Week 4 Flashcards
What is the superior boundary of the neck?
Base of skull & inferior border of mandible
What is the inferior boundary of the neck?
Top of sternum, clavicle, acromion (anterior) & C7 (posterior)
What are the boundaries of the anterior triangle in the neck?
Inferior border of mandible, anterior border of sternocleidomastoid & midline of neck
What are the boundaries of the posterior triangle of the neck?
Posterior border of sternocleidomastoid muscle, middle 3rd of clavicle & anterior border of trapezius
What 3 vessels lie in the sternocleidomastoid region?
- Great auricular nerve
- Transverse cervical nerve
- External jugular vein
What nerves lie in the posterior cervical region (near the trapezius)?
Cutaneous branches of posterior rami cervical spinal nerves
Describe the 2 midline neck compartments?
- VISCERAL compartment: parts of respiratory system, digestive system & endocrine glands
- VERTEBRAL compartment: cervical vertebrae, spinal cord, muscles & cervical nerves
Describe the lateral neck compartments?
2 VASCULAR compartments: blood vessels & nerves (CN X)
Describe the purpose of neck fascia?
- Containment of muscles & viscera
- Slipperiness, allows structures to slide over each other (expansion/contraction, up/down)
- Conduit passage of neurovascular structures
What does the superficial fascia of the neck contain?
- Cervical subcutaneous tissue
- Platysma
Describe the deep fascia of the neck?
- Connective tissue which gives protective & is strong enough to suture
- It has different layers (investing, pretracheal, preverterbal, carotid sheath)
What is the purpose of the superficial neck fascia & what does it contain?
- Continuous with superficial fascia of thorax
- Connects to mandible & facial muscles
- Contains cutaneous nerves, vessels, superficial lymph nodes & fat
What is the purpose of the deep investing neck fascia?
Musculofascial Collar
- Surrounds neck completely except for superficial layer
- Encloses SCM, trapezius & infrahyoid muscles, parotid & submandibular glands
- Pierced by external & anterior jugular veins & nerves including cervical plexus
What does the deep Investing fascia of the neck attach to posteriorly?
(Musculofascial Collar)
Ligamentum nuchae & C7 spinous process, surrounds trapezius
What does the deep Investing fascia of the neck attach to anteriorly?
(Musculofascial Collar)
Hyoid bone, surrounds infrahyoid & SCM
What does the deep Investing fascia of the neck attach to superiorly?
(Musculofascial Collar)
External occipital protuberance & superior nuchal line
What does the deep Investing fascia of the neck attach to inferiorly?
(Musculofascial Collar)
Spine of scapula, acromion, clavicle, manubrium
What does the deep Investing fascia of the neck attach to laterally?
(Musculofascial Collar)
Mastoid process & zygomatic arch
What does the pretracheal deep fascia of the neck surround?
Viscera as visceral part (trachea, oesophagus & thyroid gland)
Where is the pretracheal deep fascia of the neck?
Extends from hyoid bone to upper thoracic cavity (blends with fibrous pericardium & aortic arch)
What is the pretracheal deep fascia of the neck posteriorly called?
Buccopharyngeal fascia (runs from base of skull to thoracic cavity)
What does the pretracheal deep fascia of the neck laterally fuse with?
Carotid sheath (extends to C7)
What does the pretracheal deep fascia of the neck anteriorly separate?
Infrahyoid muscles from the trachea & thyroid glands (muscular part)
What pierces the pretracheal deep fascia of the neck?
Thyroid vessels
What does the prevertebral deep fascia of the neck surround?
Vertebral column (including cervical nerves), pre- & post-vertebral muscles (scalenes, longus colli, longus capitus, deep cervical muscles)
What pierces the prevertebral deep fascia of the neck?
Cutaneous branches of cervical plexus
Where is the prevertebral deep fascia of the neck?
- Fixed to cranial base (superior), blends with endothoracic fascia (inferior), blends with anterior longitudinal ligament at T3/4 (posterior)
- Laterally over 1st rib to surround axillary vessels & brachial plexus as the axillary sheath
How does the prevertebral deep fascia of the neck extend posteriorly?
