Lab 1 - Posterior Cervical Triangle Flashcards
In anatomical terms, state the relative position of the angle of the mandible with respect to the mastoid process.
The angle of the mandible is situated inferior, medial, and ventral to the mastoid process.
How would the relationship between structures change if the cadaver were turned into the prone position?
The relationship of any two structures does not change with the orientation of the body, since relationships are always defined as they exist in the anatomical position.
List cartilaginous structures in the neck that can be palpated through the skin.
Thyroid cartilage, cricoid cartilage, tracheal cartilages.
The laryngeal prominence is a feature of which of the skeletal components of the larynx?
It is a median projection from the anterior surface of the thyroid cartilage and is situated at the superior end of the junction of the two laminae of the thyroid cartilage.
In what layer of the neck is the platysma muscle located?
Tela subcutanea
What is another term for tela subcutanea?
Superficial fascia
What layer envelops the sternocleidomastoid muscle?
Investing cervical fascia.
From what structure does the platysma muscle take origin?
The tela subcutanea overlying the upper part of the pectoralis major muscle.
Where does the platysma muscle insert?
The inferior border of the mandible and into the corner of the mouth.
How does the platysma muscle receive motor innervation?
Through the cervical branch of the facial nerve, which enters the deep surface of the muscle below the angle of the mandible.
How is the facial nerve classified?
The facial nerve is a cranial nerve; specifically, it is the seventh in the series and may be designated by its name or roman numeral (VII).
How is the platysma muscle related to the investing fascia of the neck?
The platysma is superficial to the cervical investing fascia.
How is the external jugular vein related to the platysma muscle, and how are these two structures related to the investing fascia of the neck?
In the highest part of the neck the external jugular vein lies posterolateral to the platysma. Somewhat lower, where they are in contact, the vein is deep to the muscle; here the vessel is superficial to the investing fascia, but low in the neck the fascia is penetrated by the vein, near its junction with the subclavian vein.
How does the external jugular vein typically begin?
By the junction of the posterior auricular vein with the posterior division (branch) of the retromandibular vein.
What does the accessory nerve supply?
The accessory nerve provides motor innervation for the sternocleidomastoid and trapezius muscles.
What is the location of cell bodies of nerve fibers in the accessory nerve?
In the ventral gray column of the upper cervical segments of the spinal cord.
Where does the accessory nerve arise?
The accessory nerve arises from rootlets attached to the side of the upper segments of the spinal cord. Because it usually lacks connections with dorsal or ventral roots at these levels, this nerve may be thought of as an “accessory” spinal nerve. Nevertheless, the accessory is classified as a cranial nerve (XI). The course of this nerve takes it into the cranial cavity (by passing through the foramen magnum), where some nerve filaments arising with the vagus nerve may be added from the brainstem. As it exits the cranial cavity through the jugular foramen, the nerve fibers the accessory nerve acquired from the brainstem are shifted back to the vagus nerve and the accessory nerve proceeds through the neck to innervate the sternocleidomastoid and trapezius muscles.
How do the sternocleidomastoid and trapezius muscles receive afferent and sympathetic innervation?
Through branches of the cervical plexus.
The great auricular, transverse cervical, lesser occipital, and supraclavicular nerves are branches from what structure in the neck?
The cervical plexus, which is formed from the ventral primary rami of the first four cervical spinal nerves.
What structures are innervated by these four branches of the cervical plexus?
These branches of the cervical plexus supply skin in the anterolateral part of the neck. Specifically, the supraclavicular nerves supply the lower part of the neck, the transverse cervical nerve innervates skin of the upper part of the anterior cervical triangle, and the great auricular nerve supplies skin of the upper part of the posterior triangle. The lesser occipital nerve is distributed to skin behind the ear.
Be able to name the types of fibers in nerves encountered in this dissection and give the location of the cells of origin for each fiber type.
Example: the great auricular nerve – (1) afferent fibers from C2 and C3 spinal ganglia; and (2) postganglionic efferent fibers from the superior cervical sympathetic ganglion.
What are the boundaries of the posterior cervical triangle?
The posterior border of the sternocleidomastoid, the anterior border of the trapezius, and the middle third of the clavicle form the anterior, posterior, and inferior boundaries, respectively. This “triangle” is a three-dimensional space bounded superficially by the investing layer of cervical fascia, while the prevertebral fascia and underlying muscles make up its deep limit.
Name the subsidiary triangles contained within the posterior cervical triangle and give the boundaries of each.
There are two: (a) the supraclavicular (omoclavicular or subclavian) triangle, bounded by the clavicle and two muscles – the inferior belly of the omohyoid and part of the sternocleidomastoid; and (b) the occipital triangle, bounded by the remainder of the sternocleidomastoid, the inferior belly of the omohyoid, and the trapezius muscles.
State the origin and insertion of the omohyoid muscle and give any other attachments of this muscle to bone.
The omohyoid is a compound muscle, consisting of superior and inferior bellies connected by an intermediate tendon. The muscle arises from the upper border of the scapula and inserts into the hyoid bone. Although not a true muscle attachment, a fascial sling fastens the intermediate tendon of this muscle to the clavicle and changes the direction of pull of the muscle.
