Neck Region PA 544 Clinical Anatomy Neck Topic

Neck Region PA 544 Clinical Anatomy

Neck: Topic Objectives • Be able to describe and identify the major muscles, bones and surface anatomy of the neck. • Be able to identify the architecture of the spinal cord anatomically and functionally • Be able to list the components of ascending and descending pathways of the cord and the cervical and brachial plexi • Be able to describe the fascia of the neck and apply its significance to clinically important conditions • Be able to describe the borders of triangles of the neck and list their components • Be able to identify thyroid structures including anatomical variations • Be able to predict level of thyroid malfunction physiologically • Be able to describe hypo and hyper thyroid causes and effects • Be able to describe the action of PTH • Be able to identify the cartilage and soft components of the larynx • Be able to predict the response of the baroreceptors to changing BP • Be able to describe the sequence of the swallowing reflex

Anterior Surface

Triangles at Surface

Hyoid 1. C 3 level 2. Suprahyoid muscles 3. Infrahyoid muscles

Vertebral Column

Intervertebral disc

Vertebra Parts

C 1 & C 2

Cervical Vertebra

Typical Cervical Vertebra

Spinal Cord • Receives and generates signals to body through the spinal nerves

Cord in Spinal Canal Posterior Median Sulcus Posterior Root Denticulate Ligament Dorsal Root Ganglion Anterior Root Spinal Nerve

Spinal Cord (X. S. )

Spinal Nerve Anatomy

Functional Arrangement of SC Ascending and descending pathways

Ascending Pathways

Descending Pathways

Cervical Plexus Serves neck and diaphragm

Brachial Plexus and pectoral nerves

Brachial Plexus Innervates most of the arm and some of the body wall.

Spinal Cord Segments • 4 segments: Cervical, Thoracic, Lumbar, and Sacral (only 1 coccygeal nerve) • 31 pairs of spinal nerves

Cervical Segment

Neck Fascia Superficial fascia Prevertebral fascia Alar fascia Pretracheal fascia Investing fascia

Platysma

SCM and Trapezius SCM Trapezius

Cervical Triangles Posterior Triangle Anterior Triangle

Posterior Triangle Occipital triangle Supraclavicular triangle

Superficial and Deep Posterior Triangle Ext. jugular v. SCM Splenius Levator scapulae Accessory n. Nerve Point of Neck Phrenic n. Prevertebral fascia Platysma Scalenes Brachial plexus

Supraclavicular Triangle Brachial Plexus SCM Subclavian vessels

Anterior Triangles Submandibular Carotid Submental Muscular

Muscular Triangle

Muscles of Triangle Thyrohyoid Sternothyroid Thyroid Sternohyoid

Thyroid Location

Accessory Thyroid gland Accessory thyroid along thyroglossal duct

Pyramidal lobe (50% of people have this lobe structure)

Thyroid Follicle (follicular cells thyroxine) Parafollicular cells calcitonin

T 3 & T 4

T 3 & T 4 Formation and Secretion

Control of Thyroxine Secretion Short loop Long loop

Thyroid Malfunction • Hypothyroidism • Endemic goiters –due to iodine deffeicency • Cretinism –i thyroxine in child results in igrowth (dwarf) and severe mental retardation • Myxedema –i thyroxine in adult, leads to swelling of tissues plus other symptoms

Cretinism

Thyroid Malfunction • Hyperthyroidism • Toxic goiters (Graves disease) –Ab may stimulate thyroid without negative feedback control • Exophthalmos –symptom present in many hyperthyroid patients

Parathyroid Location

PTH Actions • Stimulates resorption of bone h. Ca+ and PO 4 - in blood • Stimulates Ca+ absorption in intestine (active Vit. D 3 necessary for Ca+ absorption) • Stimulates Ca+ reabsorption and PO 4 - excretion in kidney • Stimulates Vit. D 3 formation (skin) and activation (kidney) • Vital for life

Laryngeal Cartilages Hyoid Epiglottis (anterior) Arytenoid cartilage Thyroid cartilage Cricoid cartilage (posterior)

Voice Box Vestibular fold Ventricle Vocal fold

CN X: supply to laryngeal muscles Inf. Vagal ganglion Internal Laryngeal n. (sensory & autonomic) External Laryngeal n. (motor to inf. Pharnygeal constrictor and the cricohyoid) Recurrent Laryngeal n. (motor to all other laryngeal muscles)

Digastric Mylohyoid Submental Triangle -contains submental lymph nodes

Carotid Triangle Digastric (posterior belly) External carotid a. Internal carotid a. Common carotid a. Ansa cervicalis SCM IJV Omohyoid

Ext. Carotid Branches Hypoglossal n. Occipital Post. Auricular Int. carotid Superficial Temporal Maxillary Ext. carotid Facial Lingual Sup. Thyroid IJV Common Carotid Ansa cervicalis Asc. Pharyngeal (not show)

External carotid (isolated) Superficial Temporal Post. Auricular Maxillary Occipital Facial Lingual Asc. Pharyngeal Sup. Thyroid Note: Internal carotid has NO neck branches.

Carotid bodies

IJV Sup. Bulb of IJV Facial Sup. Thyroid Inf. Bulb of IJV

Lymph nodes of neck Deep Cervical Lymph nodes (most located in carotid sheath)

Submandibular Triangle Submandibular glands Digastrics

Submandibular Lymph nodes

Pharynx Function: deglutition Mucosa: Str. Squamous Muscularis: Skeletal

Oro- and nasopharynx Pharyngeal tonsil Pharyngotympanic (Eustachian) tube Tubal tonsils (small holes) Pharyngeal recess Palatine bone Salpingopharyngeal fold Soft palate Uvula Palatoglossal arch Tonsillar cleft Palatopharyngeal arch Lingual Tonsil

Longitudinal pharyngeal muscles Palatopharyngeus

Tonsils Pharyngeal Tonsil

Pharyngeal Constrictors Superior Middle Inferior

Peristalsis

Deglutition (Swallowing)

Fluid Drinking

Deglutition (cont’d)

Deglutition (cont’d)

Laryngopharynx Epiglottis Piriform recess