Along superior nuchal line to external occipital protuberance (eventually to superior mediastinum)
How does the prevertebral deep fascia of the neck extend anteriorly?
Attaches to basilar part of occipital
bone, area of jugular foramen & carotid canal
Where does the prevertebral deep fascia of the neck extend laterally?
Mastoid process
What does the carotid sheath surround?
Major vasculature (CCA, int CA, part ext CA, int JV) & CN X), other nerves, some cervical lymph nodes
Where does the carotid sheath extend to and from?
Runs from foramen of carotid canal to aortic arch
Describe the location of the pretracheal space?
Between investing layer & pretracheal fascia, extends between neck & superior mediastinum
Describe the location of the “true” retropharyngeal space?
Between buccopharyngeal fascia & superficial prevertebral fascia (alar fascia), extends between base of skull & superior mediastinum
Describe the location of the danger (alar) space/fascial space within prevertebral layer?
- Within prevertebral layer (alar fascia & deep prevertebral layer)
- Extends from base of skull through posterior mediastinum to diaphragm
What is the case of fascial spaces in healthy individuals?
Danger (alar) space is indistinguishable for the ‘true’ retropharyngeal space
How can infections from the pharynx spread?
Via the ‘true’ retropharyngeal (e.g. retropharyngeal abscess) & danger (alar) spaces into the posterior mediastinum
What structures are at risk during infection spread from fascial spaces?
Thoracic structures since many of the compartments & spaces extend into thorax
What vertebral level is the hyoid bone located?
C3 in anterior neck
Describe the hyoid bone?
- Suspended by muscles & ligaments
- Connected to mandible, styloid process, thyroid cartilage, manubrium & scapulae
- Doesn’t articulate with skeletal elements in head & neck
What 2 things does the hyoid bone connect?
Connects oral cavity with pharynx posteriorly & larynx inferiorly
What movements does the cervical spine allow for?
Lateral flexion & rotation
What does the ligament nuchae attach to?
External occipital protuberance & foraman magnum to spinous processes of the cervical vertebrae
What is the ligament nuchae continuous with?
Supraspinous ligament
Describe the “atypical” C7 vertebrae?
Non-bifid spinous process is attachment of ligamentum nuchae
What special feature do only the cervical vertebrae have?
Foramen transversarium (vertebral artery)
Describe the “atypical” C1 Atlas vertebrae?
- Anterior & posterior arches
- No body
- Spinous process= tubercle
Describe the main feature of the C2 Axis vertebrae that makes it “atypical”?
It has a DENS
Describe the lateral atlanto-axial joint & pivot joint of the dens?
- Allows rotation of head (side- to-side)
- Assisted by transverse ligament of atlas holding dens in position
Describe the atlanto-occipital joint?
- Allows flexion & extension (nodding)
- Condyloid joint
What is the purpose of the alar ligaments?
- Prevent excessive rotation of head & neck
- Connect dens to occipital condyles
Where in the vertebral column is there no intervertebral disc?
Between C1 & C2
Describe the result of whiplash injurys/hyperextension of the neck?
- Major area of damage for anterior longitudinal ligament
- Vertebrae can also become dislocated &/or fractured
What are the surface anatomy landmarks for the C3/4 spinal level?
- Bifurcation of common carotid artery
- Top of thyroid cartilage of larynx (palpable)
- Hyoid bone
What are the surface anatomy landmarks for the C6 spinal level?
- Lower border of pharynx & larynx (cricoid cartilage palpable)
- Upper border of oesophagus & trachea
Where is the apex of lung & cervical portion of parietal pleura located?
In the NECK NOT THORAX!
What are the 4 triangular subdivisions of the anterior triangle?
- Submandibular
- Submental
- Carotid
- Muscular
What does the submandibular (digastric) division of the anterior triangle contain?
- Submandibular gland
- Lymph nodes
- (parts of) CN XII
- Mylohyoid nerve
- (parts of) Facial artery & vein
What does the submental division of the anterior triangle contain?
- Submental lymph
- Small veins
What does the carotid division of the anterior triangle contain?
