LAB 5: The Neck Flashcards
Cervical vertebrae
- 7
- C1-C7
- foramen transversarium
- bifid spinous process
- atlas- C1 -> no spinous process
- axis- C2 -> dens
hyoid bone
- a small U-shaped bone
- suspended by ligaments and muscles below the mandible and above the thyroid cartilage
- lies at the level C3
- midline of body is extended posterolaterally by long, slander greater horns
- greater horn project posteriorly
- lesser horns project superiorly at the junction of the body and the greater horns
- *suspended from the bottom of the skull (styloid process of the temporal bone) by the stylohyoid ligament
- hyoid provides attachment for 10 muscles that connect it to mandible, the pharynx, the larynx, and the sternum
cartilage of the neck
- tracheal cartilage
- larynx
- unpaired laryngeal cartilage
- paired laryngeal cartilage
tracheal cartilage
- trachea runs down the front of the neck from the larynx into the throat
- wall of tube is comprised of 16-20 C-shaped rings of hyaline cartilage
- joined together by fibroelastic connective tissue
- cartilage rings keep the tube open despite pressure changes during breathing
- rings are open posteriorly where the trachea lies against the esophagus (to smooth muscle)
- tracheal wall is made up of a smooth muscle (trachealis) that permits the esophagus to expand anteriorly as food passes through it and that can decrease the diameter of the tracheal lumen
larynx
- voice box
- leads to trachea (larynx to lungs)
- intricate arrangement of cartilages connected by ligaments and membranes
- lies at level of C4-C6
- part of it serves to keep the airway open by routing food and drink into the esophagus
- plays an important role in voice production
- 3 unpaired and 3 paired laryngeal cartilages:
- unpaired: thyroid, cricoid, epiglottis
- paired: arytenoids, corniculates, cuneiforms
thyroid cartilage
- unpaired
- largest laryngeal cartilage
- lies at the level C4-C5
- composed of 2 rectangular laminae that meet in the midline at an acute angle (thyroid angle) to form the laryngeal prominence (adam’s apple)
- posterior edge of each lamina is prolonged upward as a long superior horn and downward as a shorter inferior horn
- change the sound of the mechanical vibrations -> voice
cricoid cartilage
- unpaired
- shaped like a signet ring
- lies at the level of C6, directly below and partly overlapped by the thyroid cartilage
- the narrow part of the ring is anterior
- back of the ring is expanded upward
- the paired arytenoid cartilages articulate with the posterolateral corners of the cricoid cartilage along its upper margin
epiglottis
- unpaired
- leaf-shaped
- attached by its narrow stem by a strong ligament to the back of the angle of the thyroid cartilage
- projects upward behind and beyond the hyoid bone
- its free upper edge sits behind the tongue
- blocks trachea
- pulled down when swallowing
arytenoids
- paired
- roughly pyramidal in shape
- each articulates inferiorly with the posterolateral corners of the cricoid cartilage
- arytenoids are capable of sliding across and rotating on the cricoid at their articulation -> synovial joint
- the base of the pyramid projects anteriorly as the vocal process -> serves as an attachment for the vocal ligament
- apex of the arytenoid cartilage supports the corniculate cartilage
corniculates
- paired
- each small cartilage sits atop the arytenoid
- serves as an attachment for the upper free margin (aryepiglottic fold) of the quadrangular membrane that extends anteriorly to the epiglottis
cuneiforms
- paired
- tiny, trivial cartilages lie in the aryepiglottic folds
laryngeal membranes
- connects laryngeal cartilages to one another by elastic membranes that permit a certain degree of movement while maintaining overall anatomical integrity
- free margin of the membrane is slightly thickened -> referred to as a ligament
- membranes are covered by squamous epithelium which lines the interior of the larynx -> the covering + ligament is called a fold or cord
- principle membranes, ligaments, folds:
- thyrohyoid membrane
- quadrangular membrane
- aryepiglottic fold
- vestibular fold
- conus elasticus
- vocal fold
thyrohyoid membrane
- runs from the superior border of the thyroid cartilage to the bottom of the hyoid bone
- laryngeal membrane
quadrangular membrane
- runs posteriorly from the lateral sides of the epiglottis to the corniculate and arytenoid cartilages
- laryngeal membrane
aryepiglottic fold
- upper fold of the quadrangular membrane
- superior border of the quadrangular membrane -> forms the aryepiglottic fold
