Anterior & Posterior Triangles of the Cervical Spine

Mylohyoid origin

Mylohyoid line of mandible

Mylohyoid insertion

Hyoid Bone

Mylohyoid innervation

Mandibular nerve (CN V3)

Mylohyoid action

Depresses mandible against resistance when infrahyoid muscles fix or depress hyoid bone

Mylohyoid blood supply

Geniohyoid origin

Inferior mental spine of mandible

Geniohyoid insertion

Hyoid bone

Geniohyoid innervation

Nerve to geniohyoid (C1-C2)

Geniohyoid action

Depresses mandible against resistance when infrahyoid muscles fix or depress hyoid bone

Geniohyoid blood supply

Stylohyoid origin

Styloid process

Stylohyoid insertion

Hyoid Bone

Stylohyoid innervation

Facial nerve (CN XII)

Stylohyoid action

Depresses mandible against resistance when infrahyoid muscles fix or depress hyoid bone

Stylohyoid blood supply

Digastric origin

Anterior belly: digastric fossa of mandible

Posterior belly: mastoid notch of temporal bone

Digastric insertion

hyoid bone

Digastric innervation

Facial and mandibular nerves

Digastric action

Depresses mandible against resistance when infrahyoid muscles fix or depress hyoid bone

Digastric blood supply

Sternohyoid origin

Manubrium of sternum

Sternohyoid insertion

Hyoid bone

Sternohyoid innervation

C1-C3 by a branch of ansa cervicalis

Sternohyoid action

Fixes or depresses hyoid

Sternohyoid blood supply

Omohyoid origin

Scapula

Omohyoid insertion

Hyoid bone

Omohyoid innervation

C1-C3 by a branch of ansa cervicalis

Omohyoid action

Fixes or depresses hyoid

Omohyoid blood supply

Sternothyroid origin

Manubrium of sternum

Sternothyroid insertion

Thyroid cartilage

Sternothyroid innervation

C2 and C3 by a branch of ansa cervicalis

Sternothyroid action

Fixes or depresses hyoid

Sternothyroid blood supply

Thyrohyoid origin

Thyroid cartilage

Thyrohyoid insertion

Hyoid bone

Thyrohyoid innervation

C1 via hypoglossal nerve (CN XII)

Thyrohyoid action

Fixes or depresses hyoid

Thyrohyoid blood supply

Genioglossus proximal attachment

Via a short tendon from superior part of mental spine of mandible

Genioglossus distal attachment

Entire dorsum of tongue; inferiormost and posteriormost fibers attach to body of hyoid bone

Genioglossus innervation

Genioglossus action

Bilateral activity depresses tongue, especially central part, creating a longitudinal furrow; posterior part pulls tongue anteriorly for protrusion; most anterior part retracts apex of protruded tongue; unilateral contraction deviates tongue to contralateral side

Genioglossus blood supply

Hyoglossus proximal attachment

Body and greater horn of hyoid bone

Hyoglossus distal attachment

Inferior aspects of lateral part of tongue

Hyoglossus innervation

Hyoglossus action

Depresses tongue, especially pulling its sides inferiorly; helps shorten (retrude) tongue

Hyoglossus blood supply

Styloglossus proximal attachment

Small, short triangular muscle

Styloglossus distal attachment

Sides of tongue posteriorly, interdigitating wit hyoglossus

Styloglossus innervation

Styloglossus action

Retrudes tongue and curls (elevates) its sides, working with genioglossus to form a central trough during swallowing

Styloglossus blood supply

Palatoglossus proximal attachment

Palatine aponeurosis of soft palate

Palatoglossus distal attachment

Enters posterolateral tongue transversely, blending with intrinsic transverse muscles

Palatoglossus innervation

Palatoglossus action

Capable of elevating posterior tongue or depressing soft palate; most commonly acts to constrict isthmus of fauces

Palatoglossus blood supply

Rectus capitis lateralis superior attachment

Jugular process of occipital bone

Rectus capitis lateralis inferior attachment

Transverse process of atlas (C1 vertebra)

Rectus capitis lateralis innervation

Branches from loop between C1 and C2 spinal nerves

Rectus capitis lateralis action

Flexes head and helps stabilize it

Rectus capitis lateralis blood supply

Rectus capitis anterior superior attachment

Base of cranium, just anterior to occipital condyle

Rectus capitis anterior inferior attachment

Anterior surface of lateral mass of atlas (C1 vertebra)

Rectus capitis anterior innervation

Branches from loop between C1 and C2 spinal nerves

Rectus capitis anterior action

Flex head

Rectus capitis anterior blood supply

Longus capitis superior attachment

Basilar part of occipital bone

Longus capitis inferior attachment

Anterior tubercles of C3-C6 transverse processes

Longus capitis innervation

Anterior rami of C1-C3 spinal nerves

Longus capitis action

Flex head

Longus capitis blood supply

Longus coli superior attachment

Anterior tubercle of C1 vertebra (atlas); bodies of C1-C3 and transverse processes of C3-C6 vertebra

Longus coli inferior attachment

Bodies of C5-T3 vertebrae; transverse processes of C3-C5 vertebrae

Longus coli innervation

Anterior rami of C2-C6 spinal nerves

Longus coli action

Flexes neck with rotation (torsion) to opposite side if acting unilaterally

Longus coli blood supply

Platysma inferior border superior attachment

Inferior border of mandible, skin, and subcutaneous tissues of lower face

Platysma inferior border inferior border

Fascia covering superior parts of pectoralis major and deltoid muscles

Platysma inferior border innervation

Cervical branch of facial nerve (CN VII)

Platysma inferior border action

Draws corners of mouth inferiorly and widens it as in expressions of sadness and fright; draws skin of neck superiorly when teeth are clenched

Platysma inferior border blood supply

Deltoid proximal attachment

Lateral third of clavicle; acromion and spine of scapula

Deltoid distal attachment

Deltoid tuberosity of humerus

Deltoid innervation

Axillary nerve (C5, C6)

Deltoid action

Clavicular (anterior) part: flexes and medially rotates armAcromial (middle) part: abducts armSpinal (posterior) part: extends and laterally rotates arm

Deltoid blood supply

Subclavius

Subclavius

Subclavius innervationn

Subclavius action

Subclavius blood supply

Sternocleidomastoid superior attachment

Lateral surface of mastoid process of temporal bone and lateral half of superior nuchal line

Sternocleidomastoid inferior attachment

Sternal head: anterior surface of manubrium of sternum

Clavicular head: superior surface of medial third of clavicle

Sternocleidomastoid innervation

Spinal accessory nerve (CN XI, motor); C3 and C4 nerves (pain and proprioception)

Sternocleidomastoid action

Unilateral contraction: tilts head to same side (i.e., laterally flexes neck) and rotates it so face is turned superiorly toward opposite side

Bilateral contraction: extends neck at atlantooccipital joints, flexes cervical vertebrae so that chin approaches manubrium, or extends superior cervical vertebrae while flexing inferior vertebrae, so chin is thrust forward with head kept level

With cervical vertebrae fixed, may elevate manubrium and medial ends of clavicles, assisting pump-handle action of deep respiration

Sternocleidomastoid blood supply