Sem 2 - P - Posterior triangle of the neck - Superficial structures, Borders, scalenes, SCM, trapezius, floor, levator scapulae Flashcards
What is the cutaneous muscle located in both anterior and posterior triangles of the neck? What is its attachment and nerve supply?
The platsyma attaches from the fascia above the pectoralis major and the clavicle to the lateral neck and mandible Small slips of the platsyma form up on the face above the mandible
The platsysma is innervated by the facial nerve (CN VII).
Which fascial layer of the neck surrounds the platysma? Which fascial layer surrounds the trapezius and SCM muscles as well as all other fascial compartments of the neck?
Which fascial encloses the internal jugular vein, common carotid arteries, vagus nerves and deep cervical lymph nodes?
The investiging fascia of the neck will lie deep to the superficial fascia of the neck surrounding the platsyma, trapezius and SCM muscles as well as the other (deep) fascial compartments of the neck
The carotid sheath encloses the internal jugular vein, common carotid artery an vagus nerve (and deep cervical lymph nodes)
Which fascial layer is deep to the investing fascia, located posteriorly and surrounds the cervical vertebrae and postural neck muscles?
Which fascia layer is deep to the investing fascia, located anteriorly and surrounds the supra/infrahyoid muscles, thyroid gland, trachea, larynx, oesophagus?
The prevertebral fascia is located deep to the investing fascia, located posteriorly and surrounds the cervical vertebrae and postural neck muscles
The pretracheal fascia is deep to the investing fascia, located anteriorly and surrounds the supra/infrahyoid muscles, thyroid gland, trachea, larynx and oesophagus
We will now discuss different superficial veins of the neck How is the external jugular vein formed?
The superficial temporal vein and the maxillary vein unite anterior to the ear to form the retromandibular vein
The posterior auricular vein (draining the scalp superior and posterior to the ear) will join with the posterior division of the retromandibular vein to form the external jugular vein
Where does the external jugular vein travel? Where does it drain?
What happens to the anterior division of the retromandibular vein?
The external jugular vein runs anterior to the SCM and into the posterior triangle of the neck before it will drain into the subclavian vein
The anterior division of the retromandibular vein joins with the facial vein to form the common facial vein which drains into the internal jugular vein
What muscle does the IJV run beneath? Where does it drain to?
What is the formed in the imaginary midline of the neck that is not always present in the population? Where does it drain?
The internal jugular vein runs deep to the SCM and drains into the brachiocephalic vein The anterior jugular vein is formed in the midline of the neck from superficial veins at the submental region. It travels laterally to go posterior to the SCM and drains into the external jugular vein.
What forms the borders of the posterior triangle?
Anterior border - posterior border of SCM
Posterior border - anterior border of trapezius
Base (inferior border) - clavicle
What is the area known as where the cutaneous nerve branches from the cervical plexus enter the skin?
The area where the cutaneous nerve branches from the cervical plexus enter the skin is known as Erb’s point - it is the middle of the posterior border of the SCM muscle
- What are the 4 nerves and their nerve roots providing cutaneous innervation that arise from the cervical plexus?
- What areas do these 4 nerves supply?
- Lesser occipital (C2) - skin of posterior superolateral neck and posterior to the external ear
- Great auricular (C2,3) - the skin anterior to the ear and the angle of the mandible
- Transverse cervical (C2,3) - skin of the anterolateral aspect of the neck
- Supraclavicular (C3,4) - skin of the supraclavicular fossa & sternoclavicular joint
Which cutaneous nerve supplies the posterior scalp? Which cutaneous nerve supplies the posterior neck?
Posterior scalps - greater occipital nerve (posterior rami C2)
Posterior neck - Posterior rami C3-5
We have now discussed the cutaneous branches of the cervical plexus (lesser occipital, great auricular, transverse cervical, supraclavicular)
Which muscles receive proprioceptive sensory fibres from the cervical plexus? (State nerve roots) State the motor nerve supply to both these muscles?
