muscles and triangles of the face Flashcards
root of neck
the thoracocervical region that forms a boundary between the neck and the thorax and is occupied by structures that enter or leave the thoracic cavity.
hyoid bone
- this bone divides the muscles of the neck based on their location to it
- is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage
- bones can be suprahyoid: above the hyoid bone and cause elevation of the hyoid
- bones can be infrahyoid: below the hyoid bone and cause depression
superficial fascia
the subcutaneous layer of the skin in the neck. This thin layer contains the muscles of facial expression, including the platysma muscle in the neck.
platysma
this is a large muscle that leads to tensing the skin of the inferior face and neck
- it is also able to depress the jaw
deep fascial layers
- lies deep to the superficial fascia and platysma muscle.
- This fascia is organised into several layers. These layers act like a shirt collar, supporting the structures and vessels of the neck.
- Pretrachial fascia
- Prevertebral fascia
- Alar fascia
- Carotid sheath
- Prevertebral space
pretrachial fascia
pretracheal fascia has two components which are continuous layers of fascia.
- A cervical layer that ensheathes cervical viscera including the larynx/trachea, pharynx/esophagus, thyroid and parathyroid glands
- a muscular layer which ensheathes the infrahyoid muscles or the suprahyoid depending on where we are in cross section
prevertebral fascia
- surrounds the vertebral column and its associated muscles; scalene muscles, prevertebral muscles, and the deep muscles of the back
alar fascia
a thin fibroareolar membrane separating the (anterior) true retropharyngeal space from the (posterior) danger space.
carotid sheath
contains the carotid artery, jugular vein, vagus nerve (CN 10) , and sympathetic plexus
preverterbral space
a space in the neck. On one side it is bounded by the prevertebral fascia.
- It includes the prevertebral muscles (longus colli and longus capitis), vertebral artery, vertebral vein, scalene muscles, phrenic nerve and part of the brachial plexus.
sternocleidomastoid
this is deep to the platysma
- it originates at the manubrium and clavicle and inserts onto the pastoid process
action:
- bilaterally: it flexes the neck and brings the ear to teh shoulder
- unilaterally: it causes lateral flexion, rotation of the head to the opposite side
innervation: accessory nerve (CN XI)
anterior middle and posterior scalenes
- these originate at the transverse process of the cervical vertebra and they insert onto the 1st and 2nd rib
- action: flexes the neck and elevates the 1st and 2nd ribs during forced inhalation
- innervation: cervical spinal nerves
suprahyoid muscles
- digastric
- geniohyoid
- stylohyoid
- myohyoid
these all insert onto the hypoid
diagastric
- a suprahyoid muscle
- this muscle has two bellies
- action: depresses mandible, elevates hyoid
geniohyoid
- a suprahyoid muscle
action: elevates hyoid
mylohyoid:
- a suprahyoid muscle
- this muscle makes up most of what is below the tongue
action: elevates hyoid, melevates the floor of the mouth
stylohyoid
- a suprahyoid muscle
- this originates at the stylohyoid of the temporal bone
action: elevates the hyoid
infrahyoid muscles
omohyoid
sternohyoid
thyrohyoid
sternothyroid
these all insert onto the hyoid bone
omohyoid
- this is an infrahyoid muscle
action: depresses the hyoid
sternohyoid:
- this is an infrahyoid muscle
origin: sternum (manubrium)
action: depresses hyoid
thyrohyoid
- this is an infrahyoid muscle
origin: thyroid cartilage
action: depresses hyoid, elevates thyroid cartilage
sternothyoid
- this is an infrahyoid muscle
- *this doesn’t insert on the hyoid but it inserts on the thyroid which in turn depresses the thyroid
- origin: posterior surface of the manubrium
- insertion: thyroid cartilage
- action: depresses the thyroid cartilage
what divides the neck into the posterior and the anterior triangles
the sternocleidomastoid
anterior triangle
- this is anterior to the sternocleidomastoid
- this is divided into the submental triangle and the pairs submandibular triangles, carotid triangles, and muscular triangles
posterior triangle
- this is posterior to the sternocleidomastoid and is in the lateral region of the neck
- it is divided into the occipital triangle and the supraclavicular triangle
-its boarders are the sternocleidomastoid, the clavicle and the trapezius
submental triangle
- this is unpaired and in the anterior triangle
- this is below the chin and contains the lymph nodes
submandibular triangle
- this is inferior to the mandible
- this contains the submandibular gland (salivary gland), facial artery, and vein
carotid triange
- this one is important
- this is in the anterior triangle
- this is where we check the pulse
- this colds the common carotid artery, jugular vein, vagus nerve, sympathetic trunk, and hypoglossal nerve
muscular triangle
this is in the anterior triangle
- this contains the infrahyoid muscles, thyroid and parathyroid glands
occipital triangle
this is in the posterior triangle
- this contains the accessory nerve, brachial plexus
supraclavicular triangle
- this is in the posterior triangle
- subclavian artery and vein
what is the “danger space”
the way the fascia are layered can create really easy pathways for an infection in the mouth or oral cavity for example to jump down to the mediastinum
- there are spaces that connect down to the mediastinum so that is super dangerous because an infection in the oral cavity could then begin to affect the heart and potentially infect the heart
common carotid artery
- this is the middle branch of the aortic arch and this is the left common carotid because of the way the aortic arch is slanted to the left side of the body
- the right common carotid will branch out of the brachiocephalic branch off of the aortic arch
- the two common carotid arteries (left and right) will branch into the internal carotid and the external carotid
internal carotid artery
this goes into the skull and eventyally connects with the ccircle of willis
external carotid artery
this is a large vessel that has many branches and supplies the majority of the head o Superior thyroid artery o Lingual artery o Facial artery o Occipital artery o Maxillary artery o Superficial temporal artery
superior thyroid artery
this is a branch of the external carotid and it travels to the thyroid
lingual artery
this is a branch of the external carotid and it goes to the tongue
facial artery
this is a branch of the external carotid and it travels and supplies the face
occipital artery
this is a branch of the external carotid and it travels to the posterior scalp
posterior auncular
this is a branch of the external carotid and this supplies the region behind the ear
maxillary artery
this is a branch of the external carotid and it runs deep and goes to the cheek region
- this supplies the muscles for mastication, teeth, nasal cavity
- this is a large artery
superficial temporal artery
this is a branch of the external carotid and this goes to and supplies the superficial lateral scalp
vertebral artery
this branches off the subclavian arteries
- these run superiorly and travel through the transverse foramen of the cervical vertebra
- these will supply a portion of the circle of willis
subclavian artery
- we have a left and right subclavian
- the left subclavian artery is the most posterior branch off of the aortic arch and these feed into the upper extremities
- the right subclavian artery going to be a branch off of the brachiocephalic trunk due to the left angle of the aortic arch
superior sagittal sinus
It allows blood to drain from the lateral aspects of anterior cerebral hemispheres to the confluence of sinuses
transverse sinus
are two areas beneath the brain which allow blood to drain from the back of the head.
inferior sagittal sinus
an area beneath the brain which allows blood to drain outwards posteriorly from the center of the head.
straight sinus
an unpaired area beneath the brain which allows blood to drain from the inferior center of the head outwards posteriorly. It receives blood from the inferior sagittal sinus
sigmoid sinus
receives blood from the transverse sinuses, which receive blood from the posterior aspect of the skull
internal jugular vein
this drains everything from the dural sinuses within the brain
- this will merge with the subclavian vein to form the brachiocephalic vein
brachiocephalic vein
the internal jugular vein and the subclavian vein merge to form this
- there is one on both sides of the body which is different than the arteries
- the left and right then merge to form the superior vena cava
external jugular vein
drains blood from the superficial structures of the cranium and the deep portions of the face
subclavian vein
this receives blood from the axillary vein and external jugular vein and drains into the brachiocephalic vein
