Muscles of the neck

Muscle groups of the neck

• Post-vertebral muscles
• Anterior vertebral muscles
• Lateral vertebral muscles
• Anterior neck muscles
• Superficial neck muscles

_____________________________________________________________________

*Refer medical museum models

Anterior vertebral muscles

• Muscles
• Rectus capitis anterior
• Longus capitis
• Longus colli
• Attachment
• base of the skull & bodies
• transverse processes of cervical
• upper 4 thoracic vertebrae
• Nerve supply
• C1 – C6
• Action
• flex head & neck

Lateral vertebral muscles

• Muscles
• Rectus capitis lateralis
• Levator scapulae
• Anterior scalene
• Middle scalene
• Posterior scalene
• Attachments
• vary
• Nerve supply
• C1 – C8
• Actions
• vary

Anterior neck muscles

• Above hyoid bone (suprahyoid)

1. Mylohyoid

• Origin
• mylohyoid line of mandible
• Nerve supply
• Mandibular division of 5th CN
• Action
• Elevates floor of mouth (Swallowing)

Digastric (ant & post bellies)

• Origin
• digastic fossa (anterior belly)
• mastoid process (posterior belly)
• Insertion
• intermediate tendon to greater horn & body
• Nerve supply
• Anterior belly: mandibular division of 5th CN
• Posterior belly: facial nerve
• Actions
• depresses the mandible (open mouth)
• elevates the hyoid bone on swallowing

Below hyoid bone (infrahyoid)

• Strap muscles

1. Sternohyoid

• Origin
• manubrium
• Insertion
• body of hyoid
• Nerve supply
• ansa cervicalis (C1-C3)
• Action
• depresses the hyoid after elevation during swallowing

Omohyoid

• Origin
• Superior border of scapula
• Insertion
• body of hyoid
• Nerve supply
• Ansa cervicalis (C1-C3)
• Action
• same as above

Sternothyroid

• Origin
• manubrium
• Insertion
• obliqueline of thyroid cartilage
• Nerve supply
• Ansa cervicalis (C2-C3)
• Action
• same as above

Thyrohyoid

• Origin
• oblique line of thyroid cartilage
• Insertion
• body of hyoid
• Nerve supply
• Ansa cervicalis (C1 – via hypoglossal nerve)
• Action
• same as above
• elevates the larynx*

_____________________________________________________________________

Superficial neck muscles

1. Sternocleidomastoid muscle

• Key muscle of the neck
• Anterior to it
• anterior triangle
• Posterior to it
• posterior triangle
• Origins of 2 heads
• sternal head
• manubrium sterni
• clavicular head
• superior surface of medial end of clavicle
• Insertion
• mastoid process
• lateral half of superior nuchal line
• Nerve supply
• spinal accessory nerve (11th CN)
• Actions
• Unilateral contraction
• tilts the head to the same side & rotate
• face turned upwards to opposite side
• Bilateral contraction
• extends neck at atlanto-occipital joint
• flexes the cervical spine anteriorly
• looking at the strs

Trapezius

• Large flat triangular muscle
• Extends covering the cervical region & thorax
• Origin
• Medial 3rd of superior nuchal line
• External occipital protuberance
• Nuchal ligament
• Spines of C7 downwards
• Insertion
• spine of the scapula
• Acromion
• Lateral 3rd of clavicle
• Nerve supply
• spinal accessory nerve (same as SCM)
• Actions
• Elevates scapula (superior fibres)
• Retracts scapula (middle fibres)
• Depresses scapula (inferior fibres)
• Rotates scapula (superior & inferior fibres)
• butterfly style of swimming

_____________________________________________________________________

Muscular triangles of the neck

• Vertebral triangle
• Gap between anterior scalene & longus colli
• Bounderies
• apex: C6 anterior tubercle
• base: subclavian artery
• Posterior triangle
• Occipital & Subclavian triangle
• Contents*
• Occipital artery
• Accessory nerve
• External jugular vein
• Subclavian artery
• Anterior triangle

1. Submental triangle

• Borders: digastric (anterior), hyoid bone, mandible

Digastric triangle

• Borders: digastric (anterior), mandible

Carotid triangle

• Borders: digastric (posterior), superior belly of omohyoid
• Contents*
• common carotid artery
• external carotid artery
• internal jugular vein
• vagus nerve

Muscular triangle

• Borders: Hyoid, Sternohyoid (2)
• Contents*
• larynx
• t
  rachea
• thyroid gland