Anterior Torso and Neck Flashcards
Anterior Torso and Neck
Platysma m.
Origin:
- Fascia of upper thorax and lower neck
Insertion:
- Mandible (lower border)
- Skin and fascia of lower face
- Blends with muscles of lower lip and angle of mouth.
Innervation:
- Facial nerve (CN VII)
Action(s):
- Tenses skin of neck and pulls lower lip inferiorly
- Tenses skin of neck and pulls lower lip inferiorly with skin
Layer 2: Muscle
Anterior Torso and Neck
Sternocleidomastoid
Origin:
- Clavicle (medial)
- Sternum (manubrium)
Insertion:
- Mastoid process of temporal bone
- Lateral one-half of superior nuchal line of occipital bone
Innervation:
- Accessory nerve (CN XI)
Action(s):
- Unilateral: rotation of head so face turns to opposite side
- Bilateral: flexion of neck
- Bilateral: extension of head
Layer 2: Muscle
Anterior Torso and Neck
Omohyoid
Origin:
- Scapula (superior border)
Insertion:
- Hyoid bone
Innervation:
- Ventral rami of C1-3 spinal nerves (ansa cervicalis)
Action(s):
- Depression of hyoid bone
Layer 2: Muscle
Anterior Torso and Neck
Sternohyoid
Origin:
- Sternum (manubrium)
- Clavicle (medial end)
Insertion:
- Hyoid bone
Innervation:
- Ventral rami of C1-3 spinal nerves (ansa cervicalis)
Action(s):
- Depression of hyoid bone
Layer 2: Muscle
Anterior Torso and Neck
Sternothyroid
Origin:
- Sternum (manubrium)
Insertion:
- Thyroid cartilage of larynx
Innervation:
* Ventral rami of C1-3 spinal nerves (ansa cervicalis)
Action(s):
- Depression of larynx
Layer 3: Muscle
Comment:
- One of four infrahyoid muscles: sternohyoid, sternothyroid, omohyoid, and thyrohyoid
- Ansa cervicalis (Latin: ansa = loop; cervicalis = neck) is a nerve “loop” formed by ventral rami of C1-3 spinal nerves
- Thyrohyoid is not innervated by ansa cervicalis
Anterior Torso and Neck
Thyrohyoid
Origin:
- Thyroid cartilage of larynx
Insertion:
- Hyoid bone
Innervation:
- Ventral ramus of C1 spinal nerve
Action(s):
- Elevation of larynx
- Depression of hyoid bone
Layer 3: Muscle
Comment:
- One of four infrahyoid muscles: sternohyoid, sternothyroid, omohyoid, and thyrohyoid
- Only infrahyoid muscle NOT innervated by ansa cervicalis
- Ansa cervicalis (Latin: ansa = loop; cervicalis = neck) is a nerve “loop” formed by ventral rami of C1-3 spinal nerves
Anterior Torso and Neck
Inferior Pharyngeal Constrictor
Origin:
- Pterygomandibular raphe (superior constrictor)
- Hyoid bone (middle constrictor)
- Thyroid and cricoid cartilages of larynx (inferior constrictor)
Insertion:
- Posterior midline raphe
- Base of skull (superior constrictor)
Innervation:
- Vagus nerve (CN X)
Action(s):
- Produces a wave of contraction (peristalsis) during swallowing
Layer 3: Muscle
Anterior Torso and Neck
Scalene (Anterior, Middle, and Posterior)
Origin:
- Transverse processes of C3-7 vertebrae
Insertion:
- Anterior: rib 1
- Middle: rib 1
- Posterior: rib 2
Innervation:
- Ventral rami of cervical spinal nerves
Action(s):
- Anterior: elevation of rib 1; lateral flexion and rotation of neck
- Middle: elevation of rib 1; lateral flexion of neck
- Posterior: elevation of rib 2; lateral flexion of neck
Layer 3: Muscle
Comment:
- Neck movements produced when rib is fixed
- Important accessory muscles of respiration
- Important anatomical relationship: roots of brachial plexus found between anterior and middle scalene muscles
Anterior Torso and Neck
Mylohyoid
Origin:
- Mandible (inner aspect of body)
Insertion:
- Hyoid bone (posterior fibers)
- Midline fibrous raphe (anterior fibers)
Innervation:
- Trigeminal nerve (mandibular division - CN V3)
Action(s):
- Elevation of floor of mouth
Chin: Muscle
Comment:
- Four suprahyoid muscles: digastric, geniohyoid, mylohyoid, and stylohyoid
- A raphe is a “seam” where two structures meet
Anterior Torso and Neck
Digastric
Origin:
- Anterior belly: mandible (inner aspect of body near midline)
- Posterior belly: temporal bone (mastoid process)
Insertion:
- Hyoid bone
Innervation:
- Anterior belly: trigeminal nerve (mandibular division - CN V3)
- Posterior belly: facial nerve (CN VII)
Action(s):
- Depression of mandible (opens mouth)
- Elevation of hyoid bone
Chin: Muscle
Anterior Torso and Neck
Stylohyoid
Origin:
- Styloid process of temporal bone
Insertion:
- Hyoid bone
Innervation:
- Facial nerve (CN VII)
Action(s):
- Elevation of hyoid bone
Chin: Muscle
Comment:
Four suprahyoid muscles:
- digastric
- geniohyoid
- mylohyoid, and
- stylohyoid
Anterior Torso and Neck
Pectoralis Major
Origin:
- Clavicular head: clavicle (medial part)
- Sternocostal head: sternum, costal cartilages 1-6, and aponeurosis of external abdominal oblique muscle
Insertion:
- Humerus (lateral lip of intertubercular sulcus)
Innervation:
- Lateral pectoral nerve (C5-7)
- Medial pectoral nerve (C8-T1)
Action(s):
- Adduction of arm
- Medial rotation of arm
- Clavicular head: flexion of arm
- Sternocostal head: extension of arm (from flexed position)
Thorax: Muscle
Comment:
- Pectoralis major and minor muscles also known as “pecs”
- Pectoralis major active during forced inspiration
Anterior Torso and Neck
Pectoralis Minor
Origin:
- Ribs 3-5
Insertion:
- Scapula (coracoid process)
Innervation:
- Medial and lateral pectoral nerves
Action(s):
- Stabilizes scapula (holds it against thoracic wall)
- Protraction (abduction) of scapula (assists serratus anterior)
- Lateral rotation of scapula (e.g., depresses the acromion)
Thorax: Muscle
Comment:
- Pectoralis major and minor muscles also known as “pecs”
- Pectoralis minor active during forced inspiration
Anterior Torso and Neck
Subclavius
Origin:
- Rib 1 and its costal cartilage
Insertion:
- Clavicle (middle third)
Innervation:
- Nerve to subclavius
Action(s):
- Depression and stabilization of clavicle
Thorax: Muscle
Anterior Torso and Neck
Serratus Anterior
Origin:
- Ribs 1-9
Insertion:
- Scapula (medial border)
Innervation:
- Long thoracic nerve
Action(s):
- Protraction (abduction) of scapula
- Superior rotation of scapula (directs glenoid cavity superiorly)
- Stabilizes scapula (holds it against thoracic wall)
Thorax: Muscle
Comment:
- Serratus anterior is a prime mover in all reaching and pushing movements
Anterior Torso and Neck
External Intercostal & Membrane
Origin:
- Inferior border of rib (ribs 1-11)
Insertion:
- Superior border of rib below (ribs 2-12)
Innervation:
- Intercostal nerves (ventral rami of T1-11 spinal nerves)
Action(s):
- Muscle of respiration
- Elevation of ribs during inhalation to increase transverse dimensions (anterior-posterior, medial-lateral) of thoracic cavity
Intercostal: Muscle
Comment:
- External intercostal muscle continuous with external intercostal membrane near sternum
- In contemporary medical anatomy books, the origins of external and internal intercostal muscles are referred to as “superior attachments” and described for both muscles as the inferior border of the rib.
- Similarly, the insertions of these muscles are referred to as “inferior attachments” and described as the superior border of the rib below.
Anterior Torso and Neck
Internal Intercostal (no photo of membrane)
Origin:
- Superior border of rib (ribs 1-11)
Insertion:
- Inferior border of rib above (ribs 2-12)
Innervation:
- Intercostal nerves (ventral rami of T1-11 spinal nerves)
Action(s):
- Muscle of respiration
- Depression of ribs during forced exhalation to decrease transverse dimensions (anterior-posterior, medial-lateral) of thoracic cavity
Intercostal: Muscle
Comment:
- Internal intercostal muscle continuous with internal intercostal membrane lateral to vertebral column
- Muscle fibers run inferoposteriorly
- In contemporary medical anatomy books, the origins of external and internal intercostal muscles are referred to as “superior attachments” and described for both muscles as the inferior border of the rib.
- Similarly, the insertions of these muscles are referred to as “inferior attachments” and described as the superior border of the rib below.
Anterior Torso and Neck
Transversus Thoracis
Origin:
- Inferoposterior surface of body of sternum and xiphoid process; sternal ends of costal cartilages of ribs 4-7
Insertion:
- Internal surface of costal cartilages of ribs 2-6
Innervation:
- Intercostal nerves
Action(s):
- Depresses ribs during forced expiration; Supports intercostal spaces and thoracic cage
Intercostal: Muscle
Anterior Torso and Neck
Rectus Abdominus
Origin:
- Pubis (crest and symphysis)
Insertion:
- Sternum (xiphoid process)
- Costal cartilages 5-7
Innervation:
- Ventral rami of T7-12 spinal nerves
Action(s):
- Flexion of trunk (sit-ups)
- Compression of anterior abdominal wall
Abdomen: Muscle
Comment:
- Three or four bellies, separated by tendinous intersections
- Encased in fibrous (rectus) sheath
- Important in “straining” (e.g., lifting, defecation, urination, child-birth)
- Functions in respiration (“abdominal breathing”)
Anterior Torso and Neck
Linea Alba
Location:
- Anterior abdominal wall (midline)
Description:
- Fibrous raphe formed by paired rectus sheaths
Abdomen:
Comment:
- Umbilicus located in linea alba
- Opening abdominal cavity by incision through linea alba avoids cutting muscle fibers
- A raphe is a “seam” where two structures meet
Anterior Torso and Neck
External Oblique
Origin:
- Ribs and costal cartilages 5-12
Insertion:
- Linea alba
- Ilium (crest)
Innervation:
- Ventral rami of T8-L1 spinal nerves
Action(s):
- Unilateral: rotation of trunk
- Bilateral: flexion of trunk (sit-ups)
- Compression of anterior abdominal wall and viscera (increases intra-abdominal pressure)
Abdomen: Muscle
Comment:
- Important in “straining” (e.g., lifting, defecation, urination, child-birth)
- Functions in respiration (“abdominal breathing”)
- At right angle to internal abdominal oblique (strengthens abdominal wall)
Anterior Torso and Neck
Internal Oblique
Origin:
- Inguinal ligament
- Ilium (crest)
- Thoracolumbar fascia
Insertion:
- Linea alba
- Costal cartilages 7-10
Innervation:
- Ventral rami of T8-L1 spinal nerves
Action(s):
- Unilateral: rotation of trunk
- Bilateral: flexion of trunk (sit-ups)
- Compression of anterior abdominal wall and viscera (increases intra-abdominal pressure)
Abdomen: Muscle
Comment:
- Important in “straining” (e.g., lifting, defecation, urination, child-birth)
- Functions in respiration (“abdominal breathing”)
- At right angle to external abdominal oblique (strengthens abdominal wall)
Anterior Torso and Neck
Transverse Abdominus
Origin:
- Ilium (crest)
- Inguinal ligament
- Thoracolumbar fascia
- Costal cartilages 7-12
Insertion:
- Pubis (body)
- Linea alba
- Sternum (xiphoid process)
Innervation:
- Ventral rami of T8-L1 spinal nerves
Action(s):
- Compression of anterior abdominal wall and viscera (increases intra-abdominal pressure)
Abdomen: Muscle
Comment:
- Important in “straining” (e.g., lifting, defecation, urination, child-birth)
- Functions in respiration (“abdominal breathing”)
Anterior Torso and Neck
Medial Pectoral n.
Location:
- Axilla
- Thoracic wall (superior lateral)
Contributions:
- Ventral rami of C8-T1 spinal nerves
Composition:
- Motor
Motor:
- Pectoralis major
- Pectoralis minor
Comment:
- Named for origin from medial cord of brachial plexus
- Pierces pectoralis minor to enter pectoralis major
- Brachial plexus roots = ventral rami of C5-T1 spinal nerves
Neurology
Anterior Torso and Neck
Lateral Pectoral n.
Location:
- Axilla
- Thoracic wall (superior lateral)
Contributions:
- Ventral rami of C5-7 spinal nerves
Composition:
- Motor
Motor innervation:
- Pectoralis major and minor
Comment:
- Named for origin from lateral cord of brachial plexus
- Brachial plexus roots = ventral rami of C5-T1 spinal nerves
Neurology
Anterior Torso and Neck
Long Thoracic n.
Location:
- Neck (inferior)
- Thoracic wall (lateral) - on superficial surface of serratus anterior
Contributions:
- Ventral rami of C5-7 spinal nerves
Composition:
- Motor
Motor:
- Serratus anterior
Comment:
- Brachial plexus roots = ventral rami of C5-T1 spinal nerves
Neurology
Anterior Torso and Neck
Thoracodorsal n.
Location:
- Thoracic wall (superior lateral)
Contributions:
- Ventral rami of C6-8 spinal nerves
Composition:
- Motor
Motor:
- Latissimus dorsi
Comment:
- Brachial plexus roots = ventral rami of C5-T1 spinal nerves
Neurology
Anterior Torso and Neck
Intercostal n.
Location:
- Intercostal spaces
- Between innermost and internal intercostal muscles
Contributions:
- Ventral rami of T1-11 spinal nerves
Composition:
- Motor and general sensation
Motor:
- Intercostal muscles
- Anterior abdominal wall muscles (T7-11)
General sensation:
- Skin of thorax (T1-11), abdomen (T7-11) and upper limb (T2)
- Parietal pleura (costal and peripheral diaphragmatic) (T1-11)
- Parietal peritoneum (T7-11)
Neurology
Anterior Torso and Neck
Phrenic n.
Location:
- Neck (inferior)
- Thorax (mediastinum)
Contributions:
- Ventral rami of C3-5 spinal nerves
Composition:
- Motor
- General sensation
Motor:
- Diaphragm
General sensation:
- Parietal layer of pleura and peritoneum over central diaphragm
- Mediastinal pleura
- Parietal pericardium
Comment:
- Supplies all motor innervation to diaphragm (hint: remember C3, 4, 5 “keeps the diaphragm alive”)
Neurology
Anterior Torso and Neck
Vagus n.
Location:
- Posterior cranial fossa
- Head
- Neck
- Thorax
- Abdomen
- Composition:
- Motor
- General sensation
- Special sensation
- Parasympathetic
- Motor:
- Muscles of palate
- Muscles of pharynx
- Intrinsic muscles of larynx
General sensation:
- Thoracic and abdominal viscera
- Epiglottis and laryngopharynx
- External acoustic meatus
- Special sensation:
- Taste from epiglottis and surrounding region
Parasympathetic:
- Mucous glands of respiratory and digestive systems in neck (pharynx and larynx), thorax, and abdomen
- Smooth muscle of respiratory and digestive systems in neck (pharynx and larynx), thorax, and abdomen
- Cardiac muscle
CNS connection:
- Motor: medulla oblongata (nucleus ambiguus)
- General sensation: medulla oblongata (spinal nucleus of trigeminal nerve)
- Special sensation: medulla oblongata (nucleus of solitary tract)
- Parasympathetic: medulla oblongata (dorsal nucleus of vagus nerve)
- Cranial foramina:
- Jugular foramen
Comment:
- General sensation from thoracic and abdominal viscera only involves stretch (e.g., distention of stomach)
- General sensation from epiglottis and laryngopharynx includes pain, touch, and temperature
- Vagus nerve also innervates carotid and aortic bodies
- Parasympathetic impulses from CNS to effector organ involve two neurons in series (preganglionic and postganglionic)
- Only cranial nerve that extends beyond head and neck
- Vagus nerve also known as CN X
Neurology
Anterior Torso and Neck
Sympathetic Trunk
Location:
- Adjacent to vertebral bodies, from base of skull to coccyx
Description:
- Nerve trunk comprised of axons connecting sympathetic (paravertebral) ganglia
- Sympathetic ganglia contain postganglionic nerve cell bodies
- Branches include gray and white rami communicans, and splanchnic nerves
Also known as:
- Sympathetic chain
- Sympathetic chain ganglia
- Comment:
- Ganglia give trunk a “beaded” appearance
Neurology
Anterior Torso and Neck
Hypoglossal n.
Location:
- Posterior cranial fossa
- Neck
- Oral cavity
- Composition:
- Motor
- Motor:
- Genioglossus
- Hyoglossus
- Styloglossus
- Intrinsic muscles of tongue
CNS connection:
- Medulla oblongata (nucleus of hypoglossal nerve)
- Cranial foramina:
- Hypoglossal canal
Comment:
- Hypoglossal nerve innervates all tongue muscles except palatoglossus (vagus nerve)
- Intrinsic tongue muscles originate and insert within tongue
- Hypoglossal nerve also known as CN XII
Neurology
Anterior Torso and Neck
Superior Laryngeal n.
Neurology
Anterior Torso and Neck
Internal Thoracic a.
Origin:
- Subclavian
Course:
- Descends adjacent to sternum within thoracic cavity
Distribution:
- Intercostal spaces
- Breast
- Pericardium
- Diaphragm
- Anterior abdominal wall
Branches:
- Anterior intercostal
- Pericardiacophrenic
- Superior epigastric
- Musculophrenic
Also known as:
- Internal mammary artery
Angiology
Anterior Torso and Neck
Internal Thoracic v.
Drainage:
- Anterior thoracic wall, including breast
- Anterior abdominal wall
- Diaphragm
- Pericardium
- Tributaries:
- Musculophrenic
- Superior epigastric
- Pericardiacophrenic
- Anterior intercostal
Course:
- Ascends posterior to costal cartilages, just lateral to sternum
- Termination:
- Subclavian
Also known as:
- Internal mammary vein
- Comment:
- Formed by union of superior epigastric and musculophrenic veins
Anterior Torso and Neck
Thoraco-acromial a.
Origin:
- Axillary
Course:
- Short artery medial to pectoralis minor muscle
Distribution:
- Anterior shoulder region
Mammary gland
Branches:
- Pectoral
- Deltoid
- Clavicular
- Acromial
Angiology
Anterior Torso and Neck
Thoraco-acromial v.
Drainage:
- Anterior shoulder region
- Mammary gland
Tributaries:
- Pectoral
- Deltoid
- Clavicular
- Acromial
Course:
- Short vein medial to pectoralis minor muscle
- Termination:
- Axillary
