Dissection 5-Anterior And Posterior Triangles Of The Neck Flashcards
Cervical Vertebra Features
- small vertebral bodies (except C1)
- relatively large vertebral foramina
- Transverse processes that contain a transverse foramen
Atlas (C1) Features
- Anterior and Posterior arches
- anterior and posterior tubercles
- groove for vertebral artery
- superior articular surface for occipital condyle
Axis (C2) Features
- vertebral body
- dens (odontoid process) extending vertically from the body
- lamina
- spinous process
- superior articular facet for atlas
External Jugular Vein
Formed by the joining of the posterior division of the retro-mandibular vein and the posterior auricular vein
Anterior Jugular Vein
Courses inferiorly near the midline to the suprasternal region where it penetrates the superficial layer of the deep cervical fascia.
-passers deep to the sternocleidomastoid muscle to join the external jugular vein in the root of the neck
Boundaries of the Posterior Triangle of the Neck
Anterior: Posterior border of the sternocleidomastoid muscle
Posterior: the anterior border of the trapezius muscle
Inferior: the middle one-third of the clavicle
Superificial (roof): is the superficial layer of the deep cervical fascia
Deep (floor): muscles of the neck covered by pre vertebral fascia
Anterior Part of the Neck houses the cervical viscera which contains….
Pharynx and esophagus: superior parts of the digestive tract
Larynx and trachea: the superior parts of the respiratory tract
Thyroid gland and parathyroid gland
Boundaries of the visceral part of the neck
Posterior: the cervical vertebra
posterolateral: the scalene muscles
Lateral: the sternocleidomastoid
Anterior: the infrahyoid muscles
Carotid Sheath Contains
Common carotid artery (internal carotid at more superior levels)
Internal jugular vein
Vagus nerve
Boundaries of the Anterior Triangle of the Neck
Anterior: median line of the neck
Posterior: anterior border of the sternocleidomastoid muscle
Superior: the inferior border of the mandible
Superficial (roof): the superficial layer of the deep cervical fascia
Deep (floor): prevertebral fascia
Hyoid Bone
At the angle between the floor of the mouth and the superior end of the neck
Thyrohyoid membrane
Stretching between the thyroid cartilage and hyoid bone
Thyroid Cartilage
In the anterior midline of the neck
4 subdivisions of the anterior triangle (separated by the digastric and omohyoid muscles)
Muscular triangle
Submandibular triangle
Submental triangle
Carotid triangle
Contents of the Muscular Triangle
Infrahyoid muscles
Thyroid gland
Parathyroid gland
Boundaries of the muscular triangle
Superolateral: superior belly of the omohyoid muscle
Inferolateral: anterior border of the sternocleidomastoid muscle
Medial: median plane of the neck
Sternohyoid muscle
Inferiorly attaches to the sternum
Superiorly to the body of the hyoid bone
Depresses the hyoid bone
Superior Belly of the Omohyoid muscle
Lateral to the sternohyoid muscle
Attached to the inferior border of the hyoid bone.
Inferior belly of the omohyoid bone
Attaches to the superior border of the scapula near the suprascapular notch
Depresses the hyoid bone
Sternothyroid Muscle
Inferior attachment is the sternum
Superior attachment is the oblique line of the thyroid cartilage
Depresses the larynx
Thyrohyoid Muscle
Inferior attachment is the oblique line of the thyroid cartilage
Superior attachment is the hyoid bone
elevates the larynx
Ansa Cervicalis
Innervates the sternohyoid, omohyoid and sternothyroid muscles
Identification of things on the trachea in the midline
Laryngeal prominence Cricothryoid ligament Cricoid cartilage 1st Tracheal Ring Isthmus of the thyroid gland
In the Clinic: Tracheotomy
Creation of an opening into the trachea. As an emergency operation, it must be rapidly performed in cases with sudden obstruction of the airway (e.g. Aspiration of a foreign body, edema of the larynx, or paralysis of the vocal fold). The opening is made in the midline between the infrahyoid muscles of the neck
Contents of the Submandibular Triangle
Submandibular gland Facial artery Facial vein Stylohyoid muscle Part of the hypoglossal nerve Lymph nodes
Boundaries of the Submandibular Triangle
Superior-inferior border of the mandible
Anteroinferior-anterior belly of the digastric muscle
Posteroinferior-posterior belly of the digastric muscle
Superficial (roof)-superficial layer of the deep cervical fascia
Deep (floor)-mylohyoid muscle and hypoglossus muscle
Features of the inner aspect of the mandible on the bone
Digastric fossa
Mylohyoid line
Submandibular fossa
Mylohyoid groove
Submandibular Gland
Portion of the gland extends deep to the posterior border of mylohyoid muscle
Facial Vein and Artery in relation to the submandibular gland
Vein Passes superficial to the submandibular gland
Artery courses deep to the gland
Anterior and Posterior Bellies of the digastric muscle
- Anterior attachment of the anterior belly is the digastric fossa of the mandible
- The anterior belly is innervated by the mylohyoid nerve (a branch of the mandibular division of the trigeminal nerve)
- Posterior attachment of the posterior belly is the mastoid process of the temporal bone and is innervated by the facial nerve
- The 2 bellies attach to each other by the intermediate tendon of the digastric muscle.
