neck is divided into _____ and _____ cervical triangles
-these triangles have several ____
anterior and posterior
subtriangles
what is the division between the anterior and posterior cervical triangle
sternocleidomastoid
- anterior boundary of the posterior triangle
- posterior boundary of anterior triangle
posterior cervical triangle boundaries
anterior -posterior border of SCM posterior -anterior border of trapezius inferior -middle 1/3 of clavicle apex -insertion of SCM and trapezius on the superior nuchal line roof -deep fascia overlying platysma muscle floor -prevertebral fascia overlying several muscles
which muscles form the floor of the posterior cervical triangle
splenius capitis levator scapulae posterior scalene middle scalene anterior scalene
posterior cervical triangle subdivisions
-division marked by…
subdivisions -occipital triangle -supraclavicular triangle division -marked by inferior belly of omohyoid muscle as it crosses inferior ends of posterior and middle scalenes
occipital triangle
-contains…
occipital artery (near apex)
-branch of external carotid artery
spinal accessory nerve as it crosses muscles of the floor of the posterior triangle between trapezius and SCM
subclavian artery and vein
what arteries cross the posterior triangle
transverse cervical
suprascapular artery
external jugular vein
- where is it located in the posterior triangle
- what does it empty into?
lies in the superficial fascia of the roof of the posterior triangle until it approaches the base
near the base it goes through the deep fascia to empty into the subclavian vein deep to the SCM
what nerves are located in the posterior triangle
ventral rami of brachial plexus
branches of the cervical plexus of nerves (ventral rami of C1-C4)
nerves of the cervical plexus
lesser occipital great auricular transverse cervical supraclavicular nerves phrenic
lesser occipital nerve
- segments
- function
C2
supplies skin of neck and scalp posterior to ear
great auricular nerve
- segments
- function
C2, C3
supplies skin of neck and part of ear
transverse cervical nerve
- segments
- function
C2, C3
skin over anterior triangle of neck
supraclavicular nerves
- segments
- function
C3, C4
skin of the chest over the clavicle and to SC and AC joints
phrenic nerve
- segments
- function
- identified…
C3-C5
enters thorax to innervate diaphragm
identified lying on anterior scalene
anterior cervical triangle (oriented upside down with respect to its base)
-boundaries
medial -anterior median line of neck lateral -anterior border of SCM base -inferior border of mandible apex -jugular (suprasternal) notch of sternum floor -next slide roof -platysma and fascia
what forms the floor of the anterior cervical triangle
pharynx
larynx
thyroid gland
deep to these
-prevertebral fascia covering the prevertebral muscles of the neck
–continuous with deep cervical fascia covering muscular floor of the posterior cervical traingle
anterior triangle subdivisions
-how are these divisions defined?
divisions -submandibular -submental -carotid -muscular how -relation to omohyoid and digastric muscles
submandibular triangle
- location
- floor formed by…
- contains
location -between inferior border of mandible and anterior and posterior bellies of digastric muscle floor -mylohyoid -hyoglossus -middle constrictor contains -submandibular gland -hypoglossal nerve (CN XII)
carotid triangle
- boundaries
- contains
boundaries -superior belly of omohyoid -posterior belly of digastric -anterior border of SCM contains -common carotid artery and branches -internal jugular vein -vagus nerve (CN X) -hypoglossal nerve (CN XII) -ansa cervicalis
vessels and vagus nerve in carotid triangle enclosed by…
fascial sheath, called the carotid sheath, from the base of the skull to the root of the neck
ansa cervicalis
- innervation segments
- location
C1-C3
draped over carotid sheath
what lies behind the carotid sheath on the surface of the prevertebral muscles
- what does this contain
- function
sympathetic chain
contains
-axons from T1-L2 region of spinal cord and travel throughout body
at this point, this nerve plexus is supplying sympathetic innervation to the head and neck
muscular triangle
- boundaries
- contains
boundaries -superior belly of omohyoid -anterior border of SCM -midsagittal plane of neck contains -infrahyoid muscles -thyroid gland -parathyroid gland
submental triangle
-“unpaired” suprahyoid region boundaries
suprahyoid region boundaries
- inferiorly: hyoid bone
- laterally: anterior bellies of right and left digastrics
- floor: mylohyoid
torticollis
- what is it
- result is…
injury to SCM or irritation of spinal accessory nerve
result
-constant contracture of SCM
-consequent flexion of neck to same side and turning to the opposite side
traumatic injury to the spinal accessory nerve
- where is it most likely to occur
- results in
as it crosses posterior triangle
results in
-slumped shoulder
-inability to fully rotate scapula superiorly
inability to fully rotate scapula superiorly
-can be seen as…
inability to “abduct” the arm above the horizontal against resistance
if you had a traumatic injury to the spinal accessory nerve that prevents inability to fully rotate the scapula superiorly, you could still have true abduction of the GH joint
- why
- what would be lacking during the movement?
scapulohumeral rhythm allows for true abduction
would occur without complete scapular rotation (serratus anterior can perform some of the upward rotation)
why isn’t SCM affected when the spinal accessory nerve is injured?
innervated first before the nerve crosses the posterior triangle
longus colli
- can be divided into…
- appearance based on orientation
- arrangement explains…
can be divided into
-superior (upper) oblique
-inferior (lower) oblique
-vertical parts
orientation assumes somewhat of a diamond appearance overlying the bodies of the cervical vertebrae
3-part arrangement explains differing actions
longus colli action
-action is opposed by action of…
longissimus cervicic (cervical component of middle erector spinae muscle)
rectus capitis lateralis action
-why is it questionable?
thought to laterally flex AO joint
-action allowed at this joint is primarily flexion-extension
muscle may be homologous to posterior intertransversarii
-provides lateral stability of AO joint
prevertebral muscles
- what are they
- covered by…
muscles -longus colli (longus cervicis) -longus capatis -rectus capitis anterior -rectus capitis lateralis covered by prevertebral fascia
prevertebral fascia
- continues laterally to…
- infections that are located within this area can reach _____ via ______
continues laterally to cover muscles forming floor of posterior cervical triangle
infections can reach thoracic cavity via the superior thoracic aperture
cervical vertebrae
-unique characteristics
transverse foramen for passage of the vertebral artery (may be diminished or absent in C7
bifid spinous process; C1 only has a posterior arch
spinous process of C7 - vertebra prominens
C1 has no body, only an anterior arch
C2 has the odontoid process (dens); developmentally formed from the body of C1
craniovertebral joints
-names
atlanto-occipital joint
atlanto-axial joint
atlanto-occipital joint
- primary movement allowed
- type of joint
- how is atlas fixed to base of skull
flexion-extension
condylar synovial joint
atlas fixed to base of skull by
-anterior and posterior atlanto-occipital membranes
anterior and posterior atlanto-occipital membranes
-attachment sites
come off outside surfaces of anterior and posterior arches of C1
attach to foramen magnum
tectorial membrane
- continuation of…
- attaches…
continuation of posterior longitudinal ligament
attaches to inside of foramen magnum
Atlanto-axial joint
-fixed by…
series of ligaments that are attached to the dens
transverse ligament of atlas (AA joint)
- what part of the arch?
- encompasses the…
anterior part of arch
encompasses the dens
superior and inferior branch of cruciform ligament (AA joint)
- orientation in relation to transverse ligament of atlas
- where do they insert?
run longitudinally across it inferior -base of dens superior -occipital bone
alar ligaments (paired)
- origin
- where do they travel?
- function
origin
-tip of dens
extend superolaterally to foramen magnum
check side-to-side movement of occiput on atlas
altanto-axial joint
-function
allows rotation of skull and C1 as a unit
what type of joint is the articular surface of the dens against the anterior arch of C1?
synovial joint, pivot type
visceral components of the neck
- lie anterior to…
- what are the structures?
- all structures pass through…
anterior to prevertebral muscles structures -trachea -esophagus -carotid sheath -sympathetic chain and ganglia all pass through superior thoracic aperture
