The Head, Face & Neck: Anatomy & Physiology PDF

Y1B4M2L1 THE HEAD, FACE & NECK ● Mylohyoid muscle ○ The floor of the mouth. ○ Drains through the floor of the mouth just beside the frenulum of the tongue ○ Lateral to the frenulum are the openings of the whartonʼs duct ○ In some babies the frenulum is very thick which causes tongue tie hence limit...

Y1B4M2L1 THE HEAD, FACE & NECK ● Mylohyoid muscle ○ The floor of the mouth. ○ Drains through the floor of the mouth just beside the frenulum of the tongue ○ Lateral to the frenulum are the openings of the whartonʼs duct ○ In some babies the frenulum is very thick which causes tongue tie hence limiting the movement of the tongue especially when talking ○ The mylohyoid muscle is one of the muscles that forms the floor of the mouth otherwise the tongue will just fall down. A. ACUTE NECK PAIN MANAGEMENT ● Muscle strain (myalgia) to the neck occurs when muscles at the back of the neck become inflamed due to exertions, prolonged static loads, repetitive work and poor position. ● Management include: ○ Massage ○ Physical Therapy ○ Paracetamol and other Nonsteroidal Anti-Inflammatory Drugs or NSAID Mefenamic acid, Ibuprofen, Naproxen, Diclofenac) as pharmacologic management B. POSTERIOR BACK VS ANTERIOR FRONT STERNOCLEIDOMASTOID MUSCLE SCM ● Used as a line guide since it divides the neck into the posterior and anterior regions ○ Posterior neck - anything at the back of the line ○ Anterior neck - anything in front of the line ○ Rotates the head to opposite side ○ Very big muscle ○ Connects the mastoid bone, sternum and clavicle ○ Has 2 bellies: → Connects sternum and mastoid → Connects clavicle and mastoid Figure 21. Mylohyoid muscle SUBLINGUAL GLANDS ● ● ● ● Found underneath the lingua or the tongue Minor salivary glands Compared to the other glands, it has multiple openings Ducts of Rivinus ○ Several ducts of the the sublingual gland that drain into the floor of the mouth Figure 23. Sternocleidomastoid Muscle TORTICOLLIS Figure 22. Salivary Glands showing Ducts of Rivinus (at the floor of the mouth). II. NECK MUSCLES BACK VS FRONT 10AM CASE SCENARIO - Medical Clinic at Molo: ● Patient 2 22/F complaining of stiff neck ○ Patient woke up with a very deep aching pain, stiffness more emphasized on neck movement, after her first time working out at home. ● A pathology of the sternocleidomastoid muscle SCM ○ When SCM becomes hypertrophic → Enlarged on one side and weak on the other ○ Net movement of head in one side ○ Small/shortened or absent SCM on one side and normal SCM on the other ● 2 Types: ○ Congenital Torticollis ○ Acquired Torticollis → Cervical dystonia III. MUSCLES, BACK OF THE NECK A. POSTERIOR NECK MUSCLES ● Includes the following: ○ Sternocleidomastoid SCM ○ Trapezius ○ Anterior/ middle/ posterior scalenes ○ Semi-spinalis capitis ○ Splenius capitis → Capitis means head. The semi-spinalis capitis and splenius capitis are two muscles found near the head at the back. ARANAS, BORRES, BUNGAY, GABATA, LABRADOR, PANIZA, REA, TUPAZ, VICTORIANO, VILLAVICENCIO | MG 8 6 of 17 Y1B4M2L1 THE HEAD, FACE & NECK TRAPEZIUS ● “TRAPS” ● Support and maintain head posture so that the head wonʼt arch forward, and also the shoulders and the back ● Responsible for shrugging action ● Big muscle that spans the back of the neck, shoulder and the back ○ It inserts into the back of the head, shoulders, and the lower back ● The left and right trapezius forms a diamond shape ● Some people like bodybuilders have a very well-developed traps by doing shrugs with a weighted object Figure 26. Scalene Muscles SEMI SPINALIS CAPITIS ● ● ● ● Found at the back near the head Deeper than splenius capitis Function to hold the head in place Help flex the head from one side to the other Figure 24 Trapezius muscle Figure 27. Splenius Capitis & Semi-spinalis capitis SPLENIUS CAPITIS ● Also found at the back near the head ● Similarly, function to hold the head in place ● Also to flex the head from one side to the other IV. ANTERIOR NECK MUSCLES Figure 25. Well-developed trapezius muscle in bodybuilders SCALENES 2 00 PM CASE SCENARIO ● “This is a case of a 70/M who presented with a 5-year history of left anterior neck mass, and 3 months enlarged lymph nodes, left. A needle biopsy was done on the mass and it revealed Thyroid Cancer.” ● Anterior, middle and posterior ● Removing the trapezius and sternocleidomastoid muscles out will reveal the scalenes ● There is a gap between anterior and middle scalene ○ Because it is where the subclavian artery and brachial plexus inserts and exists the neck ○ Subclavian artery and Brachial plexus are a network of nerves that goes into the arm Figure 28. Anterior neck mass and enlarged lymph nodes. ARANAS, BORRES, BUNGAY, GABATA, LABRADOR, PANIZA, REA, TUPAZ, VICTORIANO, VILLAVICENCIO | MG 8 7 of 17 Y1B4M2L1 THE HEAD, FACE & NECK ● Surgical Plan: Total Thyroidectomy with Neck Dissection ● Thyroidectomy - surgical procedure of removing the thyroid because of factors such as cancers ○ Thyroidectomy is a very challenging procedure because the thyroid should be removed in a safe way so that it wonʼt damage all the surrounding structures ● Papillary thyroid cancer PTC - most common thyroid cancer ○ Usually spreads (metastasize) through the neck lymph nodes ○ Total thyroidectomy is the first treatment of choice. → It involves getting the left and right thyroid. → Followed by removal of neck nodes (neck dissection) → This will allow treatment of the primary tumor and also the neck nodes wherein the tumor has spread ○ Procedure: → Open muscles of the anterior neck ■ Thyroid is situated deep into the neck. It is covered by the anterior neck muscles → Reach the thyroid gland and remove it safely from the surrounding structures: ■ Laryngeal Nerves ■ Parathyroid glands ■ Carotid vessels ■ Trachea ■ Esophagus → Remove all the neck nodes Figure 30. Platysma Figure 31. Overall components of the strap muscles. B. STRAP MUSCLES ● Called the infrahyoid muscles since they are found below the hyoid bone ● Has four sets on each side of the neck ● Joined in the midline by a tissue ● Composed of four muscles: ○ Sternohyoid - muscle that spans from the sternum to the hyoid bone ○ Omohyoid - a unique muscle which comes from the hyoid bone and goes down and then sideways → Unique since it is the only strap muscle that goes sideways ○ Thyrohyoid - spans the hyoid bone and thyroid cartilage ○ Sternothyroid - spans the sternum and thyroid cartilage Figure 29. Anatomy of papillary thyroid cancer. A. ANTERIOR NECK MUSCLES ● Platysma ○ Goes before the strap muscles ○ Most superficial ● Strap Muscles Figure 32. Frontal view of the strap muscles. ARANAS, BORRES, BUNGAY, GABATA, LABRADOR, PANIZA, REA, TUPAZ, VICTORIANO, VILLAVICENCIO | MG 8 8 of 17 Y1B4M2L1 THE HEAD, FACE & NECK D. HYOID BONE ● Horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage ● A “Floating bone” and “Suspension bone” ○ Not attached to another bone (floats due to the tension of the muscles above and below it) ○ Suspended by the muscles above and muscles below it ○ Delineate the infra- and suprahyoid muscles. ● Functions: ○ Supports the infrahyoid and suprahyoid bones ○ Determines the cervico-mental angle → Cervico - neck → Mental - area below the chin Figure 33. Lateral view of the strap muscles. C. SUPRAHYOID MUSCLES ● Above the hyoid bone ● Primarily functions to support the mouth ● Types: ○ Geniohyoid - spans from the middle of the mandible to the hyoid bone ○ Mylohyoid - floor of the mouth → Mylohyoid and Geniohyoid combined forms the floor of the mouth ○ Stylohyoid - muscle that spans the hyoid bone and styloid process ○ Digastric - V-shaped muscle that from the anterior to the posterior belly Figure 36. Cervico-Mental Angle Figure 34. Frontal View of the Suprahyoid Muscles Figure 37. Comparison of hyoid bone position in relation to cervico-mental angle. Figure 38. Varying cervico-mental angle in relation to hyoid bone orientation. E. EXPOSING THE THYROID THROUGH THE STRAP MUSCLE Figure 35. Lateral View of the Suprahyoid Muscles ● “Open” strap muscles ● Retract left and right strap muscles 4 sets on each side of the neck) ○ Like opening a curtain (no need to cut because it is joined by a fibrous tissue called the median raphe) ● After retracting the strap muscles, thyroid gland is exposed. ARANAS, BORRES, BUNGAY, GABATA, LABRADOR, PANIZA, REA, TUPAZ, VICTORIANO, VILLAVICENCIO | MG 8 9 of 17 Y1B4M2L1 THE HEAD, FACE & NECK → Having 6 cm thyroid lobe already indicates a goiter or enlargement of the thyroid gland. ○ Isthmus - bridges the right and left thyroid lobes → 1.3 cm in size ○ Pyramidal lobe - usually at the middle ● Function: produce thyroid hormones ● Anatomic position: hugs the cricoid and trachea C5 Figure 39. Exposing the thyroid through the strap muscle. Figure 42. Thyroid gland. ● The thyroid gland is distinct from the the thyroid cartilage Adamʼs apple) ● The thyroid gland hugs the cricoid and trachea like a koala ● Swallowing is a technique when assessing patients with thyroid abnormalities such as tumor or masses ○ The trachea elevates when swallowing thus thyroid also goes up alongside it allowing delineation of thyroid tumor/masses G. PARTS TO BE CONSIDERED DURING THYROIDECTOMY ● When cutting off the thyroid Thyroidectomy), we need to be careful with the following parts: Figure 40. Median raphe/midline fascia ARTERIES / VEINS ● Three Arteries ○ Superior thyroid artery ○ Inferior thyroid artery ○ Thyroid ima artery Figure 41. Strap muscle F. THYROID GLAND ● “Butterfly-shaped” gland ● Composed of: ○ Right thyroid lobe ○ Left thyroid lobe → Each lobe is approximately 5 cm x 3 cm x 2 cm in dimension Figure 43. Three arteries you need to be careful with during thyroidectomy. ARANAS, BORRES, BUNGAY, GABATA, LABRADOR, PANIZA, REA, TUPAZ, VICTORIANO, VILLAVICENCIO | MG 8 10 of 17