FASCIAE OF human neck gross anatomy mbbs

FASCIAE OF human neck gross anatomy mbbs

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  FASCIAE OF NECK 2ndyear lectures by: DR. AHMAD ALI NAEEM
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  FASCIAE OF NECK FASCIA:These are fibro-areolar membranous sheaths of variable thickness and strength found in all regions of the body investing the softer and more delicate structures. • TYPES; • A) SUPERFICIAL FASCIA: (or subcutaneous tissue) • A mixture of loose areolar and adipose tissue that unites the dermis of skin to underlying deep fascia. • B) DEEP FASCIA: a membranous layer of connective tissue that invests the muscles and deep structures. • SUERFICIAL FASICIA OF NECK: • It contains areolar tissue with platysma. Lying deep to platysma are cutaneous nerves, superficial veins, lymph vessels, lymph nodes and small arteries. • CLINICAL: the surgeon has to stitch platysma muscle separately so that skin does not adhere to deeper neck muscles. Otherwise the skin will get an ugly scar.
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  DEEP CERVICAL FASCIA(fascia colli) • It forms following layers: 1)Investing layer, 2) pretracheal fascia, 3) prevertebral fascia, 4) carotid sheath, 5) buccopharyngeal fascia, 6) pharyngobasilar fascia INVESTING LAYER: it lies deep to platysma and surrounds the neck like a collar. It forms the roof of post. Triangle of the neck. ATTACHMENTS: SUPERIORLY: a. Ext. occipital protuberance b. Sup. Nuchal lines c. Mastoid process d. Ext. acoustic meatus e. Base of mandible Between the angle of mandible and mastoid process, the fascia splits to enclose the parotid gland. The superficial lamina named parotid fascia Deep lamina: between the styloid process and angle of mandible the deep lamina is thick and forms the stylomandibular ligament which separates the parotid gland from submandibular gland, and is pierced by ext. carotid artery
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  • OTHER FEATURES: •1)The investing layer splits to enclose: a) muscles: trapezius and sternocleidomastoid B) salivary glands: parotid and submandibular C) spaces: suprasternal and supraclavicular 2) It form pulleys to bind tendons of digastric and omohyoid muscles 3) It forms roof of anterior and posterior triangles 4) Forms stylomandibular ligament and parotidomasseteric fascia
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  CLINICALS • Parotid swellingsare very painful due to underlying nature of parotid fascia • While excising submandibular gland the ext. carotid artery should be secured before dividing it, otherwise it may retract through stylomandibular ligament and cause serious bleeding • Division of external jugular vein in supraclavicular space may cause air embolism and consequent death because of cut ends of vein are prevented from retraction and closure by fascia, attached firmly to vein.
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  2)PRETRACEAL FASCIA • Itencloses and suspends the thyroid gland and forms its false capsule. • ATTACHMENTS: • SUP: a) hyoid bone, b) oblique line of thyroid cartilage, c) cricoid cartilage • INF: blends with the arch of aorta and fibrous pericardium. • ON SIDES: fuses with front of carotid sheath • OTHER FEATURES: • 1) the post. Layer of thyroid capsule is thick, on either side it forms suspensory ligaments (ligaments of Berry) for thyroid gland. They support the thyroid gland and do not let it sink into the mediastinum. • 2) it provides a slippery surface for free movements of trachea during swallowing. • CLINICAL: neck infections in front of pretracheal fascia may bulge in suprasternal area or extend down into the ant. Mediastinum. • The thyroid gland and all thyroid swellings move with deglutition because the thyroid is attached to cartilages of larynx by the suspensory ligaments of Berry.
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  PREVERTEBRAL FASCIA • Itlies in front of prevertebral muscles and forms the floor of post. Triangle of neck. • ATTACHEMNTS: • SUP: base of skull • INF: it splits into ant. And post. Layers. Ant. Layer/alar fascia blends with buccopharyngeal fascia and post. To the body of 4th thoracic vertebra. • ANT: It is separated from pharynx and BP fascia by retropharyngeal space containing loose areolar tissue • OTHER FEATURES: • 1) The cervical and brachial plexuses lie behind the prevertebral fascia • 2) as the trunks of brachial plexus and subclavian artery pass laterally, they carry with them a covering of prevertebral fascia known as AXILLARY SHEATH. • 3) it provides a fixed base for movements of pharynx, esophagus and carotid sheath during movements of neck and during swallowing.
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  • CLINICALS: • Neckinfections behind PV arise usually from TB of cervical vertebra or cervical caries. Pus produced as a result may go in various directions. It may pass forwards forming a chronic retropharyngeal abscess ( bulging in the post. Wall of pharynx). Go laterally through axillary sheath and pint in post. Triangle or in lateral wall of axilla. It may go downwards in to the sup. Mediastinum.
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  CAROTID SHEATH • Itis as condensation of fibroareolar tissue around main vessels of neck. • FROMATION: it is formed on ant. Aspect by pretracheal fascia and on post. Aspect by prevertebral fascia. • CONTENTS: 1. Common carotid artery 2. Internal carotid artery 3. Internal jugular vein 4. Vagus nerve in the upper part of the sheath there are 9th, 11th, and 12th nerves also. RELATIONS: ANT: ansa cervicalis POST: cervical sympathetic trunk