- action: elevates the hyoid bone and depresses the mandible
Intermediate tendon of the Digastric Muscle
Attached to the body and greater horn of the hyoid bone by a fibrous sling
Stylohyoid muscle
Attaches to the body of the hyoid bone by straddling the intermediate tendon of the digastric muscle
- innervated by the facial nerve
- elevates the hyoid bone
- it usually partially covers the posterior belly of the digastric muscle
Hypoglossal Nerve (CN XII)
- in the submandibular triangle
- enters the triangle by passing deep to the posterior belly of the digastric muscle
- it passes deep to the mylohyoid muscle within the submandibular triangle
Contents of the Submental Triangle
Submental lymph nodes
Boundaries of the Submental Triangle (it’s and unpaired triangle that crosses the midline)
Right and left: anterior bellies of the right and left digastric muscles
Inferior: hyoid bone
Superficial: superficial layer of the deep cervical fascia
Deep: mylohyoid muscle
Mylohyoid muscle
Proximal attachment: on the mylohyoid line of the mandible
Distal: on the hyoid bone and mylohyoid raphe
Action: supports the floor of the oral cavity
Contents of the Carotid Triangle
Common, internal, external carotid arteries
Branches of the external Carotid artery
Part of the hypoglossal nerve
Branches of the vagus nerve (x)
Boundaries of the Carotid Triangle
Inferomedial: superior belly of the omohyoid muscle
Inferolateral: anterior border of the sternocleidomastoid muscle
Superior: posterior belly of the digastric muscle
Accessory Nerve (CN XI)
- crosses the deep surface of the sternocleidomastoid muscle near the base of the skull
- passes through the jugular foramen to exit the skull
Hyoid bone in relationship to the hypoglossal nerve
- hypoglossal nerve travels superiorly to the tip of the greater horn of the hyoid bone
- a muscular branch of the occipital artery crosses superior to the hypoglossal nerve
- the hypoglossal nerve carries axons of spinal nerve C1 that branch off as the nerve to the thyrohyoid muscle
- hypoglossal nerve passes medial to the posterior belly of the digastric muscle and deep to the mylohyoid muscle. The nerves pass superficial to the hypoglossus muscle.
Thyrohyoid membrane
Extends between the thyroid cartilage and the hyoid bone
Internal Branch of the Superior laryngeal nerve
Passes through the thyrohyoid membrane
-supplies sensory fibers to the mucosa of the larynx
External Branch of the superior laryngeal nerve
Joins the internal branch of the superior laryngeal nerve
- innervates the cricothryoid muscle
- also innervates part of the inferior pharyngeal constrictor muscle
Superior Laryngeal Nerve
Might not see it
Internal Jugular Vein
Located lateral to the common carotid or internal carotid artery in the carotid sheath
Tributaries: common facial vein, superior thyroid vein, middle thyroid vein
External Carotid Artery
-passes on the medial side of the posterior belly of the digastric muscle
Branches of the external Carotid artery
- Superior Thyroid artery; arises from the anterior surface of the external Carotid artery at the level of the superior horn of the thyroid cartilage. The superior thyroid artery descends to the superior pole of the lobe of the thyroid gland. The superior laryngeal artery is a branch of the superior thyroid artery, which pierces the thryohyoid membrane together with the internal branch of the superior laryngeal nerve
- lingual artery: arises from the anterior surface of the external Carotid artery at the level of the greater horn of the you’d bone. It passes deeply into the muscles of the tongue
- facial artery: arises from the anterior surface of the external carotid artery immediately superior to the lingual artery. The facial artery crosses the inferior border of the mandible to enter the face. In 20% of cases, the lingual and facial arteries arise from a common trunk
Branches of the facial artery
- Occipital artery: arises from the posterior surface of the external Carotid artery and supplies part of the scalp
- Posterior auricular artery: arises from the posterior surface of the external Carotid artery and passes posterior to the ear to supply part of the scalp
- ascending pharyngeal artery: the 6th branch of the ext. carotid artery. It branches from the medial surface of the external carotid artery
Carotid Sinus
At the bifurcation of the common carotid artery
- dilation of the origin of the internal carotid artery
- walls contain pressoreceptors that monitor blood pressure
- innervated by the glossopharyngeal nerve (IX) and the vagus nerve (X)
Carotid Body
Small mass of tissue located on the medial aspect of the carotid bifurcation
- monitors changes in oxygen and carbon dioxide concentrations in the blood
- innervated by CN IX and X
Vagus Nerve
Lies between and Posterior to vessels in the carotid sheath
