Overview of the Neck Anatomy (PDF)

OVERVIEW AND SURFACE AND SECTIONAL ANATOMY OF THE NECK Head and Neck Anatomy II BDS-202 Dr. Jayaraj Ajman University 3-Sep-24...

OVERVIEW AND SURFACE AND SECTIONAL ANATOMY OF THE NECK Head and Neck Anatomy II BDS-202 Dr. Jayaraj Ajman University 3-Sep-24 1  LEARNING OUTCOMES ▪ Discuss the surface and sectional anatomy of the neck ▪ Describe the layers of deep cervical fascia, fascial spaces and their clinical significance ▪ Describe the cutaneous supply and cervical plexus of neck and cervical plexus block Ajman University 3-Sep-24 2  Neck ❑ Neck Is the area between the base of the skull And inferior border of the mandible And the superior thoracic aperture Is a tubular constriction ✓ Connects the head to the trunk of the body ✓ Serve as a conduit for structures passing to and from the head and the trunk Ajman University 3-Sep-24 3  Regions of the Neck Strap muscles ❑ Neck is divided into the four regions Anterior region Right lateral region Left lateral region Posterior region (nucha) Anterior region of the neck ▪ Contains Strap muscles Visceral structures Pharynx, esophagus, larynx and trachea Vessels to and from the head Four cranial nerves Thyroid and parathyroid glands Ajman University 3-Sep-24 4  Regions of the Neck ▪ Structures can be palpated in the anterior region Hyoid bone Thyroid cartilage Cricoid cartilage Tracheal rings Isthmus of the thyroid gland Thyroid lobe Suprasternal (jugular) notch Common carotid artery Ajman University 3-Sep-24 5  Regions of the Neck Right and Left lateral regions of the neck ▪ Composed of Two large superficial muscles And cervical lymph nodes ▪ Structures can be palpated in the lateral region Mastoid process Clavicle Sternocleidomastoid muscle Trapezius External jugular vein Transverse process of the atlas vertebra Ajman University 3-Sep-24 6  Regions of the Neck Posterior region of neck ▪ Includes Cervical vertebral column (C1 to C7) Spinal cord, and associated structures ▪ Structures can be palpated in the posterior region External occipital protuberance Superior nuchal line Spine of 7th cervical vertebra Ajman University 3-Sep-24 7  Langer's Lines ❑ Langer's lines ▪ (Tension lines or cleavage lines) Topological lines drawn on a map of the human body Correspond to the natural orientation of collagen fibers in the dermis Generally parallel to the orientation of the underlying muscle fibers Important for surgical operations Incisions made parallel to Langer's lines may heal better And produce less scarring than those that cut across Ajman University 3-Sep-24 8  Skin in the Region of Neck ❑ Skin Is the superficial structure covering the neck Is thin and normally under tension Direction of Langer’s lines often correspond with the wrinkle lines Surgical incisions made along these lines o Neck heal with invisible scars Ajman University 3-Sep-24 9  Fascia of the Neck ▪ Two main layers of cervical fascia Superficial fascia Deep fascia ❑ Superficial fascia Thin layer of subcutaneous connective tissue Lies between the dermis of the skin and the deep cervical fascia Contains the platysma, cutaneous nerves, blood, and lymphatic vessels Contains a varying amount of fat, which is its distinguishing characteristic Ajman University 3-Sep-24 10  Fascia of the Neck ❖ Platysma Thin broad sheet of muscle Lies in the superficial fascia Ascends onto the face from the front of the neck Extends from the pectoralis major and deltoid muscle Attached to facial skin and mandible Supplied by facial nerve ✓ Releases the pressure underlying veins and helps in the venous return ✓ Helps to depress the mandible Ajman University 3-Sep-24 11  Fascia of the Neck ❑ Deep fascia of the neck Covers the muscles, viscera, and neurovascular structures of the neck Investing layer Surrounds