The Muscular System: Exploring the Magnificent Muscles of the Human Body

Reference
Written By Deniz Ates

How many muscles are there in the human body and how are they arranged? This guide is designed to be a useful resource, providing you with the names of each muscle, categorized groupings, and accompanying images for visual reference. Whether you're a student, a health professional, or simply someone with a curiosity about human anatomy, this post will serve as a valuable reference, enabling you to expand your knowledge and explore the intricate details of each muscle.

 

Anterior

Posterior

There are approximately 650 to 700 muscles in the human body, although the exact number depends on how ‘muscle’ is defined. All the muscles may be arranged into four major groups, with sub-divisions and further sub-divisions:

 

1. Head Zone

 

Head

    • Orbitalis

    • Superior rectus

    • Inferior rectus

    • Medial rectus

    • Lateral rectus

    • Common tendinous ring

    • Superior oblique

    • Inferior oblique

    • Levator palpebrae superioris

    • Tensor tympani

    • Stapedius

    • Mucosa of tympanic cavity

    • Epicranius

    • Procerus

    • Nasalis

    • Depressor septi nasi

    • Orbicularis oculi

    • Corrugator supercilii

    • Depressor supercilii

    • Auricularis anterior

    • Auricularis superior

    • Auricularis posterior

    • Orbicularis oris

    • Depressor anguli

    • Transversus menti

    • Risorius

    • Zygomaticus major

    • Zygomaticus minor

    • Levator labii superioris

    • Levator labii superioris alaeque nasi

    • Depressor labii inferioris

    • Levator anguli oris

    • Modiolus

    • Buccinator

    • Mentalis

    • Masseter

    • Temporalis

    • Lateral pterygoid

    • Medial pterygoid

    • Buccopharyngeal fascia

    • Masseteric fascia

    • Parotid fascia

    • Temporal fascia

    • Genioglossus

    • Hyoglossus

    • Styloglossus

    • Superior longitudinal muscle

    • Inferior longitudinal muscle

    • Transverse muscle

    • Vertical muscle

    • Palatoglossus

    • Palatine aponeurosis

    • Levator veli palatini

    • Tensor veli palatini

    • Musculus uvulae

    • Palatoglossus

    • Palatopharyngeus

 

Neck

    • Platysma

    • Longus colli

    • Longus capitis

    • Scalenus anterior

    • Scalenus medius

    • Scalenus posterior

    • (Scalenus minimus)

    • Sternocleidomastoid

    • Rectus capitis anterior

    • Rectus capitis lateralis

    • Rectus capitis posterior major

    • Rectus capitis posterior minor

    • Obliquus capitis superior

    • Obliquus capitis inferior

    • Digastric

    • Stylohyoid

    • Mylohyoid

    • Geniohyoid

    • Sternohyoid

    • Omohyoid

    • Sternothyroid

    • Thyrohyoid

    • (Levator glandulae thyroideae)

    • Investing layer

    • Pretracheal layer

    • Prevertebral layer

    • Carotid sheath

    • Pharyngeal raphe

    • Pterygomandibular raphe

    • Superior constrictor

    • Middle constrictor

    • Inferior constrictor

    • Stylopharyngeus

    • Salpingtopharyngeus

    • Palatopharyngeus

    • Buccopharyngeal fascia

    • Peripharyngeal space

    • Cricothyroid

    • Posterior crico-arytenoid

    • (ceratocricoid)

    • Lateral crico-arytenoid

    • Vocalis

    • Thyro-arytenoid

    • Oblique arytenoid

    • Transverse arytenoid

 

2. Back Zone

    • Trapezius

    • (Transversus nuchae)

    • Latissimus dorsi

    • Rhomboid major

    • Rhomboid minor

    • Levator scapulae

    • Serratus posterior inferior

    • Serratus posterior superior

    • Anterior cervical intertransversarii

    • Lateral posterior cervical intertransversarii

    • Intertransversarii laterals lumborum

    • Nuchael fascia

    • Erector Spinae

    • Spino-transversales

    • Transverso-spinales

    • Inter-spinales

    • Inter-transversarii

    • Throacolumbar fascia

 

3. Front Zone

    • (Sternals)

