Functional Anatomy

Functional Anatomy Learning Objectives

• Explain functional anatomy as it relates to movement.
• Explain the effect posture has on movement and performance.
• Describe the influence of optimal neuromuscular efficiency on human movement.
• Explain potential causes for common altered movement patterns.
• Relate altered movement patterns to muscle imbalance.
• Explain the influence altered movement patterns will have on client programming.

Introduction to Human Movement Science

• Human movement science studies how the human movement system (HMS) functions interdependently.
• The HMS consists of:
  • Muscular system
  • Skeletal system
  • Nervous system
• These systems collaborate to form interdependent links.
• The system is aware of its relationship to internal and external environments.
• This awareness gathers necessary information to produce appropriate movement patterns.
• This process ensures optimal functioning of the HMS and optimal human movement.

Functional Anatomy

• Traditional training focuses on specific body parts in single planes of motion.
• Anatomy has been traditionally taught in isolated, fragmented components.
• This approach mapped the body, provided simplistic answers about structures, and categorized components.
• The everyday functioning of the human body is an integrated and multidimensional system.
• The new paradigm presents anatomy from a functional, integrated perspective.
• The central nervous system (CNS) optimizes the selection of muscle synergies, not individual muscles.
• The CNS coordinates deceleration, stabilization, and acceleration for all muscles in all three planes of motion.
• Muscles react to external stimuli such as gravity, momentum, ground reaction forces, and forces created by other functioning muscles.
• Muscles can dynamically take on one of four movement production roles based on load, direction of resistance, body position, and movement pattern.

Muscle Roles

• Agonist:
  • Prime mover for a given movement pattern.
  • Provides a majority of force generation.
  • Examples:
    • Gluteus maximus for hip extension.
    • Pectoralis major for pressing movements.
    • Biceps brachii for elbow flexion.
• Antagonist:
  • Acts in direct opposition to the agonist.
  • Relaxes when the agonist contracts, allowing joint movement (reciprocal inhibition).
  • Examples:
    • Psoas and rectus femoris (hip flexors) are antagonistic to the gluteus maximus.
• Synergist:
  • Assists the agonist but is not the primary source of force production.
  • Examples:
    • Triceps brachii are synergistic to the pectoralis major for pressing movements.
    • Hamstrings assist the gluteus maximus during hip extension.
• Stabilizer:
  • Supports associated joints while prime movers and synergists contract.
  • Examples:
    • Muscles of the rotator cuff support the glenohumeral joint.
    • Deltoids and latissimus dorsi create movement at the shoulder.
• All muscles work in concert to produce efficient motion.
• A muscle's role (agonist, antagonist, or synergist) depends on the movement pattern.
• Muscles that are agonists for flexion are antagonists for extension.
• View muscle function in all planes of motion throughout the full muscle action spectrum (eccentric, concentric, and isometric).

Skeletal Muscles

• Traditional explanation: muscles work concentrically and predominantly in one plane of motion.
• Muscles function in all planes of motion, throughout the full muscle action spectrum.
• Corrective exercise programs become more specific with a broader understanding of functional anatomy.
• The following sections list each muscle's:
  • Origins (beginning attachment point)
  • Insertions (where it connects back to the skeleton)
  • Isolated (concentric) functions
  • Integrated (eccentric and isometric) functions
  • Innervations

Leg Muscles

Anterior Tibialis

• ORIGIN: Lateral condyle and proximal two-thirds of the lateral surface of the tibia
• INSERTION: Medial and plantar aspects of the medial cuneiform and the base of the first metatarsal
• ISOLATED FUNCTION:
  • Concentric Action: Ankle dorsiflexion and inversion
• INTEGRATED FUNCTION:
  • Eccentric Action: Ankle plantar flexion and eversion
  • Isometric Action: Stabilizes the arch of the foot
• INNERVATION: Deep fibular (peroneal) nerve

Posterior Tibialis

• ORIGIN: Proximal two-thirds of posterior surface of the tibia and fibula
• INSERTION: Every tarsal bone (navicular, cuneiform, and cuboid) but the talus plus the bases of the second through the fourth metatarsal bones—the main insertion is on the navicular tuberosity and the medial cuneiform bone.
• ISOLATED FUNCTION:
  • Concentric Action: Ankle plantar flexion and inversion of the foot
• INTEGRATED FUNCTION:
  • Eccentric Action: Ankle dorsiflexion and eversion
  • Isometric Action: Stabilizes the arch of the foot
• INNERVATION: Tibial nerve

Soleus

• ORIGIN: Posterior surface of the fibular head and proximal one-third of its shaft and from the posterior side of the tibia
• INSERTION: Calcaneus via the Achilles tendon
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates plantar flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates ankle dorsiflexion
  • Isometric Action: Stabilizes the foot and ankle complex
• INNERVATION: Tibial nerve

Gastrocnemius

• ORIGIN: Posterior aspect of the lateral and medial femoral condyles
• INSERTION: Calcaneus via the Achilles tendon
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates plantar flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates ankle dorsiflexion
  • Isometric Action: Isometrically stabilizes the foot and ankle complex
• INNERVATION: Tibial nerve

Fibularis (Peroneus) Longus

• ORIGIN: Lateral condyle of tibia, head and proximal two-thirds of the lateral surface of the fibula
• INSERTION: Lateral surface of the medial cuneiform and lateral side of the base of the first metatarsal
• ISOLATED FUNCTION:
  • Concentric Action: Plantar flexes and everts the foot
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates ankle dorsiflexion and inversion
  • Isometric Action: Stabilizes the foot and ankle complex
• INNERVATION: Superficial fibular (peroneal) nerve

Biceps Femoris, Long Head

• ORIGIN: Ischial tuberosity of the pelvis, part of the sacrotuberous ligament
• INSERTION: Head of the fibula
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates knee flexion, hip extension, and tibial external rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates knee extension, hip flexion, and tibial internal rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex and knee
• INNERVATION: Tibial nerve

Vastus Medialis

• ORIGIN: Lower region of intertrochanteric line, medial lip of linea aspera, and proximal medial supracondylar line of the femur
• INSERTION: Base of patella and tibial tuberosity of the tibia
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates knee extension
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates knee flexion
  • Isometric Action: Stabilizes the knee
• INNERVATION: Femoral nerve

Vastus Intermedius

• ORIGIN: Anterior-lateral regions of the upper two-thirds of the femur
• INSERTION: Base of patella and tibial tuberosity of the tibia
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates knee extension
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates knee flexion
  • Isometric Action: Stabilizes the knee
• INNERVATION: Femoral nerve

Rectus Femoris

• ORIGIN: Anterior-inferior iliac spine of the pelvis
• INSERTION: Base of patella and tibial tuberosity of the tibia
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates knee extension and hip flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates knee flexion and hip extension
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex and knee
• INNERVATION: Femoral nerve

Hip Muscles

Adductor Longus

• ORIGIN: Anterior surface of the inferior pubic ramus of the pelvis
• INSERTION: Linea aspera of the femur
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip adduction, flexion, and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip abduction, extension, and external rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Obturator nerve

Adductor Magnus, Anterior Fibers

• ORIGIN: Ischial ramus of the pelvis
• INSERTION: Linea aspera of the femur
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip adduction, flexion, and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip abduction, extension, and external rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Obturator nerve

Adductor Magnus, Posterior Fibers

• ORIGIN: Ischial tuberosity of the pelvis
• INSERTION: Adductor tubercle on femur
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip adduction, extension, and external rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip abduction, flexion, and internal rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Sciatic nerve

Adductor Brevis

• ORIGIN: Anterior surface of the inferior pubic ramus of the pelvis
• INSERTION: Proximal one-third of the linea aspera of the femur
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip adduction, flexion, and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip abduction, extension, and external rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Obturator nerve

Gracilis

• ORIGIN: Anterior aspect of lower body of pubis
• INSERTION: Proximal medial surface of the tibia (pes anserine)
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip adduction, flexion, and internal rotation and assists in tibial internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip abduction, extension, and external rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex and knee
• INNERVATION: Obturator nerve

Pectineus

• ORIGIN: Pectineal line on the superior pubic ramus of the pelvis
• INSERTION: Pectineal line on the posterior surface of the upper femur
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip adduction, flexion, and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip abduction, extension, and external rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Obturator nerve

Gluteus Medius, Anterior Fibers

• ORIGIN: Outer surface of the ilium
• INSERTION: Lateral surface of the greater trochanter of the femur
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip abduction and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip adduction and external rotation
  • Isometric Action: Dynamically stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Superior gluteal nerve

Gluteus Medius, Posterior Fibers

• ORIGIN: Outer surface of the ilium
• INSERTION: Lateral surface of the greater trochanter of the femur
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip abduction and external rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip adduction and internal rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Superior gluteal nerve

Gluteus Minimus

• ORIGIN: Ilium between the anterior and inferior gluteal line
• INSERTION: Greater trochanter of the femur
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip abduction, flexion, and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates frontal plane hip adduction, extension, and external rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Superior gluteal nerve

Tensor Fascia Latae

• ORIGIN: Outer surface of the iliac crest just posterior to the anterior superior iliac spine of the pelvis
• INSERTION: Proximal one-third of the iliotibial band
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip flexion, abduction, and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip extension, adduction, and external rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Superior gluteal nerve

Gluteus Maximus

• ORIGIN: Outer ilium, posterior side of sacrum and coccyx, and part of the sacrotuberous and posterior sacroiliac ligament
• INSERTION: Gluteal tuberosity of the femur and iliotibial tract
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip extension and external rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip flexion, internal rotation, and tibial internal rotation via the iliotibial band
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Inferior gluteal nerve

Piriformis

• ORIGIN: Anterior surface of the sacrum
• INSERTION: The greater trochanter of the femur
• ISOLATED FUNCTION:
  • Concentric Action: Accelerates hip external rotation, abduction, and extension
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates hip internal rotation, adduction, and flexion
  • Isometric Action: Stabilizes the hip and sacroiliac joints
• INNERVATION: Sciatic nerve

Abdominal Muscles

Rectus Abdominis

• ORIGIN: Pubic symphysis of the pelvis
• INSERTION: Ribs 5–7
• ISOLATED FUNCTION:
  • Concentric Action: Spinal flexion, lateral flexion, and rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal extension, lateral flexion, and rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Intercostal nerve T7–T12

External Oblique

• ORIGIN: External surface of ribs 4–12
• INSERTION: Anterior iliac crest of the pelvis, linea alba, and contralateral rectus sheaths
• ISOLATED FUNCTION:
  • Concentric Action: Spinal flexion, lateral flexion, and contralateral rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal extension, lateral flexion, and rotation
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Intercostal nerves (T8–T12), iliohypogastric (L1), and ilioinguinal (L1)

Internal Oblique

• ORIGIN: Anterior two-thirds of the iliac crest of the pelvis and thoracolumbar fascia
• INSERTION: Ribs 9–12, linea alba, and contralateral rectus sheaths
• ISOLATED FUNCTION:
  • Concentric Action: Spinal flexion (bilateral), lateral flexion, and ipsilateral rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal extension, rotation, and lateral flexion
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Intercostal nerves (T8–T12), iliohypogastric (L1), and ilioinguinal (L1)

Transverse Abdominis

• ORIGIN: Ribs 7–12, anterior two-thirds of the iliac crest of the pelvis, and thoracolumbar fascia
• INSERTION: Linea alba and contralateral rectus sheaths
• ISOLATED FUNCTION:
  • Concentric Action: Increases intra-abdominal pressure and supports the abdominal viscera
• INTEGRATED FUNCTION:
  • Isometric Action: Synergistically with the internal oblique, multifidus, and deep erector spinae to stabilize the lumbo-pelvic-hip complex
• INNERVATION: Intercostal nerves (T7–T12), iliohypogastric (L1), and ilioinguinal (L1)

Diaphragm

• ORIGIN:
  • Costal part: Inner surfaces of the cartilages and adjacent bony regions of ribs 6–12
  • Sternal part: Posterior side of the xiphoid process
  • Crural (lumbar) part: (1) Two aponeurotic arches covering the external surfaces of the quadratus lumborum and psoas major and (2) right and left crus, originating from the bodies of L1–L3 and their intervertebral discs
• INSERTION: Central tendon
• ISOLATED FUNCTION:
  • Concentric Action: Pulls the central tendon inferiorly, increasing the volume in the thoracic cavity
• INTEGRATED FUNCTION:
  • Isometric Action: Stabilization of the lumbo-pelvic-hip complex
• INNERVATION: Phrenic nerve (C3–C5)

Back, Chest, and Shoulder Muscles

Superficial Erector Spinae

• Complex muscle group: iliocostalis, longissimus, and spinalis muscles
• Subdivided based on the vertebrae at which they insert
• Common origin: iliac crest of the pelvis, sacrum, and spinous and transverse processes of T1–L5

Iliocostalis: Lumborum Division

• ORIGIN: Common origin
• INSERTION: Inferior border of ribs 7–12
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension, rotation, and lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion, rotation, and lateral flexion
  • Isometric Action: Stabilizes the spine during functional movements
• INNERVATION: Dorsal rami of thoracic and lumbar nerves

Iliocostalis: Thoracis Division

• ORIGIN: Common origin
• INSERTION: Superior border of ribs 1–6
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension, rotation, and lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion, rotation, and lateral flexion
  • Isometric Action: Stabilizes the spine during functional movements
• INNERVATION: Dorsal rami of thoracic nerves

Iliocostalis: Cervicus Division

• ORIGIN: Common origin
• INSERTION: Transverse processes of C4–C6
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension, rotation, and lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion, rotation, and lateral flexion
  • Isometric Action: Stabilizes the spine during functional movements
• INNERVATION: Dorsal rami of thoracic nerves

Longissimus: Thoracis Division

• ORIGIN: Common origin
• INSERTION: Transverse processes of T1–T12 and ribs 2–12
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension, rotation, and lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion, rotation, and lateral flexion
  • Isometric Action: Stabilizes the spine during functional movements
• INNERVATION: Dorsal rami of thoracic and lumbar nerves

Longissimus: Cervicus Division

• ORIGIN: Common origin
• INSERTION: Transverse processes of C6–C2
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension, rotation, and lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion, rotation, and lateral flexion
  • Isometric Action: Stabilizes the spine during functional movements
• INNERVATION: Dorsal rami of cervical nerves

Longissimus: Capitis Division

• ORIGIN: Common origin
• INSERTION: Mastoid process of the skull
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension, rotation, and lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion, rotation, and lateral flexion
  • Isometric Action: Stabilizes the spine during functional movements
• INNERVATION: Dorsal rami of cervical nerves

Spinalis: Thoracis Division

• ORIGIN: Common origin
• INSERTION: Spinous processes of T7–T4
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension, rotation, and lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion, rotation, and lateral flexion
  • Isometric Action: Stabilizes the spine during functional movements
• INNERVATION: Dorsal rami of thoracic nerves

Spinalis: Cervicus Division

• ORIGIN: Common origin
• INSERTION: Spinous processes of C3–C2
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension, rotation, and lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion, rotation, and lateral flexion
  • Isometric Action: Stabilizes the spine during functional movements
• INNERVATION: Dorsal rami of cervical nerves

Spinalis: Capitis Division

• ORIGIN: Common origin
• INSERTION: Between the superior and inferior nuchal lines on occipital bone of the skull
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension, rotation, and lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion, rotation, and lateral flexion
  • Isometric Action: Stabilizes the spine during functional movements
• INNERVATION: Dorsal rami of cervical nerves

Quadratus Lumborum

• ORIGIN: Iliac crest of the pelvis
• INSERTION: 12th rib and transverse processes L2–L5
• ISOLATED FUNCTION:
  • Concentric Action: Spinal lateral flexion
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates contralateral lateral spinal flexion
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex
• INNERVATION: Spinal nerves (T12–L3)

Transversospinalis: Thoracis Division

• ORIGIN: Transverse processes of T12–T7
• INSERTION: Spinous processes of T4–C6
• ISOLATED FUNCTION:
  • Concentric Action: Produces spinal extension and lateral flexion; extension and contralateral rotation of the head
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates lateral flexion of the spine, flexion, and contralateral rotation of the head
  • Isometric Action: Stabilizes the spine
• INNERVATION: Dorsal rami C1–T6 spinal nerves

Transversospinalis: Cervicus Division

• ORIGIN: Transverse processes of T6–C4
• INSERTION: Spinous processes of C5–C2
• ISOLATED FUNCTION:
  • Concentric Action: Produces spinal extension and lateral flexion and extension and contralateral rotation of the head
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates lateral flexion of the spine, and flexion and contralateral rotation of the head
  • Isometric Action: Stabilizes the spine
• INNERVATION: Dorsal rami C1–T6 spinal nerves

Transversospinalis: Capitus Division

• ORIGIN: Transverse processes of T6–C7
• Articular processes of C6–C4
• INSERTION: Nuchal line of occipital bone of the skull
• ISOLATED FUNCTION:
  • Concentric Action: Produces spinal extension and lateral flexion and extension and contralateral rotation of the head
• INTEGRATED FUNCTION:
  • Eccentric Action: Decelerates lateral flexion of the spine, and flexion and contralateral rotation of the head
  • Isometric Action: Stabilizes the spine
• INNERVATION: Dorsal rami C1–T6 spinal nerves

Multifidus

• ORIGIN: Posterior aspect of the sacrum and processes of the lumbar, thoracic, and cervical spine
• INSERTION: Spinous processes 1 to 4 segments above the origin
• ISOLATED FUNCTION:
  • Concentric Action: Spinal extension and contralateral rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Spinal flexion and rotation
  • Isometric Action: Stabilizes the spine
• INNERVATION: Corresponding spinal nerves

Latissimus Dorsi

• ORIGIN: Spinous processes of T7–T12, iliac crest of the pelvis, thoracolumbar fascia, and ribs 9–12
• INSERTION: Inferior angle of the scapula and intertubercular groove of the humerus
• ISOLATED FUNCTION:
  • Concentric Action: Shoulder extension, adduction, and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Shoulder flexion, abduction, external rotation, and spinal flexion
  • Isometric Action: Stabilizes the lumbo-pelvic-hip complex and shoulder
• INNERVATION: Thoracodorsal nerve (C6–C8)

Serratus Anterior

• ORIGIN: Ribs 4–12
• INSERTION: Medial border of the scapula
• ISOLATED FUNCTION:
  • Concentric Action: Scapular protraction
• INTEGRATED FUNCTION:
  • Eccentric Action: Scapular retraction
  • Isometric Action: Stabilizes the scapula
• INNERVATION: Long thoracic nerve (C5–C7)

Rhomboids

• ORIGIN: Spinous processes of C7–T5
• INSERTION: Medial border of the scapula
• ISOLATED FUNCTION:
  • Concentric Action: Produces scapular retraction and downward rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Scapular protraction and upward rotation
  • Isometric Action: Stabilizes the scapula
• INNERVATION: Dorsal scapular nerve (C4–C5)

Lower Trapezius

• ORIGIN: Spinous processes of T6–T12
• INSERTION: Spine of the scapula
• ISOLATED FUNCTION:
  • Concentric Action: Scapular depression
• INTEGRATED FUNCTION:
  • Eccentric Action: Scapular elevation
  • Isometric Action: Stabilizes the scapula
• INNERVATION: Cranial nerve XI and ventral rami C2–C4

Middle Trapezius

• ORIGIN: Spinous processes of T1–T5
• INSERTION: Acromion process of the scapula and superior aspect of the spine of the scapula
• ISOLATED FUNCTION:
  • Concentric Action: Scapular retraction
• INTEGRATED FUNCTION:
  • Eccentric Action: Scapular protraction and elevation
  • Isometric Action: Stabilizes scapula
• INNERVATION: Cranial nerve XI and ventral rami C2–C4

Upper Trapezius

• ORIGIN: External occipital protuberance of the skull and spinous process of C7
• INSERTION: Lateral third of the clavicle and acromion process of the scapula
• ISOLATED FUNCTION:
  • Concentric Action: Cervical extension, lateral flexion, and rotation and scapular elevation
• INTEGRATED FUNCTION:
  • Eccentric Action: Cervical flexion, lateral flexion, rotation, and scapular depression
  • Isometric Action: Stabilizes the cervical spine and scapula and stabilizes the medial border of the scapula creating a stable base for the prime movers during scapular abduction and upward rotation
• INNERVATION: Cranial nerve XI and ventral rami C2–C4

Levator Scapulae

• ORIGIN: Transverse processes of C1–C4
• INSERTION: Superior vertebral border of the scapula
• ISOLATED FUNCTION:
  • Concentric Action: Cervical extension, lateral flexion, and ipsilateral rotation when the scapula is anchored and assists in elevation and downward rotation of the scapula
• INTEGRATED FUNCTION:
  • Eccentric Action: Cervical flexion, contralateral cervical rotation, lateral flexion, scapular depression, and upward rotation when the neck is stabilized
  • Isometric Action: Stabilizes the cervical spine and scapula
• INNERVATION: Ventral rami C3–C4 and dorsal scapular nerve

Pectoralis Major

• ORIGIN: Anterior surface of the clavicle, anterior surface of the sternum, and cartilage of ribs 1–7
• INSERTION: Greater tubercle of the humerus
• ISOLATED FUNCTION:
  • Concentric Action: Shoulder flexion (clavicular fibers), horizontal adduction, and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Shoulder extension, horizontal abduction, and external rotation
  • Isometric Action: Stabilizes the shoulder girdle
• INNERVATION: Medial and lateral pectoral nerves (C5–C7)

Pectoralis Minor

• ORIGIN: Ribs 3–5
• INSERTION: Coracoid process of the scapula
• ISOLATED FUNCTION:
  • Concentric Action: Protracts the scapula
• INTEGRATED FUNCTION:
  • Eccentric Action: Scapular retraction
  • Isometric Action: Stabilizes the shoulder girdle
• INNERVATION: Medial pectoral nerve (C6–T1)

Anterior Deltoid

• ORIGIN: Lateral third of the clavicle
• INSERTION: Deltoid tuberosity of the humerus
• ISOLATED FUNCTION:
  • Concentric Action: Shoulder flexion and internal rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Shoulder extension and external rotation
  • Isometric Action: Stabilizes the shoulder girdle
• INNERVATION: Axillary nerve (C5–C6)

Medial Deltoid

• ORIGIN: Acromion process of the scapula
• INSERTION: Deltoid tuberosity of the humerus
• ISOLATED FUNCTION:
  • Concentric Action: Shoulder abduction
• INTEGRATED FUNCTION:
  • Eccentric Action: Shoulder adduction
  • Isometric Action: Stabilizes the shoulder girdle
• INNERVATION: Axillary nerve (C5–C6)

Posterior Deltoid

• ORIGIN: Spine of the scapula
• INSERTION: Deltoid tuberosity of the humerus
• ISOLATED FUNCTION:
  • Concentric Action: Shoulder extension and external rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Shoulder flexion and internal rotation
  • Isometric Action: Stabilizes the shoulder girdle
• INNERVATION: Axillary nerve (C5–C6)

Teres Minor

• ORIGIN: Lateral border of the scapula
• INSERTION: Greater tubercle of the humerus
• ISOLATED FUNCTION:
  • Concentric Action: Shoulder external rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Shoulder internal rotation
  • Isometric Action: Stabilizes the shoulder girdle
• INNERVATION: Axillary nerve (C5–C6)

Infraspinatus

• ORIGIN: Infraspinous fossa of the scapula
• INSERTION: Middle facet of the greater tubercle of the humerus
• ISOLATED FUNCTION:
  • Concentric Action: Shoulder external rotation
• INTEGRATED FUNCTION:
  • Eccentric Action: Shoulder internal rotation
  • Isometric Action: Stabilizes the shoulder girdle
• INNERVATION: Suprascapular nerve (C5–C6)

Subscapularis

• ORIGIN: Subscapular fossa of the scapula
• INSERTION: Lesser tubercle of the humerus
• ISOLATED FUNCTION:
  • Concentric Action: Shoulder internal rotation
• INTEGRATED FUNCTION: