A&P 1 Ch 10 The Muscular System

organization of muscles

• 600 human skeletal muscles

• general structural and functional topics

  • muscle shape and function

  • connective tissues of muscle

  • coordinated actions of muscle groups

  • intrinsic and extrinsic muscles

  • muscle innervation

What are the main regions where muscles are organized?

The head and neck, trunk, shoulder and upper limb, hip and lower limb.

What are the three connective tissues associated with muscles?

Epimysium, perimysium, and endomysium.

What is the function of the epimysium?

It covers the whole muscle belly and blends into connective tissue between muscles.

What does the perimysium surround?

It is slightly thicker layer of connective tissue that surrounds bundles of cells called fascicles.

What is the role of the endomysium?

It is a thin areolar tissue around each muscle cell, allowing room for capillaries and nerve fibers.

what is the location of deep fascia?

found between adjacent muscles

what is the location of superficial fascia (hypodermis)

adipose between skin and muscles 

What is the function of muscles in the human body?

1. Movement of body parts and organ contents

2. maintaining posture and preventing movement

3. communication-speech, expression, and writing 

4. controlling openings and passageways

5.  heat production

fusiform skeletal muscle shape

ex: biceps brachii

parallel skeletal muscle shape

ex: rectus abdominis

triangular skeletal muscle shape

ex: pectoralis major

unipennate skeletal muscle shape

ex: palmar interosseous

bipennate skeletal muscle shape

ex: rectus fermoris

multipennate skeletal muscle shape

ex: deltoid

circular skeletal muscle shape

ex: orbicularis oculi

What is direct (fleshy) muscle attachment to bone?

epimysium is continuous with periosteum

• ex: intercostal muscles 

What is indirect attachment to bone?

epimysium continues as tendon or aponeurosis that merges into periosteum as perforating fibers

• ex: biceps brachii or abdominal msucle

other muscle attachments

• attachment to dermis

• stress will tear the tendon before pulling the tendon loose from either muscle or bone

Parts of skeletal muscle 

• belly

  • thicker, middle region of muscle

• origin

  • attachment to stationary end of muscle

• insertion

  • attachment to mobile end of muscle 

What are the four types of muscle actions?

1. Prime mover (agonist): produces most of the force

2. Synergist: aids the prime mover

   1. stabilizes the nearby joint

   2. modifies the direction of movement

3. antagonist: opposes the prime mover

   1. prevents excessive movement and injury

4. fixator: prevents the movement of the bone

What is the prime mover in elbow flexion?

Brachialis.

what is the synergist in elbow flexion?

biceps brachii

what is the antagonist in elbow flexion?

triceps brachii

what is the fixator in elbow flexion?

rhomboids are the muscle that holds the scapula firmly in place

What are intrinsic muscles?

Muscles contained within a specific region, such as the foot or hand.

What are extrinsic muscles?

Muscles found outside a specific region.

What are cranial nerves responsible for in muscle innervation?

They arise from the brain and exit the skull through foramina.

what is the first cranial nerve?

olfactory nerve

what is the second cranial nerve?

optic nerve

what is the third cranial nerve?

oculomotor nerve

what is the fourth cranial nerve?

trochlear nerve

what is the fifth cranial nerve?

trigeminal nerve 

what is the sixth cranial nerve?

abducens nerve

what is the seventh cranial nerve?

facial nerve

what is the eighth cranial nerve?

vestibulocochlear nerve

what is the ninth cranial nerve?

glossopharyngeal nerve

what is the tenth cranial nerve?

vagus nerve

what is the eleventh cranial nerve?

accessory nerve

what is the twelfth cranial nerve?

hypoglossal nerve

What do spinal nerves arise and exit from for in muscle innervation?

spinal nerves arise from the spinal cord and exit the vertebral column through intervertebral foramina.

What are the muscles of facial expression?

• small muscles that insert into the dermis

• innervated by facial nerve (CN VII)

• paralysis causes face to sag

• found in scalp, forehead, around the eyes, nose and mouth, and in the neck

orbicularis oculi (facial expression muscles)

sphincter of the eyelid that closes the eye

levator palpebrae superioris (facial expression muscles)

opens the eye

orbicularis oris (facial expression muscles)

four muscles that encircle the mouth

mentalis (facial expression muscles)

elevates and protrudes lower

galea aponeaurotica (facial expression muscles)

dense fibrous tissue between occipital and frontalis

what is the musculature of the tongue?

• intrinsic muscles=vertical, transverse and longitudinal fibers

• extrinsic muscles connect tongue to hyoid, styloid process, palate and inside chin

• tongue shifts food onto teeth and pushes it into pharynx

What muscles are involved in chewing?

4 major muscles

• arise from the skull and insert on the mandible

• Temporalis and masseter elevate the mandible

• Medial and lateral pterygoids help elevate, but produce lateral swinging of the jaw

suprahyoid muscles

• digastric (two bellies), stylohyoid, and mylohyoid: open mouth

• geniohyoid: widens the pharynx during swallowing

infrahyoid muscles 

• omohyoid: arises from the shoulder, under the sternocleidomastoid, then up to hyoid

• thyrohyoid: helps prevent choking, elevates the larynx during swallowing (can feel Adams apple)

what are the muscles acting on the head and neck?

• flexors: sternocleidomastoid, scalene

• extensors: trapezius, splenius (capitis & cervicis’), semispinalis

What is the diaphragm's role in respiration?

The muscular dome that connects the thoracic and abdominal cavities.

What are the 3 layers of muscle between the ribs?

1. external intercostals (11 pairs)

2. internal intercostals (11 pairs)

3. innermost intercostals (vary in #)

what are the muscles of the abdomen?

• 4 pairs of sheet like muscles

  • external oblique

  • internal oblique

  • transverse abdominis

  • rectus abdominis

What are the functions of the abdominal muscles?

1. Support viscera

2. stabilize the vertebral column

3. assist in respiration, urination, defecation, and childbirth.

more depth of muscles of the abdomen

• external oblique

  • superficial, downward, anteriorly

• internal oblique

  • anteriorly, upwards

• transverse abdominal

  • horizontal fiber orientation, deepest layer

• rectus abdominis

  • vertical, straplike

  • tendinous intersections, rectus sheath, linea alba

aponeuroses

tendons of oblique muscles

linea alba

between rectus msucles

linea semilunaris

rectus sheath meets aponeuroses

linguinal ligament

spine of illium to pubis

what are the superficial muscles of the back?

trapezius and latissimus dorsi

What is the function of the erector spinae group?

It is 3 columns of muscle that go from sacrum to ribs that extends the vertebral column.

What is the function of the semispinalis group?

it goes from vertebrae to vertebrae and extends the neck.

What is the function of the multifidis?

it goes from vertebrae to vertebrae and rotates the vertebral column.

What is the role of the quadratus lumborum?

It goes from the ilium to the 12th rib and assists in the lateral flexion of the vertebral column.

What is the levator ani?

A floor muscle of the pelvic cavity/

what is the perineum?

• inferior to the levator ani

• 4 body landmarks

  • anterior (urogenital triangle)

  • posterior (anal triangle)