    • Pectoralis major

    • Pectoralis minor

    • Subclavius

    • Serratus anterior

    • Levatores costarum

    • External intercostal muscle

    • Internal intercostal membrane

    • Internal intercostal muscle

    • Internal intercostal membrane

    • Innermost intercostal muscle

    • Subcostales

    • Transversus throacis

    • Pectoral fascia

    • Clavipectoral fascia

    • Thoracic fascia

    • Endothoracic fascia

    • Diaphragm

  • Abdomen

    • Rectus abdominis

    • Pyramidalis

    • External oblique

    • Superficial inguinal ring

    • Internal oblique

    • Transversus abdominis

    • Linea alba

    • Linea semilunaris

    • Inguinal canal

    • Quadratus lumborum

    Abdominal fascia

    Pelvic fascia

    Pelvic diaphragm

    Perineal

 

4. Limbs

    • Deltoid

    • Supraspinatus

    • Infraspinatus

    • Teres minor

    • Teres major

    • Subscapularis

    • Biceps brachii

    • Coracobrachialis

    • Brachialis

    • Triceps brachii

    • Anconeus

    • Articulasis cubiti

    • Pronator teres

    • Flexor carpi radialis

    • Palmaris longus

    • Flexor carpi ulnaris

    • Flexor digitorum profundus

    • Flexor pollicis longus

    • Pronator quardratus

    • Brachioradialis

    • Extensor carpi radialis longus

    • Extensor carpi radialis brevis

    • Extensor digitorum

    • Extensor digiti minimi

    • Extensor carpi ulnaris

    • Supinator

    • Abductor pollicis longus

    • Extensor pollicis brevis

    • Extensor pollicis longus

    • Extensor indicis

    • Palmaris brevis

    • Abductor pollicis brevis

    • Flexor pollicis brevis

    • Opponnens pollicis

    • Adductor pollicis

    • Abductor digiti minimi

    • Flexor digiti minimi brevis

    • Opponens digiti minimi

    • Lumbricales

    • Dorsal interossei

    • Palmar interossei

    • Iliopsoas

    • (Psoas minor)

    • Gluteus maximus

    • Gluteus medius

    • Gluteus minimus

    • Gluteal aponeurosis

    • Tensor fascia latae

    • Piriformis

    • Obturator internus

    • Gemellus superior

    • Gemellus inferior

    • Quadratus femoris

    • Sartorius

    • Quadriceps femoris

    • Articuloris genus

    • Pectineus

    • Adductor longus

    • Adductor brevis

    • Adductor magnus

    • Adductor minimus

    • Gracilis

    • Obturator externus

    • Biceps femoris

    • Semitendinosus

    • Semimembranosus

    • Tibialis anterior

    • Extensor digitorum longus

    • Fibularis tertius

    • Extensor hallucis longus

    • Fibularis longus

    • Fibularis brevis

    • Triceps surae

    • Plantaris

    • Popliteus

    • Tibialis posterior

    • Flexor digitorum longus

    • Flexor hallucis longus

    • Extensor hallucis brevis

    • Extensor digitorum brevis

    • Abductor hallucis

    • Flexor hallucis brevis

    • Adductor hallucis

    • Abductor digiti minimi

    • (Opponens digiti minimi)

    • Flexor digiti minimi brevis

    • Flexor digitorum brevis

    • Quadratus plantae

    • Lumbricals

    • Dorsal interossei

    • Plantar interossei

 

Muscle Actions

  • Head

    Extra-ocular (Eyes)

    • Orbitalis: Protrudes the eyeball (minimal functional effect in humans).

    • Superior rectus: Elevates, adducts, and medially rotates the eyeball.

    • Inferior rectus: Depresses, adducts, and laterally rotates the eyeball.

    • Medial rectus: Adducts the eyeball (moves it toward the nose).

    • Lateral rectus: Abducts the eyeball (moves it toward the ear).

    • Common tendinous ring: * Superior oblique: Depresses, abducts, and medially rotates the eyeball.

    • Inferior oblique: Elevates, abducts, and laterally rotates the eyeball.

    • Levator palpebrae superioris: Elevates the upper eyelid.

    Auditory Ossicles (Ears)

    • Tensor tympani: Tenses the tympanic membrane to reduce sound transmission.

    • Stapedius: Stabilizes the stapes bone to dampen loud vibrations.

    • Mucosa of tympanic cavity: #### Facial

    • Epicranius (Occipitofrontalis): Raises eyebrows and wrinkles the forehead.

    • Procerus: Pulls down the skin between the eyebrows (frowning).

    • Nasalis: Flares and compresses the nostrils.

    • Depressor septi nasi: Depresses the nasal septum.

    • Orbicularis oculi: Closes the eyelids (blinking and squinting).