- Thyroid gland
- Larynx
- Pharynx
- Carotid sheath (& its contents)
- Branches of cervical plexus
- Superior root of the ansa cervicalis
- Deep cervical lymph nodes & (parts of) CN XI & XII
What does the muscular (omotracheal) division of the anterior triangle contain?
- Sternohyoid muscle
- Sternothryoid muscle
- Thyroid gland
- Parathyroid gland
What are the 4 suprahyoid muscles?
- Mylohyoid
- Digastric
- Stylohyoid
- Geniohyoid
What are the 4 infrahyoid muscles?
- Sternohyoid
- Omohyoid
- Thyrohyoid
- Sternothyroid
What is the location & attachments of the mylohyoid muscle (suprahyoid)?
From mylohyoid line on mandible, inserts into body of hyoid & fibres of opposite mylohyoid
What are the actions of the mylohyoid muscle?
- Elevates the hyoid & the floor of the mouth
- Supports floor of mouth
What is the location & attachments of the digastric muscle (suprahyoid)?
- Anterior belly from digastric fossa on lower medial aspect of mandible
- Posterior belly from mastoid notch on medial side of mastoid process
- Both insert at attachment of their intermediate tendon at hyoid
What are the actions of the digastric muscle?
- Anterior belly raises hyoid & opens mouth by lowering mandible
- Posterior belly elevates & retracts hyoid bone
What is the innervation of the mylohyoid muscle?
CN V3 inferior alveolar branch
What is the innervation of the digastric muscle?
- Anterior belly: nerve to mylohyoid (CN V3)
- Posterior belly: digastric branch of
CN VII
What is the location & attachments of the stylohyoid muscle (suprahyoid)?
From the styloid process & inserts into body of hyoid (laterally)
What are the actions of the Stylohyoid muscle?
Pulls hyoid bone upward (posterosuperior)
What is the innervation of the Stylohyoid muscle?
CN VII (facial)
What is the location & attachments of the Geniohyoid muscle (suprahyoid)?
From the mandible (mental spine) & inserts at body of hyoid (located superior to mylohyoid)
What are the actions of the Geniohyoid muscle?
- Fixed mandible: elevates & pulls hyoid forward
- Fixed hyoid: pulls mandible downward & inward
What is the innervation of the Geniohyoid muscle?
Anterior ramus of C1 (travels with CN XII)
What is the location & attachments of the Sternohyoid muscle (infrahyoid)?
From the posterior surface of sternoclavicular joint & manubrium, inserts into body of hyoid medially
What are the actions of the Sternohyoid muscle?
Depresses hyoid after elevation during swallowing
What is the location & attachment of the Omohyoid muscle (infrahyoid)?
- Superior belly from its intermediate tendon & inserts into body of hyoid laterally (has superior & inferior bellies)
- Tendon attaches to clavicle with fascial sling
What are the actions of the Omohyoid muscle?
Depresses & fixes the hyoid
What is the location & attachment of the Thyrohyoid muscle (infrahyoid)?
From oblique line on thyroid cartilage, inserts into greater horn & adjacent body of hyoid
What are the actions of the Thyrohyoid muscle?
- Depresses the hyoid
- Raise larynx when hyoid is fixed
What is the location & attachment of the Sternothyroid muscle (infrahyoid)?
From posterior surface of manubrium, inserts into oblique line on thyroid cartilage
What are the actions of the Sternothyroid muscle?
Draws the larynx downward
What is the innervation of the Sternohyoid, Omohyoid & Sternothyroid muscles?
Anterior rami of C1-C3 (via the ansa cervicalis)
What is the innervation of the Thyrohyoid muscle?
Anterior rami of C1, fibres run with CN XII
Where is the thyroid gland located?
- Within visceral compartment of neck
- From thyroid cartilage to 5th tracheal ring
What is the thyroid gland composed of?
- 2 lateral lobes (right & left)
- Midline isthmus (level of 3rd tracheal ring)
- Midline pyramidal lobe (remnant of thyroglossal duct)
What are the 2 arterial supplies of the thyroid gland?
- Superior thyroid artery (1st branch of external CA)
2. Inferior thyroid artery (off thyrocervical trunk from subclavian)
What is the venous drainage of the thyroid gland?
