72 terms

Lec 7 Anterior Triangle

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Pharyngeal Apparatus
contribute to the formation of the head and neck. Many abormalities of the head and neck can be traced to anomalies of the pharyngeal apparatus - during transformation to the adult side. Stats to develop in a 4 week old embryo.
What are the contents of the pharyngeal apparatus
pharyngeal arches, pouches, grooves, and membranes
Pharyngeal arches
begin to develop at the lateral wall of the cranial end of the foregut (primordial pharynx) during the 1st part of the 4th week. The arches appear as rounded elevations containing cells of neurocrest origin. Stomodeum is the anterior end of the foregut - site of the future mouth. The pharynx widens cranially at the stomodeum and narrows inferiorly to continue with the esophagus. By the end of the 4th week there are 4th pairs of well developed arches. The 5th and 6th arches never develop completely and are not visible from outside
Stomodeum
site of the future mouth
Oropharyngeal memrane
separates the primordial pharynx and teh foregut from the amniotic cavity. It ruptures at about the 26th day allowing the foregut to communicate with amniotic cavity
What are teh pharyngeal arches separated by?
pharyngeal grooves on the outside and on the inside by pharyngeal pouches
What does each arch contain?
blood vessel, cartilage, muscular component, nerve
mandibular arch
the first pharyngeal arch.
maxillary prominence
prominence on the mandibular arch. gives rise to maxilla
mandibular promence
prominence on the mandibular arch. gives rise to teh mandible
Muscles of the mandibular arch
mascules of mastication, mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini
Nerve of the mandibular arch
CN V
Hyoid arch
2nd pharyngeal arch. major contribution to the formation of hyoid bone
muscles of the hyoid arch
muscles of facial expression, stapedius, stylohyoid and posterior belly of digastric
nerve of hyoid arch
CN VII
3rd pharyngeal arch
contribues to the formation of the hyoid bone
muscle of the 3rd pharyngeal arch
stylopharyngeus
nerve of the 3rd pharyngeal arch
CN IX
4th pharyngeal arch
contributes to the formation of the muscles and cartilages of larynx
nerve of the 4th pharyngeal arch
CN X
pharyngeal membranes
ectoderm of the grooves on the outside of pharyngeal wall make contact with the endoderm of the pouches on the inside to form the pharyngeal membranes. The first membrane gives rise to the tympanic membrane of the ear. All the other membranes disappear
Boundaries of the anterior cervical triangle
1. Anterior midline of the neck
2. inferior border of the mandible
3. anterior border of sternocleidomastoid muscle
4. apex of triangle is at the jugular notch
5. Base of the triangle is the inferior border of teh mandible
What is the roof of the anterior cervical triangle
superficial fascia
platysma
skin
superior boundary of the submandibular (digastic) triangle
inferior border of the mandible
lateral boundary of the submandibular (digastic) triangle
posterior belly of the digastic m
medial boundary of the submandibular (digastric) triangle
anterior belly of the diagastric m
floor of the submandibular (digastric) triangle
forumed by the mylohyoid and hyoglossal musclesq
content of submandibular (digastric) triangle
- submandibular gland
-submandibular ganglion
-submanidublar lymph nodes
-hypoglossal n (CNXII)
-facial a &v
submental triangle is inferiorly bounded by
hyoid bone
submental triangle is laterally bounded by
anterior bellies of digastic m
floor of the submental triangle is
mylohyoid m.
contents of the sumbnetal triangle is
submental lymp nodes, beginning of the anterior gular beins
what is the most imporant triangle
carotid triangle
carotid triangle
lies anterior to the superior part of the SCM. Here the infrahyoid muscles do not overlap the carotid arteries
carotid triangle is anteriorly bounded by
superior belly of omohyoid m
carotid triangle is superiorly bounded by
posterior belly of digastic m
carotid triangle is laterally bounded by
anterior border of sternocleidomastoid m
contents of the carotide trangle
carotid sheath
tubular carotid sheath contains
posterior - vagus nerve
medially - common carotid and internal carotid arteries
laterally - internal jugular vien
anterior boundary of the muscular triangle
anterior midline of the neck
laterally boundary of the musclar triangle
superior belly of the omohyoid m
inferior boundary of the musular triangle
anterior border of the SCM muscle
content of muscular triangle
thyroid and parathyroid glands - located at the C6 vertebbral levle
infrahyoid muscles "strap muscles"
covered by a layer of the deep cerical fascia
-sternothyroid
-sternohyoid
-thyrohoid
-omohyoid (superior and inferior bellies)
blood vessels of the anterior triangle
-common carotid artery
-internal carotid artery
-exernal carotid artery
-subclavian artery
common carotid artery
located within the carotid sheath
terminates at the superior border of the thyroid cartilage (upper part of C5) by dividing into the internal and external carotid arteries
right common carotid artery
a branch of the brachiocephalic trunk
left common carotid artery
a direct ranch of the aorta
carotid occlusion
atherosclerotic thickening of tunica intima - they can obstruct blood flow to the brain and can lead to stroke or transcient ischemic attack
internal carotid artery
provides no branches in the neck
carotid sinus
dilated initial segment of the artery. Innervated by CN IX and X. Acts as a receptor for monitoring arterial blood pressure
external carotid artery terminates in the parotid gland by bifurcating into
superficial temporal, maxillary arteries
While travelling superiorly the external carotid provides the following branches to the structures of the head and neck
superior thyroid, ascending pharyngeal, lingual, facial, occipial, posterior auricular, superficial temporal, maxillary
right subclaivian artery
originates from the brachiochephalic a
left subclavian
originates directly from the aorta
thyrocervical trunch
transverse cervical a, superrascapular a, inferior thyroid a
1st part of the subclavian artery provides teh following branches
vertebral a, internal thoracic a, thyrocervical trunk
2nd part of the subclavian arter gives rise to
costocervical trunk
3rd part of the subclavian artery gives rise to
dorsal scapular a
jugular bulb
dilates structure on the internal jugular v
internal juglar v
terminates by joining with the subclavian vein to form the brachiocephalic vien
anterior jugular v
begins in the submental triangle below the mandible, descends along the anterior midline of the neck, drains into the external jugular vien
veins of the anterior triangle
internal jugular v, anterior jugular v, subclavian v
nerves of the anterior triangle
vagus nerves, ansa cervicalis, hypoglossal nerve (CNXII), sympathetic trunck
vagus nerve
longest cranial nerve. it exits the skull through the jugular foramen and enters the carotid sheath.
The vagus nerve in the neck gives rise to the following main branches
recurrent laryngeal, contribution to the pharyngeal plexus, cardiac branches, superior laryngeal
ansa cervicalis
motor component of the cervical plexus
sympathetic trunk
consist of longtitudinal strands of autonomic fibers, begins at the level of C1, course inferiorly through the neck anterior to the vertebral colum and deep to the carotid sheath, the cervical component of sympathetic trunk contains 3 gaglia
3 ganglia of the cervical component of sympathetic trunk
superior cervical ganglion, middle cervical ganglion, inferior cervical ganglion
superior cerbical ganglion
lasrgest ganglion in the sympathetic chain. located at about the level of c1 and c2
middle cervical ganglion
located at the level of the cricoid cartilage (C6)
inferior cervical ganglion
is sometimes fused with the first thoracic ganglion and is then known as the Stellate Ganglion. It is located at the level of C7 (superior border of the first rib)
congential torticollis reslts from damage of what muscle
sternocleidomastoid