Anterior Torso and Neck Flashcards by Benjamin Kozak

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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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

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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.

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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

Innermost Intercostal

Origin:
*

Insertion:
*

Innervation:
*

Action(s):
*

Intercostal: Muscle

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