Posterior Triangle Of Neck Flashcards
Skin on back of scalp and back of neck is supplied by
Dorsal rami of spinal nerves C2-C5
Dorsal rami of C1 and C6-C8 have no cutaneous distribution
Skin of anterior and lateral aspects of neck is supplied by
Ventral rami of C2-C4 spinal nerves via cutaneous branches of cervical plexus
They emerge from underneath the posterior border of sternocleidomastoid muscle
Cutaneous branches of cervical plexus
Lesser occipital nerve
Great auricular nerve
Transverse cervical nerve
Supraclavicular nerve
Lesser occipital nerve
Where is and what does it supply?
Follows the posterior border of sternocleidomastoid
Supplies skin over lateral part of occipital region and upper part of medial surface of muscle
C2, or C2,C3
Great Auricular Nerve
Ascends superficial to sternocleidomastoid, parallel to external jugular vein
Supplies skin over angle of mandible and parotid gland, and both surfaces of lower part of auricle
C2,C3
Transverse cervical nerve
Run Anteriorly, superficial to sternocleidomastoid
Supplies skin of anterior and lateral aspects of neck
C2, C3
Supraclavicular nerves
Arise from a common trunk, which divides into:
- medial supraclavicular nerve
- intermediate supraclavicular nerve
- lateral supraclavicular nerve
Descend into side of lower neck
Supply skin at base of neck and skin that covers upper part of pec. Major and deltoid muscles
Platysma
LOINA
L- muscle embedded in superficial fascia of neck
O- deep fascia that covers upper parts of pectoralis major and deltoid muscles
I- over side of neck into muscles of lower lip and angle of mouth
N- cervical branch of facial nerve
A- tenses skin of neck, helps depress mandible, draws down lower lip and angle of mouth
What does the external jugular vein divide into?
Posterior auricular vein and retromandibular vein
function of Posterior Auricular vein
Drains scalp posterior and superior to auricle
Dumps into EJV
Function of retromandibular vein
Formed within parotid gland by union of superficial temporal and maxillary veins
At lower end of gland it divides into anterior (joins facial) and posterior branches (joins posterior auricular vein)
Tributaries to EJV
Transverce cervical vein
Suprascapular vein
Anterior jugular veins
Anterior jugular vein
Begins in submental region by union of several small veins
Descends close to anterior midline, just superior to jugular (Supra stern also) notch of sternum, turn laterally and passes posterior (deep) to sternocleidomastoid, then drains into EJV
Right and left jugular veins are usually join midline by jugular venous arch
Sternocleidomastoid
LOIN
L: from sternum/clavicle into anterior and posterior triangles
O: anterior surface of manubrium of sternum AND superior surface of medial third of clavicle
-sternal head and clavicular head
I: two heads join and insert into mastoid process and lateral part of superior nuchal line
N: accessory nerve (motor) and branches from ventral rami of C2 and C3 spinal nerves
Actions of Sternocleidomastoid
Unilateral vs bilateral
Unilateral:
Lateral flexion of head and neck to same side of contracting muscle
Rotation of head and neck to opposite side of contracting muscle
Bilateral:
Draws head forward
Flexion of head and neck against resistance
If head is fixed, accessory muscle of inspiration
Consists of connective tissue that supports muscles, vessels, nerves and viscera of neck
Deep Cervical Fascia
components of Deep Cervical Fascia
Investing Layer
Pretracheal layer
Prevertebral layer
Carotid sheath
Retropharyngeal space
Investing layer of Deep cervical Fascia
More superficially located
Completely encircles neck like a collar, splitting to enclose sternocleidomastoid and trapezius
Roofs over anterior and posterior triangles
Pretracheal layer of Deep Cervical Fascia
Located in anterior part of neck
Has a muscular part
-encloses infrahyoid muscles
and a visceral part
-encloses thyroid gland, trachea, esophagus, larynx, and pharynx
Posterior to pharynx and esophagus it is known as buccopharyngeal fascia
Prevertebral layer of DCF
Located in posterior part of neck
Surrounds cervical vertebrae and anterior and posterior vertebral muscles
Carotid sheath of DCF
Fascial tube extending from base of skull to root of neck
Contains common and internal carotid arteries, internal jugular vein, and vagus nerve
Retropharyngeal space of DCF
Interval between buccopharyngeal fascia (anteriorly) and prevertebral fascia (posteriorly), filled with loose CT
Closed laterally by carotid sheaths
Extends from base of skull (superiorly) to mediastinum (inferiorly)
Its loose CT accommodates movements of pharynx and esophagus while swallowing
Represents a pathway through which neck infections can spread to mediastinum
Boundaries of Posterior Triangle of Neck
Anteriorly: posterior border of sternocleidomastoid
Posteriorly: anterior border of trapezius
Inferiorly: middle 1/3 of clavicle
Covered by skin, superficial fascia, platysma, and investing layer of deep cervical fascia
Floor: splenius capitis, levator scapulae, scalenus posterior, and scalenus medius (all covered by prevertebral layer of deep cervical fascia); small part of scalenus anterior may be present, but it is usually hidden by sternocleidomastoid
What muscle crosses the inferior part of posterior triangle?
Inferior belly of omohyoid
Divides posterior triangle into occipital triangle and supraclavicular triangle
Muscles within posterior triangle
Splenius muscle
Levator scapulae muscle
Scalene muscles (posterior, middle, and anterior)
Omohyoid
(Brachial plexus, although nerves)
Scalenus anterior
OIA
O: transverse process of C3 to C5 vertebra
I: superior surface of 1st rib and scalene tubercle (bony prominence on medial border of 1st rib)
A: holds neck vertical
Scalenus medium
OI
Size and length?
O: transverse processes of C2 to C7
I: superior surface of 1st rib, between costal tubercle and groove for subclavian artery
largest and longest of scalene muscles
Scalenus posterior
OI
Size?
O: transverse processes of C4 to C6 vertebrae
I: outer surface of 2nd rib
Smallest of scalene muscles!
All scalene muscles
NA
N: direct muscular branches from ventral rami of cervical spinal nerves
A: lateral flexion of neck, accessory to muscles of inspiration
Omohyoid
What are the parts of it and how are they connected?
Inferior and superior bellies
Connected by an intermediate tendon
How is the angulated course of the omohyoid muscle maintained?
By loop of deep cervical fascia that surrounds the intermediate tendon
Attached to clavicle and 1st rib
Omohyoid
NA
N: ansa cervicalis (ventral rami of C1 to C3)
A: depresses hyoid bone
Arteries of the PToN
Subclavian artery
Superficial cervical artery
Suprascapular artery
Dorsal scapular artery
Occipital artery
Veins of the PToN
External jugular vein (and its tributaries)
Subclavian vein (occasionally)
Nerves of the PToN
Brachial plexus
Accessory nerve
Branches of cervical plexus
