TBL 24: Triangles & Root of the Neck, Thyroid & Parathyroid Glands Flashcards
Distinguish vertebrae C1 & C2 & C3-C7 from one another
C1 - Has both an anterior & posterior arch that are connected by two lateral masses. Each lateral mass contains a transverse foramina and ARTICULAR FACETS on their superior surface. Also, the anterior arch has the FACET FOR DENS
C2 - Has a dens (peg-like structure) that binds to C1/atals at the facet for dens. Has transverse lamina but on the transverse process
C3-C7 = have small bodies but large vertebral foramina. No lateral masses & transverse foramina along the transverse processes
What’s characteristic of C7?
Long spinous process & most prominent in the vertebral column
What’s the importance of the dens & what helps to maintain the junction b/w the dens & the facet for dens?
The dens allows for the head to pivot around the C2 vertebra
This junction is held together by the TRANSVERSE LIGAMENT OF THE ATLAS
Identify the layers of fascia in your neck starting from the epidermis & dermis
Dermis –> Superficial cervical fascia —> Deep cervical fascia —> ALL THE MUSCLES
Where is the platysma located? Function?
Only muscle found in the superficial cervical fascia and exception to the rule
helps to create vertical skin ridges –> convey’s tension/stress
What are the 3 different portions of the deep cervical fascia?
Investing fascia, pretracheal fascia, & prevertebral fascia
What muscles are found in the investing fascia? Where does it continue to?
Sternocleidomastoid & trapezius muscles
From the anterolateral side, it extends from the inferior part of the mandible and the hyoid bone to the clavicle & the sternal manubrium
What are the two parts of the pretracheal fascia? What are their continuations?
Posterior visceral - Covers the thyroid gland, esophagus, & trachea….Continues superiorly to become the buccopharyngeal fascia of the pharynx that attaches to the base of the skull. Continues inferiorly to fuse w/ the fibrous pericardium in the middle mediastinum
Anterior/muscular - Covers the infrahyoid muscles (sternothyroid & sternohyoid)….Goes from the hyoid bone to the sternal manubrium
What does the prevertebral fascia cover? Where does it continue to?
Covers the vertebral column & deep muscles of back
Superiorly –> Attaches to the base of the cranium
Inferiorly —> B/c the ANTERIOR LONGITUDINAL LIGAMENT OF THE SPINE in the thoracic region
What’s the importance of having the three layers of the fascia?
Helps for things in the neck to move around more smoothly when turning the neck or swallowing
What is the carotid sheath? What does it contain?
Tubular fascia that extends from the root of the neck to the base of the cranium. Connected by the alar sheath
Contains the common carotid artery, IJV, & Vagus nerve
What are the 2 potential pathways for an infection to spread from the neck?
- Carotid sheath - B/c it is open superiorly to the cranium & inferiorly to the mediastinum
- Retropharyngeal space - B/c it opens inferiorly into the superior mediastinum
What exits the scalene triangle?
Found in the posterior triangle of the neck & formed by the anterior + middle scalene, this triangle contains
subclavian artery + roots of brachial plexus pass through
What’s the embryonic path & derivation of the thyroid?
Originates as a thyroid bud that grows from the foramen cecum (located near the base of the tongue). The thyroid bud is connected via the thyroglossal duc, and is attached all during its descent until it reaches the correct position (anterior to the 2nd & 3rd ring of the trachea & deep to the sternohyoid & sternothryoid muscles). Then the thyroglossus is obliterated.
Describe the derivation of the parathyroid gland
Found on the posterior surface of the thyroid, this gland arises from two pharyngeal arches (3 & 4 for the inferior and superior portions, respectively)
As the thyroid descends, the two parts latch on and form the parathyroid gland
What is the thyroglobulin? Where is it found?
Storage form of thyroid hormone (iodinated glycoprotein precursor)
Found in the spherical follicles of the thyroid gland
Where are parafollicular cells found? Derivation? Function?
Found b/w follicles in thyroid gland and derived from the ultimobrachial body of the 4th pharyngeal arch
They counteract the parathyroid hormone by SECRETING CALCITONIN —> LOWERS BLOOD CALCIUM LEVELS
What are the two main thyroid hormones? Function/
T3 & T4
They increase oxygen consumption & metabolic rates of body tissues
Function of PTH?
Parathyroid hormone helps to STIMULATE OSTEOCLAST ACTIVITY —> INCREASES BLOOD CALCIUM by taking calcium from bones
