lesser occipital nerve - segments - function

C2 supplies skin of neck and scalp posterior to ear

Neck and Prevertebral Flashcards by Blake Miller

neck is divided into _____ and _____ cervical triangles

-these triangles have several ____

anterior and posterior

subtriangles

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what is the division between the anterior and posterior cervical triangle

sternocleidomastoid

anterior boundary of the posterior triangle
posterior boundary of anterior triangle

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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

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which muscles form the floor of the posterior cervical triangle

splenius capitis
levator scapulae
posterior scalene
middle scalene
anterior scalene

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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

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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

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what arteries cross the posterior triangle

transverse cervical

suprascapular artery

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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

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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)

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nerves of the cervical plexus

lesser occipital
great auricular
transverse cervical
supraclavicular nerves
phrenic

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lesser occipital nerve

segments
function

supplies skin of neck and scalp posterior to ear

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great auricular nerve

segments
function

C2, C3

supplies skin of neck and part of ear

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transverse cervical nerve

segments
function

C2, C3

skin over anterior triangle of neck

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supraclavicular nerves

segments
function

C3, C4

skin of the chest over the clavicle and to SC and AC joints

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phrenic nerve

segments
function
identified…

C3-C5
enters thorax to innervate diaphragm
identified lying on anterior scalene

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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

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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

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anterior triangle subdivisions

-how are these divisions defined?

divisions
-submandibular
-submental
-carotid
-muscular
how
-relation to omohyoid and digastric muscles

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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 ```