Gross Anatomy II Lab 1

Platysma

Origin: Superficial fascia over pectoralis major/deltoid

Insertion: Lower border of mandible, angle of mouth

Innervation: Cervical nerve of facial nerve (CN VII)

Sternocleidomastoid (SCM)

Origin: Manubrium, medial 1/3 of clavicle

Insertion: Mastoid process of temporal bone, superior nuchal line

Innervation: Spinal accessory nerve (CN XI)

Digastric, anterior belly

Origin: Digastric fossa of mandible

Insertion: Hyoid bone (by intermediate tendon)

Innervation: Nerve to mylohyoid

Digastric, intermediate tendon

Between anterior and posterior bellies of digastric

Digastric, posterior belly

Origin: Mastoid process

Insertion: Hyoid bone by intermediate tendon

Innervation: Nerve to mylohyoid

Mylohyoid

Origin: Mylohyoid line

Insertion: Body of hyoid bone, median raphe

Innervation: Nerve to mylohyoid

Sheetlike, deep to digastric m. (especially the anterior belly)

Sternohyoid

Origin: Medial end of clavicle, posterior part of manubrium sterni

Insertion: Body of hyoid bone

Innervation: Ansa cervicalis (C1-3)

Omohyoid, superior belly

Origin: Intermediate tendon

Insertion: Body of hyoid bone

Innervation: Ansa cervicalis (C1-3)

Omohyoid, intermediate tendon

Between superior and inferior belly of omohyoid

Omohyoid, inferior belly

Origin: Superior border of scapula

Insertion: Intermediate tendon

Innervation: Ansa cervicalis (C1-3)

Sternothyroid

Origin: Posterior surface of manubrium

Insertion: Oblique line on lamina of thyroid cartilage

Innervation: Ansa cervicalis (C1-3)

Thyrohyoid

Origin: Oblique line on lamina of thyroid cartilage

Insertion: Body of hyoid bone

Innervation: C1 via hypoglossal nerve (CN XII)

Anterior triangle borders

Superior: inferior border of mandible

Posterior: Anterior border of SCM

Anterior: Anterior midline

Submandibular triangle

Within anterior and posterior bellies of digastric and mandible, contains submandibular salivary gland

Muscular triangle

Within omohyoid, SCM, and anterior midline of neck

Carotid triangle

Within superior omohyoid belly, posterior digastric belly, and SCM

Submental triangle

ONLY UNPAIRED TRIANGLE OF NECK

Within body of hyoid bone and anterior bellies of digastric muscles (both sides)

Submandibular gland

Salivary gland contained within submandibular triangle

Thyroid gland

Left and right lobes, isthmus, pyramidal lobe (present in 50% of people)

Carotid sheath

Encloses the common and internal carotid arteries (medial), vagus nerve (CN X, in the middle), and internal jugular vein (lateral)

Within the anterior triangle of the neck (carotid triangle)

Ansa cervicalis

Nerve loop descending from hypoglossal nerve (CN XII, C1-3 branch off)

Common carotid artery

Branches off brachiocephalic trunk (R) or aortic arch (L)

Bifurcates to internal carotid artery (no branches in neck, contains carotid sinus at base) and external carotid artery (has 8 branches of its own)

External carotid artery branches

Has 8 branches, only 3 relevant (moving superior):

1. Superior thyroid artery

2. Lingual artery (inferior to CN XII)

3. Facial artery (inferior to CN XII, has slack)

Superior thyroid artery

Most inferior branch of external carotid artery, most superior blood supply to thyroid gland

Lingual artery

Branch of external carotid artery, supplies tongue (as does CN XII)

Facial artery

Branch of external carotid artery, supplies face

Includes slack (looping) to account for looking up and to the contralateral side

Sympathetic trunk

On prevertebral fascia (on top of C vertebral bodies), deep to the carotid sheath

Superior cervical ganglion (shaped like a pepita, place where it widens) is immediately below the base of the skull

Superior laryngeal nerve

Branched off the vagus nerve (CN X) inferior to the hyoid, serving the larynx

Phrenic nerve

From C3-5, on anterior surface of anterior scalene muscle

Motor control of diaphragm, sensory to some membranes of neck

“C3, 4, 5 keeps the diaphragm alive!”

Hyoid bone

Greater horn, lesser horn, body

Vagus nerve (CN X)

Contained within carotid sheath (of carotid triangle), supplies motor and sensory innervations

Includes superior laryngeal branch

Hypoglossal nerve (CN XII)

Supplies motor innervation to tongue and infrahyoid muscles, including through ansa cervicalis (C1-3)