Borders of the Heart

The right border is formed by the right atrium (Figure III-2-I4). The left ventricle and the auricle of the left atrium form the left border. The superior border is formed by the right and left auricles plus the conus arteriosus of the right ventricle. The apex is the tip of the left ventricle. The base is opposite the apex, formed mainly by the surface where the pulmonary veins enter the heart (left atrium) and by part of the right atrium. The anterior wall is formed primarily by the right...

Collateral Nerves

In addition to the five terminal nerves, there are several collateral nerves that arise from the brachial plexus proximal to the terminal nerves (i.e., from the rami, trunks, or cords). These nerves innervate proximal limb muscles (shoulder girdle muscles). Table III-4-2 summarizes the collateral nerves. Table III-4-2. The Collateral Nerves of the Brachial Plexus Table III-4-2. The Collateral Nerves of the Brachial Plexus Middle subscapular (thoracodorsal) nerve

Extraembryonic Mesoderm And Chorion Formation

Extraembryonic mesoderm is a new layer of cells derived from the epiblast. Extraembryonic somatic mesoderm lines the cyto trophoblast, forms the connecting stalk, and covers the amnion. Extraembryonic visceral mesoderm covers the yolk sac. The connecting stalk suspends the conceptus within the chorionic cavity. The wall of the chorionic cavity is called the chorion, which consists of extraembryonic somatic mesoderm, cytotro-phoblast, and syncytiotrophoblast. In the second week, implantation is...

Lymph Node

The lymph node is associated with afferent and efferent lymphatic vessels. It is surrounded by a capsule, has trabeculae, and can be divided into outer cortical, inner cortical (paracortical), and medullary regions (Figure 1-4-2) The outer cortex contains most of the nodules and germinal centers. It is populated by most of the B lymphocytes. The inner cortex is populated by T lymphocytes. The thymus contains trabecule and has a cortical and medullary region. Epithelial reticular cells and...

Brown Squard syndrome

Hemisection of the cord results in a lesion of each of the three main neural systems the principal upper motoneuron pathway of the corticospinal tract, one or both dorsal columns, and the spinothalamic tract. The hallmark of a lesion to these three long tracts is that the patient presents with two ipsilateral signs and one contralateral sign. Lesion of the corticospinal tract results in an ipsilateral spastic paresis below the level of the injury. Lesion to the fasciculus gracilis or cuneatus...

Anterior Triangle

The anterior triangle is bounded by the anterior border of the sternocleidomastoid muscle, the anterior midline, and the body of the mandible (Figure 10-6-1). Subdivisions of the anterior triangle contain the strap muscles, the submandibular gland, the common carotid, internal carotid and external carotid arteries, and parts of cranial nerves X and XII. The strap muscles consist of a series of five pairs of muscles which have attachments to bony or cartilaginous structures adjacent to the...

Neuroscience

Prevertebral Ganglia

Reduced levels of alpha-feto protein are seen in mothers of fetuses with Down syndrome. Failure to close results in ancephaly causing polyhydraminos and increased alpha-feto protein Failure to close results in spina bifida alpha-feto protein Figure IV-1-1. Third Week Neurulation Table IV-1-1. Germ Layer Derivatives Table IV-1-1. Germ Layer Derivatives Lens of eye Anterior pituitary Parotid gland Tympanic cavity Auditory tube GI tract Neuroectoderm Neural tube Central nervous system Retina S>...

Medical

Medial View Rights Eyeball

Skeletal Muscles Innervated by Cranial Nerves (continued) Table III-6-4. Skeletal Muscles Innervated by Cranial Nerves (continued) Copyright 2000 Gold Standard Multimedia, Inc. Alt rights reserved. Copyright 2000 Gold Standard Multimedia, Inc. Alt rights reserved. Figure III-6-18. Head and Neck Posteroanterior View of Skull Figure NI-6-19. Head and Neck Lateral Skull Figure 111-6-22. Head and Neck CT, Skull Figure 111-6-22. Head and Neck CT, Skull Medial Optic Lateral Rectus...

Answers and Explanations

Hemiballismus Treatment Exercises

The mesencephalon (midbrain) contains the substantia nigra, which is the location of the degenerating dopaminergic neurons in Parkinson disease. 2. Answer E. In Parkinson disease, loss of dopamine enhances the effects of the indirect basal ganglia pathway, which is also driven by cholinergic neurons intrinsic to the striatum. A muscarinic blocker will reduce the stimulatory effects of ACh on the indirect pathway. 3. Answer D. The patient suffers from hemiballismus, which affects the...

The Brain Stem

The brain stem is divisible into three continuous parts the midbrain, the pons, and the medulla. The midbrain is most rostral and begins just below the diencephalon. The pons is in the middle and is overlain by the cerebellum. The medulla is caudal to the pons and is continuous with the spinal cord. The brain stem is the home of the origins or sites of termination of fibers in 9 of the 12 cranial nerves (CN). Two cranial nerves, the oculomotor and trochlear (CN III and IV), arise from the...

