Triangles of the Neck Sanjaya Adikari Department of Anatomy

Boundaries of the neck Spinous process of C7 Acromian

Compartments of the neck Neck has 4 major compartments Vertebral compartment Cervical vertebrae and associated muscles Visceral compartment Parts of respiratory and digestive tracts, important glands (thyroid, parathyroid and thymus) Two vascular compartments Contains major blood vessels and vagus nerve

Compartments of the neck

Cervical fascia Superficial Deep Contains platysma muscle, cutaneous nerves, superficial veins and superficial LNs Deep

Deep cervical fascia Consists of 4 parts Investing layer Encircles the neck completely Pretrachial fascia Encircles the visceral compartment Prevertebral fascia Encircles the vertebral compartment Carotid sheaths Enclose the two vascular compartments

Investing layer Splits to enclose the parotid gl. Superficial layer forms parotid fascia & attached to zygomatic arch Mandible Mastoid p. E.O. protuberance & s. nuchal line Acromian & spine L. nuchae Clavicle Manubrium

Investing layer Deep layer forms stylomandibular ligament between styloid process & angle of mandible Stylomandibular ligament Mandible Mastoid p. E.O. protuberance & s. nuchal line Acromian & spine L. nuchae Clavicle Manubrium

Prevertebral fascia Lies in front of prevertebral muscles Extends from skull base to T4 body getting attached to anterior longitudinal ligament Extends around the subclavian artery and brachial plexus and becomes axillary sheath Phrenic nerve lies behind Sympathetic trunk lies in front Cutaneus branches of Cx plexus pierce it

Pretrachial fascia

Carotid sheath Anterior Vagus nerve

Triangles of the neck

Posterior triangle - contents External jugular vein after piercing the investing layer. Accessory nerve Branches of Cx plexus Lesser occipital Great auricular Transverse cervical Supraclavicular

Floor of the posterior triangle Prevertebral fascia lying on the muscles Semispinalis capitis Splenius capitis Levator scapulae Scalenus medius Scalenus anterior

Anterior triangles of the neck

Anterior triangle of the neck Suprahyoid muscles Digastric: poterior belly by facial N. & anterior belly by nerve to mylohyoid Stylohyoid: by facial nerve Mylohyoid: by nerve to mylohyoid, a branch of inferior alveolar nerve (mandibular division) Geniohyoid: by C1 through hypoglossal nerve

Anterior triangle…. Infrahyoid muscles Sternohyoid Omohyoid Thyrohyoid Sternothyroid These are depressors of the larynx. Supplied by ansa cervicalis (C1-C3)

Carotid triangle Tip of the greater horn of hyoid is an important reference point Note the relationships of hypoglossal nerve

Root of the neck All structures that pass between the head and thorax or upper limb and thorax must pass through the root of the neck

Subclavian Artery 1st part of subclavian artery Vetebral A Internal thoracic A Thyrocervical trunk 2nd part of subclavian artery Costocervical trunk 3rd part of subclavian artery Dorsal scapular A

Thoracic duct in the neck Join the junction between the left subclavian and internal jugular veins