Anterior Triangle Flashcards
What are the boundaries of the posterior triangle?
bounded anteriorly by the posterior border of the sternocleidomastoid muscle, posteriorly by the anterior border of the trapezius muscles, and inferiorly by the middle third of the clavicle.
What are the four sub-triangles of the anterior triangle?
the submandibular, submental, carotid and muscular triangles.
What is the platysma innervated by?
the cervical branch of the facial nerve [VII]
What are the boundaries of the carotid triangle?
Anterior boundary- Superior belly of the Omohyoid.
Posterior Boundary- Anterior border of the sternocleidomastoid muscle.
Superior Boundary- Post. belly of the digastric
What is the floor of the carotid triangle composed of?
Thyrohyoid, Middle pharyngeal constrictor, Inferior pharyngeal constrictor
What are the contents of the carotid triangle?
Carotid Sheath with Carotid A., Internal Jugular V., Vagus Nerve, Ansa Cervicalis.
What are the boundaries of the muscular triangle?
Anterior boundary- Median plane of the neck.
Inferior Boundary- Anterior border of the sternocleidomastoid muscle.
Superior Boundary- Superior belly of the Omohyoid.
What is the floor of the muscular triangle composed of?
Thyroid and cricoid cartilages, Middle pharyngeal constrictor, Inferior pharyngeal constrictor.
What are the contents of the muscular triangle?
Neck viscera including thyroid and parathyroid glands; Infrahyoid muscles, terminations of Ansa Cervicalis, Superior thyroid artery, Sup. laryngeal artery, internal and external laryngeal NN., Recurrent laryngeal N.
What are the boundaries of the submental triangle?
Lateral Boundary- Right and LeZ anterior bellies of the Digastrics. Inferior Boundary- Body of the Hyoid. Apex- Symphysis men@.
What is the floor of the submental triangle composed of?
Both Mylohyoids.
What are the contents of the submental triangle?
Ant. Jugular V., lymph nodes.
What are the boundaries of the submandibular triangle?
Anterior Boundary- Ant. belly of the digastric. Posterior Boundary- Post. belly of the digastric. Superior Boundary-Inferior border of mandible.
What is the floor of the submandibular triangle composed of?
Floor- Mylohyoid, Hyoglossus, Middle pharyngeal constrictor
What are the contents of the submandibular triangle?
Contents- Submandibular Gland, Hypoglossal Nerve (CN XII), Nerve to the Mylohyoid, Facial Artery and Vein.
Where do the two heads of the SCM originate from?
one from the upper, anterior surface of the manubrium, the other from the superior medial third of the clavicle
Where do the heads of the SCM insert?
It inserts into the mastoid process and extends along the lateral half of the nuchal line
What is the SCM innervated by?
It is innervated by CN XI (Accessory Nerve) and by anterior rami of C2 and C3
Where does the posterior belly of the digastric m. originate?
The posterior belly arises from the mastoid notch on the medial side of the mastoid process of the temporal bone
Where does the anterior belly of the digastric m. originate?
digastric fossa
the tendon between the two bodies of the digastric m is attached to what?
attached to the body of the hyoid bone (and is the insertion of both)
What are the possible actions of the digastric muscle?
the muscle has multiple actions depending on which bone is fixed: when the mandible is fixed, the digastric muscle raises the hyoid bone; when the hyoid bone is fixed, the digastric muscle opens the mouth by lowering the mandible
What is the innervation to the posterior belly of the digastric m.?
facial nerve [VII]
What is the innervation to the anterior belly of the digastric m.?
the mandibular division [V3] of the trigeminal nerve [V]
What is the investing fascia of the neck attached to posteriorly?
the ligamentum nuchae and
the spinous process of the CVII vertebra
What muscles does the investing fascia split to encircle?
this fascial layer splits as it passes forward to enclose the trapezius muscle, reunites into a single layer as it forms the roof of the posterior triangle, splits again to surround the SCM muscle, and reunites again to join its twin from the other side
Anteriorly, what is the investing fascia anterior to?
the infrahyoid muscles
What are the attachments of the investing fascia?
The investing fascia is attached: superiorly to the external occipital protuberance and the superior nuchal line; laterally to the mastoid process and zygomatic arch; and inferiorly to the spine of the scapula, the acromion, the clavicle, and the manubrium of sternum
What veins pierce the investing fascia?
The external and anterior jugular veins, and the lesser occipital, great auricular, transverse cervical, and supraclavicular nerves, all branches of the cervical plexus, pierce the investing fascia.
What does the prevertebral fascia envelop?
the vertebral column and the muscles associated with it. Muscles in this group include the prevertebral muscles, the anterior, middle, and posterior scalene muscles, and the deep muscles of the back
What is the posterior attachment of the prevertebral fascia?
The prevertebral fascia is attached posteriorly along the length of the ligamentum nuchae, and superiorly forms a continuous circular line attaching to the base of the skull
What are the attachments of the prevertebral fascia?
This circle begins: anteriorly as the fascia attaches to the basilar part of the occipital bone, the area of the jugular foramen, and the carotid canal; continues laterally, aFaching to the mastoid process; and continues posteriorly along the superior nuchal line ending at the external occipital protuberance, where it associates with its partner from the opposite side.
Anteriorly, the prevertebral fascia is attached to the anterior surfaces of the transverse processes and bodies of vertebrae CI to CVII
What does the pretracheal layer of fascia surround?
surround the trachea, esophagus, and thyroid gland (begins anteriorly just posterior to the infra hyoid muscles)
Where does the pretracheal fascia span vertically?
begins superiorly at the hyoid bone and ends inferiorly in the upper thoracic cavity
Posteriorly, the pretracheal layer is referred to as what?
the buccopharyngeal fascia (separates the pharynx and the esophagus from the prevertebral layer)
The buccopharyngeal fascia begins superiorly at the base of the skull and ends inferiorly in the thoracic cavity.
What triangle are the infrahyoid muscles in?
the muscular triangle of the anterior triangle
the “strap muscles.”
What is the sternohyoid innervated by?
ventral rami C1-C3 through the ansa cervicalis
action: It depresses the hyoid bone
Where does the sternohyoid originate?
originating from the posterior aspect of the sternoclavicular joint and adjacent manubrium of the sternum
Where is the origin of the inferior belly of the omohyoid muscle?
the superior border of the scapula, medial to the supra scapular notch in the POSTERIOR TRIANGLE
Does the omohyoid attach to the hyoid bone medial or lateral to the sternohyoid?
just lateral
The intermediate tendon of the omohyoid is attached to what? By what?
the intermediate tendon is attached to the clavicle, near its medial end, by a fascial sling
What does the omohyoid do?
The omohyoid depresses and fixes the hyoid bone