sternocleidomastoid and trapezius muscles Forms an outer musculofascial collar ✓ Functions to rotate the head and flex the neck ▪ Layer also creates a muscular compartment Contains a group of muscles Associated with movements of the hyoid bone Ajman University 3-Sep-24 12  Fascia of the Neck ▪ Superiorly: ❑ Attachments of Investing layer Superior nuchal line ▪ Posteriorly: Lower border of the mandible Ligamentum nuchae Mastoid process C7 cervical spine. External occipital ▪ Anteriorly: protuberance Symphysis menti ▪ Inferiorly: Hyoid bone Manubrium Fascia of opposite side Clavicle Acromion process Spine of scapula Ajman University 3-Sep-24 13  Fascia of the Neck Pretracheal fascia Forms the visceral compartment by surrounding the visceral organs in the neck Lies deep to the infrahyoid strap muscles of the anterior triangle of the neck ▪ Upward attachment Hyoid bone at the midline Oblique line of the thyroid cartilage laterally ▪ Splits to enclose the thyroid gland ▪ Blends inferiorly with the adventitia of the arch of the aorta ▪ Blends laterally with carotid sheath Ajman University 3-Sep-24 14  Fascia of the Neck Prevertebral fascia Encloses the intrinsic muscles of the neck To form the vertebral compartment Surrounds the vertebro-muscular block Extends from the base of the skull downwards to the level of T3 vertebra Prolonged laterally towards the axilla as the axillary sheath ✓ Provides a fixed basis Pharynx, esophagus, and carotid sheaths can glide during neck movements And swallowing undisturbed by movements of the prevertebral muscles Ajman University 3-Sep-24 15  Fascia of the Neck Carotid sheath ▪ Surround the nerves and vessels of the neurovascular compartment ▪ Formed by a combination of connective tissue That originates from the blood vessels and investing and pretracheal fascia ▪ Contains Internal jugular vein Common or internal carotid arteries Vagus nerve ▪ Sympathetic trunk is located behind the carotid sheath Ajman University 3-Sep-24 16  Compartment of the Neck Musculofascial collar Include muscles and the investing fascia Involved in the rotation of the head Muscular compartment Contains muscles that regulate hyoid bone while swallowing and speaking Visceral compartment Contains pharynx, larynx, esophagus, trachea, and thyroid and parathyroid glands Neurovascular compartment Contains the major arteries and veins, lymphatic vessels and nerves Vertebral compartment Contains vertebrae and the intrinsic muscles of the neck Involved in flexion, extension, and rotation of the neck Ajman University 3-Sep-24 17  Fascial Spaces and the Spread of Infection ❑ Fascial spaces ✓ Prevent structures from sticking to each other ✓ Allow movement of organs (trachea and esophagus) ▪ Clinically important Facilitate the spread of infection Fascial spaces of the floor of the mouth to the spaces of the neck Fascial spaces allows odontogenic infections to spread into the mediastinum Ajman University 3-Sep-24 18  Parapharyngeal Space ❑ Parapharyngeal space Lies immediately postero-lateral to the pharynx Extends forward into the sublingual region So that together form a ring about the pharynx ▪ Intervene between The interfascial spaces and the mandible one hand And the pharynx on the other ▪ Intimately related to the lymph nodes Receive drainage from the nose, throat and jaw Ajman University 3-Sep-24 19  Parapharyngeal Space ▪ Clinical Significance Infections from the floor of the mouth can gain access to the pharyngeal space ▪ Receive infection from Teeth Submandibular gland Masticator space Parotid space Paratonsillar space ▪ From parapharyngeal space infection pass to retrophargyngeal space ▪ Then to superior mediastinum Ajman University 3-Sep-24 20  Retropharyngeal Space ❑ Retropharyngeal space Located between the vertebral column and the visceral compartment of the neck Lying behind the pharynx In front of the prevertebral fascia Extends from the base of the skull to the diaphragm ▪ Boundaries Anteriorly - Posterior wall of pharynx Posteriorly - Pre vertebral fascia Superiorly - Base of skull ✓ Space allows the expansion of Inferiorly - Superior mediastinum the pharynx during swallowing Ajman University 3-Sep-24 21  Retropharyngeal Space ▪ Clinical Significance Act as a route for infection from the mouth and throat And infection pass to superior mediastinum ▪ Source of infection from mouth to retropharyngeal space First molar are the commonest source of infection Third molar are the second important source of infection ▪ Retropharyngeal abscess Due to involvement of retropharyngeal lymph nodes Produces paramedian unilateral bulge in the posterior pharyngeal wall Cause difficulty in swallowing and breathing Ajman University 3-Sep-24 22  Ludwig’s Angina ❑ Ludwig’s angina Bilateral swelling of the submental, sublingual, and submandibular spaces Commonly formed by the abscess of the apices of the teeth Pus penetrates the lingual plates of the mandibular teeth And gains access to submental, sublingual, and submandibular spaces ▪ Patient presents with Extreme hardness to the floor of the mouth and dysphagia Tongue is elevated and can be pushed to one side ▪ Infection then spread into the lateral pharyngeal space And cause an indurated swelling of the neck ▪ Infection can advance into the mediastinum ▪ The infection requires careful monitoring and rapid intervention for prevention of asphyxia and aspiration pneumonia Ajman University 3-Sep-24 23  Cutaneous Innervation of the Neck ❑ Cutaneous innervation Supply the skin of the neck, upper thorax, scalp and ear Is derived from C2, C3, and C4 spinal segments C1 nerve has no cutaneous branch ▪ Nerve point of the neck (Erb’s point) Nerves all enter the skin at the middle of the posterior border of the sternocleidomastoid Skin on the anterolateral aspect of the neck Supplied by ventral rami of C2, C3, and C4 spinal nerves Skin on the posterior aspect of the neck Supplied by dorsal rami of C2, C3, C4 and C5 spinal nerves Ajman University 3-Sep-24 24  Cutaneous Nerves of the Neck ❑ Skin on the front and side of the neck Each side is supplied by four cutaneous nerves Derived from ventral rami of C2, C3, and C4 spinal nerves Lesser occipital nerve (C2) Supplies to the posterosuperior scalp Posterior part of auricle Upper middle neck posteriorly Great auricular nerve (C2 and C3) Supplies skin over auricle, parotid and angle of mandible Ajman University 3-Sep-24 25  Cutaneous Nerves of the Neck Transverse cervical nerve (C2 and C3) Curves around the posterior aspect of the sternocleidomastoid Supplies to the anterior and lateral neck Upper middle neck anteriorly Supraclavicular nerves (C3 and C4) Arise from posterior border of sternocleidomastoid Supplies to skin overlying the suprascapular fossa Upper thoracic region and sternoclavicular joint Medial and lateral parts of neck Ajman University 3-Sep-24 26  Cutaneous Nerves of the Neck ❑ Skin on the back of the neck Is supplied by dorsal rami of C2, C3, C4 and C5 spinal nerves Greater occipital nerve (C2) Supply the posterior part of the scalp Thickest cutaneous nerve in the body Third occipital nerve (C3) Supplies the nape of the neck up to the external occipital protuberance Cutaneous branches of C4 and C5 Supply the adjacent skin Ajman University 3-Sep-24 27  Cervical Plexus ❑ Cervical plexus Network of nerve fibres Supplies innervation to structures in the neck and trunk Located in the posterior triangle of the neck Located halfway up the sternocleidomastoid muscle And within the prevertebral layer Formed by the anterior rami of cervical spinal nerves C1-C4 ▪ Divided into Superficial (mainly sensory): Supply skin of neck Deep (mainly motor): Supply muscles of neck Ajman University 3-Sep-24 28  Cervical Plexus ❑ Superficial Branches Formed by the anterior rami of cervical spinal nerves C1-C4 Lesser occipital nerve (C2) Great auricular nerve (C2 and C3) Transverse cervical nerve (C2 and C3) Supraclavicular nerves (C3 and C4) Ajman University 3-Sep-24 29  Cervical Plexus ❑ Deep Branches Communicating branch (C1) Merge with Hypoglossal nerve Supplies thyrohyoid and geniohyoid muscle Ansa cervicalis ▪ Loop formed by Superior root (descendens hypoglossi)(C1) Inferior root (descendens cervicalis)(C2-C3) ▪ Supplies infrahyoid muscles Omohyoid Sternohyoid Sternothyroid Ajman University 3-Sep-24 30  Cervical Plexus Phrenic nerve (C3-C5) ✓ Provide motor innervation to the diaphragm Provide sensory innervation to diaphragmatic pleura, pericardium Proprioceptive branches Branch from C2–C3 to sternocleidomastoid Branches from C3–C4 to trapezius Communicate with spinal accessory nerve Ajman University 3-Sep-24 31  Cervical Plexus Muscular branches To prevertebral muscles Rectus capitis anterior (C1) Rectus capitis lateralis (C1, C2) Longus capitis (C1–C3) Longus colli (C2–C4) Strap muscles (C1–C3) Sternocleidomastoid (C2) Trapezius (C3, C4) Levator scapulae (C3, C4) Scalene muscles (C3, C4) Diaphragm (C3, C4) Ajman University 3-Sep-24 32  Cervical Plexus Block ❑ Deep and superficial cervical plexus blocks Needle insertion during Used in a variety of surgical procedures, including superficial deep cervical blockade surgery on the neck and shoulders and thyroid surgery Block is done by giving anesthetic at the midpoint on the posterior border of sternocleidomastoid muscle (Erb’s point) ▪ Superficial cervical blocks anesthetizes Skin of anterolateral neck, anterior and retroauricular areas ▪ Deep cervical block anesthetizes Muscles of the neck, geniohyoid, prevertebral muscles ▪ Blockade of the phrenic nerve Anesthetic agents Sternocleidomastoid, levator scapulae, the scalenes, Bupivacaine trapezius, and the diaphragm Ropivacaine Ajman University Mepivacaine 3-Sep-24 33  Cervical Plexus Block ▪ Because the phrenic nerve supplying the diaphragm, pericardium is also paralyzed by cervical plexus block, this procedure is not performed on patients with pulmonary or cardiac disease ▪ A phrenic nerve block produces a short period of paralysis of the diaphragm on one side (e.g., for a lung operation). ▪ A surgical phrenic nerve crush (e.g., compressing the nerve injuriously with forceps) produces a longer period of paralysis Ajman University 3-Sep-24 34  Cervical Sympathetic Trunk ❑ Cervical sympathetic trunk One on either side of cervical part of the vertebral column Lies behind the carotid sheaths and in front of prevertebral fascia Superior cervical ganglion Form plexus around internal and external carotid arteries Middle cervical ganglion Form a plexus around the inferior thyroid artery Inferior cervical ganglion Form plexus around vertebral and subclavian arteries Ajman University 3-Sep-24 35  Horner’s Syndrome ❑ Horner syndrome Results from an interruption of the sympathetic trunk Usually in the upper thoracic or lower cervical region ▪ Characterized by the Miosis (Constricted pupil) - due to paralysis of the dilator pupillae Ptosis (drooping of the upper eyelid) - due to paralysis of the superior tarsal muscle Anhidrosis (absence of sweating of the face) - due to a loss of innervation to the sweat glands of the face Enophthalmos (sinking of the eyeball into the bony cavity) Horner’s syndrome has a multitude of causes. o These include spinal cord lesions, traumatic injury and a Pancoast tumour (a cancer affecting the apex of the lung) Ajman University 3-Sep-24 36  Ajman University 3-Sep-24 37