The Neck Anatomy PDF

THE NECK DR. SYED ADNAN QASIM M.B.B.S, M.S, M.R.C.S.  INTRODUCTION The region that lies between the lower margin of mandible and superior nuchal line of the occipital bone above and the upper border of the clavicle and suprasternal notch below.  Introduction ctd....

THE NECK DR. SYED ADNAN QASIM M.B.B.S, M.S, M.R.C.S.  INTRODUCTION The region that lies between the lower margin of mandible and superior nuchal line of the occipital bone above and the upper border of the clavicle and suprasternal notch below.  Introduction ctd. Superficial Fascia- consists of: – Platysma muscle – Cutaneous nerves – Superficial veins – Superficial lymph nodes Deep Cervical Fascia- consists of: – Investing layer – Pre-tracheal layer – Pre-vertebral layer – Carotid sheath  Ctd. INVESTING LAYER Attachments: Ant: Symphysis menti, hyoid bone Post: Ligamentum nuchae, spine of C7 vertebra Sup: lower border of mandible, mastoid process, ext. occipital protuberance Inf: spine of scapula, clavicle, sternum Contents: -Sternocleidomastoid -Trapezius -Submandibular gland -Parotid gland -Supraclavicular space -Suprasternal space  Ctd. PRE-TRACHEAL LAYER Attachments: – Sup: Hyoid bone, cricoid cartilage, thyroid cartilage – Inf: Into thorax, blends with pericardium and arch of aorta – Lat (on either sides): blends with carotid sheath Contents: – Thyroid gland – Parathyroid gland  Ctd. PRE-VERTEBRAL LAYER Attachments: – Sup: Base of the skull – Inf: Body of 3rd and 4th thoracic vertebra – Ant: separated from pharynx by retropharyngeal space – Lat: trapezius, investing layer Contents: – Cervical and brachial plexus lie behind it – Axillary sheath derives from it  Ctd. CAROTID SHEATH Condensation of deep fascia Blends in front with pre tracheal layer and behind with pre vertebral layer. Contents: – Common and Internal carotid arteries – Internal jugular vein – Vagus nerve – Deep cervical LN  MUSCLES AROUND NECK The muscles of the neck consist of 3 main groups: anterior, lateral and posterior groups, based on their position in the neck. These muscles are mainly responsible for the movement of the head in all directions.  ANTERIOR MUSCLES 1-Superficial muscles: Platysma, sternocleidomastoid 2-Suprahyoid muscles: Digastric, mylohyoid, geniohyoid, stylohyoid 3-Infrahyoid muscles: Sternohyoid, sternothyroid, thyrohyoid, omohyoid 4-Anterior vertebral muscles: Rectus capitis, longus capitis, longus colli  LATERAL (VERTEBRAL) MUSCLES Scalene muscles: – Anterior scalene – middle scalene – posterior scalene  POSTERIOR MUSCLES -Superficial layer: Trapezius, splenius capitis, splenius cervicis -Deep layer: Cervical transversospinales muscles (semispinalis capitis, semispinalis cervicis) -Deepest layer: Suboccipital muscles (rectus capitis posterior major, rectus capitis posterior minor, obliquus capitis inferior, obliquus capitis  PLATYSMA O: The platysma is a broad sheet arising from the fascia covering the upper parts of the pectoralis major and deltoid. Its fibers cross the clavicle, and proceed obliquely upward and medially along the side of the neck. I: the mandible, the skin of the lower face, lower lip and the corners of the mouth. NS: cervical branch of facial nerve (CN VII) A: Fascial expression  STERNOCLEIDOMASTIOD O: clavicular head originates from the medial third of the clavicle, while its sternal head arises from the manubrium of sternum I: mastoid process NS: accessory nerve (CN XI) A: flexion of the neck on the same (ipsilateral) side and lateral rotation of the head to the opposite side.  SCALENE MUSCLES The scalene muscles are three paired muscles (anterior, middle and posterior), located in the lateral aspect of the neck. Collectively, they form part of the floor of the posterior triangle of the neck. This is an accessory muscle of respiration. Anterior O: transverse processes of C3-C6 I: scalene tubercle, on the inner border of the first rib. NS: Anterior rami of C5-C6. A: Elevation of the first rib Middle O: transverse processes of C2-C7, largest I: scalene tubercle of the first rib NS: Anterior rami of C3-C8. A: Elevation of the first rib Posterior O: transverse processes of C5-C7 I: second rib NS: Anterior rami of C6-C8 A: Elevation of the second rib  TRAPEZIUS O: Medial one-third of superior nuchal line, external occipital protuberance, spinous processes of vertebrae C7-T12 I: posterior border of the lateral one-third of the clavicle, acromion process, and spine of scapula NS: accessory nerve (CN XI) A: Rotation, retraction, elevation, and depression of scapula. TRIANGLES OF NECK  INTRODUCTION The sternocleidomastoid muscle divides the neck into the two major neck triangles; the anterior triangle and the posterior triangle of the neck, each of them containing a few subdivisions. The triangles of the neck are important because of their contents, as they house all the neck structures, including glands, nerves, vessels and lymph nodes.  