Neck Flashcards
pharynx
fibromuscular tube that extends from base of the skull to the upper esophageal sphincter (UES)
fibromuscular walls of pharynx formed by what muscles
3 pairs of constrictor muscles: superior, middle and inferior pharyngeal constrictors
upper esophageal sphincter
- formed by lower part of inferior constrictor muscle of pharynx
- prevents reflux of food into airway and prevents air from entering digestive tract
divisions of pharynx
- nasopharynx
- oropharynx
- laryngopharynx
pharynx in relation to larynx
the pharynx is situated posterior to, and communicates with nasal cavities, oral cavity and larynx
the nasopharynx
- communicates with nasal cavities anteriorly by choanae (posterior nasal apertures)
- openings to eustachian tubes located on lateral walls of nasopharyns
- roof of nasopharynx = collection of lymphatic tissues called the pharyngeal tonsil
- inferiorly, the nasopharynx communicates with the oropharynx by the pharyngeal isthmus (can be closed by elevation of the soft palate during swallowing)
the oropharynx
- communicated anteriorly with oral cavity through the oropharyngeal isthmus
- each side of the oropharynx consists of 2 folds of mucous membranes supported by underlying muscles: anterior palatoglossal arch and posterior palatoglossal arch
palatine tonsil
- collection of lymphatic tissue located between the folds on either side
- its medial surface projects into oropharynx and its lateral surface lies against the superior constrictor muscle
the laryngopharynx
- extends from oropharynx to esophagus
- laryngeal inlet opens into the anterior wall of the laryngopharynx
- cavity of laryngopharynx extends anteriorly on each side of the laryngeal inlet forming 2 recesses called the piriform recesses (fossae)
piriform recesses
form channels that direct food from oral cavity to either side of the raised laryngeal inlet, towards the esophagus
vestibular and vocal ligaments of the layrnx
both ligaments enclosed by respective folds (the vestibular fold/false vocal fold, and the vocal fold/true vocal fold)
cricothyroid ligament
originates from upper border of cricoid cartilage and extends superiorly where its free upper margin forms the vocal ligament (true vocal cord)
arytenoid cartilage
- located at back of larynx
- primary function is to close vocal folds when swallowing
- secondary function is to change tension of vocal cords for production of sound
intrinsic muscles of larynx
- control shape of the rima glottidis, and the length and tension of vocal ligaments during breathing, swallowing and phonation
- thyroarytenoid
- cricothyroid
thyroartyenoid
- originates from inferoposterior aspect of the thyroid cartilage
- inserts on anterolateral part of arytenoid cartilage
- acts to relax vocal ligament, producing softer voice
- motor innervation from the recurrent laryngeal nerve (a branch of the vagus nerve)
cricothyroid
- originates from anterolateral aspect of cricoid cartilage attaching to inferior margin of thyroid cartilage
- cricothyroid muscle stretches and tenses the vocal ligaments for production of loud speech and different tones of voice
- motor innervation of external laryngeal nerve, branch of superior laryngeal nerve
thyroid gland
- thyroid gland found deep to musculature of neck
- consists of right and left lateral lobes with an isthmus that connects the lateral lobes and sits on anterior surface of trachea, just inferior to larynx
arterial supply of thyroid gland
thyroid gland supplied by superior thyroid artery (branch of the external carotid artery) and the inferior thyroid artery (branch of the thyrocervical trunk which arises from the subclavian artery)
venous drainage of the thyroid gland
- thyroid drained by paired superior, middle and inferior thyroid veins which form a venous plexus on the anterior surface of the thyroid gland and descends anterior to the trachea
- superior and middle thyroid veins drain into internal jugular vein
- inferior thyroid vein drains into brachiocephalic vein
- inferior thyroid veins may be source of bleeding during tracheostomy
innervation of thyroid gland
- regulated by ANS (both parasympathetic and sympathetic)
- vagus nerve: parasympathetic fibres arise from superior laryngeal nerve and the recurrent laryngeal nerve (both branches of vagus nerve)
- sympathetic trunk: fibres arise from superior, middle and inferior cervical ganglia of the sympathetic trunk
superficial muscles of the neck
- located closest to skin
- allow for gross and fine motor movements of head, face and neck
- sternocleidomastoid
- platysma
sternocleidomastoid
- originates inferiorly on manubrium of the sternum and medial end of clavicle
- inserts superiorly on mastoid process
- 2 muscles together flex the head and neck while individually will tilt head toward the shoulder on the same side rotating the head to turn the fave to the opposite side
- innervated by accessory nerve
platysma
- located in subcutaneous tissue (superficial fascia)
- runs from upper 2 ribs to lower margin of mandible
- when it contracts, tenses skin of neck and is responsible for facial expression
- much of anterior neck is covered by 2 platysma muscles
deep muscle of the neck
- stabilize and facilitate movement of head, neck and spine
- work together with superficial muscles to promote good posture and mobility
- scalenes
- levator spaculae
scalenes
- 3 muscles in deep lateral neck, spanning between transverse processes of cervical vertebrae and ribs 1 and 2
- main functions = flex and rotate neck
- accessory muscles of respiration, elevating ribs during forced inspiration
levator scapulae
- long muscle situated at posterolateral neck
- origin: transverse processes of C1-4
- insertion: scapula
- main function = lift scapula and support vertebral column
- without immobilising effect of levator scapulae, vertebral column would flex and rotate during rotation of scapula
hyoid bone
- U-shaped bone, superior to larynx and is attached by the thyrohyoid membrane
