Muscle Attachments and Functions Quiz

Intercalated Discs

• Intercalated Discs are structures that keep cells of cardiac muscle together

Smooth Muscle

• Smooth Muscle lacks striations and is involuntary
• Relatively short, fusiform cells (thick in middle, tapered at ends)
• One centrally located nucleus
• Visceral Muscle - forms layers of digestive, respiratory, and urinary tract: propels contents through an organ, regulates diameter of blood vessels

Functions of Muscles

• Movement
  • Move from place to place
  • Movement of body parts and body contents in breathing, circulation, feeding and digestion, defecation, urination, and childbirth
  • Role in communication: speech, writing, nonverbal communications
• Stability
  • Maintain posture by preventing unwanted movements
  • Antigravity muscles: resist pull of gravity and prevent us from falling or slumping over
  • Stabilize joints
• Control of openings and passageways
  • Sphincters: internal muscular rings that control the movement of food, bile, blood, and other materials within the body
• Heat production by skeletal muscles
  • As much as 85% of our body heat
• Glycemic control
  • Regulation of blood glucose concentrations within its normal range

Muscle Attachments

• Indirect attachment to bone
  • Tendons bridge the gap between muscle ends and bony attachment
  • Collagen fibers of the endo-, peri-, and epimysium continue into the tendon
  • From there into the periosteum and the matrix of bone
  • Very strong structural continuity from muscle to bone
  • Biceps brachii, Achilles tendon
• Direct (fleshy) attachment to bone
  • Little separation between muscle and bone
  • Muscle seems to immerge directly from bone
  • Margins of brachialis, lateral head of triceps brachii

Muscle Origins and Insertions

• Origin
  • Bony attachment at stationary end of muscle
• Belly
  • Thicker, middle region of muscle between origin and insertion
• Insertion
  • Bony attachment to mobile end of muscle

Functional Groups of Muscles

• Action - the effects produced by a muscle
  • To produce or prevent movement
• Prime mover (agonist)
  • Muscle that produces most of force during a joint action
• Synergist
  • Muscle that aids the prime mover
  • Stabilizes the nearby joint
  • Modifies the direction of movement
• Antagonist
  • Opposes the prime mover
  • Relaxes to give prime mover control over action
  • Preventing excessive movement and injury
  • Antagonistic pairs - muscles that act on opposite sides of a joint
• Fixator
  • Muscle that prevents movement of bone

Intrinsic and Extrinsic Muscles

• Intrinsic muscles - entirely contained within a region, such as the hand
  • Both its origin and insertion there
• Extrinsic muscles – act on a designated region, but has its origin elsewhere
  • Fingers: extrinsic muscles in the forearm

Muscle Innervation

• Innervation of a muscle - refers to identity of the nerve that stimulates it
  • Enables diagnosis of nerve, spinal cord, and brainstem injuries from their effects on muscle function
• Spinal nerves arise from the spinal cord
  • Emerge through intervertebral foramina
  • Immediately branch into a posterior and anterior ramus
  • Innervate muscles below the neck
  • Plexus: weblike network of spinal nerves adjacent to the vertebral column
• Cranial nerves arise from the base of the brain
  • Emerge through skull foramina
  • Innervate the muscles of the head and neck
  • Numbered CN I to CN XII

How Muscles Are Named

• Latin names
  • Depressor labii inferioris – depresses the bottom lip
  • flexor digiti minimi brevis – short muscle that flexes the smallest finger
• Describes distinctive aspects of the structure, location, or action of a muscle

A Learning Strategy

• Examine models, cadavers, dissected animals, or a photographic atlas to get visual images of the muscle

• When studying a particular muscle, palpate it on yourself if possible

• Locate origins and insertions of muscles on an articulated skeleton

• Study derivation of each muscle name

  • Usually describes the muscle’s location, appearance, origin, insertion, or action

• Say the names aloud to yourself or a study partner, and spell them correctly### Anterior View

• Superficial Muscles:

  • Frontalis: Located on forehead, raises eyebrows.
  • Orbicularis oculi: Located around eye, closes eye.
  • Zygomaticus major: Located on cheek, lifts corner of mouth for smiling.
  • Orbicularis oris: Located around mouth, closes mouth.
  • Platysma: Located on neck, pulls down corner of mouth.
  • Masseter: Located on cheek, elevates mandible for chewing.
  • Sternocleidomastoid: Located on side of neck, flexes and rotates head.
  • Trapezius: Located on upper back and neck, elevates and retracts scapula, rotates scapula, extends head.
  • Deltoid: Located on shoulder, abducts arm, flexes and extends arm.
  • Pectoralis major: Located on chest, flexes and adducts arm.
  • Biceps brachii: Located on front of upper arm, flexes elbow, supinates forearm.
  • Brachioradialis: Located on forearm, flexes elbow.
  • Flexor carpi radialis: Located on forearm, flexes wrist, abducts wrist.
  • Palmaris longus: Located on forearm, flexes wrist.
  • Flexor carpi ulnaris: Located on forearm, flexes wrist, adducts wrist.
  • Sartorius: Located on thigh, flexes, abducts, and externally rotates hip; flexes knee.
  • Rectus femoris: Located on front of thigh, extends knee, flexes hip.
  • Vastus lateralis: Located on side of thigh, extends knee.
  • Vastus medialis: Located on inside of thigh, extends knee.
  • Tibialis anterior: Located on shin, dorsiflexes ankle, inverts foot.
  • Extensor digitorum longus: Located on shin, extends toes, dorsiflexes ankle.

Posterior View

• Superficial Muscles:
  • Occipitalis: Located on back of head, retracts scalp.
  • Splenius capitis: Located on back of neck, extends and rotates head.
  • Trapezius: Located on upper back and neck, elevates and retracts scapula, rotates scapula, extends head.
  • Latissimus dorsi: Located on back, extends, adducts, and internally rotates arm.
  • Gluteus maximus: Located on buttocks, extends hip, laterally rotates hip.
  • Semitendinosus: Located on back of thigh, extends hip, flexes knee.
  • Biceps femoris: Located on back of thigh, extends hip, flexes knee.
  • Gastrocnemius: Located on calf, plantar flexes foot, flexes knee.
  • Soleus: Located on calf, plantar flexes foot.
  • Extensor hallucis longus: Located on shin, extends big toe, dorsiflexes ankle, inverts foot.
  • Fibularis longus: Located on outside of calf, plantar flexes foot, everts foot.

Deep Muscles (Anterior View)

• Deep Muscles:
  • Pectoralis minor: Located on chest, depresses and protracts scapula.
  • Coracobrachialis: Located on upper arm, flexes and adducts arm.
  • Biceps brachii: Located on front of upper arm, flexes elbow, supinates forearm.
  • Brachialis: Located on upper arm, flexes elbow.
  • Flexor digitorum superficialis: Located on forearm, flexes middle phalanges of fingers.
  • Flexor carpi ulnaris: Located on forearm, flexes wrist, adducts wrist.
  • Pronator teres: Located on forearm, pronates forearm, flexes elbow.
  • Flexor pollicis longus: Located on forearm, flexes thumb, pronates forearm.
  • Flexor digitorum profundus: Located on forearm, flexes distal phalanges of fingers.
  • Pronator quadratus: Located on forearm, pronates forearm.
  • Extensor digitorum (cut): Located on forearm, extends fingers, dorsiflexes ankle.
  • Extensor carpi ulnaris (cut): Located on forearm, extends wrist, adducts wrist.
  • Rectus abdominis: Located on abdomen, flexes and rotates lumbar spine.
  • External abdominal oblique: Located on abdomen, flexes and rotates lumbar spine.
  • Internal abdominal oblique: Located on abdomen, flexes and rotates lumbar spine.
  • Transverse abdominis: Located on abdomen, compresses abdominal cavity.
  • Adductors:
    • Adductor longus: Located on medial thigh, adducts, flexes, and rotates hip.
    • Adductor magnus: Located on medial thigh, adducts and extends hip.
    • Gracilis: Located on medial thigh, adducts, flexes, and medially rotates hip.
    • Pectineus: Located medial thigh, adducts, flexes, and laterally rotates hip.
  • Tensor fasciae latae: Located on hip, flexes, abducts, and medially rotates hip.

Deep Muscles (Posterior View)

• Deep Muscles:
  • Semispinalis capitis: Located on back of neck, extends and rotates head.
  • Splenius capitis: Located on back of neck, extends and rotates head.
  • Levator scapulae: Located on neck, elevates and depresses scapula, rotates scapula.
  • Supraspinatus: Located on shoulder, abducts arm, externally rotates arm.
  • Infraspinatus: Located on shoulder, externally rotates arm, adducts arm.
  • Teres minor: Located on shoulder, externally rotates arm, adducts arm.
  • Teres major: Located on shoulder, extends, adducts, and internally rotates arm.
  • Triceps brachii: Located on back of upper arm, extends elbow.
  • Rhomboideus minor: Located on back, retracts and elevates scapula.
  • Rhomboideus major: Located on back, retracts and elevates scapula.
  • Serratus posterior inferior: Located on back, depresses ribs.
  • Erector spinae: Located on back, extends and rotates vertebral column.
  • Lateral rotators:
    • Piriformis (located on buttock, laterally rotates and abducts the hip)
    • Obturator internus (located on pelvic wall, laterally rotates and abducts the hip)
    • Obturator externus (located on pelvic wall, laterally rotates and abducts the hip)
    • Gemelli (located on buttocks, laterally rotates and abducts the hip)
    • Quadratus femoris (located on buttocks, laterally rotates and abducts the hip)
  • Gluteus medius: Located on buttocks, abducts and medially rotates hip.
  • Gluteus minimus: Located on buttocks, abducts and medially rotates hip.
  • Vastus intermedius: Located on thigh, extends knee.
  • Tibialis posterior: Located on shin, plantar flexes ankle, inverts foot.
  • Flexor digitorum longus: Located on shin, flexes toes, plantar flexes ankle.
  • Flexor hallucis longus: Located on shin, flexes big toe, plantar flexes ankle.
  • Soleus (cut): Located on calf, plantar flexes foot.
  • Calcaneal tendon: (attached to the heel, known as Achilles tendon)

Test your knowledge on muscle attachment types and their functions with this quiz! Explore concepts like indirect and direct muscle attachments, origins, and the role of tendons in your understanding of human anatomy.