    • Corrugator supercilii: Draws eyebrows together medially (vertical frowning).

    • Depressor supercilii: Depresses the eyebrows.

    • Auricularis anterior: Moves the ear forward.

    • Auricularis superior: Elevates the ear.

    • Auricularis posterior: Moves the ear backward.

    • Orbicularis oris: Closes and protrudes (purses) the lips.

    • Depressor anguli: Pulls the corners of the mouth downward.

    • Transversus menti: Assists in depressing the corners of the mouth.

    • Risorius: Draws the corners of the mouth laterally (grimacing).

    • Zygomaticus major: Pulls corners of mouth upward and outward (smiling).

    • Zygomaticus minor: Elevates the upper lip.

    • Levator labii superioris: Elevates the upper lip.

    • Levator labii superioris alaeque nasi: Elevates the upper lip and flares the nostril.

    • Depressor labii inferioris: Pulls the lower lip downward.

    • Levator anguli oris: Elevates the corners of the mouth.

    • Modiolus: * Buccinator: Compresses the cheeks against teeth (chewing and blowing).

    • Mentalis: Wrinkles the chin and protrudes the lower lip.

    Masticatory (Chewing)

    • Masseter: Elevates the mandible to close the jaw.

    • Temporalis: Elevates and retracts the mandible.

    • Lateral pterygoid: Protrudes the mandible and assists in side-to-side grinding.

    • Medial pterygoid: Elevates the mandible and assists in side-to-side grinding.

    • Buccopharyngeal fascia: Masseteric fascia: Parotid fascia: * Temporal fascia: #### Tongue

    • Genioglossus: Protrudes and depresses the tongue.

    • Hyoglossus: Depresses and retracts the tongue.

    • Styloglossus: Elevates and retracts the tongue.

    • Superior longitudinal muscle: Shortens the tongue and turns the tip upward.

    • Inferior longitudinal muscle: Shortens the tongue and turns the tip downward.

    • Transverse muscle: Narrows and elongates the tongue.

    • Vertical muscle: Flattens and widens the tongue.

    • Palatoglossus: Elevates the posterior part of the tongue.

    Soft Palate & Fauces (Mouth & Throat)

    • Palatine aponeurosis: * Levator veli palatini: Elevates the soft palate during swallowing.

    • Tensor veli palatini: Tenses the soft palate.

    • Musculus uvulae: Elevates and shortens the uvula.

    • Palatopharyngeus: Tenses the soft palate and pulls the pharynx upward.

    Neck

    General

    • Platysma: Tenses the skin of the neck and depresses the lower jaw.

    • Longus colli: Flexes and rotates the neck.

    • Longus capitis: Flexes the head at the neck.

    • Scalenus anterior: Flexes the neck laterally and elevates the 1st rib.

    • Scalenus medius: Flexes the neck laterally and elevates the 1st rib.

    • Scalenus posterior: Flexes the neck laterally and elevates the 2nd rib.

    • (Scalenus minimus): Elevates the pleural dome.

    • Sternocleidomastoid: Rotates the head to the opposite side and flexes the neck.

    Sub-occiput

    • Rectus capitis anterior: Flexes the head at the atlanto-occipital joint.

    • Rectus capitis lateralis: Flexes the head laterally.

    • Rectus capitis posterior major: Extends and rotates the head.

    • Rectus capitis posterior minor: Extends the head.

    • Obliquus capitis superior: Extends the head and flexes it laterally.

    • Obliquus capitis inferior: Rotates the head.

    Supra-hyoid

    • Digastric: Depresses the mandible and elevates the hyoid bone.

    • Stylohyoid: Elevates and retracts the hyoid bone.

    • Mylohyoid: Elevates the hyoid and the floor of the mouth.

    • Geniohyoid: Pulls the hyoid bone forward and depresses the mandible.

    Infra-hyoid

    • Sternohyoid: Depresses the hyoid bone.

    • Omohyoid: Depresses and retracts the hyoid bone.

    • Sternothyroid: Depresses the larynx (thyroid cartilage).

    • Thyrohyoid: Depresses the hyoid bone and elevates the larynx.

    • (Levator glandulae thyroideae): #### Cervical

    • Investing layer / Pretracheal layer / Prevertebral layer: * Carotid sheath: #### Pharyngeal

    • Pharyngeal raphe / Pterygomandibular raphe: * Superior/Middle/Inferior constrictor: Constricts the pharyngeal wall during swallowing.