ANTERIOR TRIANGLE BOUNDARIES Anterior border of the SCM muscle midline of the neck inferior border of the mandible ROOF Skin Superficial fascia and platysma muscle Investing layer of deep cervical fascia  SUBDIVISIONS OF ANTERIOR TRIANGLE The anterior triangle is divided into four smaller triangles: 1.SUBMENTAL TRIANGLE 2.SUBMANDIBULAR TRIANGLE 3.CAROTID TRIANGLE 4.MUSCULAR TRIANGLE  SUBMENTAL TRIANGLE Borders Body of hyoid Anterior digastric on right Anterior digastric on left Floor: Mylohyoid Roof: Skin Superficial fascia with platysma Deep cervical fascia Submental triangle is unpaired Content: Anterior Jugular vein and sub-mental lymph nodes  SUB MANDIBULAR TRIANGLE Borders Inferior border of the mandible Posterior digastric Anterior digastric Floor of the triangle Hyoglossus Mylohyoid Middle constrictor Roof: Skin Superficial fascia with platysma Deep cervical fascia Submandibulartriangle is paired  SMG Ctd. Contents: Arteries – Facial – Sublingual – Submental Veins: – same as arteries Nerves : – Mylohyoid and hypoglossal Structures – Submandibular gland – Inferior portion of parotid gland – Submandibular lymph node  CAROTID TRIANGLE Named because parts of all three carotid arteries are located within it Borders: Anterior border of the sternocleidomastoid Posterior digastric Superior omohyoid Floor: Hyoglossus Thyrohyoid Middle constrictor Inferior constrictor Roof Skin Superficial fascia with platysma Deep cervical fascia Carotid triangle is paired  Carotid triangle ctd. Arteries Common carotid (with carotid body) Internal carotid (with carotid sinus) Superior thyroid (with superior superior thyroid Lingual Facial Ascending pharyngeal Occipital Vein Internal Jugular vein Common facial vein Lingual Vein Superior Thyroid vein Middle thyroid vein  Carotid triangle ctd. Nerves Vagus – External laryngeal – Internal laryngeal Spinal Accessory Hypoglossal Ansa cervicalis Sympathetic trunk Structures Larynx Thyroid  MUSCULAR TRIANGLE Borders Anterior border of the sternocleidomastoid Superior omohyoid Midline Floor Sternohyoid Sternothyroid Roof Skin Superficial fascia with platysma Deep cervical fascia Muscular triangle is paired  MT Ctd. Arteries Superior thyroid Veins Inferior thyroid Anterior jugular Nerves: Ansa cervicalis Structures Strap muscles: Sternohyoid, Sternothyroid, Thyrohyoid Thyroid gland Parathyroid gland Larynx Trachea Esophagus  POSTERIOR TRIANGLE Boundaries Anteriorly SCM Posteriorly Trapezius Inferiorly Clavicle Apex occipital bone. ROOF –Skin –Superficial fascia –Platysma muscle –Investing layer of the deep cervical fascia  Ctd. Formed by the following muscles from above downwards: Splenius Capitis Levator scapulae Posterior scalene Middle scalene Anterior scalene  SUB DIVISION OF POSTERIOR TRIANGLE The posterior triangle is further divided into two smaller triangles by the Inferior belly of the Omohyoid muscle. Supraclavicular triangle –Inferior belly of the Omohyoid –the Clavicle, –Sternocleidomastoid muscle Occipital triangle –Inferior belly of the Omohyoid –Trapezius muscle –Sternocleidomastoid muscle  CONTENTS OF POSTERIOR TRIANGLE NERVES: Spinal accessory nerve. Branches of Cervical plexus –Lesser occipital –Transverse cervical –Great auricular –Supraclavicular Roots and trunks of brachial plexus. Dorsal scapular Long thoracic Phrenic  Ctd. VESSELS: Arteries Subclavian artery Transverse Cervical artery Suprascapular artery Vein External jugular vein (terminal part) Lymph Nodes Occipital Supraclavicular  Clinical Significance of Posterior triangle The Accessory Nerve may be damaged, while taking lymph node biopsy. The External Jugular Vein is present in a superficial location here and this makes it vulnerable to injury.