has been elevated.
Also retracts and steadies the hyoid bone. C1, C2, and C3 by a branch of the ansa cervicalis. The omohyoid acts with the other infrahyoid muscles to depress the larynx and hyoid bone after these structures have been elevated during swallowing. Thyrohyoid muscle Origin: Arises from the oblique line of the lamina of the thyroid cartilage. Attaches to the inferior border of the body and the greater horn of the hyoid bone. Depresses the hyoid bone and, if the hyoid bone is fixed, draws the thyroid cartilage superiorly.
The thyrohyoid muscle is supplied by fibers of the 1st cervical nerve that happen to travel with the last cranial, or hypoglossal, nerve CN XII. Trauma to the neck may damage the ansa cervicalis C and its branches, leading to paralysis of the infrahyoid and suprahyoid muscles. Because these muscles are critical in the process of swallowing, dysphagia difficulty in swallowing may ensue.
Cricothyroid muscle Origin: Arises from the anterolateral part of the cricoid cartilage. Inserts into the inferior aspect and inferior horn of the thyroid cartilage. Stretches and tenses the vocal folds. External branch of the superior laryngeal nerve of the vagus. This muscle is innervated by the small, external branch of the superior laryngeal nerve of the vagus. Most of the superior laryngeal nerve continues as an internal branch that pierces the thyrohyoid membrane to provide sensory innervation above the vocal folds.
This muscle, similar to the other muscles of the larynx, is derived embryologically from the 4th through 6th pharyngeal branchial arches. All of these laryngeal muscles are innervated by the vagus nerve. Damage on 1 side to the superior laryngeal nerve, a branch of the vagus nerve CN X , will paralyze the ipsilateral cricothyroid muscle. Consequently, the voice will be affected because the ipsilateral vocal fold cannot be fully stretched and tensed. Additionally, the ipsilateral laryngeal mucosa above the level of the vocal folds will be anesthetized the superior laryngeal nerve is sensory to the laryngeal mucosa above the vocal folds , somewhat compromising the protective gag reflex that would normally keep foreign objects from being aspirated into the larynx.
Stylohyoid muscle Origin: Elevates and retracts the hyoid bone in an action that elongates the floor of the mouth.
Facial nerve. The stylohyoid muscle is perforated near its insertion by the tendon of the 2 bellies of the digastric muscle. The stylohyoid is 1 of the 3 muscles arising from the styloid process, each innervated by a different cranial nerve.
The stylohyoid is one of several muscles that help stabilize the hyoid bone, which is important in movements of the tongue and in swallowing. Digastric muscle Origin: The digastric muscle consists of 2 bellies. The posterior belly is the longest, and it arises from the mastoid notch of the temporal bone.
The anterior belly arises from the digastric fossa of the mandible. The 2 bellies end in an intermediate tendon that perforates the stylohyoid muscle and is connected to the body and greater horn of the hyoid bone. Elevates the hyoid bone and, when both muscles act together, helps the lateral pterygoid muscles open the mouth by depressing the mandible.
The anterior belly is innervated by the mylohyoid nerve, a branch of the mandibular division of the trigeminal nerve. The posterior belly is innervated by the facial nerve.
The 2 bellies of the digastric muscle are unique because they are innervated by different cranial nerves. The digastric muscles are important for opening the mouth symmetrically and are assisted by the lateral pterygoid muscles.
Oblique arytenoid muscles 2. Transverse arytenoid muscles Origin: Arise from the arytenoid cartilages. Attach to the opposite arytenoid cartilage. Close the inlet of the larynx by adducting the arytenoid cartilages. This narrows the rima glottidis, the space between the vocal folds. Recurrent laryngeal nerve of the vagus. Some muscle fibers of the oblique arytenoid continue superiorly as the ary-epiglottic muscle.
The vocal folds are controlled by the laryngeal muscles, all of which are innervated by the vagus nerve CN X. During quiet respiration, the vocal folds are gently abducted to open the rima glottidis space between the folds. In forced inspiration taking a rapid, deep breath , the folds are maximally abducted by the posterior crico-arytenoid muscles, further enlarging the rima glottidis.
During phonation, the folds are adducted and tensed to create a reed-like effect similar to a reed instrument , causing vocal fold mucosal vibrations that produce sound that is then modified by the upper airway pharynx, oral cavity, tongue, lips, nose, and paranasal sinuses.
Closure of the rima glottidis occurs when holding your breath or when lifting something heavy the Valsalva maneuver , and the folds are completely adducted. Posterior crico-arytenoid muscle Origin: Arises from the posterior surface of the laminae of the cricoid cartilage.
Attaches to the muscular process of the arytenoid cartilage. Abducts the vocal folds and widens the rima glottidis, the space between the vocal folds.
Recurrent inferior laryngeal nerve of the vagus. The posterior crico-arytenoid muscles are extremely important because they are the only muscles that abduct the vocal folds. Damage to the recurrent laryngeal nerve during neck surgery e.
This occurs because the posterior crico- arytenoid muscles are the only laryngeal muscles that abduct the vocal folds and keep the rima glottidis open. Ary-epiglottic part of oblique 4. Thyro-arytenoid muscle arytenoid muscle 5.