    • Stylopharyngeus: Elevates and widens the pharynx.

    • Salpingopharyngeus: Elevates the pharynx.

    • Peripharyngeal space / Buccopharyngeal fascia: #### Laryngeal

    • Cricothyroid: Tenses and elongates the vocal cords (raises pitch).

    • Posterior crico-arytenoid: Abducts the vocal cords (opens the airway).

    • (Ceratocricoid): * Lateral crico-arytenoid: Adducts the vocal cords (closes the airway).

    • Vocalis: Adjusts the tension of the vocal folds for speech.

    • Thyro-arytenoid: Relaxes the vocal folds.

    • Oblique / Transverse arytenoid: Adducts the arytenoid cartilages to close the glottis.

  • Upper Back

    • Trapezius: Elevates, rotates, and retracts the scapula.

    • (Transversus nuchae): * Latissimus dorsi: Extends, adducts, and medially rotates the arm.

    • Rhomboid major / minor: Retracts and stabilizes the scapula.

    • Levator scapulae: Elevates the scapula.

    • Serratus posterior inferior: Depresses the lower ribs.

    • Serratus posterior superior: Elevates the upper ribs.

    • Anterior / Lateral posterior cervical intertransversarii: Assists in lateral flexion of the neck.

    • Intertransversarii laterales lumborum: Assists in lateral flexion of the spine.

    • Nuchal fascia: ### Lower Back

    • Erector Spinae: Primary extensor of the vertebral column.

    • Spino-transversales: Extends and rotates the head and neck.

    • Transverso-spinales: Extends and rotates the vertebral column.

    • Inter-spinales: Extends the vertebral column.

    • Inter-transversarii: Lateral flexion of the spine.

    • Thoracolumbar fascia: ---

  • Thorax

    • (Sternalis): * Pectoralis major: Adducts, flexes, and medially rotates the arm.

    • Pectoralis minor: Protracts and depresses the scapula.

    • Subclavius: Depresses and stabilizes the clavicle.

    • Serratus anterior: Protracts the scapula and stabilizes it against the ribs.

    • Levatores costarum: Elevates the ribs.

    • External intercostal muscle: Elevates the ribs during inhalation.

    • Internal intercostal muscle: Depresses the ribs during forced exhalation.

    • Innermost intercostal muscle: Assists the internal intercostals.

    • Subcostales: Depresses the ribs.

    • Transversus thoracis: Depresses the costal cartilages.

    • Pectoral / Clavipectoral / Thoracic / Endothoracic fascia: * Diaphragm: The primary muscle for inspiration (expands the chest cavity).

    Abdomen

    • Rectus abdominis: Flexes the trunk (vertebral column).

    • Pyramidalis: Tenses the linea alba.

    • External oblique: Flexes and rotates the trunk.

    • Superficial inguinal ring: * Internal oblique: Flexes and rotates the trunk.

    • Transversus abdominis: Compresses the abdominal contents (core stability).

    • Linea alba / Linea semilunaris: Inguinal canal: Quadratus lumborum: Flexes the spine laterally and stabilizes the pelvis.

    • Abdominal / Pelvic fascia: * Pelvic diaphragm: Supports the pelvic viscera.

    • Perineal muscles: Supports the pelvic floor and helps control sphincters.

  • Upper Limbs

    • Deltoid: Primary abductor of the arm; flexes and extends the arm.

    • Supraspinatus: Initiates arm abduction and stabilizes the shoulder.

    • Infraspinatus: Externally rotates the arm.

    • Teres minor: Externally rotates the arm.

    • Teres major: Adducts and medially rotates the arm.

    • Subscapularis: Medially rotates the arm.

    • Biceps brachii: Flexes the elbow and supinates the forearm.

    • Coracobrachialis: Flexes and adducts the arm at the shoulder.

    • Brachialis: Primary flexor of the elbow.

    • Triceps brachii: Primary extensor of the elbow.

    • Anconeus: Assists in elbow extension.

    • Articularis cubiti: Pulls the joint capsule away during extension.

    • Pronator teres: Pronates the forearm.

    • Flexor carpi radialis: Flexes and abducts the wrist.

    • Palmaris longus: Flexes the wrist (weakly).

    • Flexor carpi ulnaris: Flexes and adducts the wrist.

    • Flexor digitorum profundus: Flexes the fingers and wrist.

    • Flexor pollicis longus: Flexes the thumb.

    • Pronator quadratus: Pronates the forearm.

    • Brachioradialis: Flexes the elbow.

