Organization of the Neck Flashcards
What muscle divides the anterior and posterior triangles?
The sternocleidomastoid muscle
What is the nerve supply of the sternocleidomastoid muscle?
The spinal accessory nerve (XI) provides motor output
Ventral rami of C2, C3 for proprioception
What are the actions of the sternocleidomastoid muscle?
Flex at the atlantooccipital joint and flex cervical column. One muscle alone tilts the head towards ipsilateral shoulder and turns face toward the opposite side.
What divides the posterior triangle into two parts? What are those parts?
The inferior belly of the omohyoid muscle divides the posterior triangle into two triangles called the occipital triangle and the subclavian triangle
What is the most important nerve crossing the occipital triangle?
The accessory nerve
What is included in the subclavian triangle?
The subclavian vein and the third part of the subclavian artery
What 5 muscles make up the muscular floor of the posterior triangle?
Splenius capitus, levator scapulae, scalenus posterior, scalenus medius, scalenus anterior
What are the nerves of the posterior triangle?
- Accessory nerve (CN XI)
- Cutaneous branch of the cervical plexus
- Phrenic nerve
- Roots of the brachial plexus
Where does the accessory nerve exit the skull?
Jugular foramen (9, 10, 11 pass through here)
Where does the accessory nerve run respective to the sternocleidomastoid muscle?
It runs either deep to the SCM or through it to supply it
What are the cutaneous branches of the cervical plexus? From which cervical segments do they emerge?
Lesser occipital nerve (C2)
Great auricular nerve (C2 and C3)
Transverse cervical nerve (C2 and C3)
Supraclavicular nerves (C3 and C4)
What is supplied by the lesser occipital nerve (Branch of cervical plexus)?
Ascends on posterior border of SCM and supplies skin on neck and scalp behind the ear
What is supplied by the great auricular nerve (branch of cervical plexus)?
Runs upward across SCM toward the parotid gland w/ ext. jugular vein
Supplies external ear, skin of parotid gland, and area of skin extending from mandible to mastoid process
What is supplied b the transverse cervical nerves (branch of cervical plexus)?
Curves around posterior border of SCM near midpoint
Supplies most of skin of anterior cervical region (sensory of skin of neck)
What is supplied by the supraclavicular nerves?
Emerge from common trunk at posterior border of SCM
-branches distribute as far inferiorly as the sternal angle and second rib and as far laterally and posteriorly as the skin over the spine of scapula
Also supply sternoclavicular joint
On top of which muscle does the phrenic nerve course?
Courses inferiorly on the anterior surface of scalenus anterior muscle
What two arteries cross the phrenic superficially?
Transverse cervical and suprascapular arteries
Between which two muscles do the roots of the brachial plexus emerge?
Appear between the anterior and middle scalene muscles
What 3 arteries are in the posterior triangle?
The third part of the subclavian artery
Branches of the thyrocervical trunk (from first part of subclavian): transverse cervical artery and the suprascapular artery
What are veins in the posterior triangle?
External jugular vein and the subclavian vein
What two veins join to form the external jugular vein?
The posterior auricular vein and the posterior division of the retromandibular vein
What vein does the external jugular vein drain into?
Drains into the subclavian vein
What two muscles subdivide the anterior triangle?
The digastric muscle and the omohyoid muscles
What is the nerve supply of the digastric muscle? What are its actions?
The mandibular division of the trigeminal (V) nerve supplies anterior belly Facial nerve (VII) supplies the posterior belly
It acts to elevate the hyoid or depress the mandible (e.g. in swallowing)
What nerves supply the omohyoid muscle? What are its actions?
Supplied by the ansa cervicalis
Depresses and fixes the hyoid bone
What are the 4 subdivisions of the anterior triangle?
- Submental triangle
- Digastric triangle
- Carotid triangle
- Muscular triangle
What is contained in the submental triangle division of the anterior triangle?
Submental lymph nodes
Anterior jugular vein
What is contained in the digastric triangle division of the anterior triangle?
Submandibular gland Submandibular lymph nodes Facial artery and vein Hypoglossal nerve Mylohyoid nerve
What is contained in the carotid triangle division of the anterior triangle (9)?
Common carotid artery Internal and external carotid arteries Internal jugular vein Branches of external carotid artery (superior thyroid, lingual, facial, ascending pharyngeal, occipital arteries) Vagus nerve and laryngeal branches Accessory nerve Hypoglossal nerve Ansa cervicalis Deep cervical lymph nodes
What is contained in the muscular triangle?
Sternohyoid muscle Sternothyroid muscle Cricothyroid muscle Larynx and trachea Thyroid and parathyroid glands
What two divisions of the hyoid muscles exist? What muscles are in each (4 in each)?
Suprahyoid muscles (above hyoid bone)
- mylohyoid
- stylohyoid
- geniohyoid
- digastric
Infrahyoid muscles (below hyoid bone)
- sternohyoid
- omohyoid
- sternothyroid
- thyrohyoid
What nerves supply the digastric muscle? What is its action?
Anterior belly of digastric is supplied by mandibular branch of trigeminal (V)
Posterior belly of digastric is supplied by facial nerve (VII)
Acts to elevate hyoid or depresses mandible
What nerves supply the mylohyoid? What is its action?
Mylohyoid nerve from the inferior alveolar branch of the mandibular nerve of the trigeminal (V) nerve
Acts to raise the hyoid, floor of the mouth, and the tongue during swallowing or depresses the mandible
What nerves supply the geniohyoid? What is its action?
Nerve supply is from C1 that hitchhikes on the hypoglossal nerve (not innervated by the hypoglossal)**
Acts to raise the hyoid or depress the mandible
What nerves supply the stylohyoid? What is its action?
Supplied by the facial nerve (VII)
Acts to raise the hyoid and pull it posteriorly
What are the infrahyoid muscles (4)? Which 3 make up the ‘strap muscles’ and what are these muscles innervated by?
- Sternohyoid
- Omohyoid
- Sternothyroid
- Thyrohyoid
Sternohyoid, omohyoid, and sternothyroid are the strap muscles and are innervated by the ansa cervicalis
What are the suprahyoid muscles (4)?
- Myolohyoid
- Stylohyoid
- Geniohyoid
- Digastric
What nerve supplies the sternohyoid, and what is its action?
Supplied by ansa cervicalis
Acts to depress the hyoid bone after elevation during swallowing
What nerve supplies the omohyoid, and what is its action?
Supplied by ansa cervicalis
Depresses and fixes the hyoid bone
What nerve supplies the sternothyroid, and what is its action?
Supplied by the ansa cervicalis
Draws larynx and hyoid downward
What nerve supplies the thyrohyoid, and what is its action?
Supplied by C1 (Carried via the hypoglossal nerve)
Acts to depress hyoid bone, as well as raise the larynx when the hyoid bone is fixed
What are the four distinct layers of deep fascia (underneath the superficial fascia)?
Investing layer
Prevertebral layer
Pretracheal layer
Carotid sheath