Venous Drainage of the Brain and the Dural Venous Sinuses Dural venous sinuses

Dural Venous Sinus Anatomy

The dural venous sinuses receive cerebral veins from the brain and drain the venous blood mainly into the internal jugular vein (Figures III-6-12 and III-6-13). The superior sagittal sinus is located in the midsagittal plane along the superior aspect of the falx cerebri. It drains into the confluence of the sinuses. Arachnoid granulations protrude through the walls of the superior sagittal sinus. The arachnoid granulations transmit CSJ from the subarachnoid space into the venous circulation....

Review Questions

Vitelline Duct Adults

Which structure supplied by a branch of the celiac artery is not derived from foregut endoderm 2. An infant presents with an omphalocele at birth. Which of the following applies to this condition (A) It is also seen in patients with aganglionic megacolon. (B) It results from a failure of resorption of the vitelline duct. (C) It results from herniation at the site of regression of the right umbilical vein. (D) It is caused by failure of recanalization of the midgut part of the duodenum. (E) It...

Control of Horizontal Gaze

Control Horizontal Gaze

Horizontal gaze is controlled by two interconnected gaze centers. One control center is in the frontal lobe, the frontal eye field (Brodmann area 8). This area acts as a center for contralateral horizontal gaze. In the pons is a second gaze center, known as the pontine gaze center or the PPRF, the paramedial pontine reticular formation. This is a center for ipsilateral horizontal gaze. When activated by neurons in the frontal eye field, the pontine gaze center neurons send axons to synapse with...

Dopamine and cholinergic effects

Lateral Ventricle Anterior Horn

In addition to the GABA neurons, two other sources of chemically significant neurons enhance the effects of the direct or indirect pathways. Dopaminergic neurons in the substantia nigra in the midbrain project to the striatum. The effect of dopamine excites or drives the direct pathway, increasing cortical excitation. Dopamine excites the direct pathway through D( receptors and inhibits the indirect pathway through D2 receptors. Cholinergic neurons found within the striatum have the opposite...

Parasympathetic System

Parasympathetic Craniosacral outflow Figure 111-1-9 The vertebral column is composed of a series of cervical, thoracic, lumbar, sacral, and coccygeal vertebrae connected by intervertebral disks and ligaments. The disks consist of an outer core erf fibrocartilage, the annulus fibrosus, and an inner part the nucleus pulposus, which developed from the notochord, Herniation of the nucleus pulposus is usually posterolateral where it can compress a spinal nerve at the intervertebral foramen. The...

Dorsal columnmedial lemniscal system

The dorsal column-medial lemniscal system carries sensory information for discriminative touch, joint position kinesthetic or conscious proprioceptive sense, vibratory, and pressure sensations from the trunk and limbs Figures IV-4-7 and IV-4-8 . The primary afferent neurons in this system have their cell bodies in the dorsal root ganglia, enter the cord via class II or A-beta dorsal root fibers, and then coalesce in the fasciculus gracilis or fasciculus cuneatus in the dorsal funiculus of the...

Temporal Lobe Primary auditory cortex

On its superior and lateral aspect, the temporal lobe contains the primary auditory cortex. Auditory cortex areas 41 and 42 is located on the two transverse gyri of Heschl, which cross the superior temporal lobe deep within the lateral sulcus. Much of the remaining superior temporal gyrus is occupied by area 22 auditory association cortex , which receives a considerable projection from both areas 41 and 42 and projects widely to both parietal and occipital cortices. Patients with unilateral...

Syringomyelia

Syringomyelia is a disease characterized by progressive cavitation of the central canal, usually in the cervical spinal cord but may involve other cord regions or the medulla. Early in the disease, there is a bilateral loss of pain and temperature sensation in the hands and forearms as a result of the destruction of spinothalamic fibers crossing in the anterior white commissure. When the cavitation expands, lower motoneurons in the ventral horns are compressed, resulting in bilateral flaccid...

Collateral Nerves of Lumbosacral Plexus

The collateral nerves of the lumbosacral plexus to the lower limb are summarized in Table III-5-2. Table III-5-2. Collateral Nerves of Lumbosacral Plexus Table III-5-2. Collateral Nerves of Lumbosacral Plexus Gluteus medius, gluteus 1 minimus, tensor fasciae latae Nerve to superior gemellus and obturator internus Superior gemellus, obturator internus Nerve to inferior gemellus and quadratus femoris Inferior gemellus, quadratus femoris SI through S2 posterior divisions and S2 through S3 anterior...

Descending Hypothalamic Fibers

The descending hypothalamic fibers arise in the hypothalamus and course without crossing through the brain stem to terminate on preganglionic sympathetic neurons in the spinal cord. Lesions of this pathway produce an jpsilateral Horner syndrome. Horner syndrome consists of miosis pupillary constriction , ptosis drooping eyelid , and anhidrosis lack of sweating in the face ipsOateral to the side of the lesion. Descending hypothalamic fibers course with the spinothalamic fibers in the lateral...