    • Extensor carpi radialis longus / brevis: Extends and abducts the wrist.

    • Extensor digitorum: Extends the fingers and wrist.

    • Extensor digiti minimi: Extends the little finger.

    • Extensor carpi ulnaris: Extends and adducts the wrist.

    • Supinator: Supinates the forearm.

    • Abductor pollicis longus: Abducts and extends the thumb.

    • Extensor pollicis brevis / longus: Extends the thumb.

    • Extensor indicis: Extends the index finger.

    • Palmaris brevis: Tenses the skin of the palm.

    • Abductor pollicis brevis: Abducts the thumb.

    • Flexor pollicis brevis: Flexes the thumb.

    • Opponens pollicis: Opposes the thumb (moves it toward other fingers).

    • Adductor pollicis: Adducts the thumb.

    • Abductor digiti minimi: Abducts the little finger.

    • Flexor digiti minimi brevis: Flexes the little finger.

    • Opponens digiti minimi: Opposes the little finger.

    • Lumbricales: Flexes the knuckles and extends the fingers.

    • Dorsal interossei: Abducts the fingers (spreads them).

    • Palmar interossei: Adducts the fingers (pulls them together).

    Lower Limbs

    • Iliopsoas: Primary flexor of the hip.

    • (Psoas minor): Assists in flexing the pelvis.

    • Gluteus maximus: Primary extensor and external rotator of the hip.

    • Gluteus medius: Abducts the hip and stabilizes the pelvis.

    • Gluteus minimus: Abducts and medially rotates the hip.

    • Gluteal aponeurosis: * Tensor fascia latae: Abducts and flexes the hip.

    • Piriformis: Externally rotates the abducted hip.

    • Obturator internus: Externally rotates the hip.

    • Gemellus superior / inferior: Externally rotate the hip.

    • Quadratus femoris: Externally rotates the hip.

    • Sartorius: Flexes, abducts, and externally rotates the hip; flexes the knee.

    • Quadriceps femoris: Primary extensor of the knee.

    • Articularis genus: Pulls the knee joint capsule upward during extension.

    • Pectineus: Adducts and flexes the hip.

    • Adductor longus / brevis / magnus / minimus: Adducts the thigh.

    • Gracilis: Adducts the thigh and flexes the knee.

    • Obturator externus: Externally rotates the hip.

    • Biceps femoris: Flexes the knee and extends the hip.

    • Semitendinosus: Flexes the knee and extends the hip.

    • Semimembranosus: Flexes the knee and extends the hip.

    • Tibialis anterior: Dorsiflexes and inverts the foot.

    • Extensor digitorum longus: Extends the toes and dorsiflexes the foot.

    • Fibularis tertius: Dorsiflexes and everts the foot.

    • Extensor hallucis longus: Extends the big toe and dorsiflexes the foot.

    • Fibularis longus / brevis: Plantarflexes and everts the foot.

    • Triceps surae (Calves): Primary plantarflexor of the foot (standing on toes).

    • Plantaris: Assists in plantarflexion and knee flexion.

    • Popliteus: Unlocks the knee joint to initiate flexion.

    • Tibialis posterior: Plantarflexes and inverts the foot.

    • Flexor digitorum longus: Flexes the toes.

    • Flexor hallucis longus: Flexes the big toe.

    • Extensor hallucis brevis: Extends the big toe.

    • Extensor digitorum brevis: Extends the toes.

    • Abductor hallucis: Abducts the big toe.

    • Flexor hallucis brevis: Flexes the big toe.

    • Adductor hallucis: Adducts the big toe.

    • Abductor digiti minimi: Abducts the little toe.

    • (Opponens digiti minimi): Opposes the little toe.

    • Flexor digiti minimi brevis: Flexes the little toe.

    • Flexor digitorum brevis: Flexes the toes.

    • Quadratus plantae: Assists in flexing the toes.

    • Lumbricals: Flexes the toes at the base and extends the tips.

    • Dorsal interossei: Abducts the toes.

    • Plantar interossei: Adducts the toes.

See Also

References:

Category:human muscles by body part (no date) Wikimedia Commons. Available at: https://commons.wikimedia.org/wiki/Category:Human_muscles_by_body_part (Accessed: March 23, 2023).

FCAT (Federative Committee on Anatomical Terminology), (1998) Terminologia Anatomica: International Anatomical Terminology, Stuttgart, Thieme Publishing Group.

Deniz Ates https://www.mrdenizates.com
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