- two folds form an oval opening to the larynx
- as food passes from the tongue into the throat -> the epiglottis is pushed posterior, partially blocking this opening
- prevents food and drink from entering the respiratory tract
- prevents food from getting in the trachea
vestibular fold
- inferior border of the quadrangular membrane is thickened to form the vestibular fold
- fold are also known as the false vocal cords
conus elasticus
- triangular membrane that runs from the internal surface of the back of the thyroid cartilage angle to the superior border of the cricoid and arytenoid cartilages
- certainly the most important of the laryngeal membranes because of its role in speech
vocal fold
- upper fold of the conus elasticus
- superior free margin of the conus elasticus is thickened to form the vocal fold
- folds are known as the true vocal cords
- space between the vocal cords is known as the rima glottidis
nerves of the neck
- muscles of the neck are supplied by spinal or cranial nerves
- thyroid and parathyroid glands are supplied by autonomic fibers
- autonomic fibers- parasympathetic from the cranial nerves and sympathetic from the cervical sympathetic ganglia
spinal nerves of the neck
- spinal nerves from C1-C4 supply muscles in the neck directly or via the cervical plexus
- cutaneous branches from the plexus innervates the skin over the neck, part of the head, the shoulder, and part of the chest
- side note: ventral rami of the lower cervical spinal nerves (C5-C8, together with T1) from the brachial plexus
cervical plexus
- 4 roots of the cervical plexus are the ventral rami of C1-C4
- each root gives off a branch that joins with one from its immediate neighbor creating a loop between them
- there are loops between C1-C2, C2-C3 and C3-C4
- plexus is deep to the internal jugular vein
- nerves from C1 and the C2-C3 loop join together around the internal jugular vein in along loop known as the ansa cervicalis
- provides somatic sensory innervation for cutaneous nerves below
- emerge behind posterior of the sternocleidomastoid
cutaneous nerves
- 3 nerves supply the neck and head from the loop between C2-C3 -> *lesser occipital nerve, *great auricular nerve and *transverse cervical nerve
- *supraclavicular nerve- supplies the shoulder and chest from the loop between C3-C4
- these 4 nerves emerge behind the posterior margin of the sternocleidomastoid muscle
- sensory innervation of skin on neck
- OATS
muscular nerves
- small, unnamed branches come directly from the ventral rami of C1-C4 to supply muscles nearby
- two motor nerves:
- ansa cervicalis
- phrenic nerve
ansa cervicalis: muscular nerves
- provides branches to the infrahyoid muscles (innervates)
- fibers from C1 run with the hypoglossal nerve (CN XII) for a short distance and then descend between the internal jugular vein and internal carotid artery into the beck
- this is where they join fibers from the C2-C3 loop that descend along the back of the internal jugular vein
*phrenic nerve: muscular nerves
- derives from the ventral rami of C3-C5
- supplies motor innervation to the diaphragm
- runs across scalenes muscle
- provides the only motor nerve supply to the abdominal diaphragm
- runs across the scalenus anterior muscle to enter the thorax between the subclavian artery and brachiocephalic vein
- C3, C4, C5 -> keeps the diaphragm alive
cranial nerves in the neck
- 12
- peripheral nerves of the brain
- 6 supply structures in the neck
- trigeminal nerve (V) -> mandibular division -> lingual nerve and mylohyoid nerve
- Facial nerve (VII)
- Glossopharyngeal Nerve (IX)
- Vagus Nerve (X) -> pharyngeal branch, superior laryngeal nerve, internal laryngeal nerve, external laryngeal nerve, recurrent laryngeal nerve
- Accessory Nerve (XI)
- Hypoglossal Nerve (XII)
trigeminal nerve (V)
- cranial nerve of neck
- 3 main divisions
1. Mandibular division- 2 branches that enter the neck - one of these branches if the *lingual nerve- runs across the lateral surface of the hyoglosssus muscle to relay sensation from the anterior two-thirds of the tongue
- the other branch is the *mylohyoid nerve- runs across the hyoglossus and mylohyoid muscles, supplying the latter, and the anterior belly of the digastric muscle
facial nerve (VII)
- cranial nerves in the neck
- runs from beneath the ear to enter the parotid gland in the cheek, where it divides into several branches
- one of these supplies the posterior belly of the digastric muscles and the stylohyoid muscle
- another runs along the lower border of the mandible to innervate the platysma muscle
glossopharyngeal nerve (IX)
