posterior triangle Flashcards
innervation to the back of scalp and back of neck
-dorsal rami of spinal nerves C2-C5
innervation of skin of anterior and lateral aspects of the neck
-ventral rami of C2-C4 via cutaneous branches of the cervical plexus
cutaneous branches of the cervical plexus
- lesser occipital nerve
- greater auricular nerve
- transverse cervical nerve
- supraclavicular nerve
lesser occipital nerve
- C2,C3
- supplies skin over lateral part of occipital region and upper part of medial surface of auricle
greater auricular nerve
- C2,C3
- supplies to skin over angle of the mandible and parotid gland, and lower part of the auricle
transverse cervical nerve
- C2,C3
- anterior and lateral aspects of the neck
Supraclavicular nerve
- C3,C4
- divides into medial, intermediate, and lateral supraclavicular nerves
- supplies skin at base of neck and pectoralis major and deltoid muscles
Platysma
-thin muscle embedded in superficial fascia
Origin: deep fasica that covers pectoralis major and deltoid
Insertion: lower border of body of mandible and angle of mouth
Platysma nerve supply
-cervical branch of the facial nerve (CNVII)
Platysma action
- tenses skin of neck
- depress mandible
- draws down lower lip
what makes the external jugular vein?
union of posterior auricular vein and posterior branch of retromandibular vein
posterior auricular vein
-drains scalp posterior and superior to auricle
retromandibular vein
- union of superficial temporal and maxillary veins
- divides into anterior and posterior branches
- anterior branch joins facial nerve
- posterior branch: makes external jugular vein
tributaries of external jugular vein
- transverse cervical
- suprascalpular
- anterior jugular veins
Anterior jugular vein
- union of several small veins
- drains into external jugular vein
- often joined by jugular venous arch
sternocleidomastoid origin and insertion
origin: anterior surface of manubrium of sternum and superior surface of medial third clavicle
insertion: mastoid process and lateral part of superior nuchal line
sternocleidomastoid nerve supply
- accessory nerve(motor)
- branches fro ventral rami of C2 and C3 spinal nerves(sensory)
sternocleidomastoid divides what?
divides anterolateral part of neck into anterior and posterior triangles
sternocleidomastoid action
-unilateral contraction and bilateral contraction
deep cervical fascia
-consists of connective tissue that supports muscles, vessels, nerves, and viscera of the neck
name the layers of deep cervical fascia
- investing layer
- pretracheal
- prevertebral
- carotid sheath
- retrophayngeal space
investing layer
- most superficially located
- roof over anterior and posterior triangles
- encircles neck like a collar
pretracheal layer
- located in anterior part of the neck
- muscular and visceral part
muscular part of pretracheal layer
-encloses infrahyoid muscles
visceral part of preracheal layer
-encloses thyroid gland, trachea, esophagus, larynx, and pharynx
prevertebral later
- located in posterior part of the neck
- surrounds cervical vertebrae and anterior and posterior vertebral muscles
carotid sheath
- fascial tube extending from base of skull to the root of the neck
- contains common and internal carotid arteries, internal jugular vein, and vagus nerve
retropharyngeal space
- interval between buccopharyngeal fascia and prevertebral fascia
- filled with loose connective tissue
- closed laterally by carotid sheath
- allows mobility of pharynx and esophagus
- extends from base of skull to mediastinum
what is so special about the retropharyngeal space?
-it represents a pathway through which neck infections can spread to the mediastinum
buccopharyngeal space
-pretracheal layer when it is posterior to the pharynx and esophagus
boundaries of the posterior triangle
Anteriorly: posterior border of sternocleidomastoid
Posteriorly: anterior border of trapezius
Inferiorly: middle 1/3 of clavicle
what covers the posterior triangle?
-skin, superficial fascia, platysma, and investing layer of deep cervical fascia
What divides the posterior triangle?
-inferior belly of omohyoid divides posterior triangle into occipital triangle and supraclavicular triangle
scalenus anterior origin and insertion
origin: transverse process of C3 to C6 vertebrae
insertion: superior surface of 1st rib and scalene tubercle
What is anterior to scalenus anterior?
- subclavian vein
- phrenic nerve
- superficial(transverse) cervical artery
- suprascalpular artery
- terminal part of thoracic duct
what is posterior to scalenus anterior?
- brachial plexus
- subclavian artery
scalenus medius
-largest and longest of scalene muscles
Origin: transverse process of C2 to C7 vertebrae
Insertion: superior surface of first rib, between costal tubercle and groove for subclavian artery
Scalenus posterior
- smallest of scalene muscles
- Origin: transverse process of C4 to C6 vertebrae
- Insertion: outer surface of 2nd rib
nerve supply of scalene muscles
-direct musclar branches from ventral rami of cervical spinal nerves
Actions of scalene muscles
- lateral flexion of neck
- accessory muscles for inspiration (elevate first and second ribs in forced inspiration)
omohyoid bellies
-inferior and superior bellies connected by an intermediate tendon
inferior belly of omohyoid
- attaches to superior border of the scapula
- passes anteriorly and superiorly across the lower part of the triangle
- passes deep to sternocleidomastoid and ends in intermediate tendon
superior belly of the omohyoid
- begins at intermediate tendon
- ascends vertically in anterior triangle of the neck
- attaches to body of the hyoid
omohyoid
-angulated course of muscle is maintained by loop of deep cervical fascia that surrounds intermediate tendon and attaches inferiorly to clavicle and first rib
nerve supply to omohyoid
ansa cervicalis(ventral rami of C1 to C3)
Action of omohyoid
depress hyoid bone
arteries in the posterior triangle
subclavian artery(3rd part)
- superficial(transverse) cervical artery
- suprascapular artery
- dorsal scapular artery
- occipital artery
veins in the posterior triangle
- external jugular vein and its tributaries
- subclavian vein(occasionally)
nerves in the posterior triangle
- brachial plexus and branches arising from its roots and trunks
- accessory nerve
- branches of cervical plexus
other contents in the posterior triangle
- some cervical lymph nodes
- inferior belly of the omohyoid muscle
