Makindo Medical Notes

Anatomy

Anterior Scalene

Origin: Anterior tubercles of the transverse processes of vertebrae C3-C6
Insertion: Scalene tubercle of the first rib
Action: Elevates the first rib; flexes and laterally bends the neck
Innervation: Brachial plexus, C5-C7
Artery: Ascending cervical a.
Notes: A muscle of inspiration and an important landmark of the neck. Located between the subclavian vein and subclavian artery.

Aryepiglottic

Origin: Apex of the arytenoid cartilage
Insertion: Epiglottis
Action: Draws the epiglottis posteriorly and downward during swallowing
Innervation: Inferior laryngeal nerve from recurrent laryngeal nerve (branch of vagus nerve)
Artery: Laryngeal branch of the superior thyroid a.
Notes: The aryepiglottic fold is formed by the mucosa raised by this muscle.

Oblique Arytenoid

Origin: Muscular process of the arytenoid cartilage
Insertion: Posterior surface of the contralateral arytenoid cartilage
Action: Draws arytenoid cartilages together, adducting the vocal folds
Innervation: Inferior laryngeal nerve (branch of vagus nerve)
Artery: Laryngeal branch of the superior thyroid a.
Notes: Lies posterior to the transverse arytenoid muscle.

Buccinator

Origin: Pterygomandibular raphe, mandible, and the maxilla
Insertion: Angle of the mouth and lateral portion of upper and lower lips
Action: Pulls the corner of the mouth laterally; presses cheek against teeth
Innervation: Buccal branches of the facial nerve (VII)
Artery: Facial a.
Notes: Important for mastication but innervated by the facial nerve, not by the buccal nerve from V3.

Ciliary

Origin: Scleral spur and encircling the ciliary process
Insertion: Ciliary process
Action: Relaxes the suspensory ligament of the lens
Innervation: Parasympathetic fibers in the oculomotor nerve (III)
Artery: Ophthalmic a.
Notes: Allows the lens to thicken for accommodation (near vision).

Inferior Pharyngeal Constrictor

Origin: Oblique line of the thyroid cartilage, lateral surface of cricoid cartilage
Insertion: Midline pharyngeal raphe
Action: Constricts the pharyngeal cavity
Innervation: Vagus (X), via the pharyngeal plexus
Artery: Ascending pharyngeal a., superior thyroid a.
Notes: The most external of the three pharyngeal constrictor muscles.

Levator Scapulae

Origin: Transverse processes of C1-C4 vertebrae
Insertion: Medial border of the scapula from the superior angle to the spine
Action: Elevates scapula
Innervation: Dorsal scapular nerve (C5); upper part also receives branches of C3 & C4
Artery: Dorsal scapular a.
Notes: Named for its action; levator means “to lift”.

Orbicularis Oculi

Origin: Medial orbital margin and medial palpebral ligament
Insertion: Skin of lateral cheek, lateral palpebral raphe
Action: Closes the eyelids
Innervation: Temporal and zygomatic branches of the facial nerve (VII)
Artery: Supraorbital, supratrochlear, infraorbital, angular branches of facial a.
Notes: Activated involuntarily in the blink reflex.

Orbicularis Oris

Origin: Skin and fascia of the lips and area surrounding lips
Insertion: Skin and fascia of the lips
Action: Purses the lips
Innervation: Buccal branch of the facial nerve (VII)
Artery: Superior and inferior labial branches of the facial a., mental a., infraorbital a.
Notes: Known as the "kissing muscle".

Styloglossus

Origin: Anterior side of the styloid process
Insertion: Posterolateral side of the tongue
Action: Retracts and elevates the tongue
Innervation: Hypoglossal nerve (XII)
Artery: Ascending pharyngeal a.
Notes: An extrinsic muscle of the tongue.

Temporalis

Origin: Temporal fossa and the temporal fascia
Insertion: Coronoid process of the mandible
Action: Elevates and retracts the mandible
Innervation: Deep temporal nerves from the mandibular division of the trigeminal nerve (V)
Artery: Deep temporal arteries
Notes: A powerful chewing muscle.

Sternocleidomastoid

Origin: Sternal head: anterior surface of the manubrium; clavicular head: medial 1/3 of the clavicle
Insertion: Mastoid process and lateral 1/2 of superior nuchal line
Action: Draws mastoid process down toward the same side, causing the chin to turn up toward the opposite side
Innervation: Spinal accessory nerve (XI), with proprioception from C2 & C3
Artery: Sternocleidomastoid branch of the occipital a.
Notes: Carotid sheath structures lie deep to it.

Masseter

Origin: Zygomatic arch and zygomatic bone
Insertion: Lateral surface of the ramus and angle of the mandible
Action: Elevates the mandible
Innervation: Nerve to masseter from the mandibular division of the trigeminal nerve (V)
Artery: Masseteric branch of maxillary a.
Notes: A powerful muscle for chewing.