- Superior thyroid vein (into IJV)
- Middle thyroid vein (into IJV)
- Inferior thyroid vein (into bracheocephalic)
What are the parathyroid glands?
2 pairs (superior & inferior) of small glands on posterior surface of thyroid, position varies
Describe the vascular supply of the parathyroid glands?
- ARTERY: Inferior thyroid arteries (off thyrocervical trunk from subclavian)
- VEIN: thyroid venous plexus
What is the innervation of the thyroid & parathyroid glands?
Thyroid branches from the cervical (sympathetic) ganglia
What nerves lie close to the thyroid & parathyroid glands & are commonly injured during neck surgery?
Recurrent laryngeal nerves (from CN X)
What makes up the roof of the posterior triangle in the neck?
Deep Investing fascia surrounding SCM & trapezius (CN XI)
What makes up the floor of the posterior triangle in the neck?
Prevertebral fascia surrounding splenius capitus, levator scapulae & posterior, middle, anterior scalene muscles (cervical nerves)
What is the location & attachment of the Sternocleidomastoid muscle (SCM)?
- Sternal head from
manubrium of sternum & inserts lateral 1/2 of superior nuchal line - Clavicular head from medial 3rd of clavicle & inserts into lateral surface of mastoid process
What are the actions of the Sternocleidomastoid muscle?
- Draws head forward (both SCMs)
- Tilts head toward ipsilateral shoulder while turning face contralaterally (1 SCM)
What is the innervation of the Sternocleidomastoid & Trapezius muscle?
Spinal accessory nerve (CN XI)
What is the location & attachment of the Trapezius muscle?
From superior nuchal line, external occipital protuberance, ligamentum nuchae & spinous processes (C7-T12), inserts into lateral 3rd of clavicle,acromion & spine of scapula
What are the actions of the Trapezius muscle?
- Assists in rotating scapula during abduction of humerus
- Upper fibres elevate
- Middle fibres adduct
- Lower depress scapula
What is the location & attachment of the Levator Scapulae muscle?
From C1-C4 (transverse processes), inserts into scapula (upper medial border)
What are the actions of the Levator Scapulae muscle?
Elevates scapula
What is the innervation of the Levator Scapulae muscle?
C3, C4, & dorsal scapular nerve (C4, C5)
What is the location & attachment of the Anterior Scalene muscle?
From C3-C6 (anterior tubercle of transverse processes), inserts into upper surface of rib 1 & scalene tubercle
What is the location & attachment of the Middle Scalene muscle?
From C4-C7 (transverse processes), inserts into upper surface of rib 1, posterior to groove for SCA
What are the actions of the Anterior & Middle Scalene muscles?
Elevates 1st rib
What is the innervation of the Anterior & Middle Scalene muscles?
Anterior rami of C4-C7 (both anterior & middle), C3 (also for anterior)
What makes up the cervical plexus?
Anterior rami of C1, C2-C4
What are the muscular branches of the cervical plexus?
- Phrenic nerve (C3, C4, C5)
- Ansa cervicalis (C1, C2, C3) branches to prevertebral & vertebral muscles
What are the cutaneous branches of the cervical plexus?
- C2: lesser occipital nerves
- C2, C3: great auricular & transverse cervical nerves
- C3, C4: supraclavicular nerves
What do the superior & inferior roots of the ansa cervicalis (anterior rami of C1-C3) innervate?
Infrahyoid muscles
What does the external jugular vein drain into?
Subclavian vein
What does the anterior jugular vein drain into?
External jugular vein
What is the definition of learning & memory?
Mechanism by which past experience alters present experiences or behaviours
What is termed engrams?
Link between memory’s & remembering is presumed biochemical in nature
Where do we currently think engrams are located?
All over the brain, but in places related to processing the learning (amygdala for fearful memories etc)
What is associative learning?
- As cells fire simultaneously they increase the synaptic associations
- Results in networks of cells which are synaptically linked
Who pioneered habituation & sensitisation?
Eric Kandel (Columbia) using Aplysia californica creature
What is habituation?
Decrease in response (& NT release ) with repeated stimulus
What is sensitisation?
