Triangles of the Neck: mm & vasculature Flashcards
Subtriangles of the Anterior Cervical Triangle
- Muscular Triangle
- Carotid Triangle
- Submandibular (digastric) triangle
- Submental (suprahyoid) triangle
Cervical Muscles (2)
Platysma m.
Sternocleidomastoid m.
Platysma m.
O: superficial fascia over part of deltoid and pec. major
I: Mandible; skin and muscles over mandible and angle of mouth
Inn: Facial n. (CN VII)
A: Depresses lower jaw/lip and angle of mouth; wrinkles skin of neck
Sternocleidomastoid m.
O: manubrium and medial 1/3 of clavicle
I: mastoid process and lateral half of superior nuchal line
Inn: Spinal Accessory n. (CN XI)
A: Singly turns face toward opposite side; together flex head, raise thorax
Suprahyoid mm. (4)
Digastric m
Mylohyoid m
Stylohyoid m
Geniohyoid m
Digastric m.
O: ant. belly - digastric fossa of mandible; post. belly - mastoid notch
I: Median raphe and body of hyoid bone
Inn: Ant. belly - n. to mylohyoid from trigeminal n. (CN V); post. belly - facial n. (CN VII)
A: Elevates hyoid and tongue; depresses mandible
Mylohyoid m
O: mylohyoid line of mandible
I: median raphe and body of hyoid bone
Inn: n. to mylohyoid from trigeminal n (CN V)
A. Elevates hyoid and depresses mandible
Stylohyoid m.
O: styloid process
I: Body of Hyoid
Inn: Facial N. (CN VII)
A: Elevates hyoid
Geniohyoid m.
O: Genial tubercle of mandible
I: Body of hyoid
Inn: C1 via hypoglossal n (CN XII)
A: Elevates hyoid and tongue
Infrahyoid mm. (4)
Sternohyoid m
Sternothyroid m
Thyrohyoid m
Omohyoid m (superior belly)
Sternohyoid m
O: manubrium and medial end of clavicle
I: Body of hyoid
Inn: ansa cervicalis
A: depresses hyoid and larynx
Sternothyroid m
O: Manubrium and 1st costal cartilage
I: Oblique line of thyroid cartilage
Inn: ansa cervicalis
A: depresses thyroid cartilage and larynx
Thyrohyoid m
O: oblique line of thyroid cartilage
I: Body and greater horn of hyoid
Inn: C1 via Hypoglossal n. (CN XII)
A: Depresses and retracts hyoid and larynx
Omohyoid m (superior belly)
O: intermediate tendon
I: Body of hyoid
Inn: Ansa cervicalis
A: depresses and retracts hyoid and larynx
Boundaries of the Anterior Cervical Triangle
Superior border - inferior margin of mandible
Inferior border - jugular notch
Medial border - anteriomedian line of the neck
Lateral border - Anterior margin of sternocleidomastoid m.
Anterior border (roof) - platysma m. and investing layer of deep cervical fascia
Branches of the External Carotid Artery (8 in ant. triangle)
Superior Thyroid, Lingual, Facial, Ascending Pharyngeal, Occipital, Post. Auricular, Maxillary, Superficial temporal
Retromandibular v
- Formed by the superficial temporal and maxillary veins
- Anterior branch joins facial v to form common facial v.
- Post. Branch joins post. auricular v to form ext. Jugular v.
External Jugular Vein
- Crosses the sternocleidomastoid obliquely under platysma m.
- Ends in the Subclavian vein or the internal jugular vein
- Recieves the suprascapular v, transverse cervical v, ant. jugular v
Cervical Plexus
formed by the ventral primary rami of C1-C4
Motor branches of Cervical plexus
- Arise from Ansa Cervicalis
1. n. to Omohyoid (superior belly)
2. n. to Sternothyroid
3. n. to Sternohyoid
4. n. to omohyoid (inferior belly)
Ansa Cervicalis
loop formed by superior root of C1 and/or C2 with inferior root of C2/3
Sensory Branches of Cervical Plexus
- Great Auricular Nerve (C2-3)
- Transverse Cervical Nerve (C2-3)
Lymphatic Drainage of the Head
Superficial nodes of the head, superficial cervical nodes all drain into deep cervical nodes
Boundaries of the Posterior Triangle
Anterior: Post. margin of Sternocleidomastoid
Posterior: Ant. margin of Trapezius
Inferior: Middle 1/3 of Clavicle
Roof: Platysma m. and investing layer of deep cervical fascia
Floor: Splenius Capitus, Levator Scapulae, Scalenes
Danger area of the posterior cervical triangle
- Clinically important area located between the trapezius m. and sternocleidomastoid m., inferior to the accessory n.
- Many nerves and vessels close to the skin
Splenius Capitus
O: Spinous processes C7-T3
I: Mastoid process, Superior nuchal line
Inn: Dorsal Primary rami C2-C6
A: Extend neck and head
Levator Scapulae
O: Transverse processes of C1-C4
I: Medial border of scapula
Inn: nerves to levator scapulae (C3/4), dorsal scapular n
A: Elevates scapula
Scalenus Medius
O: Transverse processes of C2-C7
I: Upper surface of first rib
Inn: C5-C8
A: Elevates first rib, bends neck
Scalenus Posterior
O: transverse processes of C4-C6
I: Outer surface of second rib
Inn: C6-C8
A: Elevates second rib, bend neck
Scalenus Anterior
O: Transverse processes of C3-C6
I: Scalene tubercle of first rib
Inn: C5-C8
A: elevates first rib, bend neck
Omohyoid (inferior belly)
O: Medial lip of suprascapular notch; suprascapular ligament
I: Intermediate tendon
Inn: Ansa Cevicalis
A: depresses and retracts hyoid and larynx
Subclavian Artery
Gives rise to the thyrocervical trunk at the medial margin of the ant. scalene muscle
Suprascapular Artery
1st branch from thyrocervical trunk
- passes in front of the ant. scalene m, parallel and inferior to the transverse cervical a.
Transverse Cervical artery
2nd branch from thyrocervical trunk
- passes laterally on ant. scalene m, in front of phrenic n, passies deep to trapezius
Venous supply of the Posterior triangle
- External Jugular
- Transverse cervical
- Suprascapular
Motor branches of the posterior triangle
- Spinal Accessory (CN XI)
- Supraclavicular portion of brachial
- dorsal scapular n.
- long thoracic n.
Sensory branches of the Posterior triangle
- Lesser Occipital n
- Supraclavicular
Congenital Torticollis
- aka Wryneck
- presents a contracted state of cervical mm, especially SCM, which results in twisting of the neck and protrusion of the chin to the side opposite of the lesion/ contracture
- caused by injury to the SCM or avulsion of CN XI at birth
- congenital torticollis - SCM fibrosis resulting in no lengthening during development
Cervical plexus block
- Regional anesthesia may be achieved bby injeting agent into the nerve point of the neck, which lies along the posterior margin of SCM, ~at the superior and middle 1/3 of the neck
Supraclavicular nerve block
- For anesthesia of the upper limb, anesthetic agent may be applied to the supraclavicular portion of the brachial plexus with the main injection site superior to the midpoint of the clavicle
Internal Jugular Vein Puncture
- The Right internal jugular Vein may be punctured or instrumented by aiming at the apex of the triangle between the sternal and clavicular heads of the SCM
