Study Guide - 3 Topography of Neck PDF

LECTURE 3 TOPOGRAPHY OF THE NECK Learning Objectives: after studying this lecture, you should be able to 1. Describe the compartments of the neck 2. Describe the structures seen in a sagittal section of the head & neck NECK...

LECTURE 3 TOPOGRAPHY OF THE NECK Learning Objectives: after studying this lecture, you should be able to 1. Describe the compartments of the neck 2. Describe the structures seen in a sagittal section of the head & neck NECK COMPARTMENTS In transverse section, the neck shows 3 compartments of structures surrounding the cervical vertebrae, each compartment has its own fascia: 1. Superficial muscular compartment: has investing fascia. 2. Visceral & vascular compartments: have pretracheal fascia and carotid sheath respectively. 3. Deep muscular compartment: has prevertebral fascia. 1. SUPERFICIAL MUSCULAR COMPARTMENT Muscles: 1. Sternomastoid & trapezius. 2. Infrahyoid muscles, mainly omohyoid, which has superior and inferior bellies. 3. Suprahyoid muscles, mainly digastric, which has anterior and posterior bellies. Investing fascia, invests the muscles & covers the triangles of the neck. Neck triangles: o Ant. Triangle: between sternomastoid - base of mandible - anterior midline of the neck. Divided into smaller triangles: ▪ Submental triangle. ▪ Digastric triangle: Contains the submandibular salivary gland. ▪ Carotid triangle: Contains the carotid sheath. ▪ Muscular triangle. o Post. Triangle: between sternomastoid – trapezius - clavicle 2. VISCERAL & VASCULAR COMPARTMENT Contains organs (medially) & vessels (laterally). The organs are surrounded by the pretracheal fascia. They are arranged from anterior to posterior as: 1. Thyroid gland: consists of 2 lobes (right & left) connected by an isthmus. 2. Larynx: made of skeleton (e.g. thyroid, cricoid and epiglottis cartilages) connected by membranes & ligaments. Continues below C6 vertebra as the trachea. 3. Pharynx: Continues below C6 vertebra as the esophagus. Carotid sheath (one on each side) is a tube of fascia that surrounds: Common & internal carotid arteries (medially). The external carotid a is outside. Internal jugular vein (laterally) Vagus nerve (10th cranial) in-between 1  3. DEEP MUSCULAR COMPARTMENT Surrounded by prevertebral fascia and contains muscles and nerves: - Muscles: Anteriorly = prevertebral muscles (longus colli). Laterally = 3 scalene muscles (anterior, medius, posterior) Posteriorly = back muscles (4 layers). - Nerves: Cervical plexus (C1-C4 spinal nerves). Brachial plexus (C5-T1 spinal nerves) → to upper limb SAGITTAL SECTION OF THE HEAD & NECK Nasal cavity: divided by nasal septum into 2 halves. Each half has: 1. Roof 2. Floor: hard palate. The hard palate is continuous posteriorly with the soft palate which projects in the middle line as uvula. 3. Medial wall: nasal septum. 4. Lateral wall: shows 3 elevations called conchae (superior, middle & inferior) and receives openings of para nasal sinuses. Para nasal sinuses: they are spaces inside some skull bones filled with air. They include: 1- Frontal air sinus. 2- Sphenoidal air sinus. 3- Ethmoidal air sinuses. 4- Maxillary air sinus. Oral cavity containing the tongue. Pharynx: a muscular tube that lies behind nose, oral cavity & larynx. Begins at base of skull.. Ends at level of 6 cervical vertebrae to become esophagus. Divided into 1- Nasopharynx: contains opening of Eustachian tube 2- Oropharynx: contains palatine tonsils 3- laryngopharynx Larynx The laryngeal inlet is guarded by the epiglottis. Ends at level of 6 cervical vertebrae to become the trachea. N.B.:  The nasal cavity is separated from the oral cavity by the hard palate.  The nasopharynx is separated from the oropharynx by the soft palate.  The oropharynx is separated from the laryngopharynx by the epiglottis.  The oral cavity is separated from the oropharynx by the tonsil and uvula. 2