- cranial nerves in the neck
- runs from between the internal carotid artery and the internal jugular vein onto the back of the pharynx, relaying sensation from the pharyngeal constrictor muscles
- a branch continues on to supply the posterior one-third of the tongue
- relays taste and sensation
vagus nerve (X)
- cranial nerves in neck
- runs between the internal carotid artery and internal jugular vein throughout the length of the neck
- gives off *pharyngeal branch to a plexus on the back of the pharynx that supplies the pharyngeal constrictors- provides 2 branches to the larynx
- 1st branch- *superior laryngeal nerve- divides into *internal laryngeal nerve- relays sensation from the larynx above the vocal cords (cough, itchy throat) and the *external laryngeal nerve- innervates the cricothyroid
- 2nd branch- *recurrent laryngeal nerve- comes off the the vagus in the thorax on the left curving around under the arch of the aorta to run back up into the neck between the trachea and esophagus (supplies intrinsic laryngeal muscles)
- on the right side it comes off the vagus at the level of the subclavian artery curving around under it to run back up along the trachea
- recurrent laryngeal nerves supply all but one the intrinsic laryngeal muscles
accessory nerves (XI)
- cranial nerves in neck
- runs below the posterior belly of the digastric muscle to supply the sternocleidomastoid
- descends within this muscle for about half its length
- turns to innervated the trapezius
hypoglossal nerve (XII)
- cranial nerves in neck
- runs into the neck with the vagus for a short distance
- runs anteriorly across the external carotid artery and medial to the digastric and onto the hypoglossus muscle -> which it innervates
- also supplies all but one of the tongue muscles
autonomic nerves in the neck
- concerned with the control and/or modificaiton of involuntary activities such as smooth and cardiac muscle contraction and glandular secretion
- 2 divisions:
- parasympathetic
- sympathetic
- both involve 2 neurons in transmission of motor impulses to a target organ
preganglionic neuron
- cell body in the CNS
- synapses with postganglionic neuron
postganglionic neuron
-cell body in autonomic ganglion close to either the spinal cord (sympathetic) or the target organ (parasympathetic)
sympathetic stimulation
- come about via mass activation
- fight or flight
- signals come from T1-L2 vertebral levels
- bc it only runs from T1-L2 -> the sympathetic chain ganglion- highway that extends the signals
- intermediolateral (IML) column, or lateral horn between dorsal and ventral horns
parasympathetic fibers
- may involve individual nerve activation
- rest and digest
- signals come from cranial nerves and S2-S4
- innervation of structures in neck derives from cranial nerves
- only one cranial nerve supplies glands that are in the neck
- Facial nerve (VII)- provides parasympathetic fibers to the submandibular and sublingual salivary glands via a branch (the chorda tympani) that runs along the lingual nerve
- chorda tympani synapses with submandibular ganglion
- parasympathetic preganglionic neurons are so long that the postganglionic is so short its in the body wall
sympathetic chain
- innervates glands in the neck
- conducted largely through a chain of fibers and ganglia located on either side of vertebral column
- preganglionic neurons of the thoracic and lumbar region of the spinal cord send their axons out into the ventral rami of spinal nerves
- some of the axons enter the chain of sympathetic ganglia via myelinated white rami communicantes
- other axons turn up or down the chain to synapse in higher or lower ganglia
- the chain enters the neck deep to subclavian artery and runs upward through the length of the neck on the front of the longus colli and longus capitis muscles -> it runs adjacent to the common carotid and internal carotid arteries, which it supplies
- these postganglionic fibers follow the internal carotid artery into the skull
- there is no sympathetic outflow form the cervical spinal nerves, but sympathetic chain extends into the neck
- from sympathetic ganglia of the neck some postganglionic neurons run to a target organ in the neck or back in the thorax (usually)
- others jump back onto ventral rami of the cervical spinal nerves for distribution to targets in body wall and limbs
- postganglionic neurons travel to the spinal nerves via unmyelinated gray rami communicantes
sympathetic trunk
- usually has 3 ganglia
- fuse at the neck
- contribute to innervation of thyroid gland, arrector pili in body wall, heart etc.