Sternocleidomastoid receives proprioception from C2,3 anterior rami Trapezius receives proprioception from C3,4 anterior rami
Both these muscles receive motor innervation from the spinal accessory nerve CN XI
There are many motor branches going to the muscles from the cervical plexus Try name all the nerves and the muscles they will innervate from the cervical plexus
- Nerve to geniohyoid - C1
- Nerve to thyrohyoid - C1
- Ansa cervicalis (omohyoid, sternohyoid, sternothyroid) - C1-3
- Phrenic nerve (diaphragm) - C3,4,5
- Direct C3,4 and C5 from dorsal scapular nerve to levator scapulae
- Anterior rami C1-3 (longus capitis)
- Anterior rami C1-6 (longus colli)
- Anterior rami C1,2 (rectus capitis anterior & lateralis)
We have named all the branches from the cervical plexus supplying sensory and motor innervation Restate the motor nerves and their nerve roots
- Nerve to geniohyoid - C1
- Nerve to thyrohyoid - C1
- Ansa cervicalis (omohyoid, sternohyoid, sternothyroid) - C1-3
- Phrenic nerve (diaphragm) - C3,4,5
- Direct C3,4 and C5 from dorsal scapular nerve to levator scapulae
- Anterior rami C1-3 (longus capitis)
- Anterior rami C1-6 (longus colli)
- Anterior rami C1,2 (rectus capitis anterior & lateralis)
CN XI pierces both SCM and trapezius to supply them with both motor innervation –
- Where in the posterior triangle does the spinal accessory nerve appear?
- What bony feature does the external jugular vein appear at?
The spinal accessory nerve appears at the apex of the posterior triangle
The external jugular vein appears at the angle of the mandible from the union of the posterior auricular vein and the posterior division of the retromandibular vein
Where do the roots of the brachial plexus arise? Between which muscles?
What nerve crosses obliquely on the anterior surface of the anterior scalene muscle? State the nerve roots
The roots of the brachial plexus arise from C5-T1 between the anterior and middle scalene muscles The phrenic nerve (C3,4,5) crosses obliquely on the anterior surface of the anterio scalene muscle
Medial to lateral
Anterior scalene, roots of brachial plexus, middle scalene, posterior scalene usually posterior to middle scalene
Scalenes act as secondary muscles of respiration
- What is the attachment of the anterior scalene muscle and what is its nerve supply?
Anterior scalene attaches from the anterior tubercles of transverse processes C3-C6 vertebrae and inserts into the scalene tubercle of the 1st rib
It is innervated by anterior rami of C3-C7
What is the attachment of the middle scalene muscle and what is its nerve supply?
Middle scalene attaches from the posterior tubercles of transverse processes C2-C7 and inserts behind the subclavian artery groove of the 1st rib
It is innervated by anterior rami C4-C7
What is the attachment of the posterior scalene muscles and its nerve supply?
Posterior scalene attaches from the posterior tubercles of transverse processes C4-C6 and inserts onto the second rib It is innervated by anterior rami C5-C7
What is the function of the scalene muscles?
Bilateral contraction - flexion of the neck Unilateral contraction - tilts head to the same side (lateral flexion) They elevate the upper ribs therefore being an accessory muscles of respiration
Where do the subclavian vein, artery and phrenic nerve pass in relation to the scalane muscles?
The subclavian vein courses horizontally anterior to the anterior scalene muscle The phrenic nerve course obliquely on the anterior surface of the anterior scalene muscle The subclavian artery passes horizontally posterior to the anterior scalene muscle
What are the attachments of the sternocleidomastoid?
Sternocleidomastoid attaches from the manubrium of the sternum (sternal head) and the medial clavicle (clavicular head) to the mastoid process and superior nuchal line
SCM is a big muscle so can be used to do a variety of things What is its function during contraction?
Unilateral contraction - will laterally flex the neck and rotate the head to the contralateral side
Bilateral contraction Extension of the head at the atlanto-occipital joint Flexion of the neck when the person is supine
Name an activity where the trapezius would hold the scapula in position
Trapezius holds the scapula in position during weightlifting
What structures form the borders of the posterior triangle of the neck? What structures form the floor of the posterior triangle of the neck?
- Anterior border - posterior border of SCM
- Posterior border - anterior border of trapezius
- Base (inferior border) - clavicle
Floor -
- * Posterior belly of omohyoid
- * Anterior scalene
- * Middle scalene
- * Levator scapulae
- * Splenius capitis
The trapezius and SCM are not in the posterior triangle The musles in the floor are in the posterior triangle What is the nerve supply to the muscles of the floor of the posterior triangle?
- Inferior belly of omohyoid - ansa cervicalis (C1,2,3)
- Anterior scalene - C3-C7 - anterior ramii
- Middle scalene - C4-C7 - anterior rami
- Levator scapulae - Direct C3,4 and C5 from dorsal scapular nerve
- Splenius capitis - Posterior rami C1-C6
What is the attachments, function and nerve supply of the levator scapulae?
- Attachments - posterior tubercles of transverse processes C1-C4 vertebrae to the medial border of the scapular between the scapular angle and above the scapula spine
- Function - elevates the scapula and when shoulder is fixed, will laterally flex the neck to the same side
- Innervation - Direct C3,4 & C5 from dorsal scapular nerve
