The
Muscular System
Chapter
11
Structure of Skeletal Muscles
Skeletal muscles generally span a joint.
Origin = fixed point of attachment
Insertion = movable portion
Muscle groups: Muscles generally act in groups.
A muscle can have any or all of the above functions.
Naming of Muscles: Examples
Shape: Rhomboid, Trapezius (trapezoid), Deltoid (D; as in greek letter "delta")
Relative Size: Gluteus maximus
Location: Gluteus maximus, Biceps brachii,
Attachment sites: Sternocleidomastoid (attachments at sternum, clavicle and mastoid process)
Heads of Origin: Biceps, Triceps, Quadriceps ("ceps" = head)
Action: Levator scapulae, flexor digitorum,
Direction of fibers or fascicles: external oblique, rectus abdominis (rectus = straight)
Biomechanics
Muscle, bone and joint can be compared to lever system of basic physics. Joint is the fulcrum, muscle provides effort or force, and bone is the resistance/load or weight.
First Class: Mechanical advantage/disadvantage depending on positions.
Second Class: Existence of a true second class lever system in the human body is controversal. Works with ___________________ advantage.
Third Class: Works at ______________ disadvantage, but gains ______________.
Muscles of Facial Expression Innervated by _____________________nerve.
Epicranius
Orbicularis Oculi: Associated with _________________________.
Levator Labii Superioris: Associated with _________________________.
Orbicularis Oris: The _________________________ muscle.
Buccinator: "_____________________ muscle;" aids chewing. (Hint)
Corrugator: Draws _______________________ together as in ____________________.
Zygomaticus: The ________________________ muscle. Major & Minor
Platysma: Tenses the _____________________ of the neck. Assists _________________.
Clinical Conditions Related to Facial Muscles
Bells Palsy Facial nerve paralysis, unilateral or bilateral. So, all muscles and glands served by facial nerve can be affected. Unknown causes and onset can be sudden.
Moebius Syndrome Congenital defect -- facial nerve doesn't develop (may involve other cranial nerves). Gracilis muscle transplants have restored the smiles of many children with this syndrome.
Movement of Mandible "Muscles of ___________________" Innervated by __________ nerve.
Masseter: ___________________ of mandible.
Temporalis: _________________ of mandible.
Pterygoid (Medial & Lateral): allows ___________________________.
Digastric: ________________________ of the mandible.
Movement of Tongue (Extrinsic Muscles)
Innervated by ______________________ nerve.
Genioglossus: __________________the tongue.
Styloglossus: ___________________the tongue.
Movement of Head and Neck
Sternocleidomastoid: _____________________ and ___________________ neck/head.
Semispinalis capitis: _____________________ neck.
Muscles Moving the Shoulder
Pectoralis Minor: deep to pectoralis major. Acts on ________________.
Serratus Anterior: _______________________ of scapula. "Boxer’s muscle."
Trapezius: 3 regions. ___________________, _________________, and
_________________________. Can retract (adduct), elevate, and depress scapula.
Levator scapulae: It does what its name states!
Rhomboideus: ________________ scapula. Fixator. Major & Minor
Muscles Moving Upper Arm
Deltoid: Prime mover of arm _____________________.
Supraspinatus: (a ________________ ___________________ muscle)
Latissimus Dorsi: Prime mover of arm __________________ and ________________.
Pectoralis Major: Prime mover of arm _________________.
Coracobrachialis: ________________ of arm. Innervated by musculocutaneous nerve,
just like ________________________
Teres Major: "the __________ ______________ little helper"
Muscles Moving the Forearm:
Biceps brachii flexes and supinates forearm.
Brachialis: flexor of forearm.
Triceps brachii: Major extensor of forearm
Supination & Pronation of Forearm/Hand:
Supinator
Pronator Teres
Flexion & Extension of the Wrist, Hand & Fingers:
Wrist:
Flexor & Extensor carpi
(radialis and ulnaris)
Fingers:
Flexor & Extensor Digitorum
Flexor & Extensor Pollicis
The median nerve innervates primarily ____________________; the radial nerve
innervates primarily ________________________.
Muscles of the Abdominal Wall
External Oblique:
Internal Oblique:
Transversus Abdominis:
Sides separated by _____________ ______________________.
Divisions are called _________________ _________________
Muscles of the Vertebral Column
Quadratus Lumborum: ___________________ vertebral column.
Erector Spinae: _______________________ vertebral column.
(We will not cover muscles of the pelvic outlet, respiratory muscles, muscles of the hands and feet)
Muscles moving the Thigh, Leg, & Foot
Hip/Thigh Flexors:
Iliopsoas
Iliacus: Prime ___________________ of hip. Like other muscles of anterior hip
and thigh, it is innervated by the ______________________ nerve.
Psoas Major: Action as above. Also important in ______________________.
Sartorius: "_________________ muscle." __________________ muscle of body. Flexes
both the _____________________ and ________________________ (weakly).
Tensor fasciae latae: Helps stabilize ____________________________.
Thigh Extensors & Abductors:
Gluteus Maximus: Major ___________________ of thigh.
Gluteus Medius: Major ____________________ of thigh. Important in ________________.
Gluteus Minimus: same as G. medius.
Thigh Adductors:
Adductor Longus, Brevis & Magnus
Gracilis
Leg Extensors:
Quadriceps femoris: innervated by ______________________ nerve.
Rectus Femoris: _________________ thigh and __________________ knee.
Vastus Lateralis ___________________ the knee
Vastus Medialis ___________________ the knee
Vastus Intermedius ___________________ the knee
Leg Flexors:
Hamstring Group: common origin on the _____________ ________________.
Innervated by the _________________ nerve.
All ______________ thigh and_______________ the knee.
Biceps femoris: _____________ position. _____________ rotates.
long head
short head
Semitendinosus: ______________ position. ___________ rotates
Semimembranosus: ____________ position. __________ rotates.
Plantar Flexors
Triceps surae
Gastronemius: _______ heads. Prime __________. Also _______the knee.
Soleus: Prime _________. Common insertion at ______________.
Peroneus (longus & brevis): ____________ and _______________.
Flexor digitorum/hallucis longus: also ________________ toes.
Dorsiflexors:
Tibialis anterior: Prime Mover of __________________.
Extensor digitorum/hallucis longus: also _____________ toes.
Familiarize
yourself with the general origins, insertions, actions and innervations of the
following muscles.
Practice sketching on skeletal diagrams provided in lecture note packet!
Muscles of Facial Expression
Epicranius
Movement of Mandible
Movement of Head and Neck
Movement of Tongue (Extrinsic Muscles)
Muscles Moving the Shoulder
Muscles Moving Upper Arm
Muscles Moving the Forearm:
Supination & Pronation of Forearm/Hand:
Flexion & Extension of the Wrist, Hand & Fingers:
Wrist:
Flexor & Extensor carpi
Extensor carpi radialis longus
Fingers:
Muscles of the Abdominal Wall
Muscles of the Vertebral Column
(We will not cover muscles of the pelvic outlet, respiratory muscles, muscles of the hands and feet)
Muscles moving the Thigh, Leg, & Foot
Hip/Thigh Flexors:
Thigh Extensors & Abductors:
Thigh Adductors:
Leg Extensors:
Quadriceps femoris:
Leg Flexors:
Hamstring Group:
long head
short head
Plantar Flexors
Dorsiflexors:
Shinsplints: Medial and Anterior. Overview.
Flexor digitorum superficialis
Electronic textbook of hand surgery Lots of Info on Hand Anatomy
Inner Body Site
Other Muscle Sites
Lab Links:
Cat Muscles: McGraw Hill site, under development, but has great cat muscle atlas with human comparisons. Good virtual practice site for lab practical!
Cat Anatomy Tutorial at Kenyon College Check out the cat muscles. Nice site!