Increase in response with repeated stimulation, mediated by interneuron
What does repeated Siphon stroke cause?
Habituation as the sensory neuron EPSP reduces
What does concurrent tail stimulation cause & why?
Sensitisation because it causes release of 5HT onto pre-synaptic membrane of siphon skin sensory neurons from interneurons. This prolongs the NT release & causes sensitisation
What do long term synaptic changes require?
Genetic involvement
What was long term potentiation (LTP) 1st shown in?
Rabbit hippocampus (1970s)
What prevents “whole brain potentiation”?
Reverse effect- habituation
What is long term depression (LTD) initiated by?
Slower train of stimulatory impulses over a longer period
What effect can long term depression (LTD) have on long term potentiation (LTP)?
LTD can modulate LTP or even reverse it
Describe what a short term memory is?
- Brief memory (sec) from external stimulus/long term memory
- Easily displaced by another stimulus
- Turns into working memory by a) repetition in phonic loop (temporal extension) b) chunking, which links familiar chunks together to extend the size
What is the most commonly used clinical test for short term memory chunks?
Digit span (read & repeat increasing series of numbers, usually 6-7norm)
Describe what working memory is?
- Maintenance & integration of info in active state for a brief time in order to achieve short term task/goal
- Mix of short &/or retrieved long term memory
How are short term & working memory linked?
Short term memory only lasts a few secs, it must be repeatedly re-activated, its reactivation & subsequent duration is working memory (this is known as an executive function)
What happens to working memory when the task is over?
- Encoded into long term memory
2. Left to lapse
How can long term memory be formed directly from sensory input?
Under control of executive functions (pre-frontal cortex)
What can long term memory be sub-divided into?
- Declarative memory
2. Non-declarative memory
What is long term memory?
Acquisition & retrieval of information over long periods
Describe the different parts of the Declarative/explicit long term memory?
- Conscious
- Semantics (language/facts)
- Episodic (events/experiences)
- Medial temporal lobe structures/association areas
Describe the different parts of the Non-declarative/implicit long term memory?
- Not requiring conscious effort to from or access
- Procedural (habits & skills)
- Associative learning (classical conditioning, emotional responses)
- Priming (habituation / sensitisation)
Describe the 4 parts of the process of learning (storing memory)?
- Encoding (memory creation)
- Storage (persistence of memory traces)
- Retrieval (memory recovery)
- Consolidation (strengthening of memory traces)
Describe the 3 parts of memory formation?
- Series of events are encoded by hippocampus & reference is made to their memory location- hippocampal index
- If this info is recalled prior to consolidation, the hippocampus performs the retrieval from its index of the events
- After consolidation of the memory retrieval can be initiated directly from the sensory cortices
What is plasticity in long term memory used for clinically?
- Counselling for post traumatic stress disorder
- Patients asked to re-live events leading to PTSD & given adrenergic beta receptor blocker (propranolol) which blocks re-consolidation of memory
What is consolidation a result of?
Physical changes at the synapse
What 4 changes in morphology on dendritic spines have been associated with long term potentiation?
- Increase no. of presynaptic vesicles, postsynaptic receptors & ribosomes
- Develop separate synaptic zones divided by wall/cleft in spine
- Single spine may divide in 2
- New dendritic spines appear ~1hr after stimulus that induces LTP
What are the 4 structures involved in non-declarative memory?
- Amygdala
- Caudate nucleus
- Putamen
- Cerebellum
How is the corpus striatum (basal ganglia) involved in non-declarative memory?
Influence memories involving movement & procedural memory e.g. Olympic diving
How is the cerebellum involved in non-declarative memory?
Influences fine motor learning including speech movements
What is dissociated amnesia?
Amnesia occurring without any other deficits
Are declarative, non-declarative, short term & long term memory processed in the same place/by the same mechanisms?
NO
What (other than temporal lobe) can cause anterograde amnesia when damaged?
Anterior/Dorsomedial nuclei of the Thalamus, or in the Mammillary bodies
What does the Dorsomedial nucleus of the thalamus receive?
Input from temporal lobe structures which is then relayed almost exclusively to the frontal cortex (executive function)