A&P 1 Ch 10 The Muscular System

organization of muscles

• 600 human skeletal muscles

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.

epimysium

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

perimysium

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

endomysium

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

deep fascia

found between adjacent muscles

superficial fascia (hypodermis)

adipose found between skin and muscles 

function of muscles

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

direct (fleshy) muscle attachment to bone

epimysium is continuous with periosteum

• ex: intercostal muscles 

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 

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

prime mover in elbow flexion

Brachialis.

synergist in elbow flexion

biceps brachii

antagonist in elbow flexion

triceps brachii

fixator in elbow flexion

rhomboids are the muscle that holds the scapula firmly in place

intrinsic muscles

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

extrinsic muscles

Muscles found outside a specific region.

cranial nerves arise from the-—and exit the skull through—-

brain and 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

Spinal nerves arise from—-exit from vertebral column through—-

The spinal cord and the intervertebral foramina.

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 lip

galea aponeurotica (facial expression muscles)

dense fibrous tissue between occipital and frontalis

muscules 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)

muscles acting on the head and neck

• flexors: sternocleidomastoid, scalene

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

diaphragm

The muscular dome that connects the thoracic and abdominal cavities.

3 layers of muscle between the ribs

1. external intercostals (11 pairs)

2. internal intercostals (11 pairs)

3. innermost intercostals (vary in #)

muscles of the abdomen

• 4 pairs of sheet like muscles

  • external oblique

  • internal oblique

  • transverse abdominis

  • rectus abdominis

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

superficial muscles of the back

trapezius and latissimus dorsi

erector spinae group

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

semispinalis group

it goes from vertebrae to vertebrae and extends the neck.

multifidis

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

quadratus lumborum

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

levator ani

A floor muscle of the pelvic cavity

perineum

• inferior to the levator ani

• 4 body landmarks

  • anterior (urogenital triangle)

  • posterior (anal triangle)