- does not articulate with any other bones, suspended in neck by muscles and ligaments
- 2 groups of muscles in anterior neck grouped according to their relationship to hyoid bone: suprahyoid muscles and infrahyoid muscles
suprahyoid muscles
- 4 pairs of suprahyoid muscles that play a role in swallowing and phonation by elevating hyoid bone and subsequently the larynx
- digastric
- stylohyoid
- mylohyoid
- geniohyoid
digastric
- posterior belly attaches to mastoid process
- anterior belly attaches to mandible
- intermediate tendon (running between anterior and posterior bellies) is held by a fascial sling to the hyoid bone
stylohyoid
- origin: styloid process of temporal bone
- insertion: hyoid bone
mylohyoid
- paired mylohyoid muscles form floor or oral cavity by joining together at midline raphe
- origin: mandible
- insertion: hyoid bone
geniohyoid
- medial and deep to mylohyoid
- originates from mandible
- inserts onto hyoid bone
infrahyoid muscles
- 4 pairs of infrahyoid muscles
- during swallowing and phonation, depress hyoid bone and subsequently the larynx
- sternohyoid
- omohyoid
- thyrohyoid
- sternothyroid
sternohyoid
- origin: manubrium of sternum
- insertion: hyoid bone
omohyoid
- 2 bellies
- inferior belly originates on scapula and inserts on intermediate tendon
- intermediate tendon attached to clavicle by fascial sling
- superior belly originates at intermediate tendon and inserts on hyoid bone
thyrohyoid
- origin: thyroid cartilage
- insertion: hyoid bone
sternothyroid
- origin: manubrium of sternum
- insertion: thyroid cartilage
arterial supply of neck
- common carotid arteries
- subclavian arteries
common carotid arteries
- internal carotid arteries supply brain and eyes
- external carotid arteries supply face and neck
subclavian arteries
- paired arteries originating in thorax
- supply thorax, head, neck and upper limbs
- on left side of body, subclavian artery arises directly from aortic arch
- right subclavian artery arises from brachiocephalic trunk
venous drainage of neck
- internal jugular veins
- subclavian veins
internal jugular veins
- drain blood from brain and superficial regions of face and neck
- at junction of neck and thorax, internal jugular vein joins the subclavian vein from the brachiocephalic vein
subclavian veins
- originate at outer border of 1st rib as continuations of the axillary veins
- subclavian veins are large, central and relatively superficial
- often used to place central venous lines
- important role in lymphatic drainage of head and neck
lymphatic drainage
- lymphatic drainage of head and neck achieved by 2 main groups
- superficial ring of nodes at junction of head and neck (collar nodes)
- 2 vertical groups of lymph nodes in neck (superficial and deep cervical lymph nodes)
superficial ring of nodes
- includes submandibular nodes and submental nodes inferior to chin
superficial cervical nodes
- in vertical group of nodes, superficial cervical nodes found on surface of sternocleidomastoid muscle and are associated with external jugular vein
- deep cervical nodes found deep to sternocleidomastoid and closely related to internal jugular vein
where does the lymphatic drainage of the head and neck go?
- ultimately all lymphatic vessels of head and neck drain into deep cervical nodes
- from deep cervical nodes, lymphatic vessels drain into the jugular trunks
- jugular trunks empty into thoracic duct on left side and right lymphatic duct on right side
cranial nerves of neck
CN IX-XII enter the neck from the skull initially passing deep to posterior digastric muscle
glossopharyngeal nerve
- CN IX
- travels anteriorly to provide sensory innervation to the tongue, pharynx and middle ear
hypoglossal nerve
- CN XII
- curves anteriorly, passing deep to posterior digastric muscle to supply the muscles of the tongue
vagus nerve
- CN X
- located in both superior and posterior mediastinum
- each vagus nerve descends through the neck, passing anterior to the subclavian artery to enter thorax
- right and left vagus nerves give rise to nerves that form the pharyngeal, parasympathetic cardiac, pulmonary and esophageal plexuses
- vagus nerve also branches to form superior laryngeal nerves
- right recurrent laryngeal nerve (branch of right vagus nerve) loops around right subclavian artery and ascends in groove between the esophagus and trachea to travel towards larynx
- left recurrent laryngeal nerve (branch of left vagus nerve) loops beneath the arch of the aorta ligamentum arteriosum and ascends in groove between esophagus and trachea towards larynx
cervical plexus
- all 4 infrahyoid muscles are supplied by the cervical plexus
- thyrohyoid innervated by C1 of hypoglossal nerve
- cervical plexus formed by ventral rami of C1-4 (these branches supply motor innervation to skin of neck and back of scalp)
phrenic nerve
- provides motor and cutaneous innervation to diaphragm
- on the way to the thoracic inlet, each phrenic nerve crosses obliquely over anterior surface of scalene muscles and subclavian arteries
right phrenic nerve
- passes anterior to right subclavian artery
- enters thorax through thoracic inlet
- descends anterior to right lung root
- courses along pericardium of right atrium of heart
- pierces diaphragm at opening of IVC
left phrenic nerve
- passes anterior to left subclavian artery
- enters thorax through thoracic inlet
- crosses aortic arch and left vagus nerve
- courses along pericardium of left ventricle
- pierces and innervated diaphragm
the sympathetic trunk
- after leaving spinal cord, sympathetic nerve fibres form the sympathetic trunk
- structure spans the length of the vertebral column from the base of the skull to the coccyx and is formed by sympathetic nerve fibres and ganglia
superior cervical ganglia
- largest of the 3 ganglia
- superior cervical ganglion, posterior to carotid arteries, anterior to C1-2
middle cervical ganglion
- located anterior to inferior thyroid artery and C6 vertebra
- absent in some individuals
inferior cervical ganglion
- anterior to C7
- usually fused with 1st thoracic ganglion