Lateral crico-arytenoid 2. Posterior crico-arytenoid muscle muscle 6. Vocalis muscle 3. Thyro-epiglottic part of 7. Vocal ligament thyro-arytenoid muscle 8. Conus elasticus Comment: The muscles of the larynx are small. They act on the laryngeal cartilages. The most superior portion of the conus elasticus is thickened and forms the vocal ligament.
The vocal folds themselves contain a small amount of muscle called the vocalis muscle, which is derived from some of the fibers of the thyro-arytenoid muscle. With the exception of the cricothyroid, all the intrinsic muscles of the larynx are innervated by the recurrent laryngeal nerve of the vagus.
All of these muscles are derived embryologically from the 4th through 6th pharyngeal branchial arches. During quiet respiration, the vocal folds are gently abducted to open the rima glottidis. In forced inspiration, the folds are maximally abducted by the posterior crico-arytenoid muscles, further enlarging the rima glottidis. During phonation, the folds are adducted and tensed to create a reed-like effect, causing vocal fold mucosal vibrations that produce sound that is then modified by the upper airway pharynx, oral cavity, tongue, lips, nose, paranasal sinuses.
Closure of the rima glottidis occurs when holding your breath or when lifting something heavy, and the folds are completely adducted. Scalene muscles Origin superior attachment: The anterior scalene arises from the anterior tubercles of the transverse processes of C vertebrae.
The middle and posterior scalenes arise from the posterior tubercles of the transverse processes of C middle and C posterior vertebrae. Insertion inferior attachment: The anterior scalene attaches to the scalene tubercle of the 1st rib. The middle scalene attaches to the superior surface of the 1st rib. The posterior scalene attaches to the external border of the 2nd rib.
The anterior and middle scalenes elevate the 1st rib. When that rib is fixed, they also flex the neck forward and laterally and rotate it to the opposite side. The posterior scalene raises the 2nd rib and flexes and slightly rotates the neck. The anterior scalene is innervated by C ventral rami; the middle scalene, by C ventral rami; and the posterior scalene, by ventral rami of C The scalene muscles are often called lateral vertebral muscles.
They form a large portion of the floor of the posterior cervical triangle. Components of the brachial plexus can be seen emerging between the anterior and middle scalene muscles.
The scalene muscles are accessory muscles of respiration and help elevate the first 2 ribs during deep or labored breathing. They are crossed by the accessory nerve CN XI as it passes between the sternocleidomastoid and trapezius muscles. The phrenic nerve C is observed on the anterior surface of the anterior scalene muscle; it courses inferiorly toward the diaphragm, which it innervates. Trauma to the neck can damage these nerves.
Longus capitis muscle 2. Longus colli muscle Origin: The longus capitis arises from the anterior tubercles of the C vertebral transverse processes. The longus colli arises from the bodies of the T vertebrae, the bodies of the C vertebrae, and transverse processes of the C vertebrae. The longus capitis attaches to the basilar portion of the occipital bone.
The colli portion attaches to the anterior tubercle of the atlas C1 , the bodies of the C vertebrae, and transverse processes of the C vertebrae. Both muscles flex the neck, although the longus colli is weak. The longus colli also slightly rotates and laterally bends the neck.
The longus capitis is supplied by the C ventral rami. The longus colli is supplied by the C ventral rami.
The longus capitis and longus colli lie in front of the cervical vertebrae and are often called prevertebral muscles. They help other muscles flex the cervical spine. They are encased in a strong fascial sleeve called the prevertebral fascia and do not tolerate swelling well because of this tight enclosure. Just anterior to the prevertebral fascia, where it covers the bodies of the cervical vertebrae, lies the retropharyngeal space this space is posterior to the buccopharyngeal fascia [the posterior portion of the pretracheal fascia] covering the posterior pharynx and esophagus.
Infections in this vertical space may pass superiorly to the base of the skull or inferiorly into the posterior mediastinum of the thorax.
Supra-orbital nerve 2. Infra-orbital nerve 3. Mental nerve 4. Buccal nerve 5. Auriculotemporal nerve 6. Supraclavicular nerves C3, C4 7. Great auricular nerve C2, C3 8. Greater occipital nerve C2 Comment: Cutaneous innervation of the face is by the 3 divisions of the trigeminal nerve CN V. The ophthalmic division is represented largely by the supra-orbital and supratrochlear nerves. The maxillary division is represented by the infra-orbital and zygomaticotemporal nerves.
The mandibular division is represented largely by the mental, buccal, and auriculotemporal nerves. The skin on the back of the scalp receives cutaneous innervation from the greater occipital nerve dorsal ramus of C2 ; the skin on the back of the neck receives innervation from dorsal rami of cervical nerves.
The 1st cervical nerve C1 has few if any sensory nerve fibers from the skin, so it is usually not shown on dermatome charts. The sensory innervation of the face is via the 3 divisions of CN V. Trauma anywhere along the pathway of the nerve, including that on the face itself e.
The innervation of the muscles of facial expression will not be affected unless a laceration also damages the terminal branches of the facial nerve. Main trunk of facial nerve emerging from stylomastoid foramen 2. Cervical branch 3. Marginal mandibular branch 4. Buccal branches 5. Zygomatic branches 6.
Temporal branches Comment: