5.1: Anatomy of the Muscular System Flashcards
Key Terms
What is conscious control?
Ability to move muscles at own will
Define peripheral nerves.
- Nerves outside of the brain and spinal cord
- they send messages to and from the brain
What constitutes the central nervous system?
Brain and spinal cord
What are motor actions?
- Message FROM the central nervous system
- TO a muscle
What are sensory actions?
- Message FROM the external environment
- TO a central nervous system
What is the function of tendons?
Connect skeletal muscle to bone; flexible, can bend at joints, cushion against sudden movement
What do ligaments connect?
Bone to bone; stabilize joints
What is the origin in muscle anatomy?
- the bony site of attachment that is stationary during the movement
- the “fixed” point
Define insertion in muscle contraction.
Place that is MOVED during a muscle contraction
What is the action of a muscle?
The EFFECT produced by the muscle’s contraction
What does innervation refer to?
The peripheral nerve that supplies a muscle with a message from the brain
What is the action of the orbicularis oculi?
Eye closure
Innervation: facial nerve (CN VII)
What action does the orbicularis oris perform?
Mouth closure; closes lips, protrudes lips forward, presses lips against teeth
Innervation: facial nerve (CN VII)
What is the function of the zygomaticus major?
Pull corners of lips upward
Innervation: facial nerve (CN VII)
What is the action of the risorius?
Pulls the corners of the mouth posteriorly (grin or grimace)
Innervation: facial nerve (CN VII)
What does the occipitofrontalis do?
Raises eyebrows
Innervation: facial nerve (CN VII)
What is the action of the buccinator?
Compress cheeks
Innervation: facial nerve (CN VII)
What action does the masseter perform?
Jaw closure
Innervation: trigeminal nerve (CN V, mandibular branch)
What is the action of the temporalis?
Elevates mandible, closes jaw
Innervation: trigeminal nerve (CN V, mandibular branch)
Define lateral flexion.
Side bending of the neck; side flexion
What is neck flexion?
Action of moving chin towards the sternum
What does bilaterally mean?
Both sides
What does unilaterally refer to?
One side
What is the origin of the semispinalis capitis?
Articular processes of inferior cervical & transverse process of superior thoracic vertebrae
What is the insertion of the semispinalis capitis?
Occipital bone
What is the action of the sternocleidomastoid?
Bilateral: neck flexion; Unilateral: turns face to opposite side
Origin: sternal end of clavicle and manubrium; Innervation: accessory nerve (CN XI)
What is the action of the splenius capitis?
Bilateral extend head; Unilateral laterally flexes neck to same side
Origin: spinous process/ligaments of inferior cervical vertebrae; Innervation: cervical spinal nerves
What does the longissimus cervicis do?
Bilateral extend head; Unilateral laterally flexes neck to same side
Origin: transverse processes of superior thoracic vertebrae; Innervation: cervical and thoracic spinal nerves
What is the origin of longissimus thoracis?
Transverse process of all thoracic and lumbar vertebrae
What is the action of the thyrohyoid?
Elevates thyroid, depresses hyoid bone
Origin: thyroid cartilage of larynx; Innervation: hypoglossal nerve
What is the action of the scalenes?
Elevates ribs 1 & 2
Origin: transverse processes of C2-C7; Innervation: cervical spinal nerves
Define spine flexion.
Forward bending the trunk; ‘cat’ stretch
What is spine extension?
Backward bending the trunk; ‘cow’ stretch
What is the medial column of erector spinae?
Spinalis
Made up of three divisions (spinalis thoracis, spinalis cervicis, and spinalis capitis)
What is the intermediate column of erector spinae?
Longissimus
Made up of three divisions (longissimus thoracis, longissimus cervicis, longissimus capitis)
What is the lateral column of erector spinae?
Iliocostalis
Made up of three divisions (iliocostalis lumborum, iliocostalis thoracis, iliocostalis cervicis)
What is the origin of the rectus abdominis?
Pubic crest, pubic symphysis
What is the action of the external oblique?
Bilateral: flexion of the spine, compress the abdomen; Unilateral: flexes trunk to same side, rotates to opposite side
Origin: sternum, ribs (5-12); Innervation: lower intercostal, ilioinguinal nerves
What does the internal oblique do?
Compresses abdomen, depresses ribs, flexes spine
Origin: iliac crest, lumbodorsal fascia; Innervation: lower intercostal, ilioinguinal nerves
What is the action of the transverse abdominis?
Compression of abdomen
Origin: lateral inguinal ligament, inner iliac crest; Innervation: first lumbar nerve (T7-L1), iliohypogastric (T12-L1), ilioinguinal (T12-L1)
What is the origin of the diaphragm?
Cartilage of ribs 7-12, xiphoid process, lumbar vertebrae
What is the action of the internal intercostals?
Depresses ribs (forced expiration)
Origin: superior border of ribs 2-12; Innervation: intercostal nerves
What is the function of the external intercostals?
Elevates ribs (normal inspiration)
Origin: lower border of ribs 1-11; Innervation: intercostal nerves
