hyoid bone, superficial neck triangles and scalp Flashcards
what is the hyoid bone?
an isolated **U shaped bone **in the anterior neck at the level of C3
what are the different parts of the hyoid bone?
- body
- 2 greater horns
- 2 lesser horns
what are the 2 groups of hyoid muscles called?
infra-hyoid muscles
**supra hyoid **muscles
they are called this as they are either superior or inferior to the hyoid bone
what are the 4 supra hyoid muscles?
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- mylohyoid muscle (mylo=molar)
- genio hyoid muscle
- digastric muscle
- stylohyoid
what does the mylo-hyoid muscle form?
the floor of the oral cavity
what is the function of the mylohyoid muscle?
- elevates the floor of the mouth
- elevates the hyoid during swallowing
what does the stylohyoid muscle originate from?
- arises from the styloid process of the temporal bone
what are the 4 infra-hyoid muscles?
TOSS
- sternohyoid muscle
- omohyoid muscle (oblique running muscles)
- thyrohyoid muscle
- sternothryoid muscle
what are the 2 divisions of the neck and what are they separated by?
- the** anterior and posterior triangles** of the neck
- separated/ where the point of division is the **sternocleidomastoid muscle **
what does the digastric muscle originate and insert onto?
-O- digastric notch on mastoid process of temporal bon
I- digastric fossa on mandible
what is the anterior triangle of the neck bordered by?
- bordered laterally by the SCM muscle
- medially by the median line of the neck
- bordered superiorly by the body of the mandible (mandible is on top)
what** 4 further smaller triangles **is the anterior triangle divided into?
MDSC
- muscular
- submandibular
- submental
- carotid
what does the mylohyoid muscle originate and insert onto?
-O- mylohyoid line (mandible)
-I - midline raphe and body of hyoid bone
what is the function of the SCM muscle?
- unilateral contraction - flexes neck to same side and rotates head to opposite side
- bilateral contraction -elevates head, flexes neck
what are the origins and insertions of the geniohyoid muscle?
-inferior mental spines on mandible
-I- body of hyoid
what are the borders of the submanibular triangle?
- it is situated inferiorly to the mandible (where the submandibular glands are located)
- bordered** superiorly by the mandible** and** anterior and posterior bellies of the digastric muscle **
what muscle divides the submandibular triangle into the superficial and deep compartments?
- the mylohyoid muscle
what structures are located on the floor of the submandibular triangle?
- mylohyoid muscle
- hyoglossus muscle
what structures are located in the superficial layer of the submandibular triangle?
- submandibular gland
- facial artery and vein mylohyoid nerve
what structures are located in the deep compartment of the submandibular gland?
- hyoglossus muscle
- hyoglossus nerve
where is the submental triangle located?
it is located at the midline of the neck
* ie it is a median triangle
what are the borders of the submental triangle?
- bordered laterally by the 2 anterior bellies of the digastric muscles
- bordered inferiorly by the hyoid bone
what does the submental triangle contain?
- contains small veins that drain into the anterior jugular vein
- submental lymph nodes
what is the function of the submental lymph nodes?
- they drain the floor of the oral cavity, middle lower lip, tip of the tongue
what structures does the muscular triangles contain?
- thyroid gland
- parathyroid gland
- infrahyoid muscles (thyrohyoid,sternohyoid)
what is the floor of the carotid triangle made up of?
- the floor is made up by part of the thyrohyoid muscle (short muscle below hyoid bone)
- hyoglossus muscle (muscle above hyoid bone)
- middle and inferior constrictors of the pharynx
what is the carotid sheath?
- fibrous connective tissue that is part of the deep cervical fascia of the neck
within the carotid sheath in the carotid triangle, what vessels are present?
- common carotid artery (located medially in the sheath)
- internal jugular vein (located laterally)
- vagus nerve (found posteriorly between the 2 vessels)
what does the common carotid artery divide / branch into in the carotid triangle?
- **internal **carotid artery
- **external **carotid artery
how is the posterior traingle of the neck bordered?
- bordered anteriorly by the by the **posterior border of the SCM muscle **
- bordered posteriorly by the anterior border of the **trapezius muscle **
- inferiorly by the **clavicle **
what muscle divides the posterior triangle of the neck into 2 smaller triangles?
- inferior belly of the omohyoid muscle
what are the 2 subdivisions of the posterior triangle of the neck?
- occipital (larger)
- supraclavicular
what borders surround the supraclavicular triangle?
- anteriorly by the** SCM muscle **
- inferiorly **belly of omohyoid muscle *
what structures are found in the supraclavicular triangle?
supraclavicular = above clavicle
- subclavian artery
- transverse cervical artery
- dorsal scapular artery
- external jugular vein
- subclavian vein
what are the borders of the** occipital triangle**?
- bordered anteriorly by the** SCM muscle **
- bordered posteriorly by the trapezius muscle
- inferiorly by the inferior belly of the omohyoid muscle
what** structures **does the occipital triangle contain?
- occipital artery
- transverse cervical artery
- accessory nerve NB runs infront of SCM muscle
what are the 5 layers of the scalp?
acronym = scalp
- S = **skin **
- C=** connective tissue **
- A = aponeurosis- thin tendon uniting the bellies of occipitofrontalis muscle
- L=** loose areola tissue** the hair bearing part of the scalp
- P =pericranium (periosteum) -adheres to the calvaria
what are the 5 layers of the scalp?
acronym = scalp
- S = **skin **
- C=** connective tissue **
- A = aponeurosis- thin tendon uniting the bellies of occipitofrontalis muscle
- L=** loose areola tissue** the hair bearing part of the scalp
- P =pericranium (periosteum) -adheres to the calvaria
what are the 4 supra hyoid muscles?
what does the mylo-hyoid muscle form?
the floor of the oral cavity
what are the surface markings of the accessory nerve (Cranial nerve 11)?
-emerges from upper 1/3 of the posterior border of sternocleidomastoid
-passes deep to the investing layer of the deep cervical fascia
-descends and enters the posterior triangle
what are the contents of the posterior triangle?
-accessory nerve
-cervical plexus
-subclavian artery
-subclavian vein
-apex of lung
-upper trunk of brachial plexus