- lowest is the *inferior cervical ganglion- located at or just below the level of C7
- it is commonly fused with the uppermost thoracic ganglion to form the *stellate ganglion
- *middle cervical ganglion lies somewhere between the levels of C4 and C6
- long *superior cervical ganglion stretches from C1 to C2
- at the level of the subclavian artery the sympathetic chain sends out a branch that courses around the artery and upward to region the chain -> this loop is the *ansa subclavia
- chain communicates with the ventral rami of the cervical spinal nerves by thin gray rami communicantes that extend from the ganglia
postganglionic sympathetic axons
- two bundles of postganglionic sympathetic axons that travel back down the neck and into the thorax to innervate the heart ->cervical sympathetic cardiac nerves
- some of these axons arise from the middle cervical ganglion to form the superior cervical cardiac nerve
- most of the axons arise from the stellate ganglion to form the inferior cervical cardiac nerve
- the chain provides innervation to the thyroid gland
- nerves to thyroid gland travel to it from the superior and middle cervical ganglia in company with the superior and inferior thyroid arteries
muscles of the neck
- may attach to one or more of the bony or cartilaginous elements in it or simply pass by on their way between the head and trunk
- some participate in movements of the shoulder (scapula)
- others move the head, the spinal column, or larynx and pharynx
muscles in the neck that that move the scapula
- trapezius
- levator scapulae
muscle in the neck that move the head
- 7
- insert onto the skull
- splenius capitis
- longissimus capitis (part of the erector spinae)
- semispinalis capitis
- rectus capitis anterior
- rectus capitis lateralis
- Longus capitis
- rectus capitis lateralis
spinal nerves
- branch from the spinal cord
- C1-C8, T1-T12, L1-L5, S1-S5
cranial nerves (CN)
- branch directly from brain, not spinal cord
- 12
- CN 1 -CN X11
cricoarytenoid joint
- abduction -> swivels and pull folds open -> forced respiration
- posterior circoarytenoid (abductor)
- adduction -> closes vocal folds -> phonation
- all other intrinsic laryngeal muscles (adductor)
- allows for speech production
- synovial
- adduct and abduct vocal ligaments
- arytenoids and cricoid articulate
- always a little open for breathing
glottis =
rima glottidis (space) + vocal folds (structures)
longus capitis
- origin- transverse processes C3-C6
- insertion- runs upward and medially inserts on occipital bone anterior to the foramen magnum
- flexes neck(head), rotates head to the same side (ipsolaterally)
- innervated by cervical ventral rami of C1-C6
muscles that move the neck: longus colli
- origin- superior oblique- transverse processes C3-C5; inferior arch- bodies of T1-T3
- insertion- superior oblique- anterior arch of atlas (C1); inferior arch- transverse processes of C5-Cs
- action- flexes the neck forward or lateral
- innervated by cervical ventral rami of C1-C7
sternocleidomastoid
- origin- arises from clavicle and by a tendon on from the manubrium of the sternum
- insertion- on mastoid process (by temporal bone) and superior nuchal line of skull
- action- laterally flexes the neck (when both sides are contracted)
- rotates head to the opposite side (contralaterally- contraction of right rotates left) (when one side is contracted)
- innervation- accessory nerve (CN XI) which communicates with spinal nerves C2-C4
- bilaterally- flexes the neck, pulls chin to sternum (if you didnt flex this during sit-ups ur head would fling back)
- unilaterally- laterally flexes neck to same side
- unilaterally- rotates head to opposite side
scalene muscles
- anterior scalenes
- middle scalenes
- posterior scalenes
- flex the neck laterally and raise either the 1st or 2nd rib during forced inspiration
- innervation- cervical ventral rami